View Full Version : Pre-Amp bake-off - What Happened...
Yesterday Saturday 28th June Jason(Figlet), David (Snapper), Marco (Marco) and I assembled together at Jason's luxury home (well, compared to my hut it is) to have a bit of a shootout of pre-amplifiers.
There were 4 pre-amplifiers present, representing 3 different ways of doing it:
Heavily modified Croft active using valves/tubes.
Stereo Coffee LDR passive
Tortuga audio LDR passive
NVA P90 SA stepped attenuator passive
Power amps was initially an NVA A80, later we swapped to EAR 509 monoblocks. Levels were matched using a noise generator and professional sound meter and microphone (Dave DSJR please take note :) ). We each contributed test tracks to be used including John Martyn, Steely Dan, Talk Talk, Ella Fitzgerald & Louis Armstrong and Hendrix. We played the same tracks with the different pre-amps in circuit and shared our conclusions as we went along.
Jason was an excellent host, we had gourmet burgers and there was a selection of beer, real coffee and posh cookies. I felt a bit guilty since all I offered him at my place was a cup of green tea and a Rocky biscuit, but in my defence I don't entertain much...
Loudspeakers were Audiovector floorstanders, I don't know the model but they are a fairly compact 2 and a half way with a downward firing port and a ribbon tweeter. A very refined sounding speaker with very natural and open mids and a sweet top end. Jason's room is quite small so this was very much a near field set up. This gave me some issues initially since at home I listen in the far-field (about 20' from the speakers) and use speakers with a very different presentation to the Audiovectors. I did acclimatise after an hour or two, though.
So on to the results. The three passives were compared first. There was no real consensus amongst the four of us as to which was preferable. For example With 'Voodo Chile' from Electric Landlady 2 preferred the NVA stepped attenuator, the others went for the Stereo Coffee. Differences were pretty small, but noticeable enough for preferences to be formed but at no-point did anyone think the reproduction to be anything other than very high quality. All three passive pre-amps gave a very good sound.
Swapping in the active Croft valve pre we did arrive at a consensus which was that we all preferred the presentation of the Croft to that of the three passive pre-amps. For me it was noticeable that the double bass on the Ella/Lois track (I forget what the tune was called) had a bit more presence, was a bit fuller sounding. With Steely Dan (Negative Girl from Two Against Nature) the 'supple' bass guitar line had a bit more weight and a bit more of a bite to the leading edges. Subjectively, it timed better. This track was my pick since I like to use high quality, modern digital studio recordings when testing as I think this gives the system the best chance to show what it can do. Marco remarked that with the Croft compared to the passives 'the twinkly bits were more twinkly'. No bollocks review speak there and I consequently understood and agreed with him.
So we swapped out the transistor NVA power amp and substituted the EAR 509 tube monoblocks. Well Jason did, I went outside for a smoke...
With the Croft/EAR combo now playing it soon became obvious that this was 'too much of a good thing' and I think we all agreed on that. Very lush with a lot of warm bass although I thought that we had lost some impact and a little bass depth with the EAR amps. Again I think that this was agreed on by all. Swapping the passive pre-amps back in confirmed this and the sound became a lot more neutral and tightened up a bit. With the EAR power amps the verdict was that of all four pre-amps we all preferred the sound with the Stereo Coffee LDR in circuit. Again the differences were not great and all 4 pre-amps performed very well.
A few caveats. The Tortuga LDR was a bit lashed up compared to the Stereo Coffee LDR (which is the one Jason has built for me and which has been lavished with attention to detail). Both pre-amps worked but we did wonder if this was a factor as between the two LDRs the Stereo Coffee tended to be preferred. When we tested all three of the passives at my place several weeks previously the Tortuga was judged to be slightly better, but that was in a very different room with very different speakers so as usual system and room synergy makes trying to come to any 'global conclusions' a fool's errand. Finally the heavily modded Croft pre cost around £3K and was therefore the most expensive of the four by several orders of magnitude. I suspect that just the NOS valves it uses cost more than my entire system ;)
In all a very entertaining, enjoyable and educational (not in a bad way but in a hi-fi way) day. Excellent company and hospitality, many thanks to Jason for having us round. Hopefully the other lads will give their thoughts and correct me if my memory has played me false with any of the above.
brian2957
29-06-2014, 10:09
Nice write up Martin and very interesting . Thanks for taking the trouble to pass on your findings .Seems like these LDRs are worth investigating as they apparently give some much more expensive preamps a run for their money . I look forward to the impressions of the others present . Interesting reading :)
Nice write up Martin and very interesting . Thanks for taking the trouble to pass on your findings .Seems like these LDRs are worth investigating as they apparently give some much more expensive preamps a run for their money . I look forward to the impressions of the others present . Interesting reading :)
Interesting stuff martin but I am not surprised by your findings, and thats not just because I run a croft pre!:) For many years I used a passive pre and although it was good in some areas, switching to the Croft showed me what I was missing. On balance I found using the croft more satisfying all round with a fuller more dynamic richer sound.
Thanks for sharing your experience.
Ali Tait
29-06-2014, 10:38
Aye, liked what I heard at Owston, sounded great.
Interesting stuff martin but I am not surprised by your findings, and thats not just because I run a croft pre!:) For many years I used a passive pre and although it was good in some areas, switching to the Croft showed me what I was missing. On balance I found using the croft more satisfying all round with a fuller more dynamic richer sound.
Thanks for sharing your experience.
James it was a good lesson to me that once the sound quality has got past a certain level it does all come down to personal preferences rather than a league table of better to worse. And a reminder of what a huge gap there can be between the way different loudspeakers present the music.
mr sneff
29-06-2014, 11:31
Interesting write-up, Martin.
James it was a good lesson to me that once the sound quality has got past a certain level it does all come down to personal preferences rather than a league table of better to worse. And a reminder of what a huge gap there can be between the way different loudspeakers present the music.
I always find it difficult to evaluate stuff with loudspeakers other than my own as they have such a huge influence on the sound. You can swap stuff left right and centre using your own loudspeakers and even small differences can be perceived but using unfamiliar speakers makes the whole evaluation process more difficult.
