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Based on experience, I found that any preamp, regardless of quality, degrades sound reproduction compared to a direct connection. My power amp has a passive source selector and passive precision stepped atteuator, allowing me to enjoy life without a preamp. Until now. I had to move my sources away from the power amp, behind my listening sofa, and the number of sources has increased. The need for switching between sources, and to drive a long interconnect (9m) from the back to the front of the listeing room forces me to re-visit preamps. Too bad for me.So how does one evaluate a preamp? I just purchased two units to audition. Since I already know it is impossible to "improve" and only alter the signal from the source, I want to begin by assessing the extent to which a preamp damages the sound compared to no preamp at all. How much transparency is lost by inserting the unit in the system? If all is not lost at this point, I want to assess "how" the unit alters the signal. I don't understand the usual reviewer approach that analyzes individual facets of sound, i.e. deep bass, mid-bass, mid-range, hf, micro dynamics, macro dynamics, etc. Rather I hear different genres of music reproduction that I call "synthetic sound", "euphonic sound" and "natural sound". These are complicated to explain, but the names communicate an idea of the meaning.
Synthetic sound is typical contemporary high-end sound. My reaction to synthetic sound is "this is (or is not, as the case may be) the most amazing sounding stereo system". Synthetic sound excels at resolving detail like the number of cymbal shimmers, background sounds, fingers working frets and keys, breathing, recording session editing, etc. I can hear individual parts, but synthetic systems tend to fail at synthesizing and integrating the parts in to the whole. Or they simply distract from the holistic experience of reproduced music. Euphonic sound is just that - very pleasing to the ears. Music sounds beautifully enhanced on euphonic systems. They may or may not also be resolving and accurate - I've heard both. When I listen to euphonic systems, the experience is like viewing through a golden-tinted lens. It can be pleasurable, but over the long term not my cup of tea. Natural sound is typically unspectacular and unimpressive at first listen because nothing jumps out. No earth-shaking bass, ultra-sonic "air", or microscopic resolution. I guess they error in being subtractive rather than additive. Over time, they become extraordinary for not imparting electronic artifacts or artificial additives. To me, this is the correct approach.
An observation on the "absolute sound", comparison to live music. This is a very silly concept. First, no audio system compares to a live event. Yes, I listen to a lot of live music. Yes, I play instruments (piano now, alto sax and clarinet in the past). Yes, I have listened to some very expensive SOA systems. None of these remotely compares to a live experience. None. But what is intereting are systems that elicit reactions similar to the reactions we experience while attending exceptional live music events. In other words, an exceptional system is one that is able to re-create reactions in the listener that the listener might experience during a live musical event - not trying to re-create the sound of a live musical event, because that is an exercise in futility.
So what does this have to do with evaluating preamps (finally! get to the point!)... To my way of thinking, synthetic sounding preamps are doomed from the beginning. The perceived resolution they render is distracting and has no contribution to recreating the emotive experience of live music. Ask yourself this: when was the last time you were at the symphony or a Stones concert and thought, "I can hear the sound of Mick Jagger's heavy boots when he is strutting across the stage" or "listen to the breathing of the third chair viola in the second row". Who cares? On the other hand, on a euphonic system I listened to some of the most heart-achingly beautiful classical music (Michelangeli on the second movement of Ravel's concerto in G), and on the same system listened to Dereck and the Dominos play "Why does love got to be so sad" recorded live. Clapton's guitar was more beautiful than ever! It was a little weird hearing rock sound so beautiful, but not entirely objectionable.
So, how do you evaluate a preamp? I'm seeking one that allows me to switch sources and control volume, while minimizing corruption to the input signal, and imparting a natural sound.
Follow Ups:
The more it sounds like nothing the better.
That is, unless you are looking for a specific sound.
Unfortunately everything sounds like something so you will just have to accept what is tolerable or pleasing to the ear. Many people [including me at times] claim no preamp is the best preamp, however a very good preamp will have the ability to paint a musical picture that running a Dac straight into an Amp for example just can not duplicate.
Dynobots Audio
The best way I know of to evalute a preamp to first figure out what your system sounds like with no preamp, and then compare the results against the inclusion of a preamp. Having no volume control is not practical and DANGEROUS (don’t try it if you’re unsure), but running a CD player directly to the power amp “commando style” with no volume control device in the loop tells me exactly what my system is capable off without a preamp. Use something like Ravel's Bolero as it starts extremely low and progressively increases in volume, but keep your finger on the STOP button (just in case). I’ve done so numerous times with no ill effects, but I’m not sure if others can.Running commando style, ims produces less "garbage" (noise, distortion, etc.), more details, a higher level of transparency, etc, inserting a lesser quality preamp adds a layer haze or veiling and / or mucks with the signal (trading something like warmth for articulation, liquidity for pace, etc). While I don’t believe anything can be as transparent as one less link in the chain or running commando style, the preamps further up the food chain do less damage and the exceptional ones can somehow make things better than no preamp.
