My #102 Review

[Dr d]

Hi Tony, what do you think makes it "take off" so easily. Is it the PI set up and or the 50uf on the plates (output tubes I assume!)? Tube choice maybe?

[Structo]

That's what I was wondering how much the low plate filtering helps sustain and feedback.

I have dual 320uF on mine for a total of 160uF.
Three times what Tony has.

My amp seems a bit tight and does not sustain all that well unless I use PAB.

[Dr d]

Hi tom, I have dual 220uf on my 50W 102 with the very same issues!

[talbany]

Guys
To be honest I wish I knew or could at least point out some definitive answer..I honestly do not think it is any 1 thing perhaps several things.. The filtering is a possibility... I do have 100uf filtering on the bias supply BTW..50uf on plates/40uf on the OD Perhaps the resistors and pots or perhaps everything just came together on this particular amp?..All I know is this thing just does not want to let go even with my drive pot on 3 trimmer set @28k volume on 4 and master @ 12 through the lator.. Sitting here with a strat at moderate volume hitting an open D and never ending right into feedback (no PAB).. I really need to post some clips so you can hear this... Go Figure..
BTW it doesn't really matter what type of preamp tubes I put in this thing she still wants to take off..Perhaps I should keep this one..I have never had one go this NUT'S

Tony

[sergio]

nice work Tony! I like your coaxial cable!

I have also made ​​changes to the overdrive stage of my #102 to improve it!

S.

[vibratoking]

Tony - sounds like a great build. Congrats. I am not clear on what cap values you have and where. Here is a comparison of 102, 183 and what I think you have based on this thread. Is this correct?

102
B1 2 - 220 in series = 110uF OPT center tap
B2 20uF Output screens
B3 20uF PI plates
B4 40uF OD plates
B5 40uF CL plates
Bias 100uF Bias
NFB 4.7K 4 Ohm tap

183
B+ 2 - 330 in series = 165uF OPT center tap
B2 2 - 47 in series = 23.5uF Output screens
B3 2 - 47 in series = 23.5uF PI plates
B4 2 - 47 in series = 23.5uF OD plates
B5 2 - 47 in series = 23.5uF CL plates
Bias 47uF Bias
NFB 4.7K 8 Ohm tap

Tony's 102
B1 2 - 220 in series = 110uF OPT center tap
B2 20uF Output screens
B3 20uF PI plates
B4 40uF OD plates
B5 50uF CL plates
Bias 100uF Bias
NFB 2.2k or 7K? 4 Ohm tap

[talbany]

Vibro

Tony's 102
B1 2 - 100 in series = 50uF OPT center tap
B2 20uF Output screens
B3 20uF PI plates
B4 40uF OD plates
B5 20uF CL plates
Bias 100uF Bias
NFB 3k3 /390 5K pot 4 Ohm tap

This should be correct.. Here is a Classic with 50uf as well..Nothing new..

All The Best..

Tony

[Structo]

Perhaps the increase in neg feedback also plays a role.

[CHIP]

Nice, Tony. Looking forward to hearing it.

A D'Lite has 2 100uf in series, on the power supply.

[heisthl]

Another fabulous build Tony - I think you should send it to me for further testing.

- Sustain, bloom and feedback are all influenced by B+1 filtering, less is more to a point, it's a fun experiment to find a pet note and just keep playing it as you change the filtering. Usually the best is right at the point before the hum becomes annoying. You know you went too far when the bias adjustment set low (say 20 ma below perfect) is quiet and the hum comes in as you turn the control up and the load increases. Had this happen last weekend on a dual Kt-88 build - couldn't get away with 50uF, had to jump up to 100uF. Watching the ripple on a scope it would double as things started pulling.

[boldaslove6789]

Great build as usual Tony! Diggin the NOS parts.

I'm gettin ready to change out most of the parts out in my Quinn SDO-R 183 to some NOS stuff from Shad (Sprauge Q-lines, Piher, Beyshlags, NOS Orange Drops etc.). The result should be steller.

[Dr d]

Hi Tony, what made you reduce the filtering on the clean valve back down to 20uf? Also, the grid resistors on v1,v2 look massive! Are they 1/2w or bigger?
Cheers Doc.

[ToneMerc]

Also, the grid resistors on v1,v2 look massive! Are they 1/2w or bigger?
Cheers Doc.

They are 1W

TM

[Dr d]

Thanks for that TM!!!

[talbany]

Well you have to figure how many Twin Reverbs are out there using only 40uf on the screens.. ..Henry..Thanks for the test tip..After the amp settles the scope will be pulled..

I do notice that the OD hisses more than usual.. Not bad but more obvious than usual...The reason for the 20uf on V1 is I didn't have another 40uf TVA in the drawer (damn these things are getting expensive!)..
The pots and resistors do have a direct effect on the amps tone..A smoother less fuzzy tighter OD tone along with enhanced string definition..

Perhaps maybe HAD stopped building the ODS as these parts became extinct..No doubt a Big part of why these amps do what they do.. I think I will try a 183 next and see if the results are the same..Anyone who wants to donate or sell NOS for the expierment you can hit my PM..
Worked in the studio late, almost there...Clips shortly..

Tony