AudioNervosa
Systemic Development => Amplification and Preamplification => Topic started by: richidoo on April 25, 2007, 03:04:46 PM
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I am starting to audition preamps to go with my new Manley Snapper mono amps. Obviously, I know I need a volume control, and source switching. But surely that can be had for a lot less than some high end preamps cost, so what does a preamp actually do to make it so valuable?
Some people want a transparent volume control "wire with gain", and think of the preamp as a necessary evil. Others want some lovin added to their dish and think of the preamp as the backbone of the system, determining the basic sonic character. With some costing $10k and way up a preamp should get you more than volume control and input switching!?!
I heard Placette "active" pre and it was extremely transparent. I heard Levinson preamps and they are neat looking, very flexible interface but sound pretty boring to me. I have heard Audio Research Ref 3 and that set my soul on fire, but I'm not sure how much of that was the other parts of the system. Carl's Mac sounded "perfect," like Mac stuff does. I am demoing a Manley Shrimp, running it in for about a week now. My budget is more like the Shrimp than the lobster, but I like the sound, clean, direct, ballsy, just like the amps. All tube so my precious highs are intact. I will audition it and some others over the next month or so.
I would love to hear your views on preamps, active, passive, tube, solid state, impedence, coloration (the good and bad), and anything else about preamps or whatever comes to mind!
Thanks!!
Rich
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It's a 'system conditioner', IMO.
Even with high-output cd players and dacs with 2 volt to 4 volt max. outputs...there is usually not enough current to properly drive the line cable capacitance and/or amplifier input without running out of gas..or maybe clipping. Sometimes there is, but not usually. So, a pre-amp is usually better at this function. ( a pre-amp will put out anywhere from 2 to 20 volts)
Not to mention, that a tape deck or tuner, likely won't even achieve 2 volts; more like .5 to 1 volt. (A phono section even less). And... even 'less' current than a cd player or dac. So, you'll not achieve full power from the amplifier with those sources. The sound will be 'weak' or 'thin'.
More.......
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A good pre-amp will provide the source(s) with a high input impedence making it's load 'invisable' to the source(s) connected to it. And provide a low output impedence to the amplifier..making it 'invisable' to the pre-amp. The amplifier is driven with the same impedence regardless of which source is selected.
A passive volume control/switcher will not do this. The impedence will vary with the rotation of the volume control..causing the frequency response to vary at different volume settings. And, as mentioned above, it's now up to the 'source' to drive the amplifier. And the inerconnect capacitance. And whatever capacitance exists at the amp input. Usually not good. [-X
More...
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Sorry you asked? :lol:
So what about gain? Here's the rub..
Many amplifiers today have too much gain. Too damn much. Blasts you out of the room at 9:00 on the volume dial. Some have 30db or more. That's enough to play plenty loud with 'most' speakers in 'most' rooms. So 'passives have become popular. Only problem is, there are the 'problems' listed above. So what to do?
:(
More....
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To me, the purpose of a preamp is to put you in control of your very own audio switchyard without actually getting in the way of the traffic going thru it.
I've been using an ARC SP9 for probably going on 10 years and had it modded by Steve Huntley @ Great Northern Sound awhile back. It has operated as a switchyard for my tuner, my CDP and all my vinyl playback (it has an excellent phono section). I've also used it at times to integrate video and for evaluating different CDPs. I thought it was very good before I had the mods done, but I was totally amazed at how much the mods improved it. To coin an overused phrase - numerous veils were lifted letting thru a far more defined, refined and detailed soundstage.
Currently, I'm just using the SP9 as a phono section having recently acquired the master of all switchyards and control, Carl's modded Tact 2.0s - which I am lovin!.
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Mike...
I've been using an ARC SP9 for probably going on 10 years and had it modded by Steve Huntley @ Great Northern Sound awhile back. It has operated as a switchyard for my tuner, my CDP and all my vinyl playback (it has an excellent phono section). I've also used it at times to integrate video and for evaluating different CDPs. I thought it was very good before I had the mods done, but I was totally amazed at how much the mods improved it. To coin an overused phrase - numerous veils were lifted letting thru a far more defined, refined and detailed soundstage.
