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trane
22-06-2009, 20:49
hi, there, all,
i am a newbie here though have read certain threads as a visitor earlier, and now have decided to join this community :)
i am from hungary, where availability of the well-known british hi-fi stuff is realitvely easy due to the now-existing dealer network for i believe all the 'major' brands.
however, judging from the accessible reviews on Croft makes, and backed by some (mainly Ken Kessler) articles, it seems this marque is not as yet at its well-deserved place in its, and your, country regarding it (not) being in the 'mainstream' of hi-fi.
that said, i do not attempt to compare Croft products to e.g. marantz models in any way, only that i'd love to see more Croft items in the mags and the shops.
of course, i am aware of the fact that Croft is quite a unique mark in terms of production, too, thus, there is an evident reason why it's not kinda mass-produced...
now, i hope all above have made sense and has not distracted anyone from reading further - i'll stop the intro, and switch for the main points.
which is, that in spite i have never heard a Croft amplifier, but had read some amazing reviews on them, i decided to go for one, preferably an integrated.
as a valve-fanatic, i had used almost exclusively all-valve design integrated amps before from Audio Innovations (S300, 400, 500) and Audio Note (Oto Phono), and some hungarian-made models under the Pointe trade name (Sima, Medium, Classic), and heard quite a numerous.
whatever pure and truly musical the voicing of those amps had been, i got tired of exchanging the tube compartment in every 2nd year and, thus, decided to go for a tranny amp that sounds as a valve-based one.
the mission was not easy to fulfill since - despite having listened to a lot of ssd makes - the magic of valves, that natural, open and airy midband, had always been missing. the only trannies i loved were the Audio Innovations Alto (MK I), Audio Refinement's Complete, and YBA's Intégré - nothing else.
the first 2 were unfortunately below the potential of my system, so they got ruled out, and the YBA proved to be somewhat uninvolving in the long run, so my quest began again.
and it was then when i got intelligence on Mr. Glenn Croft's ssd Integrated, the GCi. pretty scarce info was available on the amp on the net, but i was somehow directed by an internal force towards that amp - and at once it was at ebay. i could not belive it was there - but did not hesitate much, and acted... i finally managed to win it, and now it's with me :)
the sound is magical: open, airy, sweet, dynamic - almost everything i wanted is laid in front of me in the form of MUSIC by this amp. i am extremely happy to own it :)
however, there are certain issues that i would need help to solve.
namely, the sound is somewhat not transparent enough in the lower midband (btw, here i am talking about nuances, but don't forget, i used to listen to valve amps for ~25 years). as the Integrated uses mosfets, i am not too much surprised at this imo typical charcteristics, though here it is pretty much a minor issue as compared to other (e.g. creek) mosfet desings - it is just not that transparent that i was used to.
so, i wonder if anyone here has the same experience, and whether has managed to solve the matter?
i learnt that in the latest GCi models a new cathode follower circuit, based on a mosfet instead of a valve, was installed and that made the voicing of the amp even better - but do not know in what aspect? btw, is there anyone here having the schematics for that part?
also, i recognised that the inner cabling is made from a shielded type, which may also contribute to the above-described phenomenon, together with the Croft-branded caps at the speaker terminals (by the way, is anyone here familiar with those caps' origin and material?).
moreover, there is a little pcb with a relay for each channel that might as well contribute to (degrade) the sound - what if de-connecting it and taking power directly to the ecc83 valves?
finally, i got nothing with the amp regarding manuals, leaflets, anything - i wonder if there is any of these around available that could be photocopied/photoed and posted to me (at a cost, of course)? not as if it was really needed, e.g. operation is pretty simple - only, i would just like to own it and read it for the sake of it ;)
so, should anyone be in the position of helping with an answer/material, please do not hesitate much but write on - thanks :)

DSJR
22-06-2009, 22:27
www.croftacoustics.co.uk

Email Glenn. I'm sure he can help you.

trane
23-06-2009, 13:15
hi, thanx for the reply :)
i did that but he could not help for... anyway, i do not believe i am authorsied to 'publicise' for what reason, but that does a lot with him, even though him being an unbeliveably human and hospitable person, but at the same time being kinda unfortunate as well...
that's why i chose to turn to community of this forum...

technobear
25-06-2009, 16:57
Hi trane :)

Welcome to the wonderful world of Croft!

