View Full Version : Passive pre
I go through a love/hate relationship with passive preamps.
I am now using the slagle passive volume controller which I love I get plenty of grunt but this might be due to the fact the Bantam has active gain.
In the past I loved the transparency passive give but missed the grunt a good active gives (in other words the system rocks but can do good acoustic too). I feel I now got to the stage not only can I have my cake and it, but I have icing on top and some Red Chimay to go with it
I am interested to hear other peoples thoughts
I've oscillated between active and passive over the years, the active drive on rock is great but the drop in transparency is the dilemma on othrt matetial. Slagle txs are about as good as it gets but I only listen to rock 10% of the time.
Due to active stage in the Bantam I get plenty of drive I listen to rock about 80% of the time and the system really rocks. Which is not something I am used to with passive preamps so getting the best out of both worlds.
I think with the higher efficiency of the Bastanis They do quite a convincing job with Rock
I think my view is that they are great under the right circumstances
walpurgis
05-06-2013, 19:34
I've used and built passive pre-amps (volume controls, if you want the correct term) and they suit some source and power amplifier combinations better than others.
I've used and still own potentiometer and stepped attenuator types. BUT! I've lately been using a Ming Da MC-9 TVC (transformer) design. Wow, this is great, seemingly total neutrality and transparency with no effective loss of weight. It sounds better than ANY other pre-amp I've ever used. I've compared it to my old EAR 834L (now sold 'cos it was totally outclassed), my valve VTL Deluxe and my pure Class A, Forte Model 2, both very good pre-amps. None come close to the TVC which at £300 (+ duty and carriage) has to be a whopping bargain. It's also beautifully made.
realysm42
05-06-2013, 19:54
:popcorn:
I've used and built passive pre-amps (volume controls, if you want the correct term) and they suit some source and power amplifier combinations better than others.
If they have input selection then I'd call them a passive pre. With some TVCs or AVCs there is gain available, eg the Slagles provide for +7db so these can be used at the heart of a preamp....not that I'm splitting hairs.:)
Interesting. I have a simple passive from ebay which easily outclasses a modified Quad 34 in terms of transparency and soundstage. It has a Alps blue velvet (i think) volume control and some silver wiring and cost about 70 EUR. I'm wondering if more expensive passive's are really that much better ?
southall-1998
05-06-2013, 20:10
Interesting. I have a simple passive from ebay which easily outclasses a modified Quad 34 in terms of transparency and soundstage. It has a Alps blue velvet (i think) volume control and some silver wiring and cost about 70 EUR. I'm wondering if more expensive passive's are really that much better ?
Very interesting, Rupert.
Is your Passive pre made in UK?
Interesting. I have a simple passive from ebay which easily outclasses a modified Quad 34 in terms of transparency and soundstage. It has a Alps blue velvet (i think) volume control and some silver wiring and cost about 70 EUR. I'm wondering if more expensive passive's are really that much better ?
Yes, very much so in a system with good resolution. There are better pots, switched attenuators and transformers. Blue Velvet is a decent starting point...
The preamp is a key section to your system. It pays to get it right. Saying that sounds like Shane has a great bargain
southall-1998
05-06-2013, 20:42
The preamp is a key section to your system. It pays to get it right. Saying that sounds like Shane has a great bargain
Shane ??
:)
Very interesting, Rupert.
Is your Passive pre made in UK?
Got it from ebay, but I'm sure you could quite easily make it yourself. Here the reference: I think that photo could be the one I have :)
http://www.ebay.co.uk/itm/bte-designs-passive-pre-preamplifier-preamp-valve-or-solid-state-amps-/251278121485?pt=UK_AudioTVElectronics_HomeAudioHiF i_Amplifiers&hash=item3a8157da0d
edit: the Ming Da MC-9 TVC looks interesting.
walpurgis
05-06-2013, 22:48
the Ming Da MC-9 TVC looks interesting.
You have to hear this thing to believe how good it is. My friend heard mine and was immediately convinced (as I was) and he also bought one and sold his EAR 834L. Just as I did. Now the 834L is a pretty nice sounding pre-amp, but it comes nowhere close to the MC-9 for sheer lucidity.
southall-1998
05-06-2013, 22:57
You have to hear this thing to believe how good it is. My friend heard mine and was immediately convinced (as I was) and he also bought one and sold his EAR 834L. Just as I did. Now the 834L is a pretty nice sounding pre-amp, but it comes nowhere close to the MC-9 for sheer lucidity.
