Tweaking existing solid state

ranmart · « **Reply #40 on:** 11 Apr 2003, 06:37 am »

Thanks for the help as for a amp do you know of any good cheap 2 speaker amps under $400 that can be tweaked later on.If I could spend $5-6k on I amp I would but make little money so cheap is all I can get.Thanks

ABEX · « **Reply #41 on:** 11 Apr 2003, 06:45 am »

Good question!

I own a B&K ST-202 that can be upgraded by Musicalconcepts.com.

At present I might sell it because I have learned of an amp that is coming out that goes for $400 for Monoblock set made by nOrh.

It is the set of amps located at the bottom of the following page.I am getting speakers that can be used in a Vertical amp setup so I would need atleast 2 pairs.These amps are suppose to e killer deals and I am waiting for feedback on them.I would not wait long because they will be going for $600 soon.
http://www.norh.com/news.html

More info can be found here:
http://www.audiocircle.com/index.php?board=12

If they can compete with amps going for 10X's the price they are a steal!

Good luck!

ABEX · « **Reply #42 on:** 11 Apr 2003, 06:46 am »

The original LeAmps could be tweeked and I'll bet these can be also!

Rocket · « **Reply #43 on:** 11 Apr 2003, 07:20 am »

hello ranmart,

try tnt audio they give simple information for upgrading amplifiers.

regards

rod

George W · « **Reply #44 on:** 11 Apr 2003, 11:17 am »

ranmart if you want to build your own for $350 or so you can also look into the AKSA stereo amps mentioned earlier. If you go down to manufacturer's forums it's under Aspen Amplifiers.

George

JoshK · « **Reply #45 on:** 11 Apr 2003, 02:32 pm »

I would like to tweak my Rotel 985 amp. I bought this for $400 on the 'gon. It is my HT amp so I didn't need a SOTA amp and it sounds decent. I would like to mess around with it and take it up a notch though.

DVV · « **Reply #46 on:** 11 Apr 2003, 08:45 pm »

Quote from: JoshK

I would like to tweak my Rotel 985 amp. I bought this for $400 on the 'gon. It is my HT amp so I didn't need a SOTA amp and it sounds decent. I would like to mess around with it and take it up a notch though.

Josh, the first step is to get hold of its schematics. These are invaluable when deciding to go for what and where. Shure, you can always replace the filter caps, output devices, etc, but that's the short-sighted route. For example, what use of replacing the original say 100W output transistors with say 150W devices, if you don't modify the protection circuit? It will simply continue behaving as if nothing has changed, in which case you lose out on the benefits of more powerful output devices.

Also, a VERY worthwhile (thanks for the tip, Dan!) upgrade is replacing existing critical resistors with Vishay bulk foil resistors. Dan Banquer told me about this, I tried it and all I can say is that was right all the way. I'm hoping he'll read this, because he has more experience than I do in this respect.

The point is, you need the schematics to make your work easier, both mechanically (replacing) and electronically (to see where to get the most benefit in terms of sound). As Murphy would have it, while I have quite a few Rotel schematics, I do NOT have your model.

I would suggest you get the service manual first - then I could help you far more than now, using the tried methods which are simply scratching the surface.

Cheers,
DVV

ABEX · « **Reply #47 on:** 11 Apr 2003, 08:57 pm »

DVV Is it the output resistors that make the difference when Forward Biasing the amps to run more in CLassA operation.That is what I was told and am wondering weather that iss correct.

The thing which I think is important is taking the signature of veiling out of the amp.I go listening to amps today and I only need 1 minute to start hearing vocals that sound like they are being masked before I say I have heard enough.

My B&K is Forward biasd and the Odyssey(?) amps are forward biasd also which I assume is the reason people like them so much.Rotels have this signatire also.Atleast the reciever I heard recently has it.Anthem and HK which is the darkest amp I have ever heard.Adcom has it.Mark Levs and Krells don't.

What are your thoughts?

JoshK · « **Reply #48 on:** 11 Apr 2003, 09:56 pm »

Thanks Dejan,

I will go scouring the web looking for a schematic or electronic reference for the Rotel. Maybe I can drudge one up somewhere. I am also looking for info on my Sony XA777's clock info, namely the frequency to see which superclock II to buy. I was thinking of upgrading that guy too. This is going to be an addictive hobby I can just see!

Too bad Dan Wright wouldn't give me a list of the part he replaces (and with what obviously) in his parts upgrade.

Rocket · « **Reply #49 on:** 12 Apr 2003, 01:30 am »

hello josh,

elso kwak also makes master clocks for modding, i think his clocks are a fair bit cheaper than audiocom's.

here is his email address if your interested:

elsokwak@keyaccess.nl

regards

rod

DVV · « **Reply #50 on:** 12 Apr 2003, 07:14 am »

Quote from: ABEX

DVV Is it the output resistors that make the difference when Forward Biasing the amps to run more in CLassA operation.That is what I was told and am wondering weather that iss correct.

Not the only factor, but an important part of the equation, yes. Power supplies are another, for example. It's all about proportion - build up one, and you need to build up another to keep pace.

Quote

The thing which I think is important is taking the signature of veiling out of the amp.I go listening to amps today and I only need 1 minute to start hearing vocals that sound like they are being masked before I say I have heard enough.

My B&K is Forward biasd and the Odyssey(?) amps are forward biasd also which I assume is the reason people like them so much.Rotels have this signatire also.Atleast the reciever I heard recently has it.Anthem and HK which is the darkest amp I have ever heard.Adcom has it.Mark Levs and Krells don't.

What are your thoughts?