I have a Croft Syntegra which was the model above the GCi. It's a great amp. Probably the easiest way to change the sound is by changing the tubes. You mention that they are ECC83 but which ones?

I got a sound more to my liking using GE JAN 5751 (cryo'd). These have greater transparency, better bass and better treble than the Ei ECC83 which came with my amp. They only have about 75% of the gain of the ECC83 so you need to turn the volume up a bit more. I also tried JJ Tesla ECC83S which are not bad and have great treble but were a little bright in my system. The 5751 is better balanced with deeper tighter bass.

Others have recommended Siemens and Telefunken but these attract high prices and I have not tried them.

The only other change I have made so far is to change the selector switch for an Elma and the volume pot for a Seiden/Takman metal foil stepped attenuator. This has given a useful uplift in transparency. The volume pot was an Alps Blue which is pretty good but the stepped attenuator is better. You do have to run it in at every one of the 23 positions though it only takes a few hours for each one.

Actually I did make one other change. I removed the blue LEDs around the selector switch and added several extra resistors to the main blue LED so it is now much dimmer.

Glenn would probably shoot me :guns:

trane
26-06-2009, 21:12
hi, Chris,
thanx for the great reply - and congrats to the syntegra :)
sure, for being a long-time valve guy, i did pay attention to the valves, and now am using jj ecc83s' exactly for their more open balance. actually, the ones that i really preferred were original mullards, but i simply do not want to pay the silly price they are sold as now, that's why i gave a try for these new-batch teslas. my other favourites are the sovtek 12ax7lps' but i have as yet not tried them - but will ;)
however, transparency did not really change, thus, i still am to do something to open the mids.
i had the same intention regarding the vol pot and input selector switch, but first i will change the internal wiring (mainly those copper bars carrying signal) for kimber hook-up, and the speaker output ones for coincident (that's my speaker cable as well), cables.
also, asap i realised that the current for the blue leds passes through the same switch, though on a different circuit, that distributes the signal, i resolved to cut the leds out of current - i believe there is some counteraction between the signal and current deteriorating (even slightly) the former...
finally, don't you happen to know about that cap pair hanging on the speaker outputs, namely, what make and material they are, and whether you or anyone in your circles have experimented with replacing them?
p.s.: hope mr. Croft will not change and spares our lives when informed on 'destroying' his truly excellent makes ;)
cheers,
Attila

technobear
27-06-2009, 09:58
finally, don't you happen to know about that cap pair hanging on the speaker outputs, namely, what make and material they are, and whether you or anyone in your circles have experimented with replacing them?


The Croft Transcapacitor and resistor is a closely guarded secret it seems. My guess is that it acts as some kind of Zoebel network although normally that would be tailored to the impedance curve of a particular speaker system. It surely must tailor the response in some way but I don't know how.

There are a few other resistors in the amp that might benefit from changing and I'll be looking at those in due course. Also the bridge rectifier might usefully be changed for Hexfreds or Schottkys. I don't know. I'm a bit nervous of over-egging the pudding now that it is sounding so good.

trane
27-06-2009, 13:50
yes, Chris, you're rigth, the cap plays part in a Zoebel network. i may ask Glenn whether he could help determining the best value for my speakers, and the best replacement type as well.
of the other changes, i agreee on replacing the bridge rectifier for Schottkys, but i won't go any further than described before - otherwise the whole amp would be re-built, and though that may result in a 'better' sound, would cost a lot extra. i reckon i will leave it as it will be after the cable, cap and diodes mod, and do the others only when its due for the ageing elco caps...

trane
28-06-2009, 11:11
one more thing: what if the little pcb sitting in the amp gets disconnected mainly for the reason that it has a relay for each channel, which may well be not truly needed apart from safety reasons, though acting as a limiting device in terms of sonics...

technobear
28-06-2009, 12:15
In so far as I could tell, the relays are not directly in the signal path so I decided to leave them alone. They mute the valves in some way but it isn't by getting in the way of the signal.