On my current experience of a 'baby' NVA amp, and first hand using the 509's, the only thing I can comment on is the slight and deliberate 'lushness' of the 509's, as many E.A.R. products exhibit this (yet Tim's MF designs more often don't!). An observation, not a criticism of any kind.
I don't know how much better Marco's custom-Croft is to my own 4PP model (lightly tweaked under Glenn's instruction), but there is 'very slight' gentle/refined touch with mine that 'straight through' from source to preamp lacks in comparison (NOT scientifically compared though, just an impression :))
Well done for trying to keep it as fair as possible :respect:
The Black Adder
29-06-2014, 13:15
Great write up, Martin.
Very interesting indeed. All amps (pre and power) are very good amps, the pre's all have a decent pedigree too. Having owned NVA kit they are no slouches at kicking a good groove that's for certain.
Regarding the Croft, this is *exactly* what I find with mine. Realism, weight with no artificial emphasis throughout the spectrum and mine is't as tuned up as Marco's... Yet..lol. I've now owned a few of the Croft kit and I do much prefer the larger octal valves than the smaller 82/83 types. They just have more air and feeling.
thank's for sharing your thoughts & impressions.. very interesting to follow.
The old Octal equipped Crofts from the early 90's were anything BUT honest and neutral (standard Series 4 and Mega Micro) though! Maybe he changed the circuit in later models.
On my current experience of a 'baby' NVA amp, and first hand using the 509's, the only thing I can comment on is the slight and deliberate 'lushness' of the 509's, as many E.A.R. products exhibit this (yet Tim's MF designs more often don't!). An observation, not a criticism of any kind.
I don't know how much better Marco's custom-Croft is to my own 4PP model (lightly tweaked under Glenn's instruction), but there is 'very slight' gentle/refined touch with mine that 'straight through' from source to preamp lacks in comparison (NOT scientifically compared though, just an impression :))
Well done for trying to keep it as fair as possible :respect:
I very much like a forensic presentation so for me the EAR amps although impressive did offer their own 'sound' and I prefer the amplification to be as 'invisible' as possible. Although I used a Croft pre (the micro-basic) for several years it was not a 'neutral' pre amp. Marco's Croft pre sounded a lot less 'valvey' (i.e warm and lush) compared to the micro-basic. You would not be able to tell that it is a valve pre from the sound alone, much like the Firebottle valve MM stage that I have. None of the combinations we tried were anything less than top notch in terms of the quality and none sounded in any way 'unrefined', particularly in the mid and top. For me it was in the bass response that the subtle differences were easier to spot.
Interesting findings, having too tried an NVA P90SA, a fine preamp, I found my active LFD pre gave more drive and fullness, a richer sound, compared to using a passive that didn't manage to "flesh" the sound out as much. This is using power amps optimised for passive preamps.
Haselsh1
29-06-2014, 15:16
Back in 2009 I was using a Creek passive, the one with a remote control, I then changed to a Croft Micro 25 Basic and the difference was truly astonishing. Bucket loads of detail that had been so clearly missing, dynamics, clarity and power all suddenly came from nowhere. I will say right now that in terms of 'fit and finish' the Creek bettered the Croft and with a single remote volume control was miles ahead of the Croft but in terms of musical content and especially detail, the Croft was well and truly worth the miserly asking price.
wee tee cee
29-06-2014, 16:21
Great write up Martin. The LDR passive looks like an interesting route to take....
Don't get me all excited, big boy! :bum:
Marco.
So, are you still excited Marco? The results seem to indicate that the LDR may be a better volume control but less positive with regard to passive pre-amps (at least in this instance).
Interesting and slightly opposing views on the Micro Basic here methinks :) It's certainly a touch 'uncouth' in comparison with a 'proper' Micro 25, which itself gets a little more 'flesh' on its bones when in 'R' form - and so on.
I still love my truly geriatric Amcron/Crown stuff. The pre in particular, now it's had a little subtle attention, is amazingly transparent and I do use the controls on occasion - this in comparison with the CD player going straight into the power amps (I made some cables especially for the job) since the latter have gain controls on them. The almost geriatric Croft I have (all new valves but nothing fancy), has something about it which means I'll NEVER sell it on and in fairness, it's got better and better with the cheapo tweaks Glenn got me to do to it. Horses for courses I know.
I truly believe that out there in Hifi land, active preamps were the scourge of the earth. All those slushy valve jobs from the US (op amps are still a dirty word in audiofoo land to this day) and rather veiled discrete ss jobs from Quad, Naim and others in the 70's and early 80's - I haven't forgotten... Today though, I firmly believe things have improved - and that Croft RIAA measured via the variable line outputs is fine! So there!
Nobody has still properly explained the pros and cons of domestic gear impedance matching and how important or not it is. Some power amps are only 10k where vintage ones can be 50k or loads higher (good for passive controls if the gain is enough). The 10k power amps may have an issue possibly I believe, but don't really know for sure (I still believe that if we can hear it consistently there's a genuine objectively measurable reason why!).
Dave -There is only likely to be a problem if the ouput impedance of the source (the preamp) is high and the capacitance of the interconnect, used between the pre and power amp, is also high. But even this is unlikely: if we assume the output impedance is as high as 5KOhm, an interconnecting cable, having a typical capacitance of 100pF/m, would need to be 16m long before the response was -3dB down at 20kHz.
If the input impedance of the power amp is as low as 10KOhm, then with 16m of cable the -3dB point is lowered to 17.3kHz, so the maximum cable length would need to be reduced to 13.5m to move the roll-off point to just above 20kHz.
This is an extreme and pessimistic worse-case. Most preamps will have a much lower output impedance (as low as 10 Ohm for some SS designs) and the length of the interconnects are usually ~1m or less in length.
Hi folks,
Sorry for the delay in posting. With friends and family visiting and the football being on, time has been limited!
Anyway, I have to concur with Martin in that Jason's hospitality was top notch, and my thanks go to him for hosting what was a truly excellent day. Snapper and I arrived there around 12.30pm and didn't leave until nearly midnight! However, the day just flew by, as we were all having such a good time chatting and listening to tunes.
