Modify tone control on Pioneer SX-1080

[ultrasparc]

Hi AK'ers


I wonder if I can modify the tone control in my Pioneer SX-1080, by changing the value on some capacitors on the tone control board?

I've read a couple of places that the specs of the caps can enhance/reduce the amount of bass/treble an amp (pre-amp?) will let out, and also a while ago I watched a youtube video, where a guy had made a very simple curcuit that clearly demonstrated this correlation.

The reason I'm looking into this modification is, that I still miss the clarity and open airy sound this receiver used to be able to sound like. I have replaced ALL electrolytic caps, all trannys, many diodes and some resistors, on ALL boards, along with the protection- and soft start relays, since it was beginning to sound rather dull and confined. I was never really satisfied with the result of the re-cap, and have been searching for that last thing that will make the difference and bring back the quality sound the baby once was capable of.

So if any one would care to comment on the idea (hopefully positive) I'd really appreciate it.

If I should give a guess, I would try and replace C23, C24 (47 µF) with 33 µF caps, in order to enhance the treble.

What is the function of the low capacity caps of 0.02 ceramic and 0.0015 mylar caps? Will it influence tone level to replace them with other values?

 

[Denten]

I still miss the clarity and open airy sound this receiver used to be able to sound like.

If it sounded good with the original value caps, why would changing the values now "fix" the sound? I think you are barking up the wrong tree.

I have replaced ALL electrolytic caps, all trannys,

Everything I've learned here suggests changing ALL trannys is a real bad idea.
I'm sure someone with more knowledge will be along that can point you in the right direction.
Good Luck

 

[ultrasparc]

If it sounded good with the original value caps, why would changing the values now "fix" the sound?

As I mentioned I have read that the value of the capacitor determines which frequencies that are filtered out.
Because I am missing the level of treble from when it was in good shape, and I am grasping for a solution after *all* other options are exhausted.

I think you are barking up the wrong tree.

Maybe so

Everything I've learned here suggests changing ALL trannys is a real bad idea.

OK, again maybe so - I'm by no means any better than a solder-monkey, able to follow a recipe, and as such I copied what other people have done (seen in the Pioneer forum)

I'm sure someone with more knowledge will be along that can point you in the right direction.

That's what I'm hoping for.

Good Luck

Thanks - I think I need it

 

[avionic]

verything I've learned here suggests changing ALL trannys is a real bad idea.

Don't tell MTF.

 

[KingBubba]

What about considering the possibility that it is the speakers that have the problem, not the receiver?

 

[ultrasparc]

Don't tell MTF.

I think he knows - he has helped me out on this one from back when I started more two years ago

 

[ultrasparc]

What about considering the possibility that it is the speakers that have the problem, not the receiver?

Ohh, I have been thinking about that too. Actually I had a buddy come over, bringing his SX-1080, and my speakers (ELAC BS 253) sounded fine on his...

And, well, it's not like it totally misses the treble, but I find that its only 'good enough' on very few CDs (Metallica Black is one), but most of my CDs are dissapointing, soundwise...
My vinyls are another (and worse) story, but here I think I need to get my wallet out and get me a decent pickup.

But its just that I want to see if I can tweak it, by replacing a cap or two, and see if there is difference.

 

[savatage1973]

You may have just answered your own question. Perhaps the receiver did benefit from all of the work you put into it, and now you are hearing the deficiencies in your source components. I have been down this road before (albeit slightly differently)--I bought and built up a monstrosity of a main system that was so revealing and detailed that I couldn't stand to listen to a lot of the music that I used to love--I listen to a lot of 60's-80's rock/punk/alternative, and a lot of it is not engineered well. With the highly revealing system, all I could hear were the flaws--not the music. I ended up selling that gear and "downgraded" my system a notch or two to make the music sound good again. I know it sounds stupid/counterproductive, but it works for me.

 

[moewillis]

As I mentioned I have read that the value of the capacitor determines which frequencies that are filtered out.
Because I am missing the level of treble from when it was in good shape, and I am grasping for a solution

If the value of the cap filters out certain frequencies and you put in the same value you took out then how would deviating from the factory values somehow restore a sound it once had.

My personal opinion is pioneer knows better than a guy on YouTube or a guy who watched a video of a guy in YouTube.

I too wonder if it's in the transistors

 

[ultrasparc]

You may have just answered your own question. Perhaps the receiver did benefit from all of the work you put into it, and now you are hearing the deficiencies in your source components. I have been down this road before (albeit slightly differently)--I bought and built up a monstrosity of a main system that was so revealing and detailed that I couldn't stand to listen to a lot of the music that I used to love--I listen to a lot of 60's-80's rock/punk/alternative, and a lot of it is not engineered well. With the highly revealing system, all I could hear were the flaws--not the music. I ended up selling that gear and "downgraded" my system a notch or two to make the music sound good again. I know it sounds stupid/counterproductive, but it works for me.

