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Scott 130 question

24.42.83.12
Posted on November 16, 2014 at 20:11:09
David Smith



Can anyone have a look at the schematic above and confirm whether V3 and V103 are entirely for the tone controls? And V201 is for the center channel output and phase reversal only? If I rewire R33/133 in the position that R30/130 is (switch the two, really) do I get output at the "playback" tape outs that has bypassed the tone controls but uses the front panel volume control? Listening from the tape outs right now sounds pretty good...

Dave

 

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RE: Scott 130 question, posted on November 16, 2014 at 23:17:05
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 David
The Scott 130 has become my favorite preamp right along side the Fisher 400cx2..In spite of the tone controls,the performance of this preamp is phenomenal to say the least.V3 and V103 are there for the tone controls as it steps the gain back up from insertion loss from the tone controls.
Don't bother with R33/R133 and R30/R130 if you want to eliminate the tone controls..Simply disconnect V3b and V103b by pulling off the 100k plate loads on each and hook a .1 cap off V3a and V103a and go directly to the output jacks and that will eliminate the tone controls.
I think it's crazy to do it because if you have ever heard one of these preamps done with an all film cap power supply and new coupling caps and rebuilt DC filament supply,it will knock your socks off.I did use one F&T cap but here is the way you rebuild one of these..It is 90% done in these photos.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Scott 130 question, posted on November 17, 2014 at 05:40:22
David Smith
 Thanks Michael. Are V3A and V103A not just for the rumble filter and loudness?

It's partly rebuilt - PS caps are Atoms and coupling caps are K40s, new bridge for the filaments etc. I'm getting some distortion from that last part of it so something is amiss in there, but it sounds great and very clean just skipping all of that by going out the tape outs.

Film caps I have on hand are MKP, not sure I can fit them, but I'll keep your comments in mind and try to find the problem.

Did you try the tape outs on the one you rebuilt?

Dave

 

RE: Scott 130 question, posted on November 17, 2014 at 14:32:22
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Are V3A and V103A not just for the rumble filter and loudness?
No,that is another gain stage for which the volume control hooks into and rumble filter you can shut off..Just cap couple off V3a and V1013a with a .1uf to the output jack and that way you will eliminate the controls and that last stage.Be sure to pull the plate resistor off the last stage so it's inactive and just bypass the way I told you.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Scott 130 question, posted on November 17, 2014 at 14:40:35
David Smith
 Cool, thanks, I'll try that.

Dave

 

I didn't try the tape outs but I have another one, posted on November 20, 2014 at 17:15:40
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 to go thru and I can try them..
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

I think I found my distortion, posted on November 20, 2014 at 19:13:28
David Smith
 Seems it was a bit of dirt in the aux level pot. I had cleaned them before but I guess just tons of cleaning for all of those pots?

The tape outs sound clean but the pre outs are fuller, and do sound damned good. I'd be curious if you had a chance to check the tape outs what you thought.

Dave

 

RE: I think I found my distortion, posted on November 22, 2014 at 11:07:44
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Dave
The tape outs are ok and I have tried them but there seems to be a bit more gain and I prefer the preamp outs.Shoot me an email when you get a chance.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

You have mail. nt, posted on November 22, 2014 at 23:03:52
David Smith

 

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