Audiophile quality preamp

[AudioLapDance]

Cello Palette Style EQ Design (was High End Tone Control)...
"
Bass [20Hz]
Drum [120Hz]
Lower Voice [500Hz]
Presence [2Khz]
Rasp [5KHz]
Air [20KHz]
"

[SonyFan]

Sounds like you like to play DJ, why not just get some pro audio kit? Best EQ you can buy as well as various other functions. If you are playing a preamp as an instrument you'll have a blast with a DJ controller, mix console, and rack EQ. Assuming money is no object, that is.

[Bob Richards]

I agree with benphysics, flat is usually harsh or brash or thin etc. The recording process is often a crapshoot created by a poorly educated mixer guy. Level changes bring up the issue of a "loudness comp" function, but it's got to be done right (variable). More bass should always sound better, but there's the shroeder frequency room acoustics issue that usually causes boominess, so more bass will often make that worse.

Personally I think it's laughable that high end preamps rarely have tone controls, and if they do the tone functions are meager. I prefer a 4 section Baxandall (variable slope) tone circuit myself. Any less is not enough, and any more becomes a distraction from the listening experience.

I chose to design and build my own preamp just for this reason. See it at my website: Bob's Website

[kouiky]

Originally Posted by benphysics

I used to have an acoustic room strictly for listening. Ceiling and walls were 12" thick with 5 layers of sound isolation materials. The floor was mounted on pneumatic suspension. Had over 8,000W of amp power divided into a three way active crossover network.

Did you haveto pump it up before each listening session?

[benphysics]

Actually the room was virtually maintenance free. The floor was built out of 2x10 joists sandwiched between 5/8 baltic birch plywood and all was glued together. Between joists the floor was filled with insulating materials and the upper part, the part we sit on is carpeted with a 1/2 inch underlayer of felt material. The entire floor was octogonal 16 feet diameter on the corners. It rested on 12 firestone suspension airbags (automotive type) inflated at 20# pressure. I would verify it every 3 months, but never had to readjust in 9 years I owned the home. I then moved from Quebec to British Columbia, in Canada that is. When the music would play in the neighborhood of 115 to 120 db, it was easy to hear a fly sooming around. Actually, it was even disturbing; we had to catch it and throw it out of the room.

[adason]

Originally Posted by benphysics

Actually the room was virtually maintenance free. The floor was built out of 2x10 joists sandwiched between 5/8 baltic birch plywood and all was glued together. Between joists the floor was filled with insulating materials and the upper part, the part we sit on is carpeted with a 1/2 inch underlayer of felt material. The entire floor was octogonal 16 feet diameter on the corners. It rested on 12 firestone suspension airbags (automotive type) inflated at 20# pressure. I would verify it every 3 months, but never had to readjust in 9 years I owned the home. I then moved from Quebec to British Columbia, in Canada that is. When the music would play in the neighborhood of 115 to 120 db, it was easy to hear a fly sooming around. Actually, it was even disturbing; we had to catch it and throw it out of the room.

...I know the feeling, and then you woke up...

[kouiky]

Woah...the fly was audible with music playing at 115-120 dB. I'm glad that part is over!

MiniDSP is said to be good for bass management, but not so much for main channel audio listening. Their support forum is also a mess and I will leave it at that. You might want to look into the preamp/DSP/digital crossover from DEQX. That would be worth a listen. Another would be the Accuphase DG-28 DSP that was said to be sonically invisible, and may have had a volume control for preamp duty. Stay away from the Classe crap.

On the other hand, the distributor of Harbeth once said "You should never try to compensate for something a speaker can't do". In light of that, I have yet to see a perfect speaker, recording, or room all in coincidence.

[benphysics]

Originally Posted by Bob Richards

I agree with benphysics, flat is usually harsh or brash or thin etc. The recording process is often a crapshoot created by a poorly educated mixer guy. Level changes bring up the issue of a "loudness comp" function, but it's got to be done right (variable). More bass should always sound better, but there's the shroeder frequency room acoustics issue that usually causes boominess, so more bass will often make that worse.

Personally I think it's laughable that high end preamps rarely have tone controls, and if they do the tone functions are meager. I prefer a 4 section Baxandall (variable slope) tone circuit myself. Any less is not enough, and any more becomes a distraction from the listening experience.

I chose to design and build my own preamp just for this reason. See it at my website: Bob's Website

Hey Bob you are my kind of guy. We are definitely on the same page. I went onto your site and saw your preamp. This is what I want to build; something in the same range with preferably 5 bands (enhanced parametricly variable) including a sub control crossed in the vicinity of 125hz as a bi-amp network. I don't know if you ever heard of an audio decompressor. I made one in the early 70s. I made it differential amplitude variable. When music were recorded onto vinyls, (mind you they still are), the physical size of the groove was too narrow to reproduce the full spectrum of the signal. Therefore, during the recording process the signal was compressed: this means that the lower amplitudes were increased while the higher ones were decreased. The decompressor was a little trickier to reverse the process. therefore I made it differential amplitude variable. In my room, I would reach the same effects as if the band was live inside the room, but we would be inside all speakers facing us. Quite a treat. Hey keep me informed if you decide to revamp that preamp of yours with state of the art components.

Stay in touch,
Ben

[Jonathan Bright]

Hi Ben,
I like your thinking. The "loudness control" is an interesting area. To my mind far and away the best one I have seen is in an old "Journal of Audio Engineering Society" mag from the 70's. It was good, very clever and cheap to DIY. It was interesting because the designers built it with a variable "break point" for the bass reinforcement. I.e. as the volume decreased the point at which the extra bass increased moved up the frequency scale. (Or more correctly, the point at which the lower mids were depressed moved up in frequency....)
From memory each channel involved only one op-amp and a handful of passive components, the final result was within plus or minus 3db of the Fletcher/Munson (if I've spelt it correctly) curves over a 50 plus db range, all controlled through one linear pot that carried no DC current.
Now I can't put my hands on my copy at the moment. If you're near a Uni you might chase it up. But I can recall that it was NOT an item listed on the cover (sorry) which will make it harder to find but was down the back in the "Engineering briefs" section I think. If you do physical search you will need to check the index....
I'll have a look at my "archives" and see if I can get a more precise reference, date Vol. No. etc......then you can but a copy from them for a small fee even if not you're a Audio Society member.
Cheers,
Jonathan

[Jonathan Bright]

Hi Ben found the complete details for the reference above;
"Practical Loudness:An active circuit design approach." Arthur L Newcomb and Richard N. Young. JAES Jan/Feb 1976 Volume 24 No.1. Down the back in "Project Notes?Engineering Briefs"
Cheers, Jonathan