Sounds good......I too have an old SP9 mkII (since 1986). And have read about the GNS mods....good to hear about a nice improvement. 8)
Chris
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More More More!! Thanks everyone. Hey WEEZ don't stop now, you're on a roll! Some great points, things I had not thought of.
I was concerned what a Noble or Alps pot would do to the signal. Will have to try with and without to know for sure, but I see that the sound of a source will gain in other ways even if a little detail is lost to VC.
Any value in using same brand preamp as power amps, for synergy? Or doesn't really matter?
Thanks
Rich
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Rich,
As to the same brand matching components... Using the same brand name usually means nothing other than how it's going to look in your rack... However, in some cases it can mean they are similarly voiced components... but that has it's pros and cons also. This is where finding a synergistic match becomes really flaky, trial-and-error business.
Some companies make great amps and horrible preamps. In my opinion, older B&K amps are fantasticly musical but their preamp counterparts were dead boring and very veiled.
In your particular case, I don't know. Manley is a company I've often heard about but rarely experienced. Unfortunately, I think it will be near impossible to make any conclusions until your speakers are back together... The ones you have now aren't yours so it's not the same.
I ended up with the Mac preamp because I heard something similar at a friend's house. Plus it had the bonus feature of a tubed phonostage. If he'd had an ARC or a Minimax combined with his system, I would've tried that instead. However, I liked a particular sound and knew I could get my money back out of the deal with Mac gear if I didn't like it. At first I wasn't in love... but after some tweaking, I am.
I've never heard a passive that I liked, even using a fancy pot with 1 source and a super-nice implementation. Remind me about it and I'll give you someone to contact about trying one.
They always sound 'dark' to me, which is the opposite of what I think you like. This is certainly not always the case, just my experience. On a previous forum folks would tell me I don't know what I'm talking about... but I know what I've heard... about 3 or 4 different passives that all sucked. ;) However, I've never heard a Bent, which looked to be the most promising of all.
Preamps are a good control center. Finding a really good one (transparent, detailed, musical) under 2,k with a remote is going to be tough.... (not that you said 2,k was your ceiling... just saying that's about the normal threshold I've found for everything you want)
-C
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Thanks Carl,
I can agree with all that, no surprise. I am just doing research now, looking into what's available, not listening seriously until speakers are back and broken in. I want to make sure I don't have any mental veils of ignorance or misunderstanding.
As to the dark sound of passives, my word would be clean or cool. The reason I am interested in passives is only because of the placette active experience I had at RMAF and comments from placette users who I know have similar taste as me and were very impressed. I love the direct sound of tuner and SB into my amps, the detail, and I think a placette resistor network would not veil this at all. But I also think as WEEZ so eloquently said that SB especially is not up to the challenge of driving an amp to full musical output, hence the popularity of all the power supply mods. But living with the tube preamp for a couple weeks I am getting accustomed to a fatter, calmer, smoother sound, and I don't think any details are missing, at least nothing worth crying over. Seems more musical in a sense, more listenable. I notice the music more when playing in the background.
I could shell out 20k and get a handful of pres here to fart around with for a month, but that seems like a waste of time and money when I know I won't be buying more than one. Better to do the math in my head first. One thing that endears me to Manley, besides the performance value is the incredible service. I get emails back from the owner and the service manager in a couple hours with detailed helpful info the first time., so I am leaning in that direction, pending listening with my speakers.
Rich
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Good points made by everybody. I particularly agree with Carl, in that I've never heard a system with a passive that I liked very much. No meat on the bones with a passive. (among other troubles..)
Diatribe continues:
So, what about gain? If the amp has 30db, that's prolly enough. What to do? Fairly simple..you can use a preamp with less gain; or you can 'pad' down the gain with resistors, either in the preamp or at the amplifier.
