Tweaking existing solid state

G-7 · « **Reply #20 on:** 4 Mar 2003, 12:42 am »

Do you mean Pass, the famous DIY design. Nah!
I don't understand what you mean by forward biased?

Tweak1 · « **Reply #21 on:** 4 Mar 2003, 12:42 am »

G-7. I am very happy with BV Audio PA300. Clearest window to the actual event I have owned. See reviews at www.bvaudio.com

JohnR · « **Reply #22 on:** 4 Mar 2003, 12:44 am »

Quote from: ABEX

In my opinion if an amp is not forward Biased tp run closer to ClassA SUCK!There is a veiling that once you get rid of it you'll never go back to listening to amps that are not.

I beg to differ. I have tried the Monarchies and did not buy them. I now use a low-bias class AB amp. In all fairness it was a few years apart, perhaps my speakers sucked back then. At any rate, it's becoming clear to me that it's much more about the implementation than the technology (class A/B/D; tubes/solidstate etc etc)

G-7 · « **Reply #23 on:** 4 Mar 2003, 12:48 am »

Quote from: Tweak1

G-7. I am very happy with BV Audio PA300. Clearest window to the actual event I have owned. See reviews at www.bvaudio.com

What is it? Another DIY project?

JohnR · « **Reply #24 on:** 4 Mar 2003, 12:51 am »

Oh, sorry, I thought you were asking for suggestions

G-7 · « **Reply #25 on:** 4 Mar 2003, 12:52 am »

Yes, but good one.

JohnR · « **Reply #26 on:** 4 Mar 2003, 01:00 am »

How are you going to know what's a good suggestion if you can't even be bothered to spend five minutes looking into them?

JohnR · « **Reply #27 on:** 4 Mar 2003, 01:55 am »

Lemme try again

Someone said, if not in this thread then somewhere around here very recently, that commercial designs are subject to all kinds of cost constraints. The infamous beancounter effect, the ol' 5 to 1 retail to actual cost ratio. Many tweakers believe -- rightly or wrongly -- that they can overcome the worst of these limitations by tweaking. Fast diodes, better caps, wire, connectors and so on.

So in response to a question like "what amp can I get that doesn't need tweaking," my suggestion is to make (or have made) one that is "pre-tweaked." The AKSA Nirvana is the sum of a bunch of "tweaks" developed over time. So, build (or have built) one of those, together with the wire and hardware you think you would use as replacements if you were going to tweak an off-the-shelf amp... and bingo! an amp that never needs tweaking. With more predictable results.

OK. It's a suggestion, you can do what you like with it. Cheerio

JohnR

audioengr · « **Reply #28 on:** 4 Mar 2003, 02:08 am »

JohnR wrote:

Quote

At any rate, it's becoming clear to me that it's much more about the implementation than the technology (class A/B/D; tubes/solidstate etc etc)

Sure, circuit design is important, but for detail rendering and natural sweetness, you need class-A operation. I have compared scads of A/B SS amps to my CODA and they are never as sweet, including Spectron class-D. I believe that class-D can be as sweet, but it is harder to get right. Every class-D designer has their own secret circuit topology and feedback etc... I believe that these have the same drawbacks as class A/B. Needs to run open-loop and be very fast responding. There is one amp from Chateau Research that is digital, but not class-D that shows a lot of promise. I believe it is the only "sweet", fast digital amp on the market. $6K for a 500W/chnl stereo amp, with transient capability to 1500W/chnl.

JohnR · « **Reply #29 on:** 4 Mar 2003, 02:13 am »

Quote

Sure, circuit design is important, but for detail rendering and natural sweetness, you need class-A operation.

Again, this is the kind of absolute statement that just doesn't jive with real experience, and which I think is responsible for leading a lot of people up the garden path. I've heard class A amps too. A huge Pass amp in a system with monstrous Dunlavy speakers, I forget the rest of the equipment. I couldn't wait to get out of there.

YMMV, as the saying goes...

ABEX · « **Reply #30 on:** 4 Mar 2003, 02:18 am »

The following is a thread that was about veiling of vocals and what the cause was .It was answerd by Ralph of Atma-Sphere .It was intresting when I first read it and makes sense to me anyway's.

