Spectra Sonics 610 Limiter help

[soundguy]

Any experts in the house on this one? Im having some wierd stuff go on and could use some help if anyone has practical experience calibrating these. I dont have a schem for the 601 card, which is helping none. I have two cards and there are some different cap values on each. Since there is no silk screen on the cards, try to follow-

Looking at the board component side up with the edge connector on the left, what is the function of the cap second position in from the left in the row closest to you on the lower board (eck, follow that...)? One card I have is a 2u2 and the other is a .68u.

The problem Im having is that I can get the thing calibrated to see the first 3dB of gain reduction and the meter doesnt track the release at all. The card with the smaller cap in that position tracks a bit better but not by much. Followiing the cal procedure gets me nowhere, the unit isnt metering the first 3 dB of reduction at all.

Also on the 601 card, on the top daughter board, what is the value of the electrolytic on the lower right, 56u 6v?

If anyone has a factory schematic it would make this a whole lot easier to communicate...

dave

 

[edanderson]

maybe these could help:

http://edanders.home.comcast.net/diy/spectra601.pdf
http://edanders.home.comcast.net/diy/spectra603.pdf
http://edanders.home.comcast.net/diy/spectra610.pdf
http://edanders.home.comcast.net/diy/ss_schem.pdf

ed

 

[guavatone]

I have the limiter's manual. I think it has some schematics -I can check. I don't have a scanner though.

I thought I remember hearing that these boxes just don't tell you anything by the meters.

 

[soundguy]

thanks for the info, printing all that out now.

I found the patent, its number 3,550,028 if you do a search. some more circuit stuff in there.

big question still remains, how well do these things track? perhaps what Im dealing with is normal...

dave

 

[soundguy]

update, I had two different editions of the manual, one says to cal at 50hz, the other at 1K, my unit definitely needed to be set up with the 1K tone, tracks much better now. The meter still does not show the release, Im going to assume for now that this is normal. Any feedback on that?

dave

 

[Gus]

If it is a 601 card like the the hand drawn schematic in one of the links are you posting about the .68uf at the bottom middle.

could be and Al or tant electro because it has a + sign and it goes to a fet gate

So I am thinking cap leakage current. Try a film of .68uf to 2.2uf something like a polypro or other film types. Make sure the board is very clean around the gate of q2

 

[soundguy]

thanks gus. 2u2 electrolytic so far has sounded the best, .68 film tracks slightly better but not so much more efficiently to compromise over the sound difference. I imagine this would be a place to look at ESR if you wanted to get the microscope out, right?

dave

 

[Gus]

More the DA and leakage current: however low ESR electros seem to have better DA and leakage measurements

try a blue cap

 

[soundguy]

i did, of course it rules. higher esr though.

dave

 

[SonsOfThunder]

[quote author="Gus"]try a blue cap[/quote]

:?:

 

[martthie_08]

Wow, old topic, but heck I've got some troubles with one of my 610 limiters and was too lazy to start a new topic, so here we go.

One of my two units has very low gain, but the meter shows full swing. By changing the cards around the two units I have identified the 601 card to be the troublemaker. After recapping the "problem card" things are still the same, output level is really low compared to using the other (working) 601 card. So I presume the output stage of that card is the culprit and since all resistors measure right on, it will probably be one of the transistors in that stage. I have linked up a schematic of the 601, that was floating around here some time ago:

http://www.martenthielges.com/image/Spectra%20Sonics%20610.pdf

Since the original transistors are not available, I am looking for a modern day replacement for the PNP Q104 (2N4248)  and NPN Q103 (FPN 3566), can I use BC560 and BC550 types, for example?

any other hints on troubleshooting are welcome of course, I really miss using both of them at the same time mixing, they are pretty cool on snare and bass sometimes...

thanks, Marten

 

[martthie_08]

could anyone have a quick look at these datasheets and tell me if it'll be safe to substitute

2N4248 with BC560c

and the NPN Q103 (can't find the datasheet) with BC550c

thanks!!!

 

[martthie_08]

OK, it was Q104, replaced it with a BC560c (specs seemed to be close enough) and the 610 is crunching again

 

[bobschwenkler]

One of my two units has very low gain, but the meter shows full swing.

These compressors are weird in that they GR metering has no actual correlation to the actual amount of GR being applied. They're separate circuits and the metering is calibrated to the GR.

Do your units have the tinted or clear VU panel?

 

[martthie_08]

yes, that is correct.

My units have the tinted glass and the lights are out at the moment, which makes it really hard to see what is going on

 

[bobschwenkler]

I bet they're hard to see! I'm not much a sucker for flashy baubles, but I'm totally into the tinted window on my 610. The school I teach at has one with a clear meter and it's just not as cool looking.