Never mind about the 'gourmet burgers' (which were excellent) - it was the home-made Greek salad, and the black olives from his parents place in Greece, which stole the show... Simply superb! :eek:
Ok, so onto my impressions of what I heard... First of all I'd like to say that, overall, Jason has an excellent sounding system; one that he's obviously taken great care in assembling, and also which offers genuine high-resolution, allowing one to both accurately assess and analyse the sonic results of changes made to the system whilst, most importantly, enjoying the music!
So on to the results. The three passives were compared first. There was no real consensus amongst the four of us as to which was preferable. For example With 'Voodo Chile' from Electric Landlady 2 preferred the NVA stepped attenuator, the others went for the Stereo Coffee. Differences were pretty small, but noticeable enough for preferences to be formed but at no-point did anyone think the reproduction to be anything other than very high quality. All three passive pre-amps gave a very good sound.
I would agree that all three passive preamps produced an excellent sound - certainly there were none that I couldn't listen to and enjoy with all genres of music. However, as you say, with 'Voodoo Chile' (which is actually from Electric Ladyland, although 'Electric Landlady' evokes a somewhat more amusing theme :eyebrows:), two of us [you and me] preferred the musical presentation of the NVA.
To my ears, used in conjunction with the A80 power amp, the P90SA continually produced a very satisfying, detailed and musically coherent rendition, not just of the aforementioned Hendrix track, but anything else we chucked at it. If I were to offer any criticism of the P90SA, in comparison with the LDR passives (when the A80 power amp remained in the equation), it would be that it sounded a little soft and slightly rolled-off in the upper-frequencies, and also in terms of soundstage width, height and depth. Music played through the NVA lacked the wide-open expansiveness of the LDRs, and so in comparison, it produced a somewhat 'letter box' effect with instruments and vocals.
However, I must stress that the above effect was subtle and could well be ameliorated, or even removed completely, if the NVA were assessed within the context of a different system and/or cables. What I did like about the P90SA, which I heard throughout the course of the day, whenever it was being used, was an inherent 'relaxing musicality', allowing one to 'listen into' the mix, arguably making the assembled LDR-based passives sound 'super clean' but a little etched and 'hi-fi' in their handling of music. In my experience, it's a hard balancing act to get right, trading what many would perceive as 'crystalline clarity' for a sound which initially may not seem as 'impressive' or 'accurate', but ultimately to some listeners, in the long term, proves to be more musically satisfying.
I would guess that, in that respect, and also depending on how one's system is 'voiced', LDRs could divide opinion. Of the two, the Stereo Coffee, to my ears, consistently produced the more musical results. The Tortuga was to all intents and purposes excellent, but had the tendency to sound a little clinical and musically un-involving, in comparison with the SC, perhaps due to the fact that it had literally just been 'thrown together' by Jason, using rather cheap wiring, etc, simply to allow it to be used for the bake-off. Whereas, the SC had been 'lovingly constructed' with all the best bits used to build it, and completed as a finished product for Martin to buy. I strongly suspect that this was a significant contributory factor as to why the Tortuga, IMO, wasn't quite at its best. Therefore, it would be interesting to hear it again once the build has been properly finished to Jason's exacting standards.
Swapping in the active Croft valve pre we did arrive at a consensus which was that we all preferred the presentation of the Croft to that of the three passive pre-amps.
Yup, that was one of the few times, throughout the course of the day, where a true consensus of opinion was reached. I won't dwell on matters here, but when the Croft was introduced into the equation, partnering the NVA A80, the sonic improvement gained overall, over all three passives present (including the P90SA), was significant and of the 'no brainer' variety. The Croft was by far the most expensive preamp there - and it showed. Consequently, the Croft/A80 combined to deliver a beguiling musical performance with all the test tracks we'd played before, while using the passive preamps, which the latter just couldn't match. 'Voodoo Chile', in particular. to my ears, sounded simply wonderful and scarily 'real'!
I have to say that I was very impressed with the A80, especially used in conjunction with the Croft. It's most certainly one of the best solid-state power amplifier designs I've heard to date, and unless what I heard in Jason's system was simply a happy accident, (excluding any weird mismatches with my Tannoys), it's a combination that I could happily live with at home. I can go into more detail here if anyone wishes.
When Jason's EAR 509 valve monoblocks entered the equation and partnered the Croft, initially playing the Talk Talk track 'Happiness is Easy' (and also with Steely Dan), I thought it sounded really good, but upon closer inspection and more prolonged listening, the bass was a little too 'phat', although the effect wasn't as obvious with the other tracks we played. However, overall, I would say that the Croft/509s combo sounded a bit too rich, and although enjoyable enough to listen to, wasn't musically ideal. We then, thinking that the perceived 'cleaner and leaner' sounding LDRs would produce a better balance with the 509s, swapped out the Croft and replaced it with Jason's current LDR of choice, the Tortuga, and instantly this brought about an improvement in tonal balance, if not necessary to my ears in overall musicality.
It certainly resulted in removing a somewhat 'fruity' quality the Croft had contributed to, in conjunction with the 509s, but which had been totally absent with the A80, allowing the midrange and top-end of the system more freedom to 'breathe' and consequently produce a more tonally accurate sound. The 'precision' and clarity of the Tortuga also helped to ameliorate the, IMO, inherently rich sounding nature of 509s, at least in the context of Jason's system, although it must be said that the mid and top-end, in typical valve tradition, were beautifully detailed and textured, with vocals always being portrayed with consummate expressiveness and fluidity.
After that, we took out the Tortuga and replaced it with the Stereo Coffee unit, and for me, this produced the best sound so far (with the 509s in the equation), instantly eliminating the somewhat clinical and 'dispassionate' style of music-making, produced by the Tortuga (although, as I said before, there may be reasons for that which could be relatively easily sorted). However, the SC allowed me to 'connect' with the music in a way that had escaped the Tortuga, and I found myself really enjoying the sounds produced by the SC/509s combo. The SC seemed to project music with the same clarity and precision as the Tortuga, whilst also allowing one to 'listen into' performances, in the way allowed by the Croft or NVA P90SA; if not to my ears, with quite the level of expressiveness or sense of 'emotional involvement', achieved when the Croft was in line.