I hear what you are saying, but I don't think this is the case for me. The thing is that I couldn't hear any difference from before to after the initial re-cap . I do have had some improvement later on, though, but from the most surprising (for me) replacements, i.e. replacing the soft start relay helped a bit, and cleaning up the power supply! By cleaning up the PSU I mean, that I had to repair delaminated lead-tracks, that had been fried by, what must have been extreme heat. I had solved the lead problem by pulling a couple of jumper wires where needed, but that introduced some very audible noise. And since the project have taken so long, I'm sure my perception of things may have changed.

Anyway, I'm glad you found the way that was right for you - that's what it's all about

 

[ultrasparc]

If the value of the cap filters out certain frequencies and you put in the same value you took out then how would deviating from the factory values somehow restore a sound it once had.

The point being that I would experiment with alternative values

My personal opinion is pioneer knows better than a guy on YouTube or a guy who watched a video of a guy in YouTube.

I'm not saying some guy on utube claims to know better than Pioneer engineers, how to design Pioneer units - all I'm saying is that I have seen an explantion on how cap values influences tone control

I too wonder if it's in the transistors

In which way?

 

[Denten]

The point being that I would experiment with alternative values

If there is a fault somewhere, you don't fix it by compensating for it somewhere down stream, you find the fault and fix it.
Are your speakers wired in phase?
Have you confirmed that it is actually playing in stereo? Do you hear a difference when you switch between stereo and mono?

OK, again maybe so - I'm by no means any better than a solder-monkey, able to follow a recipe, and as such I copied what other people have done (seen in the Pioneer forum)

http://audiokarma.org/forums/index....es-in-a-working-36-year-old-amplifier.274845/

 

[Denten]

I had a buddy come over, bringing his SX-1080, and my speakers (ELAC BS 253) sounded fine on his...

I would run your pre to his main in, and see what that sounds like, then try his pre to your main in, see what that sounds like, then maybe you can isolate the issue to the preamp or the amp.

 

[ultrasparc]

I would run your pre to his main in, and see what that sounds like, then try his pre to your main in, see what that sounds like, then maybe you can isolate the issue to the preamp or the amp.

That is an idea I've been nursing - I'll have to ask him if he will let me have it over again

 

[ultrasparc]

If there is a fault somewhere, you don't fix it by compensating for it somewhere down stream, you find the fault and fix it.

I hope/suspekt that there is a degraded ceramic or mylar somewhere that need replacement. I don't regard the receiver faulty as such - everything works, it doesn't run hot, voltages are within spec... (yeah, I contradict myself here, I hope you get my point )

My ambition is merely to play with alternative cap values to test if I can make a change to my liking...

Also see post #10

The thing is that I couldn't hear any difference from before to after the initial re-cap . I do have had some improvement later on, though, but from the most surprising (for me) replacements, i.e. replacing the soft start relay helped a bit, and cleaning up the power supply! By cleaning up the PSU I mean, that I had to repair delaminated lead-tracks, that had been fried by, what must have been extreme heat. I had solved the lead problem by pulling a couple of jumper wires where needed, but that introduced some very audible noise. And since the project have taken so long, I'm sure my perception of things may have changed. ​

Pics of the revived PSU
http://audiokarma.org/forums/index....wer-supply-awr-152.729933/page-2#post-9880410

Are your speakers wired in phase?
Have you confirmed that it is actually playing in stereo? Do you hear a difference when you switch between stereo and mono?

Yeah, all of those obvious test have been done No difference between mono/stereo

http://audiokarma.org/forums/index....es-in-a-working-36-year-old-amplifier.274845/

Good thread there, but since I heard no difference from before to after recap, replacing transistors didn't make a differnce (I kept the old ones, should I ever feel like putting them back in )

 

[Denten]

I hope/suspekt that there is a degraded ceramic or mylar somewhere that need replacement. I don't regard the receiver faulty as such - everything works, it doesn't run hot, voltages are within spec... (yeah, I contradict myself here, I hope you get my point )

My ambition is merely to play with alternative cap values to test if I can make a change to my liking...

Also see post #10

The thing is that I couldn't hear any difference from before to after the initial re-cap . I do have had some improvement later on, though, but from the most surprising (for me) replacements, i.e. replacing the soft start relay helped a bit, and cleaning up the power supply! By cleaning up the PSU I mean, that I had to repair delaminated lead-tracks, that had been fried by, what must have been extreme heat. I had solved the lead problem by pulling a couple of jumper wires where needed, but that introduced some very audible noise. And since the project have taken so long, I'm sure my perception of things may have changed. ​

Pics of the revived PSU
http://audiokarma.org/forums/index....wer-supply-awr-152.729933/page-2#post-9880410


Yeah, all of those obvious test have been done No difference between mono/stereo



Good thread there, but since I heard no difference from before to after recap, replacing transistors didn't make a differnce (I kept the old ones, should I ever feel like putting them back in )

Oh, ok, I must have misunderstood your op, I will stop talking now.

 

[goat67]

Turn tone off this bypasses all but one cap. Do you like the sound? If not you are just increasing the gain at the frequencies you dial in it will not make it clearer or more detailed.
If you do not like the sound fing around with caps is not going to help ya, But do what you like it is your receiver