Many preamps have 20db of gain. Add that to an amp with 30db and you barely crack open the volume control. (I've argued with Frank Van Alstine about this a couple times. Why 20db (10 times the signal)? "Industry standard" he says. Bullshit, I say. (to be fair, his stuff sounds great..but.. his amplifiers have around 25db of gain, so they work well together)
More.....
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So enough boring technical stuff...
But which one to buy? Hell if I know :shock:
The Manley is priced right. Has enough inputs and outputs. Has a mute. Uses good parts and readily available tubes. Has more modest gain (4x). And it's well made. If I were shopping for preamps it would certainly be on my list.
Good luck if you want to spend a lot less. Now, if you want to spend more, there are certainly options :P
WEEZ
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BTW, after some further thought...if you can live with only (3) ins and (1) out; no monitor function; pedestrian looks; and want to save some money; the Transcendent Grounded Grid is worth a look.....gotta get the volume control upgrade, though.
Then again, if you get the vinyl disease :lol: well, ah, mmm, er, ah... :twisted: well.....umm
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Thanks WEEZ. I will be checking out a few choices in the next month. Thanks for the tip and the insight into preamps!
Rich
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I've been quietly grinding my teeth :shock: I like a good passive straight-wire pre! never heard "dark" or anything untoward. I guess it depends...talk about vague...well I just hope my perception hasn't changed since all that will stand between me and the music is a cluster of Vishay resistors.
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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... ;)
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Has anyone the placette resistor network volume controls? Some pure passive and the big dog has active output buffer.
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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.
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... 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.
:lol: I love it!
More great advice. Thanx Mike
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miklor, great post. You just described the sonic 'result' of all the good 'electrical' reasons a preamp 'is' the soul of the system.
WEEZ
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"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. :shock: ps Had "we" been able to use the tube section, this would be a non-issue.
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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
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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.
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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
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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! :D 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
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Rich,
With Mother's Day rapidly approaching...I think a nice new PRE-AMP would be a GREAT gift, for her :lol: !
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You read my mind!!
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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
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So Rich, where do you stand on a pre-amp? :)
WEEZ
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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
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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
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Welcome!
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Just to muddle it up a little more, I took and connected a gold point stepped attenuator up to my buddies Burson Buffer (6dB of gain) and put it between my phono stage, a Hagerman cornet and the electronic crossover. This was in place of my UltraVerve clone. I can say that it worked very well and I didn't miss my tubes, which I was sure I would. Just another path on the way to audio nirvana (which I'm sure doesn't exist :))
mike
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Thanks Dave, welcome to AN. Glad to know more AR fans onboard!
Mike, your post is very timely as I just sat down to force myself to make a decision.
Thanks
Rich
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Mike, you put the buffer after the attenuator, right? or before?
WEEZ
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Weez, I put the attenuator on the input of the buffer (before). The chain looked like this:
TT -> Cornet -> attenuator -> buffer -> XO => power amps => speakers. The only downside (in my admittedly short audition) was the attenuator caused small pops when the level was changed. However, this is an older "mini shunt" attenuator. Series mode attenuators don't have this problem but they also cause more impedance mismatches than do shunt mode attenuators. :(
A very interesting but also very DIY attenuator option is the "Joshua Tree" ladder attenuator that Twisted Pear Audio makes. http://www.twistedpearaudio.com/joshuatree/jt.aspx
It doesn't cost much and the few reviews I've read pretty much rave about the sound in comparison to pots and ordinary stepped attenuators. Of course the downside is one has to build it (an upside for me) and that it currently doesn't support remote control (natively) but that appears to be coming soon. I believe they have a prototype up and running.
Mike
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Right.... (on all counts :))
Curious what attenuator value you use....25K? 50K? Thanks..
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I'll have to look at it. I literally pulled it out of a box and wired it up just to play with. :)
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I understand.
...but if you get a chance to check, I'd appreciate it.
WEEZ
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...but if you get a chance to check, I'd appreciate it.
