# Amp mod question



## ecbmxer

You guys who have amps modded, is that really only beneficial if you are starting with a very high end amp? Or should I say, are some (maybe mid-level) amps not worth modding because of power supply limitations or similar?


----------



## jcollin76

Thank you for that explanation, I've often wondered the very same thing. If my amps would benefit, or even be good candidates for modding.


----------



## TrickyRicky

Tru amps are modified in different stages. Wonder why not just do it in one mod, may be more $$$ when done in stages.


----------



## envisionelec

cajunner said:


> Now, if we're strictly talking about measurement performance, I believe it is true that using higher quality low-gain devices will end up measuring better to a meter, but will you hear the improvement? Maybe in the noise specs, but that's about it and if the amp's a halfway decent product, maybe not even then.


And sometimes mods make things worse if you don't know exactly what you're doing. As they say..."If you have to ask."...


----------



## jcollin76

I would never mod an amp myself, I don't have the technical understanding, or the ability. Lol

My question would be, what are the criteria for deciding to mod an amp, as far as you guys are concerned?

Does it boil down to..

1. It's an older amp you want to freshen up.
2. You love the amp, and decide to keep it for the long haul.. so improve it.
3. Only for competition purposes.
Etc...

Just curious how and why a guy decides to mod an amp.


----------



## jcollin76

cajunner said:


> like using some poly caps in pulsed circuit proximity?
> 
> or oscillating because your super duper op-amp runs too hot?
> 
> jcollin76:
> 
> amp modification is a peculiarity in car audio. People that do it, usually are paid to do it for someone who wants it done, and there's your sign.
> 
> Now, don't get me wrong, if your nice amp that you love the sonics of and has served you well for half a decade decides to just belly up and you want to put the money into it, then sure go ahead, put in some better parts because the designer didn't have access when he was choosing the bill of materials, or decided that an 80 cent jellybean kicked all kinds of ass compared to a 3 dollar one.... and don't get me started on the silk capacitor versus the Black Gates....
> 
> the simplest thing is to simply buy a better amplifier.
> 
> modification is sort of like when you see people re-use stuff in an unintentional setting or purpose. That they get something to feel good about is part of the point, along with the belief that buying a new item is wasteful and likely to end in an inferior product in the end.
> 
> Think of a guy that grows up on Breyer's Vanilla ice cream. He may try 20 different kinds of vanilla frozen treats over his lifetime, but he'll usually find the most satisfaction when the old Breyer's bean specks can be seen, and that familiar taste brings him back to what vanilla is supposed sound like, er.. taste like.


Thanks for the explanation and insight. Every now and then I'd see a thread on it, or a modded amp would pop up on the classifieds.
Just curious to the how's and why's.

Thank you Lol


----------



## envisionelec

jcollin76 said:


> Just curious how and why a guy decides to mod an amp.


I have "modded" a few amps, but I always had a specific reason. 

1. Permanently changing the PS voltage up or down to suit a different impedance driver. This works on most amplifiers, and only if you know you're not pushing the VI limiter out of range - in either direction. If it's a MosFet output amplifier, you must also change the tertiary windings - or at least confirm that they are at the correct voltage.
2. Changing all the OpAmps out of an Xtant 3300c because it was a newer version. The original had LM833 (or was it NE5532?) while the newer one had TL072. Everything else remained the same. I wanted it to match my other one. I didn't bother measuring it because I don't care. I just want two identical 3300c's. 
3. Fixing the input gain so that the channels are in close balance.
4. Changing the switching frequency in the power supply to reduce RFI on a particular AM station. Stop laughing. 
5. Changing the VI limiter to stop...uh...limiting prematurely. 

It's not "Well, _I_ heard that I should change xyz because my buddy said it made a difference in the dielectric absorption ratio of the hexfet multivibrator." 

All specific reasons with specific goals in mind.


----------



## jcollin76

So a guy would need to be well versed in the technical aspects of the amp to understand what he wants, and how to go about that... I completely understand that.
Unfortunately, that's not me. Lol

I have often read guys wanting to remove the pre-amp, effectively making it an amp with a gain. They refer to it as their preferred amp.
Is there any truth to improved sq in this situation? Or would that only be the case if the pre-amp was inferior components?

I completely understand I'm asking questions above my understanding, but I'd like to understand. Lol

I appreciate your patients...


