Passive or active?

[ian]

I've read various bits and pieces over the years extolling the virtue of passive pre amps, usually by manufacturers of this type of product.  Then again there have been similar articles espousing the benefits of active preamps.  The arguments seem to revolve round reducing the number of components in the signal path vs better ability to drive the power amps.  My knowledge of electronics as many of you know is severely limited but I just thought I'd ask if any of you have an opinion on this matter based on theory and practical experience.  

Cheers, Ian

[rfgumby]

  I almost always prefer an active pre, for 2 reasons:

1) dynamics can be more realistic

2) I like getting a tube buffer stage in the system somewhere (it helps for digital) and the midrange glow
is always welcome.

   Now there are a few caveats IMHO.   A ridiculously sensitive amplifier (let' say anywhere under a half volt)
doesn't really need a hard driving preamp stage.  Also, a system with tubed source components (a CD output section and/or tube phono pre) driving some tube amplifiers will work fine with a quality passive.  A transformer based passive will keep a consistent load that the source component "sees" so sound quality should never change with volume control position.  But my experience with transformer based passives still runs parallel with other passives (as long as the parts are of good quality).

Again, that's been my preference, but I have heard some great passive pre based systems as well.  If you prefer the clean presentation of good solid state, for example, a passive may be wonderful if the associated components lean a bit warm or vintage.

[brian]

I think it is very system specific Ian. I ended up using transformer passive, i.e. a transformer with multiple secondary tappings selected by a rotary switch. Nowadays I use military-spec carbon pots for volume on the grid of the output valve.

[daiwok]

From personal experience, I have yet hear a good passive amp even with the most expensive selectors, volume pots and transformers. I find them very clean - could be a true representation of the source, but it was less involving, less dynamic. Like Scott I am a warm person - so its only tubes for me 

[willbewill]

A good description David i.e. very 'clean' - The Kerr I have that Scott totally rebuilt into a passive is exactly that, it hardly alters the signal. In fact most of the time there is only one resistor in the path.

But I think I will end up going with Scott and having a tube phono up front and probably a valve buffer on the cd as well.

[wesley]

 

i've used the django (from brian cherry at diyhifisupply) many years ago.  it used the expensive s&b transformers.  it was very nice and i used it for a year or so.  it gave a very natural presentation and was very detailed, however, it lacked LIFE  .  though good, i wouldn't waste my time.  just go with an active preamp, tube of course  .

[jloveys]

I never use a preamplifier in my system with vinyl. The sound is much more clear and free of artifacts when I go direct from the phonopreamp to the amp. My amp has vol. attenuators. I use the preamp (ARC LS 25 MKII ) only with CD and tuner.

Jean.

[willbewill]

I never use a preamplifier in my system with vinyl. The sound is much more clear and free of artifacts when I go direct from the phonopreamp to the amp. My amp has vol. attenuators. I use the preamp (ARC LS 25 MKII ) only with CD and tuner.

Jean.

Which are basically the same as a passive pre albeit permanently part of the power amp - or is it an integrated?

[Mike2000]

I currently have 3 pre amps, a TC-754 (active), Avreavox Arcana 81 (active valve) and a Rothwell Indus SE (passive).

The Rothwell is the one that remains a fixture in my system, for me it offers a cleaner more detailed sound (whilst price does not always reflect quality, this retails at a significantly higher cost than the others).

If anyone wishes to compare, I will bring the Rothwell along to the get together .

Mike

[ian]

Thanks Guys, interesting if inconclusive stuff.  I suppose it's like asking which type of cartridge do you prefer, there are bound to be advocates for each and every option.  What stirred me to ask was Scott's conversion of the Kerr and my messing with the little Norh.  I used it straight with its passive pre then with a solid state (Meridian 201) pre mainly for its phono stage.  The extra gain was certainly welcome but I was quite surprised that I didn't find this a degradation of sound quality. 

Cheers, Ian

[Francesco]

Hello Everyone,

during the years and my experiments, I prefer the passive amplifier even tough I don't have any. First of all because if is based on a good stepping-up trafo, the sound is much more neutral and without any colour. The tube are great, but is always a big deal to find good tubes, every time needing matching and finding the right sounding tube. The trafo in the years will be always the same, just is hard to find very good trafos, will be very expensive, maybe in super permalloy.... and find the person who does build it in the state of art.

Cheers from Italy.

Francesco.

[daiwok]

Hello Everyone,

during the years and my experiments, I prefer the passive amplifier even tough I don't have any. First of all because if is based on a good stepping-up trafo, the sound is much more neutral and without any colour. The tube are great, but is always a big deal to find good tubes, every time needing matching and finding the right sounding tube. The trafo in the years will be always the same, just is hard to find very good trafos, will be very expensive, maybe in super permalloy.... and find the person who does build it in the state of art.

Cheers from Italy.

Francesco.

Francesco has a very good point here. It has taken me many years to find a pre-amplifier with phono that I can really enjoy and part with well earned money.

