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Expensive Preamplifiers = Big Scam?

N

nedgar

New Member
Not really trying to troll here; I just need to be edumacated.

I'm in the market for a preamp.

I have a few pairs of modest but nice speakers (small Thiels, small Martin Logans, and small a/d/s/ towers) and a few good power amps (McIntosh MC250, Adcom 555 and a very nice sounding Xindak).

I only have two rooms suitable for listening, so I rotate the equipment from the attic, museum style, every few weeks. The two things that stay unchanged in each room are the CD players and the Yamaha HTR-5790 receivers (with pre-outs) which I use as preamplifiers/surround processors.

The McIntosh and Xindak amps have volume control pots, so they can be used without preamplifiers. Just for fun, I tried hooking up the CD players directly to the amplifiers, bypassing the Yamahas, and lo and behold: it sounds MUCH BETTER! The Yamahas seem to really degrade the sound.

So, isn't the function of a preamplifier ideally to simply get out of the way? Need it be more than a selector switch and a high quality potentiometer (excepting the phone stage for turntables).

What am I missing?
 
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nedgar said:
So, isn't the function of a preamplifier ideally to simply get out of the way? Need it be more than a selector switch and a high quality potentiometer (excepting the phone stage for turntables).

What am I missing?
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You're not missing anything. You broke the code.
 
A "pre-amplifier"'s function is to provide signal switching and attenuation, but also to provide "unity gain". Different sources have different signal levels, so the preamp functions as a way to give the same level signal to the power amp, regardless of input level. So it has amplification duties, albeit with limited gain. A good preamp does this amplification with a minimum of distortion, and keeps the signal pure. Using your "home theater" receiver as a preamp is a poor choice, because it was never intended to be high fidelity--in fact far from it. A true hi-fi preamp will be an asset to your system, rather than a liability. If you want to run a turntable, tape loops, or even more than one source, you need a good preamp.

Something like a Kenwood Basic C2 is a fine unit, and not very expensive. There are other good ones out there, but this is one I have personal experience with, and can unequivocally recommend.
 
You are missing the additional gain necessary to compensate for loss in the volume pot, tone control circuit, and any other "sound shaping" circuits.

It's true that passive preamp could work if it is purely source selection and volume control and used with a well matched source and amplifier. As soon as you add sound shaping circuits, simply subtracting from the signal does not work too well.
 
IMO your using an inferior preamp and that is the true root of the problem.

Some systems sound great with no preamps, and some sound terrible. That is why they call them a "system" because everything has to work well together.

I say if you like it without the preamp, then don't use it!

Evan
 
preamps are like sportscars... the more you spend, the less you get, be it features, hiss, distortion, controls, etc.

running without a preamp can make for wonderful sound, until you want to add some bass or some highs.

im on the fence with this. if im gonna have a preamp in line, i want tone controls. to have a preamp without tone controls i might as well go direct.
 
It's fine with no pre if:

you don't miss source selection.
your source equipment has enough output available to drive your amp to max.
your source equipment has a variable output control.
You don't miss Tone/Loudness/Balance controls.

If all these are okay, it's better to remove the active gain stages (preamp).
 
A great preamp is better than no preamp, or passive.

If in and out impedances are a good match, an autoformer vol control is right up there with the best preamp, but obviously no signal gain. Dave Slagle's are THE BOMB.

This is something I've tried a lot of ways, including Ampex 350 mono preamps with outboard tube-rectifiied power supplies yada yada which sound really great and BIG TONE, but... sometimes 4 separate boxes just for preamp is, ya know, kinda over the top.
 
Jon_Logan said:
For the tone functions or what??
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Dynamics.

I know it's system-dependent, but I've found that a significant loss of dynamics often accompanies the removal of a really great preamp. This assumes your speakers don't have a lot of power compression etc.

I found that the autoformer control gives you the vol control without the loss of dynamics -- but with all the transparency and clarity of no preamp. Resistive and shunt vol controls suck some life out.
 
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tubino said:
Dynamics.

I know it's system-dependent, but I've found that a significant loss of dynamics often accompanies the removal of a really great preamp. This assumes your speakers don't have a lot of power compression etc.