In my opinion, the best sounds of the day were produced by the Croft/A80 and Stereo Coffee/509s. Unfortunately, after listening to the latter for many hours, we didn't have time to swap back to the former and reassess things, as for me that would've been very interesting and I suspect in some ways also quite telling... I'm not sure, despite how superb the SC/509s sounded, with pretty much any genre of music (and we played a whole load of stuff through it), that I'd heard a better sound all day than when the Croft/A80 was playing 'Voodoo Chile', which really was rather special......
Anyway, all in all, it was a fantastic day, and my thanks again go to Jason. I very much enjoyed listening to both LDR passives, preferring overall the Stereo Coffee unit. However, the jury is still out as to whether either LDR, used as a volume control, would fundamentally improve my Croft preamp. Certainly for me, as standalone passive preamps alone they wouldn't, although I did hear aspects of their performance that I liked. Therefore, it would be interesting to assess both when implemented into the circuit of the Croft, just to see what would happen, which in due course, is precisely what I intend to do! :cool:
Marco.
The Black Adder
30-06-2014, 14:35
Great write up, Marco.
It's been a very good experiment indeed. Great read both Marco and Martin. Jason sounds like a great host too... Home made burgers, authentic greek salad..mmm!
NVA kit can do great things when partnered right. They can groove, that's why I liked them but I never got round to trying them with an active preamp. I seem to remember that it wasn't recommended but could be wrong... well, obviously wrong in this case...lol
When are you planning to get the LDR fitted in the Croft? - Would be good to come over and have a listen once that is installed and verified.
No worries, Joe :)
Experiments are currently on-going between some LDRs, the culmination of which will result in the best one being fitted to the Croft (most likely of the remote control variety), where a direct comparison between it and the DACT stepped attenuator will be performed, and then a decision made from there. That should all happen within the next month or so.
I never rush into these things, in order to minimise the risk of making any mistakes! ;)
When all is finalised, you're welcome to pop over for a listening sesh and, if you wish, bring your own Croft over for comparison purposes.
Marco.
The Black Adder
30-06-2014, 16:01
Coolio Iglesias :)
So, are you still excited Marco? The results seem to indicate that the LDR may be a better volume control but less positive with regard to passive pre-amps (at least in this instance).
Hi Mark,
See my summary of the bake-off at Jason's. There appear to be some positive aspects of the sonic performance of LDRs, although nothing is yet conclusive.
Marco.
Mr Kipling
30-06-2014, 16:30
Coolio Iglesias :)
Julio Doubleglazing
Mark Grant
30-06-2014, 17:49
Back in 2009 I was using a Creek passive, the one with a remote control, I then changed to a Croft Micro 25 Basic and the difference was truly astonishing. Bucket loads of detail that had been so clearly missing, dynamics, clarity and power all suddenly came from nowhere. I will say right now that in terms of 'fit and finish' the Creek bettered the Croft and with a single remote volume control was miles ahead of the Croft but in terms of musical content and especially detail, the Croft was well and truly worth the miserly asking price.
I think a croft pre with a remote control volume rather than two separate controls would be popular if it sounded as good.
The two separate controls does put people off I think.
Dave -There is only likely to be a problem if the ouput impedance of the source (the preamp) is high and the capacitance of the interconnect, used between the pre and power amp, is also high. But even this is unlikely: if we assume the output impedance is as high as 5KOhm, an interconnecting cable, having a typical capacitance of 100pF/m, would need to be 16m long before the response was -3dB down at 20kHz.
If the input impedance of the power amp is as low as 10KOhm, then with 16m of cable the -3dB point is lowered to 17.3kHz, so the maximum cable length would need to be reduced to 13.5m to move the roll-off point to just above 20kHz.
This is an extreme and pessimistic worse-case. Most preamps will have a much lower output impedance (as low as 10 Ohm for some SS designs) and the length of the interconnects are usually ~1m or less in length.
Thanks Barry, I'll shush now :)
But before I do :rolleyes: Marco's preamp has but one volume control. If the twin control Crofts had proper stepped attenuators, far fewer of us would have an issue at all. Trouble is, to get 500k or 1M stepped attenuators, they have to be custom or end-user make I believe.
I think a croft pre with a remote control volume rather than two separate controls would be popular if it sounded as good.
Hi Mark,
Happy 1000th post!
The last bit is the key factor, and not that simple to achieve without sacrificing sound quality. However, I suspect it can be done :)
Marco.
P.S Any sign of those Furutech plugs yet, matey? It's been ages! :eek:
Figlet108
30-06-2014, 22:29
I appreciate the kind words of Macca and Marco and here are my thoughts on the day.
As always with these events, it's the social aspect that I enjoy the most and in particular in this case Marco, Martin and David were very pleasant company indeed.
I agree with Marco and Martin's comments so I'll just highlight what made particular impressions on me.
I plugged in the NVA A80s downstairs (with the Tortuga pre) instead of the usual EAR 509s in the morning, and it was the first time I'd swapped the NVA back into the downstairs system for a year or so since I got the 509s. I listened for a few hours while I waited for the others to arrive.
I wasn't enjoying it much as I remarked to Martin when he turned up. The balance of sound was wrong, the bass was not tight and defined and overall there was a softness and a lack of boogie.
None of the passive pres really fixed any of those issues for me and along with Martin we were pretty convinced that the A80 was the problem and wanted to get the 509s in asap. However, when we plugged in Marco's Croft with the A80s, what a surprise! As Marco said, Voodoo Child was simply sublime (all 15 mins of it). Up to that point there had been no consensus between the 4 of us. But there was no doubt that the Croft/A80 combo in my Audiovector system was producing exceptional sound.
So this was the first big surprise, as I never expected an active pre to beat so convincingly 3 top passives when paired with a power amp that was designed to work best with passives. It's interesting that Neil found the same thing when he replaced his P90SA with an LFD pre.
We replaced the A80s with the 509s and straight away (with the Tortuga initially I think) things improved for me as I expected, as that's the combo I'm used to. Bass was tighter and more authoritative, mids and top were less veiled and much sharper and everything boogied a lot better.
