How to choose a quiet pre-amp? And understanding the specs on it?

HiFiJeff

Super Member
I have been looking at multiple amp options. a guy who owns the amp that I am looking at said that it's a great amp but needs a quiet pre-amp, especially with efficient speakers, which mine are. 97db.
I have no idea what to look for or what constitutes a pre-amp being "quiet"
 
Read reviews from established Audio magazines is a start. Look on line for explanations of specs from reviews. Narrow down brands your interested in and go out and listen
That said my Adcom 750 is the quietest pre amp I've ever owned. After modification it still is.
The noisiest Phono stage in a pre amp I have ever owned is a VTL ULTIMATE which is in storage. The Cd output was quiet as a church mouse though.
 
Good question. In amplifiers, quiet amps are typically amps that are very fast and objectively accurate. Slew rate, rise time, DF will give some indication of speed and accuracy but the real test is on a 'scope. Preamps can be tested with a 'scope and will show what is being added or subtracted. Not sure what preamp spec to look for.
 
If this amp I am going to buy is going to add significant noise or hiss or add anything, I don't want to buy it. My system is pretty dead silent as is. Here are the specs on my pre. I have NO IDEA what they mean.

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Better certainly exists but should do fine for $350. The key specification is signal to noise ratio, but note that it has a switch mode power supply which can inflict noise on other components. I would isolate it from the AC using a power conditioner.

You can likely find a vendor with a money back guarantee to check it out first. A couple of reviews said the upper midrange/top end could be shrill. You're definitely getting op amps at that price.
 
I don't quite get "says it's a great amp, but needs a quiet preamp." All amps need quiet preamps. The quieter, the better. Of course, if the amp itself is making noise, it won't matter much how quiet the preamp. Sounds almost like someone is trying to prepare a buyer for a noisy amp. No, I don't get it. I just get suspicious.
 
What is the impedance of your pre amp? Is it a good match impedance wise with this amp? Is it an option to hook your pre amp up to the amp for a listening session?
 
What is the impedance of your pre amp? Is it a good match impedance wise with this amp? Is it an option to hook your pre amp up to the amp for a listening session?
Most connections between pre-amp and amp are unbalanced. (low impedance to high) Therefore, impedance matching is out the window. What you should try to match is sensitivity.
 
Thanks for all the input. I am just going to buy it and try it out. It's a $1300 amp on sale for $499. If Ilike it cool, if not will send it back. But I will re-visit this thread just to give you guys an update.
 
Jeff: As E-Stat already mentioned, signal-to-noise ratios would be the key specs to compare in that case. However, unfortunately that isn't always so easy - or respectively one has to heed the details, in order not to compare apples to oranges.

Example NAD 1130: Signal-to-noise ratio specs look somewhat modest at the first glance, but then the 98 dB(A) for the line-ins are for a rated output level of only 0.5 V - and, similarly, the 76 dB(A) for the MM input also arent for the usual 10 mV input signal reference level and shorted inputs, but for a 5 mV signal and cartridge connected. So if you'd compare those specs to those of a pre-amp with a rated output level of 1.0 V as well as the usual 10 mV and shorted inputs in case of the MM input, you'd have to add a few dB each, as the 1130 would measure better under these conditions.

Unfortunately one is often confronted with such fine details in the realm of hifi specs. And unfortunately manufacturers often enough don't even provide sufficient details - so not rarely one can't be quite sure, whether one's actually comparing apples to apples...

Greetings from Munich!

Manfred / lini
 
You want low THD and high SnR in a preamp. It also needs to be able to "drive" your amp. So, you want to match it to your amp. For this, you need to know output impedance and voltage of the preamp and input impedance and voltage of the amp for best results.

Preamp voltage must be high enough to bring the amp to full power so greater than the amps input voltage. Amps input impedance should be minimum 30x the preamps output impedance unless you are running super short interconnects.

The yammy you listed has low THD and high SnR but is missing the rest. The amp's spec list are beyond useless and more a bunch of marketing speak. Anyway, hope it works out should be okay.

Edit: Saw the amp spec now. Your pre is fine for those specs. As is a passive if you are using a digital source as those mostly have a low output impedance and output 2 volts. Just don't run really long interconnects.

However, it has been my experience that while passives sound super clean they lack slam. Every time I have used an active preamp in place of a passive the music just sounded more dynamic with better bass response. YMMV.
 
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If you are using digital (DAC, DVD/SACD) as your source, you might try one of the inexpensive passive pre-amps that are out there. If no added gain is needed, that might be a simple answer.
 
If you are using digital (DAC, DVD/SACD) as your source, you might try one of the inexpensive passive pre-amps that are out there. If no added gain is needed, that might be a simple answer.

If your digital source has variable output, you don't need a preamp at all. In fact this is how I test a preamp. Put it in and listen. Remove and listen. Whatever the pre adds or takes away is what the pre sounds like.
 
With your high efficiency speakers, and with that amp that appears to have a high enough input impedance, you might try the $60 Nobsound or the Schiit passives. My prior preamp is on the shelf now. The transparency is a step up. With efficient speakers gain can often be an enemy.
 
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