2. amps-preamps
  3. 1060874640

What does a pre amp do

I have been trying to get an answer to this question, but so far have not been enlightened

In a modern system, the role of a pre amp is really questionable.

Historically, a pre amp would provide quite a number of real functions such as source selection, impedance matching, maintain volume consistency from different sources, volume adjustment, mute, balance, even tone control, high/low filters

Today, most people have a single CD source with XLR interconnection, which standardized impedance and signal level. Some CD and DAC (such as wadia) has digital volume control. In fact wadia does recommend people to connect directly to their amps

At least in thoery, the best preamp is no preamp. Even the preamp manufacturers agree as evident by the extent they go to separating power supply, minimize signal path. Then there is the passive preamp

So here is the question, is preamp a historical appendix that audiophiles are afraid to get rid of due to the fear of missing out on some unknown elements of music. Or is it really a percived need created by good marketing programs to exploit audiophiles

The obvious answer may be to try it out with and without preamp in the same system. The results I have heard so far are controversial, some claims much better transparency and clarity while others claim there is a lack of dynamics and less musical

I do not believe answers from "experts" who happens to be in a sales position. They always give a very affirmative answer and yet refuse to let you do an A/B comparision.

Most modern preamps are an empty box, and do we need to pay high prices for a piece of equipment with no known function
ag007
rgodin
85 posts
 
Wadia's site clearly states that there a loss of resolution unless the digital volume control is run at maximum (no attenuation). The more the attenuation, the higher the loss of resolution. If your amp has average gain and your speakers are more than average in efficiency, you are going to have the volume much closer to the bottom of the settings than the top.

I wasn't able to find a discussion of Musical Fidelity's volume control on their site. Is there a link ?

If transparency is what you want, then test driving a Placette passive might be worth the effort. It's not overly expensive, but supremely transparent and your money back if you don't like it. www.placetteaudio.com
ag007 OP
3 posts
 
Rgodin, many thanks for the info on Placette. It is worth looking into

I read the info on Wadia website and the understanding I have is that there are switches at the back of the unit that can be set to match the input signal level of the amp. It also states the volume is manipulated in the digital domian which does not introduce any losses or distortions. In fact Wadia does so much DSP to shape the noise based on empirical data from listening tests, the volume adjustment is just another step within this DSP which is taking place already.

As for Musical Fidelity, my understanding is that they actually have a preamp section (from their preamp product) integrated into the pre CD. MF is known to do that and spares no expensive to achieve good results. The Trivista SACD is actually a CD and a SACD inside the same box. Unlike other SACDs which is usually weak in CD playback due to sharing of same circuits which are optimized for SACD. This is one of the main reasons I bought the MF Trivista

Back to the original question of pre amp, notwithstanding that this is a known controversial subject, we should continue to get different views from people who have experimented. This does not mean all of us have to come to the same conclusion, but all of us will be making more informed decisions in pursual of our hobby

Happy listening
redkiwi
1,092 posts
 
I should add, the problems I reported on above were more with the Res Audio than the Audio Aero and I still run my Audio Aero into my tube monos. But the Res Audio runs through an SCE HRS before my Plinius SA102 - and there is no doubt the SCE HRS is worth its cost, the cost of a PC and an extra interconnect.
mjcc
3 posts
 
The stage of gain that a preamp induces is critical to complete the musical signal. Its like reversing the DNA of the signal and playing it back. (riaa curve)

Passive preamps just dont make it. People think they sound better but in the end, and on whole, they don't.

Forget the new wave of thinking, get a killer tube pre-amp and get happy.
redkiwi
1,092 posts
 
I share your views on passive preamps. But the Res Audio players do not have a passive preamp in them. They have an active line stage that that follows the volume control and that, on paper, looks as good as any decent silly state preamp, with oodles of drive and low output impedence. Maybe it is not as good as claimed - don't know. But I find that the problem manifests itself, even with a preamp in place, if I run the Res Audios at lower than full volume. Again, I doubt you can point your finger at the quality of the volume control, but it appears more likely to be the problem than the output stage. I think I recall hearing that the volume control is the same as that used by Rowland. My theory is that when implemented in a CD player that it attracts more RF problems the more resistance is introduced into the signal path. I have that theory for no other reasons than that; one-box CD players are tricky beasts to keep digital nasties out of the analogue (which is why DVD players sound bad IMO - much more digital rubbish sprayed around inside the box); the effect on the sound increases as volume is attenuated; and, the effect sounds awfully like RF problems I have experienced at other times and in other systems.
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