Howdy all and Happy New Year!

[dado5]

First time on this forum although I am on other audio forums using the same handle (dado5 or dado4).

My one question so far: what is the voltage rating for the 220uf smoothing caps?

Thanks much in advance.

Best wishes to all for the new year,
Rob

[Shannon Parks]

First time on this forum although I am on other audio forums using the same handle (dado5 or dado4).

My one question so far: what is the voltage rating for the 220uf smoothing caps?

Thanks much in advance.

Best wishes to all for the new year,
Rob

They are 250V caps, with two in series for 500V rating. At least this was true in 2003. The Rev B has been retired. Along with the New Year will come a new revision for the ST35 board which will employ four 450V snap mount caps which will clear a 2" high chassis. But first I must edit the manual. :cry:

Get a peek here:
www.diytube.com/gallery/st35revC_med.jpg

Shannon

[Guest]

Thanks much for the quick reply. When will the new rev be available?

Thanks,
Rob

[Guest]

Love the smaller size of the new board!

Another question: My pre-amp line out is AC coupled, can I bypass (not install) the line input caps (C18 & C19 in the manual)?

Thanks again,
Rob

[Shannon Parks]

You may certainly bypass the DC blocking caps. ETA is as soon as I get the manual rev'd up. Hopefully next week.

HNY, :morning:
Shannon

[Guest]

Yet another question: How is the circuit ground attached to the chassis? Is it via the mounting screws or is there a separate connection. Thanks much in advance.

Regards,
Rob

[Guest]

I am logged in but my username comes up as guest and I get a rejection message when I type in dado5...what gives?

Thanks,
Rob

[Shannon Parks]

Yet another question: How is the circuit ground attached to the chassis? Is it via the mounting screws or is there a separate connection. Thanks much in advance.

There's safety ground and there's analog ground. In the Rev B circuit, the green safety ground was directly connected to PCB and the safety ground was then attached to the chassis via the mounting screws. As far as the analog circuit, it is self contained on the PCB and all ground connections should be attached to the PCB. Incidental chassis connections, like in a RCA connector, shouldn't cause a ground loop problem as the primary path should be less resistance. I've tested this, btw.

My comments for the analog ground are the same for the Rev C. But I will probably suggest a more UL approved approach with the safety ground connection. The safety ground should be attached to a dedicated chassis bolt immediately upon entering the chassis. Then a small, green jumper wire could go from here to the PCB.

Some may claim you don't need a safety ground or want it attached to analog ground. Especially in a DIY amp you want earth ground potential everywhere.

I'll look into your login problems, Rob. Does logging in twice fix it?

Shannon

[dado5]

Man you are quick....you must be single.

Looks like the double log in did it. There is no username field on this screen as there was before.

My main reason for asking the ground question was for avoiding loops/noise, not so much the safety issue.

Thanks,

Rob

[Shannon Parks]

Man you are quick....you must be single.

Looks like the double log in did it. There is no username field on this screen as there was before.

My main reason for asking the ground question was for avoiding loops/noise, not so much the safety issue.

Luckily my wife puts up with the tubes. :bad-words:

I have yet to hear from anyone with ground loop problems. I did try to even make cleaner ground plane on the new Rev C as well as the Ikes. Works great!

Shannon