Well, I never saw anything that could not be improved, mine certainly included. But changing the overall tonality of an amp is no small job, it takes much experimenting.

Cheers,
DVV

ABEX · « **Reply #51 on:** 12 Apr 2003, 07:42 am »

DVV--Thanks for your comments it helps to further understand the workings behind improving and looking into the tech that goes into amps.

One last question:
I remember reading that a one benchmark about how good an amp is can be measured at how much power can be deliverd when Halfing the Impedance rating.

As an example lets say an amp is stated to deliver 200watts at 8ohms and then delivers 400watts at 4ohms then deilver 800wats into 2ohms.Does the ability to double it's rated output that way tell you anything about the amps ability besides being able to drive a wider range of speakers?

TIA,ABEX

DVV · « **Reply #52 on:** 12 Apr 2003, 01:32 pm »

Quote from: ABEX

DVV--Thanks for your comments it helps to further understand the workings behind improving and looking into the tech that goes into amps.

One last question:
I remember reading that a one benchmark about how good an amp is can be measured at how much power can be deliverd when Halfing the Impedance rating.

As an example lets say an amp is stated to deliver 200watts at 8ohms and then delivers 400watts at 4ohms then deilver 800wats into 2ohms.Does the ability to double it's rated output that way tell you anything about the amps ability besides being able to drive a wider range of speakers?

TIA,ABEX

Actually, it tells you several things.

1. It tells you the designer was using his head while working, and recognizes the fact that nasty things like impedance drops, phase shifts, etc actually do exist, operate in real life like it or not, and attempt to modify the amp's performance into real world speakers, as opposed to lab test loads (usually a bank of high power resistors);

2. It tells you the power supply of that amp has been really well done, no skimping. No output stage can deliver real world power into real world speakers if it doesn't have an enbergy pool to draw that power from;

3. It tells you the output section in particular, but also the whole amp, has been concieved with proper capability to negotiate even very difficult loads, which gives you freedom to choose among speakers according to taste, and not to have to think about drive capabilities, and

4. It tells you the amp's performance, such as distortion and frequency response, will be modified very little by even evil loads, which is a hallmark of any good design.

As a sideline, it also tells you whoever designed it, was one competent designer and worthy of respect.

On the other hand, however important that is, it's not the only factor deciding on the overall quality of the sound. Let me put it this way - such an amp stands a better chance of sounding good than another without such capabilities.

This means the amp's dynamics will not be curtailed by less than perfect loads, and that it will in fact drive almost anything somebody decided to call a speaker.

Cheers,
DVV

JoshK · « **Reply #53 on:** 12 Apr 2003, 04:56 pm »

Dejan,

Would you say that starting with learning up on power supplies is a good place to start for someone wishing to learn about building/modding audio electronics? I really want to learn about all this stuff but I have no/little electronics background. I have learned a lot and picked my father in law's (chief electrical engineer for an Audi subsidiary) brain quite a bit. I am starting to find that learning how to build/mod is ALMOST as fun as listening to music.

DVV · « **Reply #54 on:** 12 Apr 2003, 05:09 pm »

Quote from: JoshK

Dejan,

Would you say that starting with learning up on power supplies is a good place to start for someone wishing to learn about building/modding audio electronics? I really want to learn about all this stuff but I have no/little electronics background. I have learned a lot and picked my father in law's (chief electrical engineer for an Audi subsidiary) brain quite a bit. I am starting to find that learning how to build/mod is ALMOST as fun as listening to music.

Josh, I'd do more than that - I'd say power supplies are THE place to start. It's quite simple - the whole product rests on power supplies, without good power supplies, the rest is usually meaningless, and in any and all cases devalued.

The most common and sensible tweak of any product is modding the power supplies. No matter how poor it may sound, after that mod it will sound better, every time, never fails.

Of course, those are absolutes, and there is a relativity factor here as well. If you have to double the product's price to get a 15% improvement in sound, well, that's hardly rational, is it?

Josh, there are TWO things I'd say to you:

1. By all means, do start from the power supplies, and
2. Remember, it's all a balance, to have significant gains you need to mod at least a few things, never just one.

BTW, you found some good brains to pick; Audi has one of the best electrical arrangements in the entire car industry, in my view, better than Mercedes-Benz and BMW. Your paw-in-law sure knew what to pick, kudos to him.

Cheers,
DVV

ABEX · « **Reply #55 on:** 12 Apr 2003, 05:21 pm »

DVV
That statement you made went a long way in helping me decide on weather I am going to buy some amps I am thinking about.Thank You VERY MUCH!

It shows you took some time at what you wrote and I do appreciate it!

Cheers!

Jay S · « **Reply #56 on:** 12 Apr 2003, 05:31 pm »

Josh, you're lucky to have your father in law!! Besides audio, my passion is cars... seems like through your father in law you can further your understanding of both!

DVV · « **Reply #57 on:** 12 Apr 2003, 09:19 pm »

Quote from: ABEX

DVV
That statement you made went a long way in helping me decide on weather I am going to buy some amps I am thinking about.Thank You VERY MUCH!

My pleasure, amigo. And after all, isn't that the initial meaning of this bulletin board and site as such?

Quote

It shows you took some time at what you wrote and I do appreciate it!

Cheers!

You know, I'd feel damn stupid if I just read half the messages. But in all truth, I'm a quick reader, been reading since I was 6, which was 44 years ago, and while practice may not make perfect, it does come in handy.

But the REAL beauty of this place is that you can have second and third opinion from us technologically orientated guys - Dan and Hugh are here as well, and both have proved their worth by their products.

Cheers,
DVV