----------



## jcollin76

A lot of variables to look at... Okay.

So could easily fall under diminished returns, depending on the reasons for modding. When it could just be easier and cheaper to upgraded to a better amp.

Thanks


----------



## jcollin76

Lol thanks for your detailed explanations, and I think I follow what you saying. 

Upgrading a component/s isn't modding (in your eyes) as long as it doesn't change how the amp is designed to work. 
Changes to freshen old components, be it to spec or slightly better, don't change the design characteristics of the amp.

To coin an auto analogy... Like putting new tires or muffler on a car, doesn't change it, but brings it back to spec. Whereas throwing a blower, cam, and putting it on the bottle, would change the original design of the vehicle.

Am I close, or still lost? Lol


----------



## jcollin76

Lol sounds like a difference in definitions. I appreciate your time on this... If I wasn't on my phone I'd give ya a thanks (doesn't register it when clicked from my mobile browser)

What would be a good site or link to look at, to start to understand amp basics?

I'm no ee, and I don't compete, I just really enjoy the hobby. Is there a suitable site geared for the novice... In laymans terms basically, so I can bone up on the basics.


----------



## Mike_Dee

jcollin76 said:


> I would never mod an amp myself, I don't have the technical understanding, or the ability. Lol
> 
> My question would be, what are the criteria for deciding to mod an amp, as far as you guys are concerned?
> 
> Does it boil down to..
> 
> 1. It's an older amp you want to freshen up.
> 2. You love the amp, and decide to keep it for the long haul.. so improve it.
> 3. Only for competition purposes.
> Etc...
> 
> Just curious how and why a guy decides to mod an amp.


I have an old Linear Power 2002 made in the late 80's. I've replaced the standard op amps with Analog Devices OP275's, all the metal T03 devices in the output and power supply, every capacitor with same value Nichicon Muse, and every power resistor with Caddock film resistors. It should last another 20 years......lol.


----------



## jcollin76

Oh yeah, I know it. Have it bookmarked even... Lol guess I should dig in it deeper. I usually direct people to it for basic wiring, volume calculators, etc.
Didn't realise went into amp structure. Lol

Thanks again!


----------



## TrickyRicky

Mike_Dee said:


> I have an old Linear Power 2002 made in the late 80's. I've replaced the standard op amps with Analog Devices OP275's, all the metal T03 devices in the output and power supply, every capacitor with same value Nichicon Muse, and every power resistor with Caddock film resistors. It should last another 20 years......lol.


The output transistors too?  Are you using it? Because am curious to know how that op amp compares to the new one? Does it have the same characteristics as the stock op amp?


----------



## Mike_Dee

TrickyRicky said:


> The output transistors too?  Are you using it? Because am curious to know how that op amp compares to the new one? Does it have the same characteristics as the stock op amp?


Yes, I replaced all output, and power supply transistors. I also added additional heat sinking to them for better thermal performance. In this pic you can see a good view of the op amp, transistors and heat sinks, caddock resistors, and Muse Capacitors:

AMPGUTS :: DSCF0050.jpg picture by BoomBoomBoy - Photobucket

As far as improved sound goes, it's running my 2x8" JL Audio subs do it's kind of hard to tell:

JLGrillsOff.jpg picture by BoomBoomBoy - Photobucket

JL Grills On picture by BoomBoomBoy - Photobucket


----------



## ecbmxer

Wow, forgot about this thread! Thanks for the responses and discussion. I was just primarily curious being that you see some people on here get amps or processors modded. I found it interesting. But even before asking I kind of figured if you have a good working amp it's probably not worth messing with.


----------



## TrickyRicky

Mike_Dee said:


> Yes, I replaced all output, and power supply transistors. I also added additional heat sinking to them for better thermal performance. In this pic you can see a good view of the op amp, transistors and heat sinks, caddock resistors, and Muse Capacitors:
> 
> AMPGUTS :: DSCF0050.jpg picture by BoomBoomBoy - Photobucket
> 
> As far as improved sound goes, it's running my 2x8" JL Audio subs do it's kind of hard to tell:
> 
> JLGrillsOff.jpg picture by BoomBoomBoy - Photobucket
> 
> JL Grills On picture by BoomBoomBoy - Photobucket


Nice, those are some mean looking heatsinks on the TO3's.


----------