I fully expected the Croft (valve paired with valve) to again take things to another level with the 509s. This was the second surprise, as it didn't. As others have said the sound was overcooked, especially in the bass.
The third surprise was that the Stereo Coffee LDR sounded consistently (albeit marginally) better than the Tortuga. And there was a reasonable consensus on this I think. It was a surprise as Martin and I found the opposite when we listened to them at his place. There the Tortuga had the slight edge.
However, as well as the negative effects of having 'vomited out' the build of the Tortuga, there is also a firmware update that I haven't had a chance to apply that changes the output impedance from 10k to 20k that apparently makes a noticeable difference according to Morten. So sorting out the Tortuga and doing another comparison with the Stereo Coffee is required, since in theory both LDRs should sound very close if not identical (as they use the same optocouplers).
The final thing that really struck home during the course of the day is how much a hifi is complex system that is made up of many interacting components and is greater than the sum of it parts. One minute we were dismissing the A80s, the next minute we were mesmerised when the Croft made it sing. No sooner was I starting to convince myself that I'd have to acquire a Croft similar to Marco's when the Stereo Coffee/EAR 509 combo was on stage and making me smile once again.
Was the NVA/Croft better than the Stereo Coffee/EAR? It's hard to say as we didn't swap back and forth (it was getting late, I was tired and it was a PITA to swap). Ultimately for me it doesn't really matter that much, as both combos produced top notch sound.
In the end a very enjoyable and interesting day and one I'd love to repeat in the future.
Hey Joe,
there was a Croft Charisma for sale on ebay this week for £500, just if your interested? :eyebrows:
Jason, it might be interesting sometime to compare an AVC preamp with the LDR. The one I use has Dave Slagle iron and it betters the S&B TX102 TVC. As you're in Macc and I'm in Altrincham this might not be to difficult to setup.
john dolan
01-07-2014, 09:42
I have 12 preamps and tested them for honesty with my M-dac.
Id play a high res flac using the headphones plugged into the M-dac then id play again with M-dac direct to the power amps using its on board digital preamp then id run the M-dac through my preamps.
3 preamps stood as being honest my Michell Argo hr with DACT attenuator fitted my DIY Glasshouse passive with Seiden 43 stepped attenuator and the one that sounded near as I could tell identical to M-dac direct to power amps is my AS Passion.
To me the idea of best is the unit that's adds nothing to the signal its fed but its very hard to do and I doubt any product manages to do it but some do it better than others.
In the case of Valve preamps I believe they add colour and distortion which you may or may not prefer and they can over egg the pudding as in the case with the EAR amps.
I really enjoyed reading this thread thank you guys this is hifi forum at its best.
In the case of Valve preamps I believe they add colour and distortion which you may or may not prefer and they can over egg the pudding as in the case with the EAR amps.
Hi John,
In the case of the Croft, definitely not to my ears or those of anyone else who attended the bake-off. If that were the case, the Croft wouldn't have been the clear winner out of all the preamps present (including the three passives), when the NVA A80 was in the equation.
It wasn't preferred by everyone because it sounded 'nicer'/more euphonic, but rather that it simply revealed more musical information and presented it more believably, all of which points to it being more accurate.
The only reason the Croft didn't perform as well with the EAR 509s (as it had done with the NVA), was because of a sonic mismatch, which in some situations partnering power amps from different manufacturers, can happen with any preamp, valve, SS or passive, simply due to a lack of synergy.
Marco.
john dolan
01-07-2014, 10:24
Thanks for the reply Marco
Interesting that the passives performed better with the amps designed to be used with active preamps and the active preamp performed better with amp designed for passive preamps.
I have both SS power amps and valve and from my tests passives give the cleanest purist sound because they have very little in the signal path and zero distortion but they can sound lean and flat if not partnered right.
My valve amp has fuller sound with richer textures so can afford to be fed the leaner signal of a passive if that makes sense and from your bake off you found the richer textures and fuller sound of the valve preamp enhanced the SS amp.
Really enjoyed reading your findings Marco very much.
Re: the passive/active thing I think it is possible to have an active pre-amp that approaches or is equal to the transparency of a passive, the drawback being that they do seem to be very expensive. For those of us who don't have several grand to allocate to the pre-amp a passive can be a very cost effective solution, offering most of what the hi-end active pre delivers but without the price tag.
john dolan
01-07-2014, 11:13
Re: the passive/active thing I think it is possible to have an active pre-amp that approaches or is equal to the transparency of a passive, the drawback being that they do seem to be very expensive. For those of us who don't have several grand to allocate to the pre-amp a passive can be a very cost effective solution, offering most of what the hi-end active pre delivers but without the price tag.
That echoes my findings Macca you can DIY a passive for £50 than can match a 5K active that has to make the simple passive a desirable thing.
john dolan
01-07-2014, 11:34
You could always try a passive with a valve buffer if you want the best of both worlds.
You could always try a passive with a valve buffer if you want the best of both worlds.
A valve buffer?! >involuntary shudder<
john dolan
01-07-2014, 11:47
A valve buffer?! >involuntary shudder<
lol I sometimes use my TVC as a buffer into my Passion which gives the sound a little more weight and I get fine volume steps from the 2 volume controls but it doesn't feel right feeding one preamp with another to me even though it seems to work well.
Hi John,
Interesting that the passives performed better with the amps designed to be used with active preamps and the active preamp performed better with amp designed for passive preamps.
Indeed. What it shows is that despite what specs or measurements say will work or not, the best thing to do (as long as it's safe) is just to try things, and most importantly, USE YOUR EARS to judge the results! ;)
By doing that, one can often discover the most unlikely of partnerships performing together superbly well. Quite simply, it pays to experiment!
:exactly:
Marco.
Re: the passive/active thing I think it is possible to have an active pre-amp that approaches or is equal to the transparency of a passive, the drawback being that they do seem to be very expensive. For those of us who don't have several grand to allocate to the pre-amp a passive can be a very cost effective solution, offering most of what the hi-end active pre delivers but without the price tag.
Yup, totally agree - and you've now heard what a valve preamp can sound like when the technology is implemented correctly... Valve buffers? :nono:
...only if you want to employ the use of a glorified tone control!!
