Encore style build needs trouble shooting

[M Fowler]

Yes you will need to take some time and get that bias range higher so you can adjust.

Use plate voltage reading to determine bias needed.

I'm going to check out your MV wiring and circuit too. That can cause problems too.

[angelodp]

Mark, here is what I have on the OT. So we are talking about swapping the primary blue and black wires that are on pin 3 of each power tube?

[IMG:744:1024]http://i260.photobucket.com/albums/ii9/angelodp1/OT-P-108forEmcorebuild_zpsa999374d.jpg[/img]

[M Fowler]

V7 isn't wired correctly it should have blue wire from 220k on board to pin 1 just like V6 has.

Scratch that I now see your tube socket is mounted different, it is OK.

[M Fowler]

Yes swapping black and blue around to balance the OT. This can be tested by removing the NFB wire from speaker jack too.

[angelodp]

Mark, it is wired to pin 1. I know its a bit confusing to look at . I did not reorient the power sockets as this chassis already had so many holes, I suppose I should have done so. It is at pin 1.

V7 isn't wired correctly it should have blue wire from 220k on board to pin 1 just like V6 has.

Scratch that I now see your tube socket is mounted different, it is OK.

[angelodp]

Ok so if I remove the NFB wire and it cleans up then I know I have them reversed?

Yes swapping black and blue around to balance the OT. This can be tested by removing the NFB wire from speaker jack too.

[angelodp]

Mark, the NFB pulled did cut back the chirping, but the amp has no volume. I'll try swapping those leads on the OT tomorrow. Thanks for the help, back at it tomorrow.

At least there is sound.

[M Fowler]

Okay take care Angelo.

[angelodp]

Hi mark, I switched the leads on the to… squeal gone. I adjusted the dias circuit so that I am getting -55v with some range. I do hear the amp but its at a very low level, as if the amp was one 3. I am going to collect some voltage readings.

[angelodp]

Hey Mark, nailed it…. one bad connection. I wired the .022 to the cathode instead of the plate. All is well and a very nice amp indeed. Love the RAW control and the Master is great. Wide open clean is SRV land. The verb is pretty swampy and I intend to implement the dwell control on the back wall. I am also going to slow down the speed a tad with one additional .01 in the term circuit. Other than that it really rocks. Allen did a fine job with this tweaked Vibroverb circuit. I appreciate you saving my ass from the power cathode fumble. I have the bias jacks and 1% 1 ohm'ers on the way. Pal had an external Bias tool and we got pretty close to optimal settings. I may have to back off the course adjust resistor a tad more to 27k so I can get more range. All in all a fine amp.

[M Fowler]

Angelo,

Glad it worked out so well, I like my Accomplice clone in a Bassman 1-12 size combo too, very close circuit. Enjoy.

Mark

[angelodp]

Mark, one little item, I would love to implement some bleeder resitors for the amp. 220k 3w sound about right across the reservoir cap from + to - ?? Same for the other B+ cap?

[M Fowler]

Mark, one little item, I would love to implement some bleeder resistors for the amp. 220k 3w sound about right across the reservoir cap from + to - ?? Same for the other B+ cap?

Yeah I use either 220k or 270k 2w or 3w whatever I have on hand for balancing resistors for caps in series or as bleeder resistors.

Your gut shot looks like a pair in parallel so use some bleeder resistors like Trainwreck does between B1+ and ground.

The other caps do not need this.

[M Fowler]

Also read Tubeswell post on this subject.

https://tubeamparchive.com/viewtopic.ph ... highlight=

[angelodp]

Will do

Thanks Mark