What is a preamp?

[richidoo]

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

[WEEZ]

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.......

[WEEZ]

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.  

More...

[WEEZ]

Sorry you asked?  

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....

[mdconnelly]

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!.

[lonewolfny42]

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.

Chris

[richidoo]

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

[Carlman]

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

[richidoo]

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

[WEEZ]

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.....

[WEEZ]

So enough boring technical stuff...

But which one to buy? Hell if I know

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

WEEZ

[WEEZ]

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 well, ah, mmm, er, ah... well.....umm

[richidoo]

Thanks WEEZ. I will be checking out a few choices in the next month. Thanks for the tip and the insight into preamps!
Rich

[shep]

I've been quietly grinding my teeth 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.

[Carlman]

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...