Weez,
This particular attenuator came from a deHavilland Ultraverve where the owner wanted a remote control and it is wired differently from my other gold point "Mini H" attenuator. It measures about 43-50K on the input for most of the range, increasing to 143K on the next to the last position and 1M when wide open. Zout runs from about 20R to 3.3K at 12:00 o'clock to 100K at the next to last position. It's 1M wide open, obviously somewhere you wouldn't want to go. In my system I never went above about 9:30 or 10:00, so the Zout was still reasonably low. If I was doing this for a keeper project I'd definitely choose something else but it worked surprisingly well.
mike
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Just came across this article on switched ladder networks. Lots of good info here.
http://jos.vaneijndhoven.net/switchr/index.html
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Thank you very much, Mike. Useful info....
WEEZ
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" The only downside (in my admittedly short audition) was the attenuator caused small pops when the level was changed."
Hi MG,
Quick question. Is the switch a make before break contact switch? If break before make, popping can occur. Or the possibility, any chance that a little DC voltage might be present at the switch, from the source? Doesn't take much voltage.
Take care and hope this helps.
Steve
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Steve, It's not, the switch is an ELMA of the type used in the DACT attenuators, many of these are shorting but this one is not. It's what Gold Point used to sell as a "Mini H", which is a shunt attenuator but not a full ladder.
I fully understand about having small amounts of DC on the inputs. In this case the source was capacitively coupled and it didn't have any DC. One of the reasons Gold Pt doesn't sell these anymore is that they were noisy, at least I believe that's what I read. In any event, connecting it up to the Burson buffer was just an experiment. :)
mike
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Mike, just fwiw...my pre uses a DACT/ELMA series type. Dead quiet and the best volume control I've ever used.
Steve, welcome! (SAS Steve?)
WEEZ
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Weez, I have a DACT as well and they are quiet and sound excellent. This is because they have a continuous string of resistors (series attenuator) and that the circuit is never broken. When the level is changed the wiper simply selects the next resistor in the string. With a shunt or ladder attenuator there are only two resistors in the circuit at any one time. While there are some potential noise advantages (resistor noise) to this, the downside is that the circuit must be broken and reconnected each time the level is changed.
Steve refers to a make before break switch. This means that it makes contact with the next element before disconnecting from the previous one. In the case of my test attenuator it's not using this type of switch and it's a shunt attenuator, so it makes a little noise. Some folks put a high value resistor across the shunt attenuators so that the circuit is never truly broken and this reduces the switching noise. This is the case with the one I have (and older Gold Point). While quieter, it's not completely silent.
There is a lot of information on stepped attenuators on the Gold Point web site if you want more info. http://www.goldpt.com/index.html (no, I'm not affiliated with them except as a customer) :)
Mike
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Thanks for the info MG.
And thanks for the welcome gentlemen.
I just setup my signature so all will know I am a manufacturer, that I have an affiliation, my company.
Cheers.
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That's cool you added your sig, it's appreciated. But so you know... There is no requirement to do that here on AudioNervosa... We don't have an 'FAQ'... We like freedom. You could be plain ol' Steve if you want. 8) There are no manufacturer forums here and I hope no ones holds their breath about anyone's products... So far we just tell it how we hear it... I really like the analysis and honesty of comments I've read here.
The only real rule we have is to stay out of truly dangerous topics like religion and politics... which was decided on day 1... and so far has been our only real rule. Hope things continue like they are...
Sorry for the interruption... I just wanted to be clear this site isn't run like other forums you may enjoy. ;) Back to your preamp discussion....
-Carl
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mgalusha,
As near as I can tell, the Goldpoint Mini V and the Dact are pretty much the same type control, except for the attenuation values at the 'bottom' of the range. They both use an ELMA switch..and seem to be 'series' type attenuators.
Anyway, IMO, once you use one of these...it's hard to go back to a traditional pot. Very precise controls. Absolutely love mine :)
WEEZ