I found that the autoformer control gives you the vol control without the loss of dynamics -- but with all the transparency and clarity of no preamp.
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???? Dynamic Range?? Dynamic range will only get worse when more noise is added. This something that definitely should be in the realm of measurement. Or is this one of those "subjective" only findings?
 
Jon_Logan said:
???? Dynamic Range?? Dynamic range will only get worse when more noise is added. This something that definitely should be in the realm of measurement. Or is this one of those "subjective" only findings?
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No, you misunderstand. Dynamic compression is a form of distortion. When you pay the bucks for a big 4" voice coil pro woofer, you get specs on DB of compression at different power ratings. Or you can just listen and hear how the peaks are not as compressed. To my ears DYNAMICS are the big difference between a weenie stereo and a genuine hi-fi.

Same thing when you take out a really good preamp and just use a passive vol control.

Come by my place and I can let you hear it. On a big horn-loaded system, it's not subtle. For pro drivers, there's a measurement, and there COULD be for systems... but that would be hard to do. Doesn't it mean it isn't real though.
 
I've read a number of times where people say passive pres suck the life out. Often wonder if that's really true, or if it's one of those illusion-type of things.

Certainly there could be some placebo effect, for lack of better terms, if one has to turn the volume knob to the 3 o'clock position with a passive, to get the same volume that may have been attained at 10 o'clock position with a preamp having gain.
 
Like everything else, you get what you pay for. If you are looking for a good vintage preamp, there are many out there. I sure love my GAS Thaedra and Carver C4000, but any good preamp should serve you well. Also go with fairly good interconnects.
 
whoaru99 said:
I've read a number of times where people say passive pres suck the life out. Often wonder if that's really true, or if it's one of those illusion-type of things.
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Forget reading. Set it up on the best system you can put together. Do it with the equipment of 2 or 3 friends on an audio night, if that's what it takes. If the rest of your system is not suffering from a lot of dynamic compression, you can hear the difference between amps, speakers, and switching out preamps, all in terms of dynamics.

Other than my horn-loaded system (the he-man rig), I like to listen to JBL 2226 in a 4ft cab. Spec sheet shows it has power compression of 0.7db at 60w. Maybe that doesn't sound so great, but remember this is a 97db/1w/1m driver, so 60w is a LOT of decibels, and 0.7 is not a lot. (I never get close to 60w, though the driver is rated for 600w.) For your amp to keep up (avoid compressing) it will need an overbuilt well-engineered power supply (not just a lot of watts). That rules out a lot of amps.

Get a decent CD player and try it. You want to compare a special preamp to a passive/nothing -- preferably low-gain linear low-distortion octal tubes like 6SN7. If you can get your hands on an autoformer for comparison, so much the better. Tell us what you find.
 
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You make no sense whatsoever. Perhaps you meant terms other than dynamic compression and power compression? They do not mean what I think you think they mean...
 
Yamaha HTR-5790
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IMHO not a very good audio HiFi preamp.Geared more for home theater duty . Get yourself a seperate HI FI preamp. There are tons of pretty decent sounding preamps out there.:yes:
 
I've got a passive attenuator and a number of active preamps. I prefer the active preamps. The passive doesn't sound good with most of my amps. It sounds great with one of them. The quality of the preamp makes a big difference in the sound quality of the system.
 
A good 2 channel preamp will sound an order of magnitude better than the preamp section of a HT receiver. However, most "good" preamps have no tone or loudness controlls. IMO the way to go is with a preamp that has an HT bypass. An HT bypass allows you to connect a tuner, TT and CD player to the preamp and power only the front channels. With the HT receiver's front preamp outs connected to the bypass input on the preamp (set to bypass position) you can still use the multichannel capability of the HT receiver driving the same front channel amp(s) and speakers.
This is how I do it.
My Lexicon processor goes to an input on my preamp. It doesn't have an HT bypass. I made some measurements and found the volume control position that gives unity gain. When I switch to that input I just set my preamps volume control at the unity gain position and use the Lexicon to control system volume. When I play CD's, LP's or any 2 channel sources my preamp controls volume. The Lexicon controls volume for all multi-channel material.
 
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