What is a preamp?

[richidoo]

Has anyone the placette resistor network volume controls? Some pure passive and the big dog has active output buffer.

[miklorsmith]

Very good advice all around.  Nice summary of the electrical concerns, Weez.

Being as technically savvy as a butterfly, my comments are limited to sonics.  

When I got my Zu Druids, I was running a Modwright 9.0SE and full-tilt Clari-T.  It was a great combination, then I upgraded to the Definition 1.5s.  I thought they should be capable of more low bass so I sold the Modwright and went with a TacT 2.0s.  A personal arms race led to the XP/Pro combination - the ultimate expression of that idea.

Sound?  Evenhanded from bottom to top, with no obvious errors, very impressive.  But, even with an outstanding 45 SET amp saturation was incomplete.  Tube lovers know exactly what this is, the roundness of tone and instrumental vibration.  Granted, my SET is more angular and less billowing than average for the breed but it is a color enhancer.

The moment of enlightenment came after a lengthy series of changes, all using the Signature amps.  I had been using them to evaluate the changes, arguing to myself that they had less self-voice than the Yamamoto and would be the better assessment-tool.  I just wasn't feeling involved.  Talking of his own setup, by buddy mca said "I want to be excited to listen to music."  That pretty much expressed my feeling about my rig.

The Yammie was getting dusty in a box, feeling neglected.  I took out out of cold storage, warmed it up, and Hello!  I flashed back to the Modwright and knew a tubed preamp was coming back.

After much research, I settled on a Lamm LL2 Deluxe.  With the Signature amps, it's like a SET preamp.  I need to do a comparison with no preamp to the Yamamoto vs. the Lamm/Sig vs. the Lamm/Yamamoto.  I wouldn't be surprised if the Lamm/Sig sounds more classic "tube" than the Yamamoto by itself.

In many systems, a high-quality tubed preamp can be its soul.  Philosophical detractors can float numerous theories about why it should not be so, yet for me there is NO DOUBT this is the case.  Depending on listener priorities and system configuration, there are certainly cases where an active linestage is not preferred.  My speculation is this is a significant minority and many clinging to the thought could/would be swayed by a copascetic match if they had a chance to hear it.

I wholeheartedly recommend the Lamm LL2 Deluxe.  These recommendations are always tainted because the proponent is always touting what they have.  So, take with a measure of salt.  Some of these clowns have to be right though, occasionally.  This pre is a ridiculously amazing performer.  It is a completely musical piece that soothes and jumps with equal aplomb.  It goes way deep in the bass with big texture, is sufficiently sparkly on top, but makes its big hay in the midrange which is simply sublime.

There are 4 or 5 reviews available on this one, each positively glowing.  On the used market, they're around $2,800 and retail for $5,000.  It's a smokin' deal.  Add the Lamm to the Def's on the "bury 'em with me" list.

p.s.  - Just saw the passive resistor question - I haven't but I have a pair of in-line RCA Endler attenuators that are a GREAT, cheap passive or they can serve as gain-limiters to allow a wider range of volume control in the preamp.  I have the 11-step models which retail for around $80.   The 24-step versions are $150 I think.  It's a pretty cheap audition for truly "passive" sound and a valuable addition to any neurotic's toolbox.

[richidoo]

... But, even with an outstanding 45 SET amp saturation was incomplete.

... Add the Lamm to the Def's on the "bury 'em with me" list.

  I love it!

More great advice. Thanx Mike

[WEEZ]

miklor, great post. You just described the sonic 'result' of all the good 'electrical' reasons a preamp 'is' the soul of the system.

WEEZ

[shep]

"Hey Shep... don't grind teeth over this old debate. Passive vs. Active preamp's have been discussed at length... If I ever hear a passive I like, I'll change my mind instantly... just haven't yet. Of course, I haven't put the effort into auditioning them like I have with active's.

I certainly wouldn't scratch anything off my list because of audio-forum opinions..."
Carl the grinding wasn't about the debate exactly, since this wasn't a debating thread, rather the fact that I do repect all your opinions (otherwise what in the world would I be doing here?) and I have no idea why some people absolutely love a good passive and others are dismissive (and apparently with good reason either way). It's a little late to change my order anyway. I could have gone for a good Nobel pot but my past experience with resistor-based attenuators was wholly positive. The Aussie one is absurdly cheap, and well made apparently. The fact that it is chassis mounted (not ic's) and connected directly should be in its favor. Resistor/ladder types are VERY cable or cable-less dependant.
The point of informing oneself thru forums is precisely because we/I can't find out any other way! If three people oppinionate on a single subject, I usually take that as pretty much gospel. In this case I just gnash teeth and hope for the best. Michel pretty much has refused to take a stand. I guess he wants me to be the final judge.   ps Had "we" been able to use the tube section, this would be a non-issue.

[WEEZ]

Mike, your Lamm IS a single ended triode preamp. As are most tube preamps.

Shep, I would concur that a resistor based stepped attenuator is a superior performer. And, if it is chassis mounted in your amplifier..not in it's own box connected by cables..it is the best way to implement a 'passive' volume control.