Does the EAR require careful matching with power amps? Is it fussy?
julesd68
05-06-2013, 23:02
Now the 834L is a pretty nice sounding pre-amp, but it comes nowhere close to the MC-9 for sheer lucidity.
What power amp are you using it with Geoff?
I tried an Icon Audio passive a couple of years ago but found it flat as a pancake dynamically - maybe it was just a bad match in my system ...
walpurgis
05-06-2013, 23:20
Does the EAR require careful matching with power amps? Is it fussy?
No, the 834L seems pretty power amp friendly. Obviously some matches are better than others, but it turns in a decent result generally.
You heard mine through your Leak Stereo 20. I thought the pair sounded fantastic together.
walpurgis
05-06-2013, 23:22
What power amp are you using it with Geoff?
I tried an Icon Audio passive a couple of years ago but found it flat as a pancake dynamically - maybe it was just a bad match in my system ...
Hi Julian, most of the time I'm using the MC-9 with a Monarchy Audio SM-70 Pro.
It's a great pairing and sounds incredibly good with my Cheviots.
Drop by sometime and have a listen.
julesd68
05-06-2013, 23:27
Hi Julian, most of the time I'm using the MC-9 with a Monarchy Audio SM-70 Pro.
It's a great pairing and sounds incredibly good with my Cheviots.
Drop by sometime and have a listen.
Yes sounds like an interesting combo, would like to come over - will PM you ...
Passive in the wrong set up can sound very flat. for most people they will be transparent and holographic but lack the gain needed to bring you the real excitement of music. Thankfully in the right circumstances they can have the grunt needed to bring you the excitement of music
Gordon Steadman
06-06-2013, 05:30
Creek passive and Leak Stereo 20. As dynamic as reality!! I tried lots of preamps before settling on the Creek, Quad33,34 etc but always came back to the passive. Plus it appeals to the couch potato in me as it has a remote control:cool:
maxrob200
06-06-2013, 05:51
IMO, I prefer the passive pre for its transparency. Matching to the input sensitivity of the power amp will determine the drive that you get when listening. Also the value of the potentiometer used can also affect the sound. Interesting to note that some of the best sounding integrated amplifiers use a passive pre
another advantage i see is that it doesn't use any electricity ! one less box getting hot..
I have found that passives work great with power amps having high sensitivity and gain, and connected with short and high quality interconnects. I have been using a passive in my system for a long time; started off with an Alps Blue Velvet based passive and I was stunned by the transparency it brought for the low price. But it suffered from channel imbalance in low volumes.
Then I moved to a stepped attenuator and things improved considerably.. the channel imbalance was corrected, and I came to realize that this was also noticeably quieter than the Blue Velvet.
My next step is to build myself an impedance buffer circuit into the volume control, so that I have a passive volume control but without the headache of impedance matching.
For those willing to go through slightly techie articles, something like this (http://www.stereophile.com/content/aunt-coreys-homemade-buffered-passive-preamplifier-page-2)
Oldpinkman
06-06-2013, 08:41
Now I fear I am about to reveal the depths of my ignorance. I understand the idea with passive pre-amps, and clearly don't know how to build one (conversation on a beach this weekend with someone who does - my "bung an alps pot on the tape output" comment receiving a detailed explanation as to why that wouldnt work, which was lost in a fierce Norfolk wind).
It was that discussion about what mattered. And I go back to my PT days. Since PT, although I have managed without by just not listening to music any more, apart from on an ipod or in the car, I have found that there were some references I could not enjoy music without. I thought one of them was the Technics U205C cartridge, but AK steered me towards the Goldring and its ok. 2 others were the Pip and DaCapo - both only very recently restored to a very recently accomodated HIFI in the living room.
My point on the beach discussion was I knew there was a difference between Pip 2 (passive or active) and Pip 1 (active only) but that didnt matter to me. Pip 2 may be better, but it wasnt a deal-breaker. Pip 1 is. (PIP 2 has a passive option). As a quick aside, DaCApo 22 bit - deal breaker. Add the DC powersupply? - not enough for me to fuss about. It's not that there is not difference - its easy to hear one on A:B's. But I wouldnt sit down and think "that's not right" . Diferrences which matter enough for me to notice when I just sit down to listen to music matter. The "I can tell when I do the test" differences don't matter - albeit they may well be real.
