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View Full Version : Anyone modded the pre amp section of the TC 7520?



kininigin
06-02-2010, 16:23
Im just curious to know if anyone has modded the pre section and got worth while results?

I guessing most people have a dedicated pre or intergrated so there aren't
going to be many if any that have done any mods,but i can't help but wonder
if you can get the same sort of improvement that the changing of op-amps and dac chip brings.

DSJR
06-02-2010, 18:37
I'm reliably informed that DAC's these days are very much of a muchness and shouldn't need replacing on the whole. As for op-amps, I haven't a clue, but surely, used within their parameters *properly* there shouldn't be a huge difference. I suspect those that roll these things almost on a daily basis are changing things they possibly don't know about and if anything making it worse.

"Our" Stan will advise I'm sure, since he specified it to start with.

StanleyB
07-02-2010, 11:28
I'm reliably informed that DAC's these days are very much of a muchness and shouldn't need replacing on the whole.
It's time to re-evaluate your source of information and seriously consider replacing it:). I used to listen to such advise, until I realized I knew a lot more than my advisers.


As for op-amps, I haven't a clue, but surely, used within their parameters *properly* there shouldn't be a huge difference.
Oh, if that was true, life would be so much easier for designers like me. Opamps tend to be made according to the frequency spectrum they are likely to be used in, and that alone makes them difficult to cope with. A video opamp used in an audio circuit can break into spontaneous oscillation and kill itself well before one gets the chance to switch off the equipment. so designing a circuit that can take a wide range of opamps is full of pitfalls.

Marco
07-02-2010, 11:40
Hi Dave,


I'm reliably informed that DAC's these days are very much of a muchness and shouldn't need replacing on the whole.


I'm firmly with Stan on this.

"Reliably informed" indeed! Stop letting that idiot from AVI rot your mind.... :doh: :rolleyes:

Why on earth you post there Dave, and succumb to his narrow-minded blinkered bullshit, God only knows.

Marco.

DSJR
07-02-2010, 11:58
Having been taken to task for daring to suggest that a preamp that has sat in a wardrobe for a year may just need or even like (;)) to be left on for a few hours to settle back into its role, I'm reviewing my situation. Oh, "and a £1.50 mains lead will have no more than 0.02 ohm difference than a 37A rated naim one so forget about it" does make me cringe more than a little. Why the entrenchment in absolutes?

Sure you can tweak your DAC's Stan, but shouldn't the object of the thing be to re-create the analogue signal EXACTLY as it was before conversion. I do worry about the fact that you can change the "tone" of the reproduced signal so. I'd rather the DAC was "right" and then tune my system around that, rather than the other way round, which takes me back to the dark era of the 1980's, where a soggy sounding source was livened up by an amp with shedloads of odd-order and crossover distortion and then played through screechy speakers........

Marco
07-02-2010, 12:06
Having been taken to task for daring to suggest that a preamp that has sat in a wardrobe for a year may just need or even like (;)) to be left on for a few hours to settle back into its role, I'm reviewing my situation. Oh, "and a £1.50 mains lead will have no more than 0.02 ohm difference than a 37A rated naim one so forget about it" does make me cringe more than a little. Why the entrenchment in absolutes?


Simple:

Because you're dealing with a clown who has (very obvious) commercial agendas, so you'll never get any real truth out of him!

He'll just tell you what he feels best serves his particular agenda. You'll never learn anything there, Dave, so in my view you're wasting your time.

This is your 'spiritual home' :)

Marco.

StanleyB
07-02-2010, 12:14
Sure you can tweak your DAC's Stan, but shouldn't the object of the thing be to re-create the analogue signal EXACTLY as it was before conversion. I do worry about the fact that you can change the "tone" of the reproduced signal so. I'd rather the DAC was "right" and then tune my system around that, rather than the other way round, which takes me back to the dark era of the 1980's, where a soggy sounding source was livened up by an amp with shedloads of odd-order and crossover distortion and then played through screechy speakers........
Whilst apples and peers both grow on trees and require the same nutrients to stimulate healthy growth, and the same pollination process to facilitate survival of the species, they come out in different shape, colour, and taste;).

The same goes for any piece of audio equipment. What the music sounded like in its analogue state is irrelevant. What the music that is buried in the 16 to 32 bit/42KHz to 192KHz audio file sounds like is what the listener is after. How each of us expects it to sound is the core of the argument. There is not a single piece of equipment in existence that can undo the distortion etc. from the tip of a microphone, through the audio mixing and editing process, all the way to the speaker cone. What we do have is a rough guess as to what the original might have sounded like.

Since you mention distortion:)... I use to spend good money buying all sorts of gadgets that could distort the sound of my electric guitar. Guitar players still do that. Some of the greatest recordings would not have been that great had it not been for a healthy dose of distortion:).

kininigin
07-02-2010, 12:59
Hi stan,can i just get back to the original question for a moment?

Is it possible to get as big an inprovement out of modding the pre section
as it is with the dac section?

I have no knowledge of modding or d.i.y. just mearly curious.

p.s.

Distorted bass,one of man's greatest inventions :eyebrows:

StanleyB
07-02-2010, 13:54
Is it possible to get as big an inprovement out of modding the pre section as it is with the dac section?

What pre section:scratch:?

kininigin
07-02-2010, 14:26
the pre amp part of the dac.

i thought that maybe you could change some componants in this part,or have i got something totally wrong with this assumption.

I've just realized your confusion.The op-amps are what you change.

I was connecting the the op-amps with the dac and not as seperate parts my mistake.:doh:

End of thread :lolsign:

DSJR
07-02-2010, 14:52
Before i shuffle off this thread, I was trying to say that the DAC shouldn't ADD any distortions to what is there.

I'm not a total fool, but apologies for coming across as one.......

leo
07-02-2010, 15:27
I have three main dacs in use here , modified Sabre based, Stans Caiman and an Audial AYAII.

Behaving (no noise,instability etc) and within spec are the main important measurements for me, my ears decide the rest and these three dacs sound very different even though they all measure well

Regarding the pre section in the Caiman, theres nothing really to upgrade, don't mean to sound boring but I'd only start fiddling if your 100% confident what your doing and what your working on, you've got much more of a chance sorting any faults caused by mistakes:)

Shanedudddy2
07-02-2010, 22:34
Which of those DAC's sound the best to you Leo?