WEEZ

[miklorsmith]

To clarify, I wouldn't describe the Modwright as SET sounding, regardless of topology.  Some of the modern breed of tubed preamps have gravitated toward a SS presentation.  This is not the same as a true SS preamp, and I would take the Modwright over any SS preamps I've heard.  The Lamm is of the deep colors camp and lends that holographic SET aspect to the final result.

[mgalusha]

A good friend of mine went through this exercise a few years ago. He bought or borrowed a good number of high end tube preamps and I let him borrow a Grounded Grid and a homebuilt Decware ZLSA pre, which is more of a buffer.

Some were very nice but not exciting, some overly syrupy and too colored. The little Decware clone sounded better than all of them except for one glaring problem, it had no gain. It's really a buffer and has a gain of about .9dB, so it just wouldn't get loud enough but was otherwise supremely musical.

One day I get a call and he tells me he's found his new preamp. He'd purchased a DeHavilland Ultra Verve and was thrilled. The next time I heard his system I understood why he was so happy. It was clean and clear but with that certain richness that using a tube provides. A short time later he was moving to a new home and I had the DeHavilland in my system for about three weeks and fell in love. I really didn't want to give it back. DeHavilland has since released the Mercury series of preamps which I suspect are even better.

I've built a couple of passive volume controls, one using pots and another using a Gold Point stepped attenuator. I chose values that would provide the best possible impedance match and avoided some of the problems that WEEZ mentions and the sound was extremely transparent. Ultimately I ended up going back to an active design as the trade off's in my system (lack of dynamics mostly) eventually bothered me too much.

I know Jim (Double Ugly) used a Placette resistor unit for quite a while and was very happy with it. I believe him as he's a very straight shooter and won't coat anything with BS. I suspect that there is a lot of synergy involved. A source with a good enough output stage that can drive the cables and resistor network, amps with a high enough input impedance so the frequency response isn't modified greatly by the high Zout of the passive and of course the amps would need to have sufficient gain.

For myself, I liked Jerry's DeHavilland enough to DIY my own that was very similar to it tho not a direct copy as that wouldn't have been right.

Having recently heard the Burson buffer in my system between the SB and the Altmann I think this could be the basis of a very nice preamp. I believe that Wayne at Bolder Cables is working with John Chapman from Bent Audio on just such a beast. I'm building a 6 channel version myself using a 6 deck Gold Point attenuator for the volume control and hope to have it completed soon.

mike

[richidoo]

Mike, thanks for the great ideas. I was checking out decware and dehavilland this morning. Next up Burson.

My amps are 450kohm input Z on the RCA inputs, and only 1.5ohm outputZ. Good enough for a tube amp!    Squeezebox is my weakest source although not too bad with the 2A linear power supply. It seems to sound better without the pre than with it, at least in terms of detail resolution. So maybe the high amplifier input Z makes current drive issues less significant? Other sources like tuner and phono pre have volume controls that can dish out the power as needed. If I were to go with a placette passive, I could place it within a foot of the amps, using Grover's low impedence cables.

The Manley Shrimp preamp I am auditioning now uses a White follower buffer circuit after the cathode gain stage to give only 50ohm output Z and 26dB of power gain and 12dB voltage gain. It is a great design and is extremely quiet. It fattens up the sound quite a bit, and smooths things out making everything very listenable, but not sure it has the zing I'm looking for and in some quick comparisons yesterday I think it might be eating some resolution compared to direct connection to amps, but I can't tell for sure yet. There's some huge multicaps in there which will have some effect. Gotta get my speakers back together before I make any judgements.
Thanks Mike!
Rich

[stereofool]

Rich,

With Mother's Day rapidly approaching...I think a nice new PRE-AMP would be a GREAT gift, for her   !

[richidoo]

You read my mind!!

[richidoo]

DU, Do you still use Placette RMC? Stock RCA or did you get any options like silver wiring?  

Did you have to add a buffer stage? Would it go before or after the VC?

How long did it take to get used to the level indictor LEDs? Can you easily see it from a distance?
Thanks
Rich

[WEEZ]

So Rich, where do you stand on a pre-amp?

WEEZ

[richidoo]

Hi WEEZ, thanks for asking. I have speakers down for repair and been shuffled off to a new sound room. So I have bigger fish to fry right now, but it is next on the list.

I want a Ref3, but that will have to wait for my next generation system. This gen 2 system will be based around the Snappers, they are vry exciting. Surprising that the the Shrimp took a little away from that, maybe to balance it out, tone down the flamethrowers. I want even more, not less!  So far I'm thinking about T8/Ultra, Placette with Burson buffer if necessary, Candella, MiniMax, even Coral. If I come across any others in the meantime I will put them on the list to learn about.

Once I get things settled down over here I will pick your brain to narrow the field and get a couple in for listening. I think we have similar taste so your experience is valuable to me!
Rich

[twitch54]

I've enjoyed reading this thread for I too am a huge believer in the importance of the "sonic signature" that ones pre-amp imparts on the system. Both 'Mikorsmith and Weez' had great comments on the topic and to sum up everything in a nutshell........synergy; something we all strive for with respect to all componetry within our systems.

FWIW, I too love the ARC Ref3, but after hours of comparative side-by-side listening I couldn't justify the 4k over the LS-26. The LS-26 has been in system for a year now and I could not be happier !

good luck with your journey !



Dave