S800 Support Thread

[craigmorris74]

Thanks for the reply, Peter.  The opamps were in when this happened, so I can check those, and replace the two lytics first.  Appreciate the feedback!

UPDATE:  One of the opamps was causing the noise.  Replaced them all and the problem went away.

 

[NannerPuddin]

I tried the white market link so I could get a few of the boards.  I got an error.  What do I need to do to either get on the white market or otherwise get a few of the boards?

Thanks,

Doug

 

[audiophreak]

I may have a couple of these , I'll check and send PM

 

[audiophreak]

I tried the white market link so I could get a few of the boards.  I got an error.  What do I need to do to either get on the white market or otherwise get a few of the boards?

Thanks,

Doug

  I have a couple of these , just have the links ( jumpers) soldered in , whats your location ?

 

[NannerPuddin]

Hey Audiophreak,

Sorry for the delay in getting back to you, I was on family vacation for a week and just now got back on the board.  I am in East Tennessee. I would love to get a couple of them if you could spare them.

Thanks,

Doug

 

[audiophreak]

pm sent

 

[ZekeProductions]

I've already built this EQ a while back, it definitely is a great EQ. I may want to build another one but I'm curious if anyone has built this EQ with Stepped potentiometers for both the gain and frequency. is it possible? it would definitely make recall much easier.  ;D

 

[dogfaceaudio]

Does anyone have the dimensions for front panel holes? Or an FPD file? Thanks.

 

[brewbacca]

I'm also wondering if anybody has an FPD or dimensions for the front panel.

 

[JW]

Question about the cheap yellow and blue polyester caps. I have some recent kits from AML that came with Wimas. After having compared I like the yellow and blue polyesters that came with my earlier kits better. Interesting, but to my ear the bands seem to blend better.  Does anybody know exactly which series of cap these are that originally came in the AML kit? I think I read at one point that they were Dubilier type? Like these?: https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/185103J100RAA-F?qs=sGAEpiMZZMv1cc3ydrPrF6kAfBcSzk7fYKtmY0JDDVM%3d

Or perhaps these? https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/184333K250RBB-F?qs=sGAEpiMZZMv1cc3ydrPrF8gMTJ0uZsYN7SxNnmJTges%3d

 

[JW]

Bump. No one knows the answer to my last question? (AML not getting back to me)

This kind of capacitor looks very similar to those found in the Soundcraft Ghost I've noticed. . . I'm gonna go researching that.

 

[Timjag]

https://uk.rs-online.com/mobile/c/passive-components/capacitors/polyester-film-capacitors/

 

[JW]

Hey,
Thanks for that link, but it's just to polyester films at RS UK. Not even Dubilier type? ? ? ? ? 

Good idea narrowing it down to them though because Colin did probably buy from UK for these kits? (Sheesh I don't know)

 

[ZekeProductions]

So I had an issue with noise in my EQ and decided to pull it apart and check the wiring. Long story short I think I messed something up and went to buy another AML kit but they don't sell them anymore. Has anyone recently put the kit together from mouser or somewhere like that and share the BOM.

I also just recreated the FPD and ordered it.  So if the holes are right I may have a spare front panel for sale soon if someone wants it.

 

[ZekeProductions]

If anyone is looking for a faceplate for this project I have an 8ch face plate for sale. PM me if you are interested.

https://groupdiy.com/index.php?topic=68967.0

 

[Le Roux]

Wow,well done...!..

great pics ,but my browser is having immense difficulty in loading them all..

OK I have a question about unity gain with the S800 , in unbalanced mode.. I have read this entire thread a number of times.

So..yeah we have the trimmer on board , and I've set it for unity , in a balanced situation.

Now..I rig it up in an unbalanced situation..i.e my home studio where it will live , and so I have, our old friend, the 6dB level drop.

I can readjust the trimmer for unity in unbalanced mode, but my question is if this is the best remedy , or should the trimmer be left alone , and some other resistor values be changed?

Only asking , since in other circuits like the calrec eq,input res could be changed , and the vca i/p resistors on the gssl were the best spot.

I cant find anywhere, the official word on the purpose of the trimmer; I'm assuming it's to set balanced unity/CMR...but is it ok ,or a bit crude perhaps , to use it as a 6dB compensation boost ?

any thoughts anyone?

Cheers

nEon.

Hi nEon,
looking at the schematic and leaving the trimmer (shunt in a U-pad) alone, R36 would need to be increased from 15K to 30K and compensation cap C21 decreased from 100pF to 47pF for your required +6dB unbalanced gain. Could be made switchable by paralleling a 2nd 30K and a 2nd 47pF to alter between balanced and unbalanced mode. (IMHO C21 could be kept at 47pF. The NE5532 is unitygain stable and the LPF increase from 106kHz to 225kHz for balanced operation seems safe and far enough outside the audible range to get noticed, i.e -0.034dB vs. -0.134dB tested at 20kHz). Another approach could be to measue the trimmer for the required shunt resistor values for both operation modes. Just my 2ct.
Good luck.

Is any of this necessary?
I run unbalanced and the eq sounded great. Any drawbacks from just leaving it alone running unbalanced?

Thanks
Neil

 

[fazeka]

Hey all,

I've been trying to finish my build but I think I shorted something when the power was inadvertently left on while I was assembling it.  On one channel, the LF and HF doesn't seem to work. LMF and HMF boost/cut and sweep controls work. Signal at output seems low, too, even with trim max'ed out and compared with my known good working channel.

I started trying to signal trace using my 'scope from input, comparing to the known good channel. I get to pin 2 on U3 and see a signal that's not there on the known working channel pin 2 U3. The signal is slightly lower in amplitude than the input.

Any advice? I'm not versed enough to know what my next step is. Am I getting close to finding the problem given the symptoms?

Best,
Chris

 

[Le Roux]

Awesome updated schematic!! Was looking for one that I could read!!

I just built 8 channels, 2 of which had that issue.

Was in the wiring for the bypass switch.
One channel with a little buzz....still working on that!

 

[fazeka]

Update: I replaced U2 and U3. Unit is now back fully functional.  ;D

However, I do have a hum/ground problem with the EQ engaged...  I suspect it is due to the wiring of the pots (I am not using PCB mounted pots but smallbearelectronics pots) because when I move the wiring around, the hum gets a little better/worse.

I know that the wires are longer than I'd like, but I suspect even if I were to get them shorter (as long as they need to be), I will still have hum due to varying positions they will be in, quite close to each other. No?

Otherwise, I have the unit wired up as:

• AC inlet earth to star
• power transformer secondary CT to PSU (peterc green pre PSU) AC input "GRD"
• PSU output "0" to star and to "0" on channel PCBs
• All XLR pin 1s to star

I tried taking the GRD from the PCBs to the star: no improvement. 

Any other tips? Shielded cable from the pots to the PCBs? Something else?

Thanks,
Chris

 

[peterc]

Hi Chris

You could try moving the toroidal transformer and see if that makes a difference.

Loosen the nut and turn it on it's axis,see if that changes.

Take the nut off and physically move the transformer around and see if the hum levels change. If that is the case, you could try  an external PSU or mount the transformer on the back of the case.
Or get some shielding for the transformer, one of our members was selling mu metal (I think)  strips for this purpose.

Here it is
https://www.don-audio.com/radiation-shielding-magnetic-shielding-tafo-hum-trafo-shielding-electro-magnetic-sheets-grain-oriented-electric-sheets-electro-magnetic-foil-shielding-foil-shielding-sheets

Regards Peter