Marco.
anthonyTD
01-07-2014, 13:24
Very in-depth, and thought provoking write up guys,:)
Your findings with the LDR are consistent with my own here, so’ I was relieved to read that!
I have said many times here, Synergy is the key to getting a system to truly sing, and your findings just go to re-enforce that.
I have another LDR type to try before I make up my mind on whether it would be beneficial to substitute one into an active preamp instead of a decent stepped attenuator, I will report my findings here when I have completed my tests.
What I can say without hesitation is’ over-all and to date' I still prefer a decent active preamp that has the ability to drive any load a power amp can throw at it…
A…
john dolan
01-07-2014, 13:44
Active preamps do indeed offer greater drive and impedance matching ect but in a system that's passive compatible a simple little passive for just a few ££ can match or beat a 5k active preamp.
Now in a age with dac outputs putting out plenty of volts way more than most power amps need for full power a passive is a good simple and cheap way to adjust your volume.
Why pay 5 grand when 50 quid can sound as good.
anthonyTD
01-07-2014, 15:00
Cant argue with that, i repeat, synergy,synergy,synergy!
Active preamps do indeed offer greater drive and impedance matching ect but in a system that's passive compatible a simple little passive for just a few ££ can match or beat a 5k active preamp.
Now in a age with dac outputs putting out plenty of volts way more than most power amps need for full power a passive is a good simple and cheap way to adjust your volume.
Why pay 5 grand when 50 quid can sound as good.
Why pay 5 grand when 50 quid can sound as good.
Indeed, John. However, it depends on what you're comparing things against. In audio, price is not always the arbiter of what produces the best performance. Some £5k preamps cost what they do for reasons other than how they sound, especially when they possess a 'desirable badge'...
The Croft has cost me the best part of £4k (including all mods and what I originally paid for it in stock form), but when compared with the assembled 'cost effective' passives at Jason's place (used in conjunction with a power amp with which it achieved synergy), as good as they were, the Croft's sonic superiority was obvious - and that's because the money has been spent on where it matters most: under the hood, not on pretentious frippery! ;)
Marco.
Indeed, John. However, it depends on what you're comparing things against. In audio, price is not always the arbiter of what produces the best performance. Some £5k preamps cost what they do for reasons other than how they sound, especially when they possess a 'desirable badge'...
The Croft has cost me the best part of £4k (including all mods and what I originally paid for it in stock form), but when compared with the assembled 'cost effective' passives at Jason's place (used in conjunction with a power amp with which it achieved synergy), as good as they were, the Croft's sonic superiority was obvious - and that's because the money has been spent on where it matters most: under the hood, not on pretentious frippery! ;)
Marco.
Hi Marco, as a fellow Croft enthusiast I would be most interested in what you have had done to the Charisma X since you have had it. Could you list the mods? - might be a useful upgrade path for others to follow:) -thanks
Hi Jim,
Mods to C-X as follows:
1) Internal PSU removed and externalised, whilst simultaneously being upgraded, in order that separate parts of the circuit were individually regulated (including the internal hard-wired MM phono stage). Also larger toroids fitted, in order to 'stiffen' and increase the size and capacity of the PSU.
External PSU housing fitted with Furutech IEC inlet socket (featuring Rhodium plated solid-copper contact pins).
2) 6080 regulator valve replaced with a MOSFET, thus enabling the amplifier to use solid-state, as opposed to valve regulation (which when done properly is usually more accurate and 'cleaner'/tighter sounding).
3) Coupling capacitors upgraded from electrolytics to Obbligato LCR Teflons.
4) Power supply capacitors upgraded to Mundorf TubeCaps.
5) All original Russian-type 6SL7 valves upgraded with various 1940s/50s premium (cryo-treated) NOS varieties [GE 5691, RCA VT-229, etc]. Original ECC83 and voltage regulator valve upgraded for 1950s NOS Mullard varieties.
6) Original ALPS Black volume pot upgraded for DACT stepped attenuator. Similarly, the original selector switch upgraded for one from Seiden. Jewellery grade solid-silver internal wiring used throughout.
7) All original brass-type RCA sockets upgraded with Eichmann solid-copper varieties.
I think that's it! :D
Marco.
P.S All of the mods carried out simply allow the superb circuit Glenn has designed to release its full potential!
The Black Adder
01-07-2014, 20:09
Hey Joe,
there was a Croft Charisma for sale on ebay this week for £500, just if your interested? :eyebrows:
Hi Jim.
Cheers matey... Mine is a modded Epoch Elite which has been updated and added to by Glenn so it has the same line stage, phono, teflon caps, updated psu caps, current mosfet regulation as Marco's. Marco's has more mods done but a list is building to do more on mine. The external PSU is the next biggie for mine.
http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/DSC08979.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/DSC08936.jpg
Everything I've done so far that Marco has suggested have had very positive 'real' improvements to the sound.
Hi Jim,
Mods to C-X as follows:
1) Internal PSU removed and externalised, whilst simultaneously being upgraded, in order that separate parts of the circuit were individually regulated (including the internal hard-wired MM phono stage). Also larger toroids fitted, in order to 'stiffen' and increase the size and capacity of the PSU.
External PSU housing fitted with Furutech IEC inlet socket (featuring Rhodium plated solid-copper contact pins).
2) 6080 regulator valve replaced with a MOSFET, thus enabling the amplifier to use solid-state, as opposed to valve regulation (which when done properly is usually more accurate and 'cleaner'/tighter sounding).
3) Coupling capacitors upgraded from electrolytics to Obbligato LCR Teflons.
4) Power supply capacitors upgraded to Mundorf TubeCaps.
5) All original Russian-type 6SL7 valves upgraded with various 1940s/50s premium (cryo-treated) NOS varieties [GE 5691, RCA VT-229, etc]. Original ECC83 and voltage regulator valve upgraded for 1950s NOS Mullard varieties.
6) Original ALPS Black volume pot upgraded for DACT stepped attenuator. Similarly, the original selector switch upgraded for one from Seiden. Jewellery grade solid-silver internal wiring used throughout.