StanleyB
28-06-2009, 12:21
If you are serious about modifying any of the Croft amps then you need to speak to Adrian at http://www.audioflair.co.uk/ . EXcept for Glen himself, I don't know of anyone else who knows the Croft amps to that sort of level.

Stan

trane
28-06-2009, 13:27
Chris and Stan, thanx for your kind replies - i will contact that named Adrian and let you know of the outcome asap done

matodono1
03-12-2009, 08:44
one more thing: what if the little pcb sitting in the amp gets disconnected mainly for the reason that it has a relay for each channel, which may well be not truly needed apart from safety reasons, though acting as a limiting device in terms of sonics...

Hi,

The relays are there to allow time for the valves to stabilise before switching on the solid state output stage of the amplifier.

Otherwise the output is allowed to inject DC into your speakers while the valves heat up and you lose your bass units.

As far as I know the relays are not in the signal path.

Regards, Matt.

matodono1
03-12-2009, 09:35
hi, there, all,
however, there are certain issues that i would need help to solve.
namely, the sound is somewhat not transparent enough in the lower midband (btw, here i am talking about nuances, but don't forget, i used to listen to valve amps for ~25 years). as the Integrated uses mosfets, i am not too much surprised at this imo typical charcteristics, though here it is pretty much a minor issue as compared to other (e.g. creek) mosfet desings - it is just not that transparent that i was used to.


finally, i got nothing with the amp regarding manuals, leaflets, anything - i wonder if there is any of these around available that could be photocopied/photoed and posted to me (at a cost, of course)? not as if it was really needed, e.g. operation is pretty simple - only, i would just like to own it and read it for the sake of it ;)
so, should anyone be in the position of helping with an answer/material, please do not hesitate much but write on - thanks :)

Hi Trane,

Glenn may have already told you but I think it is safe to say publicly that he hates the integrated with a passion. They are difficult to build and don't sound as good as separate pre-power combos.

He only built the GCi's because of the demand for integrateds and the fact that Amar was making such a fuss about including an integrated into the EA range at that time. Amar was happy to give people what they think they wanted as long as there was money in it. Glenn now only builds what he believes in so hence no Integrateds in the current range.

There were never any manuals or schematic on anything specific to the GCi. All you ever got was a leaflet instructing you how to plug in a switch on.

The GCi is very nice but is limited by the fact it is a one box design. It has a small power supply and a passive pre. Nothing about it is cutting edge.

The real solution is to get the new amps. Ideally the Micro 25 R and the Series 7 R. But even the standard Micro and Series 7 would make a GCi sound a shade primitive.

regards, Matt.

trane
09-12-2009, 21:53
hi, Matt,
thanx for the great replies :)
actually, having read it I was a bit shocked at learning Glenn's opposition against the GCi, and overall against integrateds...
anyway, by now the GCi and I have parted and I am again in for the valve gear :) , though would definitely not go for a Croft design until 'only' pre/pwr combos are available - I am too much in love with the integrateds. they need less space and cabling (I am a cable fan, consequently, when I speak of cables it means a - for some - more than reasonable amount of money), thus, are a more tempting design for me. it seems I will turn my head towards the good ol' Audio Innovations Series line again (I have as yet had 6 AI integrateds: 300.1, 300.2, 400.1, 500.2, 500 harmonie, 700) - they are THAT great :)
however, in case Glenn decides making an integrated again, drop a line, please, urgently! :)

hifi_dave
09-12-2009, 23:26
The latest pre's and power's from Croft are really quite small and if you put the two together they are smaller than many 'high-end' integrateds. They also sound far better than the amp you just disposed of.

trane
11-12-2009, 22:03
you mean the 7 series? i reckon they still need more space and cables than integrateds, ain't they? sonics-wise i am sure they must be great by any standard though :)

hifi_dave
11-12-2009, 22:42
They are really quite small and the two together are far smaller than yer average home cinema receiver. To connect the two you need one short incon. Job done.

trane
12-12-2009, 13:58
thanx for the advice, may consider - though feel a bit silly as a pre/pwr combo (however, of the ea times) was sold at ebay.co.uk just 2 weeks ago...