Someone referred to the quad 34 (comments will apply equally to the 44). Nice. With all the complimentary and perjorative connotations of nice. Inoffensive. Nothing wrong with it. Very boring. (I speak as one who worked for a company that used it as demo amp before PIP arrived, and recently had one whilst said Pip was utterly kn****red. On phono particularly (where the RIAA is a significant factor) listening on the quad was like a perfectly photographed cardboard cut-out, compared with the PIP as the live human being. Big difference. Nothing to do with active or passive.
In theory a good passive is the perfect amplifier - since the perfect amp is a wire with gain (or control of it in the case of a passive). In practice - other things seem to matter more. The real low blow was that we're not really sure why or how.
julesd68
06-06-2013, 09:22
I have found that passives work great with power amps having high sensitivity and gain
What does this mean in terms of figures?
I would be interested in trying another passive in the future if I could take the guess work out of buying the power amp. Would love to try a Leak Stereo 20.
walpurgis
06-06-2013, 09:29
Yes, the Leak Stereo 20 is a goodie. I've never heard one sound bad. Even my early ones, with a right old assortment of ancient valves used to sound great.
9921
while googling around for the PIP I found this .. looks like the original passive
What is the PIP ?
http://www.etsy.com/listing/88103763/ibamboo-iphone-speaker-black-limited
jandl100
06-06-2013, 11:21
Passives are very system dependent - but I've been using a Tisbury passive pre for quite a while now and I absolutely love it.
It's got real transparency, rez, drive and control into my Krell power amp.
Many integrated amps were designed to be basically a power amp with input selector and volume control feeding it, most notoriously the Cyrus 1 and 2 models of yore and I'm sure there are many others too.
I think that high input impedance, as well as high sensitivity/gain, is very important for a passive control to work well. Old Quad power amps (and possibly new ones?) should be perfect with a passive - the 303 especially and I think most vintage valve power amps had high input impedance down to a fine art. Not at all sure about things like Albarry's though, where the input impedance seems very low indeed (one reason why some haven't had good experiences with using croft pre's with them I wonder).
On the other hand, if longer interconnects are required, an active stage is mandatory and there are some good transparent ones around, some using op-amps too :eek:
Ali Tait
06-06-2013, 12:20
Impedance matching is the key I think, or do what Nick did and put a buffer each side of a passive so it isn't an issue.
Oldpinkman
06-06-2013, 13:06
99239922
For the benefit of our friend from Switzerland, the PIP was a tranconductance pre-amp produced (briefly) by Pink Triangle. Brilliant design electronics - terrifyingly bad construction - a nightmare to service. Its the box underneath in the 2nd photo - the valve thing on top is a chinese ebay thing I am playing with as a headphone amp.
The PIP does not use valves, it's designer being very rude about them (or I should say observing some of their limitations and design constraints). What is really odd is it sounds like it uses valves
There are all sorts of techie aspects to take into account with passive pre-amps (where pre means before the amp...:)). Potentiometers (normal volume controls) and switched attenuators are usually recommended to be around 10k in value as they need to be used with a power amp that could be 10k to 100k input impedance. Closer to 100k power amp input impedance tends to work out better than 10k. Many modern valve power amps are 100k, solidstate can be typically 10k to 50k though I have one that's 100k. Also power amp sensitivity close to 1V than 2V will work better with most sources.
When you move to transformer, eg AVCs life actually gets easier as they lower impedance, some people even manage to drive headphone directly from the Dave Slagle AVCs. Matching issues with power amps and sensitivity to interconnects diminish. You can even have gain with some transformers. Transformers I find are better at dynamics than potentiometers.