7) All original brass-type RCA sockets upgraded with Eichmann solid-copper varieties.
I think that's it! :D
Marco.
P.S All of the mods carried out simply allow the superb circuit Glenn has designed to release its full potential!
Thanks for that Marco, can you remember which mods made the biggest impact?
Is the PSU now a separate unit similar to the Micro 25RS?
Interesting you modified the regulation stage with a MOSFET, I expect this gives a tad more control.
I am thinking of upgrading the Micro 25R and have a few routes to go depending on what Glenn will do. There maybe a halfway house between the R and RS although this maybe ultimately where I end up:D
Hi Jim.
Cheers matey... Mine is a modded Epoch Elite which has been updated and added to by Glenn so it has the same line stage, phono, teflon caps, updated psu caps, current mosfet regulation as Marco's. Marco's has more mods done but a list is building to do more on mine. The external PSU is the next biggie for mine.
http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/DSC08979.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/Tannoyista%20System/DSC08936.jpg
Everything I've done so far that Marco has suggested have had very positive 'real' improvements to the sound.
Hi Joe, I am thinking of upgrading my micro 25R but it will always be limited to a certain extent by the fact it uses ECC83 valves throughout rather than the larger valves used in some of Glenns older pre amps. This also true of course for the RS. Maybe I should by a Charisma or Epoch Elite when i next see one on the second hand market!:lol:
Thanks for that Marco, can you remember which mods made the biggest impact?
Is the PSU now a separate unit similar to the Micro 25RS?
Not sure about the PSU in the Micro 25RS, as I've not seen inside it. However, the external PSU on my Croft weighs about 20kg! I think there's about four or five different sized toroids inside it.
I'd say the biggest improvements came from externalising/upgrading the PSU, together with upgrading the coupling caps and changing the ALPS volume pot for a DACT stepped attenuator. The cumulative sonic improvement that brought about was huge.
Good luck with your own forthcoming mods :)
Marco.
montesquieu
01-07-2014, 20:43
Interesting write-up.
Tis a shame though you didn't get a good TVC in the mix. I've recently been playing with a Music First MkII (with the bigger transformers from the Classic V2) and it's been very interesting .... I've always been a fan of active valve preamps but this runs any I've heard very close. With vinyl (through Nick Gorham's valve phono stage) it's absolutely stunning.
The overall results tally with my findings though - it's all about synergy with the power amp. Sometimes a passive really just wimps everything out.
The Black Adder
01-07-2014, 20:50
Hi Joe, I am thinking of upgrading my micro 25R but it will always be limited to a certain extent by the fact it uses ECC83 valves throughout rather than the larger valves used in some of Glenns older pre amps. This also true of course for the RS. Maybe I should by a Charisma or Epoch Elite when i next see one on the second hand market!:lol:
Hi Jim.
I really like the current Croft pre's. I've had the basic, 25 Micro and heard the 25R. I've also owned the 7 and the 7R power amps. Glenn really knows his onions and the new pre's sound superb so getting yours upgraded to straddle the R and RS would I'm sure be a superb upgrade.
But with these older versions with the octal valves I feel that there is certainly more feeling somehow. Much like comparing the current power amps with a well made KT-120 amp, the sound seems to bloom, move and become even more organic/addictive to listen to.
One of the great things about Croft as you may know is the customer service. A pleasant, human experience with no catches with care and build quality to match.
The Black Adder
01-07-2014, 20:55
Not sure about the PSU in the Micro 25RS, as I've not seen inside it. However, the external PSU on my Croft weighs about 20kg! I think there's about four or five different sized toroids inside it.
I'd say the biggest improvements came from externalising/upgrading the PSU, together with upgrading the coupling caps and changing the ALPS pot for a DACT stepped attenuator. The cumulative sonic improvement that brought about was huge.
Good luck with your own forthcoming mods :)
Marco.
20kg's..!!!!! :eyebrows:
The Black Adder
01-07-2014, 21:01
Interesting write-up.
Tis a shame though you didn't get a good TVC in the mix. I've recently been playing with a Music First MkII (with the bigger transformers from the Classic V2) and it's been very interesting .... I've always been a fan of active valve preamps but this runs any I've heard very close. With vinyl (through Nick Gorham's valve phono stage) it's absolutely stunning.
The overall results tally with my findings though - it's all about synergy with the power amp. Sometimes a passive really just wimps everything out.
I've had a TVC using S&B transformers in my system. I really liked it. Differences between the croft and the TVC was that the TVC was more delicacy transient whilst the Croft's main advantage was drive. Nothing wrong with either for me, just different.
Thought you had the Pure Sound pre?
Hi Jim.
I really like the current Croft pre's. I've had the basic, 25 Micro and heard the 25R. I've also owned the 7 and the 7R power amps. Glenn really knows his onions and the new pre's sound superb so getting yours upgraded to straddle the R and RS would I'm sure be a superb upgrade.
But with these older versions with the octal valves I feel that there is certainly more feeling somehow. Much like comparing the current power amps with a well made KT-120 amp, the sound seems to bloom, move and become even more organic/addictive to listen to.
One of the great things about Croft as you may know is the customer service. A pleasant, human experience with no catches with care and build quality to match.
I agree Joe, the latest Croft amps do sound absolutely superb but there is always a temptation to eek out even more if possible. I am also looking at upgrading the Series 7 power amp but not sure which route to go, thinking possibly of mono blocks rather than 7R.
The Black Adder
01-07-2014, 21:15
Oh yes. Yes, I've also heard the mono's too. ... lol
I'd go for the mono's if I was you... gives a nice base to then get them upgraded to the R. Mono's will sound superb. Take it one step at a time, you will get the bigger picture that way. :)
Differences between the croft and the TVC was that the TVC was more delicacy transient whilst the Croft's main advantage was drive.
With most types of music, I'd take drive over delicacy every time - especially when the valve preamp in question is also, erm, none too shabby at the latter! ;)
Marco.
The Black Adder
02-07-2014, 09:18
Absolutely... There is no doubt that Croft does both really well, that's for certain. I suppose it's a taste thing with Passive and active (when done right) for the end user to choose between.
