John Curl's Blowtorch preamplifier part II

[Esperado]

Originally Posted by Kindhornman

John,
What was left of the original circuit of the Berhinger by the time you made all of those changes? It would seem that the only thing you kept was perhaps the A/D D/A converters. Sounds like you found not much to like with the unit as it was delivered. I see people on many forums recommending those units, seems like something is amiss here. Perhaps those others have a lower standard than you do for acceptable sound quality?

Original SMPS is a miss with a lot of hf leakage and noise. And do not long last.
Replaced by an analog one with low noise +-12V regulators.
+5v regulated for DACs and ADC replaced by a very very low noise one.(critical)
2 Clocks replaced.(Jitter)
DAC ak4393 replaced by ak4396 (a bug in the original one plus better linearity).
Output stage, using poor op-amps, replaced and simplified (some use only one cap/channel).
Each step brought a very clear improvement (not some cable sound ;-)
It is just playing with some circuits around, the main thing remain unchanged. Modifs until everything satisfied-me.

At the end, it makes for few buck a may-be better powerful digital filter than X10$ equivalent equipments. In his original state, it was ruining my system, but my system and i are, how to say, very intolerants. :-).

[fas42]

Originally Posted by Joshua_G

Indeed.
It seems to me that my CDP (AMR CD-777) is on the short list of the really good ones.

Good to hear, ...

John, to give you some perpective, at the hifi show I went to recently, the room with the best sound -- smooth as silk, beautiful treble -- when I revisited it a little while later had fallen off its pedestal, Oh no!!, the classic CD sound, edgy, uncomfortable, didn't want to hang around. What had happened? The demonstrator, who in fact was the principal of the business, had switched from music server to an Oppo player, which in fact was only performing as a drive, the DAC was a Lampizator. To play a disk a visitor had brought. And the sound quality was dragged down severely by that single factor ...

Asked the guy later about it, and he agreed, the Oppo was causing a major "problem", said music server was the only way he would go otherwise. But wasn't going to rip the CD on the spot just to do a quick demo ...

Frank

[Esperado]

Very often, i chose consumer parts, chosen to sound near ok, and do the job i need. Then modify-it for the best result, instead of buying "Golden Pinnae" i can't afford.
Everything, even my Revox tape recorder are modified that way, except my DAT (i hate DATs) and my minidisk witch sound ok from origin for what it is.

Did you do the same, or do-you prefer to build everything from scratch ?
Of course i designed and build my own analog power amps and enclosures from scratch.

[SY]

Originally Posted by john curl

DARN, and it should be so easy! '-)

And it is, if you approach it without the chains of tradition and preconception.

[kgrlee]

Originally Posted by Kindhornman

Since we are talking here about discrete transistors and not ic's is there a point where the newer devices are no longer relevant to audio reproduction? What I am asking is, is there a point where the increased bandwidth and speed of the transistors becomes more of a problem with rf , emi, and other high frequency anomalies that actually are a detriment to the production of audio frequencies?

Yes. For OPAs, this point is probably at Guru Wurcer's AD797.

OPA measurements has a good discussion and though I don't agree with all his recommendations, the tech stuff is mostly accurate.

eg OPA627 is probably more trouble than its worth for little or no real life gain. There are loadsa threads on diyaudio and groupdiy where careful attention to decoupling & earthing gives MUCH more benefit then slotting in a supa dupa OPA.

It's almost certain that where real differences are heard with OPA rolling, its due to the supa dupa OPAs complaining by oscillating & distorting.

Both AD797 and the supa stuff discussed in 'Discrete Opamp Open Design" need meticulous attention to earthing & decoupling. As does a 5532 or even NJM4558 to achieve their potential.

Exactly the same principles apply to a discrete design. You design for a target performance. Otherwise you are just playing at being a pseudo guru.

Usually, better transistors with good ft etc make it easier to meet stability targets but it's all dependent on the design. Good design is robust in the face of poorer bits but also benefits from better bits.

IMHO, stuff that need cables incubated for 12 mths in the crotches of virgins will probably not pass the important Hirata & Quan tests .. and will also be rejected in simple Blind Listening Tests.

[john curl]

Gee, and I thought OPPO to be pretty good. Shows what I don't know.

[john curl]

4558?

[fas42]

Originally Posted by kgrlee

Good design is robust in the face of poorer bits but also benefits from better bits.

That's the key, for me. Again, what I'm using at the moment is a piece of rubbish, a throw-it-in-the-bin really, but it's helping to prove a point, for me. Good parts, quite well assembled, but absolutely nothing special, and it's on its last legs. The aim here has turned out to be to see how cleaning up the mains supply coming in "fixes" things, and when all cylinders are firing it can put on a pretty special turn.

Christophe, if you're talking to me, over the years it has been a mixture; but more often than not, epecially of late, it's sorting out over the counter gear, nearly always 2nd hand or worse.

Frank

[Joshua_G]

Originally Posted by fas42

Good to hear, ...

John, to give you some perpective, at the hifi show I went to recently, the room with the best sound -- smooth as silk, beautiful treble -- when I revisited it a little while later had fallen off its pedestal, Oh no!!, the classic CD sound, edgy, uncomfortable, didn't want to hang around. What had happened? The demonstrator, who in fact was the principal of the business, had switched from music server to an Oppo player, which in fact was only performing as a drive, the DAC was a Lampizator. To play a disk a visitor had brought. And the sound quality was dragged down severely by that single factor ...

Asked the guy later about it, and he agreed, the Oppo was causing a major "problem", said music server was the only way he would go otherwise. But wasn't going to rip the CD on the spot just to do a quick demo ...

Frank

I had a similar experience. A while ago there was fire in my house. Of the stereo setup gear, only the transport part of the CDP was damaged, the DAC part of the CDP works fine. For few months I couldn't listen to music at all, because of the curtains (drapes), which serve as acoustic treatment, burned. I don't enjoy listening to music in my reverberating living room, without any acoustic treatment. A couple of weeks ago I ordered from AMR the spare parts for the CDP, they are on their way. Yesterday, at long last, curtains were installed again. Finally I can enjoy listening to music again. The turntable is intact. Until the CDP will be repaired, I played few CDs, when my universal player, OPPO BDP-83SE Nuforce Edition, served as transport and the AMR served as DAC. This way, CDs sound much better than the analog out of the OPPO, yet the CDs are barely tolerated this way, while they were highly enjoyable with CDP serving both as transport and DAC.

It is my experience that in audio everything matters, including power cable and interconnect cables. In digital audio, it is far more noticeable that everything matters.

[Esperado]

Originally Posted by fas42

Christophe, if you're talking to me, over the years it has been a mixture; but more often than not, epecially of late, it's sorting out over the counter gear, nearly always 2nd hand or worse.

Thanks, Franck. i was asking to everybody here, you included, of course :-)
There is lot of things you can reuse in an industrial part: trasfo, chassis and plugs, and even a good part of components. Sometimes, changing few things (regulators, caps, Ac filtering, some OPA replacements, boosting current after out stages you can bring the thing to the top in little time and few bucks. And keep the very clean industrial aspect, once closed.

By example, i have dumped the CD mechanic of my Marantz with lead foils, replaced the DAC and clock, and the analog stage in less than 5 hours. Sound like a charm.