You're driving 9m of interconnect, there's no doubt an active pre is yer best choice. Preamps are funny. As the wag Sam Tellig once said, you have to spend a LOT of money for one that does nothing to the sound! And one that's heavenly in one reviewer's system might sound lifeless in yours. While theoretically a passive is best, I think active preamps often help bring out the best of your sources because they give them a CONSTANT, high impedance load-a MUCH easier thing for most sources to drive. This will often offset the (more than) theoretical insertion loss.
You already know the basics:If yer power amp is low input impedance SS, you're going to have better luck with a preamp that has a low output impedance, most of the time. If you're driving long interconnects, that's a good idea anyway. The bigger the power supply of the pre, the better the sound, IME, all other things being equal. Not all tube preamps sound warm and euphonic anymore; not all SS preamps sound thin or hard anymore, either. Oftentimes, a preamp from the same maker of your power amp will have system synnergy, so maybe that's where you should start.
wow, 9m of interconnect..I'd re-arrange if it were me.
does not guarantee if a preamp works to your liking but it is a good place to start I think.My amps don't like high impedance output preamps.
So, no matter how well-regarded they might be, they just didn't work.
It was not that a pairing sounded horrible or anything ( altho, some were ) but somehow, somewhere, a system lacked in subtle cues that make up a believable hifi reproduction. ( I agree no hifi comes close to the real thing )*I'm seeking one that allows me to switch sources and control volume, while minimizing corruption to the input signal, and imparting a natural sound.*
The one possesses all those traits, for me, was a Naim NAC 552.
> Based on experience, I found that any preamp, regardless of quality, degrades sound reproduction compared to a direct connection.>Theoretically, I'm with you. However, some have found that they prefer the sound with a preamp vs a direct connection without one. Dynamic contrasts may be better with a preamp, for example.
I've questioned Charles Hansen of Ayre and he says many times a preamp will sound better (depends on many things, including which preamp) but he can't explain why.
> My power amp has a passive source selector and passive precision stepped atteuator, allowing me to enjoy life without a preamp.>
I use my Wadia 850 directly into my amps and I'm happy with the sound.
> An observation on the "absolute sound", comparison to live music. This is a very silly concept.>
If you are familiar with the sound of live, unamplified music occuring in real space, then what you are trying to achieve with your system in your room is to get as close to that sound as possible.
Not exaggerated hi-fi with sizzling highs and boomy bass or an overly etched, more detailed, colder than real sound, for example.
What 'the absolute sound' represents is a concept also called 'musicality' - it sounds like real music and draws you in emotionally - like real, live music does.
> So, how do you evaluate a preamp?>Ok, here's what I suggest - find a few of well recorded reference cuts to use in your evaluation. I could name a few I use, but they need to be music you're familiar with and enjoy.
Now swap in one of the preamps and listen for a few days to a variety of music.
Now it's time to switch back to your original set-up. Listen to your reference cuts. Now using a 1kHz test tone, measure the output of your amp at one of the speaker terminals with a voltmeter.
Switch the units. Adjust the volume so the measured output is the same. Listen to your reference cuts in reverse order (last first).
The differences should be obvious. Whether they are ultimately positive or negative may take longer to discern.
Whenever you switch, be sure to match the output.
Have fun with it. Invite a friend or two over (a listening panel) to see if they hear the same things you do.
Various passive attenuators can sound quite different and the same goes for active preamps. You have to try them and listen then choose one that suits your needs.I've had bad passive attenuators and one that was outstanding. Similarly for active linestages, I've had several that were veiled, warm, rolled off, bright, dull, sterile, etc. And a couple that I like very much.
My setup has become more complex over the years with more sources so I gave up the passive linestage for an active solid-state preamp. My system still sounds very good.
Good luck.
Yes keep it simple. The OPs post makes me think he is complicating almost every aspect of the decision making process.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
Don't forget to level match though, very important to not draw false loudness based conclusions.
Didn't you answer your own question: "All preamps degrade sound". Buy a digital source that is close to meeting the gain needs of your amp; attenuate the rest. No preamp would fit you best.
I don't care for attenuating myself. What I find is that the direct hookup is much too edgy. Add attenuation and you shrink the edgyness, but lose detail. Active preamps can do anything you want. They are not edgy and add detail and smoothness.
My Wadia 301 sounds better running through the preamp (ARC LS17) than when connected directly to the power amp. Also, my Wadia dealer told me that it would sound better through the preamp....and for what it's worth, I did not buy the preamp through this dealer....