Hi Marco,
I think sometime back you had the opportunity to listen to the Croft Micro 25RS, how did this compare with your Charisma X and what were your thoughts in general regarding Glenns top of the range Pre?
Figlet108
02-07-2014, 17:38
Jason, it might be interesting sometime to compare an AVC preamp with the LDR. The one I use has Dave Slagle iron and it betters the S&B TX102 TVC. As you're in Macc and I'm in Altrincham this might not be to difficult to setup.
Hi Clive,
yeah I'd love to get together and try different things out with you. Given your location we should have hooked up ages ago.
However, it'll have to be in couple of months though as for personal and professional reasons I'm going to have to pretty much kill spending time on hifi dead for a couple of months.
I'll PM you when my time gets freed up again.
montesquieu
02-07-2014, 18:22
I've had a TVC using S&B transformers in my system. I really liked it. Differences between the croft and the TVC was that the TVC was more delicacy transient whilst the Croft's main advantage was drive. Nothing wrong with either for me, just different.
Thought you had the Pure Sound pre?
Not for a while ... went integrated for a bit then had various, Glasshouse passive, C-J PV14L, Tram2.
I would agree to some extent on the lack of drive on some TVCs, wasn't fussed with the Prometheus, Music First V1 was better, but the MFA MK II, with the V2 transformers in (25% bigger and not sold to anyone outside MFA) the clarity, space, soundstage etc is all there but no drive whatsover is lost, to my ears at least. This stacks up really well against both the C-J and the Tram2, and that into a power amp (Lyngdorf SDA2175) that is renowned for needing an active pre as it's not all that high gain. And compared to any valve pre I've heard the 'blackness' is stunning.
With most types of music, I'd take drive over delicacy every time - especially when the valve preamp in question is also, erm, none too shabby at the latter! ;)
Marco.
I'm not a huge fan of the Croft pres to be honest. Those I've heard have been musical, but compared to more high-end valve preamps (never mind the TVC) they have left a bit to be desired in terms of sophistication ... more to it than delicacy, more about naturalness IMO. Jolly good fun though. But my diet is mainly classical, in rock'n'roll sophistication isn't necessarily the name of the game. It's not really a criticism of the Crofts, I do think they are fantastic value for money but they are hardly the last word.
As far as any passive goes I think it's entirely down to synergy with the power amp, I don't think TVCs are a panacea by any means, but where there are no impedance issues (as there generally aren't with a TVC) and there's a nice healthy gain on the power amp (perhaps a juicy tube input stage), there's a fair chance an active pre will only muddy the sound to some extent. (Whether you enjoy the mud is a different issue entirely!).
Hi Tom,
No mud here, muchacho! :nono: Only beautifully clean white sands :D
The Croft I'm using has been very heavily modified, so probably unlike any other you've heard. Whether you'd like how it sounds or not, however, is another question.
We've been threatening to have a bake-off for a while, so perhaps I could bring the Croft down and you could compare it in your system to your TVC? :)
Marco.
Great thread guys, and fab write-ups from all of you - sounds like it was a great day spent with kindred spirits listening to great tunes on great hi-fi with great food & drink - feck, it sounds like heaven!
Hi Marco,
I think sometime back you had the opportunity to listen to the Croft Micro 25RS, how did this compare with your Charisma X and what were your thoughts in general regarding Glenns top of the range Pre?
Hi Jim,
One of my mates had a loan of a 25RS, and it was very good indeed. However, we both preferred my own Croft. The main difference, sonically, is the influence of the bigger valves used in the C-X, as the musical presentation of 6SL7s is very different from that of ECC83s (or other small signal valves) - and that difference superimposes itself rather significantly on proceedings.
Marco.
montesquieu
02-07-2014, 21:01
Hi Tom,
No mud here, muchacho! :nono: Only beautifully clean white sands :D
The Croft I'm using has been very heavily modified, so probably unlike any other you've heard. Whether you'd like how it sounds or not, however, is another question.
We've been threatening to have a bake-off for a while, so perhaps I could bring the Croft down and you could compare it in your system to your TVC? :)
Marco.
Sounds like a plan Marco, would love to hear it. I'm currently awaiting arrival of a Radford STA100 from 1967 ... this arrived with a slightly sub-par output transformer. Radford Revival are winding a new pair from Radford's original spec sheets ... system sounds pretty good at the moment with the Lyngdorf but when that's here I'm hoping that will kick it up a notch. (Be an interesting comparison anyway). Anticipated in next 3-4 weeks. Wife is away most of August so maybe could pencil in a day and have a few more of the lads round?
The Radford STA100 thing is actually a wee bit more complicated ... it's one of those amps that have polarised opinion, those that have used it as a 100v line amp for studio work seem to think it's the best thing since sliced bread, but feelings seem to be more mixed for hifi use, perhaps in part because of optimisation for 100v line and 16 ohm speakers, rather than more modern 4-8ohm ... it's a bit borderline with 8ohm speakers especially cranked up a bit, which didn't help reliability.
Will and Steve have actually recommended winding a set of transformers from the TT100 spec sheet, one of old Arthur's very last designs which marked a return to valves after quite a few years in the 70s when Radford went solid state. The TT100 had a solid state front end but (I'm told) an almost identical power stage to the STA100 (100w from KT88s) except the OPTs are wound for 5.3ohm/8ohm nominal and the 100v line secondary has been removed - ie, exactly what we need to do to make the STA100 a proper hifi amp and probably more reliable as well (the TT100 didn't have the STA100's reputation for eating tubes). Graeme Hirst (Valvebloke/'Ampregen' is liaising with Will and Steve and knocking it into shape for me. (We'll keep the original transformers and everything done will be reversible).
It's low sensitivity so I'm anticipating that the TVC might be a better bet than an active pre (that's why it's here, in anticipation ....). But would be great to try the Croft on it.
If it all works out I'll almost certainly be giving it over to Radford Revival to do a full restoration on it (paint job, new boards etc). Their work is fantastic.
Hi Tom,
August could be good, mate. Swing me a PM when you've got a better idea of a date :cool:
Love Radfords!
Marco.
Powered by vBulletin® Version 4.2.3 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.