Here's a link to the basic Slage AVC site: http://www.intactaudio.com/
Here's a link to the jazzed up version I use which sounds much the same but it's a much more functional pre-amp. http://www.enjoythemusic.com/diy/0513/bent_audio_avc_1_autoformer.htm
http://i43.photobucket.com/albums/e359/cmeakins/AVC-1front_zps70700476.jpg (http://s43.photobucket.com/user/cmeakins/media/AVC-1front_zps70700476.jpg.html)
http://i43.photobucket.com/albums/e359/cmeakins/AVC-1notop2_zps2de735cf.jpg (http://s43.photobucket.com/user/cmeakins/media/AVC-1notop2_zps2de735cf.jpg.html)
http://i43.photobucket.com/albums/e359/cmeakins/ACC-1corner_zps1b505896.jpg (http://s43.photobucket.com/user/cmeakins/media/ACC-1corner_zps1b505896.jpg.html)
http://i43.photobucket.com/albums/e359/cmeakins/AVC-1remote_zps50ffe181.jpg (http://s43.photobucket.com/user/cmeakins/media/AVC-1remote_zps50ffe181.jpg.html)
julesd68
06-06-2013, 13:32
There are all sorts of techie aspects to take into account with passive pre-amps (where pre means before the amp...:)). Potentiometers (normal volume controls) and switched attenuators are usually recommended to be around 10k in value as they need to be used with a power amp that could be 10k to 100k input impedance. Closer to 100k power amp input impedance tends to work out better than 10k. Many modern valve power amps are 100k, solidstate can be typically 10k to 50k though I have one that's 100k. Also power amp sensitivity close to 1V than 2V will work better with most sources.
Thanks for that Clive, most helpful!
What does this mean in terms of figures?
I would be interested in trying another passive in the future if I could take the guess work out of buying the power amp. Would love to try a Leak Stereo 20.
In terms of figures, ideally a passive pre should be sitting after a source which has an output voltage at least double the input sensitivity of the power amp after the passive; higher the ratio the better. For power amps with input sensitivities approaching 1v or above, the gain should to be nice and high, say about 30db or more.
As David mentioned, a high input impedance in power amp (>=20k) and low output impedance in source (<=100) is also required, since in a purely passive setup(no transformers or buffers) the source has to bear the load of driving the amps input.
For example, my source has output voltage and impedance of 2.7v and 100ohms respectively, while the sensitivity and input impedance of my Quad 306 are .375v and 20KOhms resp. So they are pretty well matched. There is room for improvement, of course.. especially in the impedance dept. Which is why I am considering the building of a buffer.
Leak Stereo 20 has a nice high input impedance of 100KOhms. Should play well with a passive.
All said and done, there is actually a mind boggling array of hardware and personal tastes, and I dare say it is practically impossible for anyone to say for certainty what will work where. The best we can do is make an educated guess on what should work and then see what has worked for us.
99239922
For the benefit of our friend from Switzerland, the PIP was a tranconductance pre-amp produced (briefly) by Pink Triangle. Brilliant design electronics - terrifyingly bad construction - a nightmare to service. .....
:)
[QUOTE=Clive;452365]
Here's a link to the jazzed up version I use which sounds much the same but it's a much more functional pre-amp.
http://i43.photobucket.com/albums/e359/cmeakins/AVC-1front_zps70700476.jpg (http://s43.photobucket.com/user/cmeakins/media/AVC-1front_zps70700476.jpg.html)
Is this the $1400 version from BentAudio ?
Is this the $1400 version from BentAudio ?
Yes, though it's more like $1,600. When editing the photo links I lost the link to the article, I've put it back in there and here it is as well: http://www.enjoythemusic.com/diy/0513/bent_audio_avc_1_autoformer.htm
Very interesting, thank you !
I've got three preamps at the mo.
1) Air Tight ATL10a whihc uses an ALPS RK50 (http://www.ebay.com/itm/ALPS-RK50-rotary-Potentiometer-10K-50K-100K-250K-logarithmic-pot-Japan-RK50112-/260966536400). This pot is excellent but not cheap. It is kind of bodged up to an electric motor to provide remote volume control via some gearing.
2) A Marsh P2000B active solid state jobbie. Very GVFM and really well thought out design. Top for the money (£380 on ebay 2nd hand).
3) A modified Cayin SC10 tube preamp which uses 274Bs. Trashes the EAR 868PL preamp I had TBH. No comparison - just much better in my system.
At the mo the Air Tight is geting swapped in and out with the Cayin. Both are excellent in different ways. The Cayin is exceedingly fast on transients which I find appealing as I like to move a lot of air VERY quickly. But the Air Tight is more neutral sounding.
I was going to sell the Air Tight but I've realised I can't do that cos I like it too much. It has also been with me a very long time and is like an old friend.
I also used to have a Mod Squad Line Drive with Penny & Giles plastic pots in. It was truly excellent - as good as the Air Tight IMHO. The P&G pots are excellent.
anyone have this one ? it looks nice but it's hard to find any opinions
http://www.khozmo.com
http://www.khozmo.com/stereo_selector/1.jpg
or the LDR based one from here http://www.tortugaaudio.com ?
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