How important is the pre-amp?

ing@azwineguy

Dare I ask if it is possible to get decent sound from a home theater preamp?

sound quality is a combination of a number of things.

on this forum with it’s 2 channel focus signal path’s need to be as pure as possible (including the most pure preamp) to optimize the 2 channel media. along with rooms and acoustics which promote 2 channel listening, which is mostly diffusion. the subtle nuance is critical. the speakers are intended to work ’with’ the room.

but a dsp based multi-channel Home Theater system has a different set of rules. the room needs lots of absorption since with 11 to 15 surround speakers for performance you want direct sound not reflected sound. the challenge is still low noise but the dsp process and adding all those speakers makes it less critical (the concept of noise.....is actually signal to noise); especially if you play at the top of the dsp food-chain with 15 speakers and a Trinnov Altitude 16 or 32 processor (it's damn quiet).

https://www.trinnov.com/en/products/altitude16/

but rooms are not chameleons; you have to choose......and if you combine 2 channel and serious multi-channel then one (or likely both) will be compromised. i’m talking degrees of good here, not saying both cannot still be enjoyable.....but still they both can’t be truly optimal since the room rules are different.

i have 2 separate serious rooms; one for 2 channel with mostly diffusion for the walls and one for dsp multi-channel/movies.....with 15 speakers and 3 subwoofers.....and lots of absorption.

you can get fantastic sound from a Home Theater processor, but it’s lots of effort. and if you get fantastic multi-channel sound, then playing 2 channel media will be compromised......although it’s possible you might like some sort of multi-channel effect more than just using 2 speakers for the 2 channel media from that Home Theater processor.

A few comments on the "transformers are the answer" topic.  I agree that especially when you have an impedance mismatch, particularly the wrong way (high into low), that needs **transformation** rather than gain or attenuation (fractional gain),a transformer could be very good.

Its that "could be" part.  They have many issues - several notes above, several not. And like most problems, they can be mostly solved with money, lots of money, and few have attempted it.   No market maybe, or very very hard.   An ideal, variable, volume-controlling transformer must be VERY expensive.

Ditto resistors.  They have issues.  You can buy better ones.  But.... I actually think even modestly good (name brand 1% metal film) resistors are pretty transparent. And with resistors there is a mature market for VERY good ones, and while they too are expensive (like 10-50X the cost of modestly good ones), even at 10-50X they are still less than half a buck (Caddock, DALE mil-spec noise controlled, non-inductively wound, blah blah) or were the last i checked which i admit was years ago.  To be clear, you need a dozen to hundreds of pairs depending on how you implement the solution.  I use 11 pair.  Oh, and a micro-controller  to control the mess.


But look a the big picture: we are now worrying about two more resistors in the signal path, one series one shunt. There are likely dozens in your signal path already. Are you replacing all of those too? Or removing them and inserting.... what?

I firmly believe that for 99% of applications, a true, discrete, stepped attenuator using a minimal number of resistors, great contacts, and good (not awesome) resistors is pretty darn transparent. I can say for sure its revelatory compared to what nearly all of us have heard - and I can do A-B-C side by side tests since i have them all, independent of the preamp circuitry, with a switch to do the rest evaluations.

I firmly believe that for 99% of applications, a true, discrete, stepped attenuator using a minimal number of resistors, great contacts, and good (not awesome) resistors is pretty darn transparent.


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I might have to agree. My tech geek swaers by a good Acoustics (made in Italy) 44 step ateenuator,,but sadly my Jadis DPL has no room for the vol pot..
I’d bet your DIY attenuator + resistors sounds as good/better
as my Jadis DPL with
Mundorf + Philips caps, Takman Rey Metal resistors.
Shorter path = cleaner path...
  Am I following you right.
For just 1 added component, saya  CD player, we only need 1 out
So you are saying a simple DIY 44 step attenuator + some resistiors, = beats high priced pres?
Yes??

as far as volume attenuation, easily the best i’ve heard is on the battery powered darTZeel NHB-18NS; there is no potentiometer or resistor network in line with the audio, volume control being by passive attenuation governed by a dedicated processor via analogue optical couplers, offering 192 steps in increments of 0.5dB.

it is truly transparent, yet dynamically alive. alas, it does run $50k.

i've compared it with other active preamps, as well as the MSB Select II passive, and the Placette Remote Volume Control passive. so far it's my preference to any of those.

For just 1 added component, saya CD player, we only need 1 out
So you are saying a simple DIY 44 step attenuator + some resistiors, = beats high priced pres?
Yes??

Well....sorta. Mine is intended to go into volume production in products so it s a bit more complex. It was never intended to be independent from a preamp or integrated amp, and i have never used it stand-alone.  Mine involves 4 inputs, 32 x 2dB steps, a bunch of relays (not cheap if you want good ones to control all this stuff and get you down from 128 to say 44 resistors) a display, a micro-controller, an IR receiver, and a TON of code. The code is a big challenge - especially controlling the IR, synchronizing actions, displaying where you are, etc. but the results, yes, are clearly superior to my monolithic ladder chip solution (also intended for volume production, in fact sooner) and that is superior to an ALPS or Nobel POT (IMO).


You will also have to design and fab some fairly complex mixed analog and digital circuit boards.


A project like this is not for the feint of heart.

There is a dutch guy selling a complete attenuator kit (two units, dual mono i believe).   I think his are intended to go into an amp, but you could build a box and a power supply.  No balance to the best of my knowledge (which, along with mute, is a logical nightmare BTW since both are stateful and you don’t want to swap states wrong). 


For DIY i’d look at the Dutch kit. I suspect his day job is with Philips. Can’t recall his name, Google is your friend. I really wanted remote control that was as good as the best rotary pots. I suspected they could be better (even the monolithic ones) and they are. See my post way way above.