He by the way makes and designs Tube gear.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1028117475&openflup&5&4#5

ABEX · « **Reply #31 on:** 4 Mar 2003, 02:31 am »

My impression has always been that the less of a crossover glitch there is the more effiecient an ampifier would run when concerning switching inside the amp.Class A means that this loss that can be accounted for when transistors are acting back and forth by just running as in a straight line draw.

Another words ClassA amps run more linear.This why I and other would much rather have a Class A amp then one in Class A\AB although there are some great A\AB amps that are forward Biased to run closer to ClassA,they will run hotter.That is what I was saying by Forward Biasing.

BTW Rotel amps show this characteristic of a veiling that even a set of $3200 Transparent cable cannot cover up to my ears.

G-7 · « **Reply #32 on:** 4 Mar 2003, 02:33 am »

Quote from: ABEX

The following is a thread that was about veiling of vocals and what the cause was .It was answerd by Ralph of Atma-Sphere .It was intresting when I first read it and makes sense to me anyway's.

He by the way makes and designs Tube gear.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1028117475&openflup&5&4#5

Bi-polars are more linear amigo!

ABEX · « **Reply #33 on:** 4 Mar 2003, 02:40 am »

08-01-02: [email protected]
Hi Rwwear, if you remember reading that mosfets are not linear either you remember wrong or the material you read was wrong. Mosfets tend to have greater linearity then most bipolar devices.

The Gamut is a good example of what can be done with them.
[email protected]

That was in the post I just put up.You might be correct in your assumption ,but that is what Ralph from Atma-Sphere said about it.I have had both types of amps and I am using a Mosfet design at present.Intrestingly Pass and Coda went to different approaches.

G-7 · « **Reply #34 on:** 4 Mar 2003, 02:51 am »

MOSFETs are more thermally stable than BJTs thanks to their negative thermal coefficient. They are easier to design with, no beta droop, no
secondary breakdown, automatic current limiting.
BJTs have a much higher transconductance and thus higher linearity.
Capish? I don't care what your buddy wrote. Can imagine those amps........This is a fact you know.

ABEX · « **Reply #35 on:** 4 Mar 2003, 03:01 am »

Well without more dialog of tweeking to get better sound using either Bipolar or MOSFET my choices still stand.Odessey & Monarchy.

I have been seeing more great quality amps showing up on A-Gon for around the $1K mark and that is where I would look.Krell,ML,B&K,Adcom and Coda can all be bought for under $1K if you are patient enough and are the first in line.Beyond that there's always DIY.

Happy hunting!

ranmart · « **Reply #36 on:** 11 Apr 2003, 05:42 am »

I'am new to tweaking so does any one know if you can tweak a sony STR DE-575 AMP and where I could get the parts and any how to info.Thanks

ABEX · « **Reply #37 on:** 11 Apr 2003, 05:48 am »

I use to own Sony amps and there is no one I know of that does mods to them.

I do not think there are any Japanese amps that are tweeked to my knowledge.There are plenty of Japanese based DVD's that are.

Most people that tweek amps do it to american made amps.

I do not think you'll find a schematic to any either because they guard their designs like it's the post Japanese attack on Pearl Harbor.

Ypu could try to open it up and exchange the Caps and Transformers though,but thats risky if you do not know what your doing or you get the values wrong.

Happy hunting!

ranmart · « **Reply #38 on:** 11 Apr 2003, 06:18 am »

I've never open any of my stuff before so where are the Caps and Transformers on most machines and what will that do to the machine to make it better?Are there any good on line stores that sell parts.Thanks

What I want tweaked the most it the power supply so I can get a better cable and the binding posts for better speaker cables.Are these tweaks hard I gussing they are.Thanks

ABEX · « **Reply #39 on:** 11 Apr 2003, 06:22 am »

Ranmart:
P would venture to say it would be to hard to do on your own.There is a shock hazard also.

I would ask a person to look at it that has experience in your area then decide.It might be better to just get a better amp that is more in line with your needs.

Sorry I cannot help further.

Regards!