My Wadia 302 sound best direct to a tube amp using KT88's. Go figure. :-)
delaney - I have an ARC LS15 -I posted earlier this morning asking if people had hooked up their cdp's to amp and am wondering if I should hook my Mark Lev up to my Solid state or tube (ARC VT100) directly. Your post says it sounds better with the ARC in the chain. Are you using a ss or tube amp with that and what, in your opinion, defines sounds "better"?
thx
jmr
SS -- Pass Labs 250.5. The improvement to me is that the apparent dynamic swing or dynamic range seems greater, with more solidity in the bass, and oh so sweet highs..Let me put it this way, using the ARC-LS17, my system sounds more like real music. W/O the LS-17, the system sounds more digital and lifeless.
thanks delaney - an answer I was looking for.
To follow up on your question about McAlister Audio.
I took delivery of a PP-160 and PL-12 preamp. The two are a lovely sounding combination. However, in building this equipment a number of construction mistakes were made:
1. The screws in the case to the power supply for the amp were drilled in a sloppy manner, some not even holding the case together, while others had been redrilled more than once. (I had the case repaired and mounting pieces were welded in the case.) 2. One of the transformers inside the power supply was flopping around on arrival. The bolts were loose. (The floppy transformer was attached to the case with new bolts and isolated with plastic).
3. The volume and balance pots were not grounded and caused a terrible hum when i touched them. They had been glued to the case because the builder did not take the time to counter sink the holes for the shfts, which could then be grounded with the usul locking nut to the case. The shft on one ws bent. (Chiseled old pots off and bought and installed new (better) pots properly grounded to case. Hum went away).
4. The wrong tube sockets were installed for the power tubes and the tubes wobbled. (Installed new sockets and rewired them of course).
5. The transformer covers on the power amp were put on unevenly with reference to the top of the unit. (Cosmetic only).
6. It was delivered with a bad premp tube. (Threw away)
7. The two units in combination had excessive gain, and the preamp volume was loud with the control at 7 o'clock. (Added dual attenuators)
8. Peter McAlister told me he listened to the amp for a number of hours before he sent it. Surely he would have discovered the hum from the preamp due to improper grounding of the pots.
9. It has cost me over $600 to get all this repaired.
The combo sounds lovely. He hand builds and hand winds his own transformers. Everyone who saw them, said they were beautifully made and rugged.
Let me tell you a short story about Peter McAlister. In early June, 2011 I contacted Peter about purchasing a pair of his OTL-195 amplifiers. We agreed upon a price, and about 3 weeks later I received them. Immediately it was apparent they both had a distortion problem. For the next eight days Peter told me how I should adjust them, but nothing solved the problem. I then sent them back to him, at my expense. He said he would get me a new pair immediately. Three months later, and under the threat of legal action, I received a new pair. Immediately, I was not happy with the hum from the separate power supplies. I'd estimate it at 75 to 80 db. I could hear it plainly from thirty feet away! Again Peter said he would get me new power supplies "immediately", That was Sept. 21, 2011. It is now December 22, 2011, and I have not heard from him since November 14, when he said he "almost" had them completed, and would call me the next day. He never called, and I have not heard from him. I have written, and called him, but he has not emailed me or returned my call. I might add, he stated he had played them for several days before getting them to me, and they were wonderful! R E A L L Y !!!!!!
A very brief digest of my 15+ month "odyssey" (to be polite): My pair of McAlister MB-130 monoblocs and separate power supply were finally shipped but packed very poorly (in single wall fresh tomato produce boxes with scraps of rigid styrene randomly crammed inside and a 2" gap between the carton lids and top edge of carton bottoms, sealed with flimsy clear tape and shipped UNINSURED via Post Canada / USPS. Chassis were so severely damaged from (not surprisingly) multiple rough handlings that I would not plug them into the electric service for fear of fire.
Months and dozens of calls and emails later, smooth and fast talking Peter McAlister finally agreed to wire me a full refund per his original verbal "complete satisfaction guarantee" but reneged and went silent.
More months went by and I finally located a Canadian collection firm who went to Canadian court and got McAlister's attention. I received all but $1,500 of the $5,000 he agreed to refund to me. He then demanded that I return the amps. I told him I will when he pays me the shortfall. More silence and incomplete performance on his obligation.
Peter presents himself as a knowledgeable, can't-do-enough-to-please-you guy. So do many used car and time share salesmen. The Barrie constable and collection firm who spoke to him multiple times said he's a "smooth talker" but wouldn't do what he promised them he would do.
That's a shame. You should also post this on the 'Shady Lane' forum.
When the tunes sound more natural....with more swing...more solidity....more sweetness..... Call it what you want, but I call it sounding better.
Define "better". What may look "better" is most likely a coloration.
There is only one objective test for preamps - a by-pass test. The closer a preamp sounds to a direct linked source, the better it is.
But - very often a preamp is needed to compensate weaknesses of a source through added colorations that are considered to be "better".
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