S800 Support Thread

[stitch-o]

Tested some different chips the other day. Some OPA604s and a set of OPA134. the 134´s won. OPA134s are quite expensive, but if you don´t like hiss, then I would recommend them over the TL071s.

Would a chip like the OPA134PA be a drop in replacement for the TL071 in the S800 or is there some calculations to do? (I can't seem to find my TL071 datasheet offhand...)

 

[Siegfried Meier]

Ok, a couple of tips for you 8 chn chassis builders, and some PSU questions.

1. Drill out the chassis threads, that way the screw that holds the panel on won't bottom out before you tighten it up.  This frustrated me so much. 

2. Also, use a 5/16th drill bit to drill out all the pot holes on the front panel.  Why they weren't made larger than the pots is beyond me, but I almost lost my mind after putting the entire thing together 3 times and finding out that half the pots didn't turn because of the friction.  Do yourself a favour, and drill once, and once only.

3. Stick the LED's in last, and take off the bottom cover and feed them in.  I tried doing it while doing the rest of the front panel and it drove me nuts, and I broke off several LED's when I pulled the panel off again and again.  Do it last, and you'll have a much easier time.

Now, here's my question.  I've built up the PSU with flying leads on molex connectors for the regulators, which are destined to be attached to the chassis.  I'm getting +-22.54 with the PSU unloaded.  I believe the S800 modules want to see +-18v (yes, no?), so am I correct in assuming that when al 8 channels are connected, this will drop down?  Or should I be changing a resistor now to drop it?

Thanks!
Sig

 

[3nity]

TL071 can hadle the +/- 18 but to be on the longevity side use +/- 15.

If you setled the psu to sit at +/- 18 you should read +/- 18!!

Seems like those cases are just a pain in the back.

BTW: those EQ's are just awesome eq's.  8)

 

[Siegfried Meier]

Ok, so then my PSU voltage is too high.  What resistor do I swap out to bring it down to +-15v, and what value should I be using?

The EQ's do sound fantastic though, and it's funny because they were so easy to build, but racking them into this case with all the wiring is the biggest pain.

Thanks,
Sig

 

[3nity]

you using the Peter C psu?
http://www.twin-x.com/groupdiy/albums/userpics/Green_PSU_V6_Overlay_%2B_trax.pdf

You should use 2K2 to get +/- 15V.

 

[Siegfried Meier]

Hmmmm I stuffed the board with the values that were listed on the silkscreen, so it appears I did use 2k2, no?  Why am I getting 24v?

 

[Davo]

Are you getting 24v on both + and - rails.... you could have a blown regulator in there somewhere... Peter indicated that you should be getting roughly 21.5v before the regs.... doesn't look like the voltage is dropping at all.  The Lm317 and 337 should bring the voltage to 15v with the 2k2 and 220r resistors.... when I want an adjustable voltage psu, I toss 500r trimpots on the 220r spots and tweak it to the voltage I need

 

[mrphotodude]

Tested some different chips the other day. Some OPA604s and a set of OPA134. the 134´s won. OPA134s are quite expensive, but if you don´t like hiss, then I would recommend them over the TL071s.

I had put 2134's in U6 and thought it sounded better myself over a 2604(instead of the 5532).
When i turn up the high end all the way and max the eq out i could hear hiss and putting in a opa267 in U1 dropped that right out. Now it is silent and tight sounding. Tried some ada797,opa627, 5534 ect in the other positions but it didnt alter the sound much so i left U2-U5 tl071 and am very happy.
I thought about tweaking the HF caps and maybe putting in a larger log tapered pot. It gets noticeably bright at about 75% rotation then not much more.
will drop pic in tonight of the unit.

 

[peterc]

Hmmmm I stuffed the board with the values that were listed on the silkscreen, so it appears I did use 2k2, no?  Why am I getting 24v?

Check the voltage before the regs & after the regs. If it is the same you've got either blown regs or the protection diodes are the wrong way round.

 

[mrphotodude]

here is my unit..

I had to take an old chassis and cut and bend the back and rig it to make it work...but it is going into a rack, not a beauty contest.
I have a dual 115in/15vac out transformer..ended up changing the 2k2 to 2k6 i believe it was on the powersupply board to give me 18-0-18. Its ghetto compared to some of the projects i have seen here, but it sounds good and i am going to use the heck out of it 8)
I will have those cool little knobs on the black market shortly. They are all black, i roughed a few up and spray painted them white for the frequency selector.

 

[matta]

here is my unit..
http://img142.imageshack.us/img142/1489/16068657uf5.jpg
I had to take an old chassis and cut and bend the back and rig it to make it work...but it is going into a rack, not a beauty contest.
I have a dual 115in/15vac out transformer..ended up changing the 2k2 to 2k6 i believe it was on the powersupply board to give me 18-0-18. Its ghetto compared to some of the projects i have seen here, but it sounds good and i am going to use the heck out of it 8)
I will have those cool little knobs on the black market shortly. They are all black, i roughed a few up and spray painted them white for the frequency selector.

Looks great, the S800 'Blue Stripe' Edition

Matt

 

[mrphotodude]

yeah, its a webpress plate i made at work. Its more of a green.
http://www.houstonfreeways.com/images/printing/krehbiel_mitsubishi_plate_in_machine_B_2003-08-21_700.jpg
they wrap around a cylinder and attract ink which images on a rubber roller and then presses on the paper.
Now we have a new machine with baby blue plates.

 

[Siegfried Meier]

Hmmmm I stuffed the board with the values that were listed on the silkscreen, so it appears I did use 2k2, no?  Why am I getting 24v?

Check the voltage before the regs & after the regs. If it is the same you've got either blown regs or the protection diodes are the wrong way round.

Can someone send me a large close up pic of their PSU so I can see if the orientation of everything is correct?  I'm positive I'm right and I've followed the silkscreen.  I checked the voltage before and after, and I believe it's the same, +-23v, but how did I blow both regulators??

Thanks,
Sig

 

[Davo]

Here's everything that's got an orientation  (this is for V4 PSU)

 

[Siegfried Meier]

Here's everything that's got an orientation

For real??  Then that top Diode is incorrect on the silkscreen, because it shows the white band should be on the left hand side for both diodes.  This seems like my problem then, I'll correct it and see.

Thanks!
Sig

 

[matta]

There have been multiple versions of Peter's PSU, some had Diode facing the other way from others... make sure the overlay you have follows the schematics... it is pretty simple to trace out as well.

Cheers

Matt

 

[Siegfried Meier]

I have Green PSU V6a 1-3-7, and I just assumed following the silk screen would be correct...

 

[Davo]

Yeah, ignore my post.... 6a 1-3-7 has got em just like the silkscreen, hmmm... sorry for the stupid question, but did you hook up your ground?

 

[Siegfried Meier]

Ok, well I swapped the diode and I'm still getting the same voltage.  Could the problem be my bridge rectifier?  They didn't have a 1A so the guys gave me a 10A.  That doesn't seem like it would cause an issue though.

However, in testing, my - rail touched the leg of a cap and the 337 exploded in a flash of blinding light.  Need to go and order a new one now F*^k.

If this thing frustrates me any further, I'll just use the JLM supply.  Those things are always solid and work great, and it's already built up.

Thanks,
Sig

 

[Siegfried Meier]

Yeah, ignore my post.... 6a 1-3-7 has got em just like the silkscreen, hmmm... sorry for the stupid question, but did you hook up your ground?

Hook up my ground...?  To where?

That leads me to the question of why that extra screw is in the 8 chn chassis...is this something to do with the ground you speak of?

My apologies, first time building up these Green PSU's.

Thanks,
Sig