All those issues which Francesco has mentioned, I tend to agree. It is also the same argument on phono amplifiers, MM design with an expensive Step up ? of a full blown MC design amplification. I spent like 5 years with a number of Step ups and the prices can be insane. One thing I must highlight is gain ! gain is everything in a MC world and it is harder to get a decent tube MC phono amplifier which is sonically sound yet has jet black background.

Ian is right, it depends on what you prefer and also your system which you are happy to "settle on". I believe we all have a type of sound which we enjoy and a system which we "settle on". Those words are easier than you think. For example, I decided many moons ago to go for all tube, low power amps and high sensitive speakers because I love this type of sound, and then build around and discover what I "prefer" - yes even low power, there are many types of tubes.

Before I found Supratek, I always thought that passive was the way, one of the best Phono stages on the market and still is very good is the KONDO pre-amps and phono. Mostly are aged silver step ups - the infamous M7 (which is almost empty inside). The price just blew me away and sometimes this can misrepresent in ones mind that this is got to be the "best". When I first met Mick Mahoney of Supratek - purely by chance on the internet, it allowed me to ask and probe questions and even without hearing, I decide that is what I want. It sounded like a moment of madness, but I guess it was  The KONDO sound is very refine and clean, but I prefer the excitement and that spine tingling dynamics Mick gives.

I think even when giving opinons nowadays, I would keep an open mind - especially a few years ago when I thought belt drive, high mass and lots of money = the best turntable money can buy 

[rfgumby]

  It's also important to remember that circuit topology can help dictate the best choice.  Integrated amplifiers, becoming far more popular in the last 10 years (deservedly so because of their potential of cohesive sound) are often simply a power amp with an attenuator at the input.  And that input attenuator is 99% of the time, a passive device.

  So, if your source component has enough gain to drive your amp to it's fullest potential, and your interconnects are short and/or of minimal characteristic consequence, a passive may be the cleanest and least degrading device available.

  SUT's are a different matter, my experience has been that if you're using an SUT, you need a healthy gain stage to wake the amplifier up a bit.
And there's the primary and secondary loading issues to muddy the mix.  I do like SUT's, and yes as David mentioned, they get better but far more expensive as you go up in quality.  I happen to have an all valve phono preamp with a solid but consequently noisy 75 dB of gain.  It's all just tube
rush, 10 of any valve will have a noisy floor-  I haven't used step ups since getting that, simply because I don't have to.  SUT's as with passive preamps, are cleaner, but I like the added midrange bloom of valves, even if it is a harmonic "distortion".

Great conversation guys, keep it up!

[hatehifi]

My Gryphon Tabu and Dayens Ampino are integrated with passive preamp sections as Scott mentions. I still own a Red Wine Audio Signature 30 [integrated, but the DACT attenuator went bust so now it is a] power amp too. Its sound is good but nothing to play serious poker with and to get it upgraded to Sig30.2 status, cost, postage and duty runs so high that I opted for upgraded Promitheus Audio (PA) TVC & tube buffer stage 'preamp' (ca. 900 EURO) combination instead. After reading up on Supratek, I may inherit my PAs... I've always wanted a 'very good' preamp and now I happily do.

The PA in front of the Tabu and Ampino is nice but 'no.' Matched with the Sig 30 is dynamite. Just the TVC, in turn, or just the buffer make the Sig30 'much nicer' again. It, the power amp, is still for sale... I'll keep the PA [unless my price is met] at least till Dayens' Ampino monos arrive. Years ago I owned a 2x50W classA my friend Larry Whitfield (used to be Audio Intl's -Klipsch, Infinity, GAS, etc.- service tech and later Nakamichi's service boss) built (Escape Electronics), that shamed the Krell KSA50 and got Mark Levinson's ML-3 most insecure indeed and I wish I still had it! I know that the two-piece PA and the Escape (mine was aluminium but Larry was building them on wood, vertical standing, stove pipe-like, too by '82 - BTW they were voiced on Larry's Klipsch La Scala) would satisfy me, maybe even more than my present ss gear. And my present ss gear sounds such that anybody who 'loves' tubes, will love my stuff.

My friend has money and went for Pass' (I like Nelson's sonic thumb print!) XP20. After reading up on it I wrote him that I wonder how it compares with a good TVC... especially since he goes into Pass' main amp and all his front ends (no tubes) have gain to spare.

[Francesco]

Yes is true the tubes gives a boost on the mids, but I tend always in every project that I build, to give less colour to music as possible. The more neutral sound from my point of view is reached using trafos, with a resistive attenuator. But music is a very personal thing, everyone likes to listen in the way they want.... But the real sound is an acoustic orchestra live, then after having this in mind I try to build my amps projects. The LPs that I often use to judge a amps, are Miles Davis "Kind Of Blue" or John Coltrane "Africa Brass & A Love Supreme" and more jazz LPs of the 60s, where all acoustic instruments must be amplified in the same way and all in focus, and in the right place in sonic scene.

Italian greetings to everyone at Lenco Lovers.