Ultraphonix adventure

[Reeltarded]

Swapped OT to CT 3.4k on this amp. Bluesbreaker model 1962.

[Reeltarded]

What have you all decided about NFB?

I have tried a few things with my (inspired by) and I guess the 4k7/100k fixed is about as good as anything.

It just isn't as good as anything else. lol

[fred.violleau]

I am going in!

16993279505335954937282762255603.jpg

100 watts is going to be loud!!
Will require a Master Volume.

Checked some voltages
Unloaded B+ is 450V
And filaments 6.9 V
What choke would you recommend?

Want to switch from clean to mean with relays ala Dumble.
Do I need to think of cascading? Maybe enough gain already?
Effects Loop to add delay pre PI
Rocka and Jazz on the clean
Bright switch on the mean channel

Any other tweaks to recommend?
I am excited!

Cheers and thanks for all the info you brought already!

Fred.

[bepone]

nice, for the choke anything, 3-5H, 100-150mA

[bepone]

p.s. this bassman 100 i have at home , it has just one of the best clean sounds in general, for the movies directly! without too much processing
i think is material selection so i would leave all of this inside, i changed only all electrolytics and PI output coupling caps to the output tubes for the new ones , just in case of leaking and preventing destroying the out tubes

[fred.violleau]

Hey Bepone,

I will build a new board for the preamp and power amp.
Not a fan of the leaky waxed cardboard.
may re-use components that did not drift too much to keep some of the mojo.

I want to add a mid control as well.
Thanks for your valuable input!

Fred.

[bepone]

motorboating on V1! through the power supply! 16-17Hz
im not so thrilled , cause is taking my (expensive) time..

this is the gain pot position where it starts,

IMG_20231213_181844.jpg

IMG_20231213_181826.jpg

Ub+ is going crazy after the pot pass this value, caps are ok

[bepone]

Ub+ for V1 on the pot position, and slightly back

IMG_20231213_182415.jpg

IMG_20231213_182426.jpg

[Reeltarded]

It just started spitting?

[Reeltarded]

I am going in!

16993279505335954937282762255603.jpg

100 watts is going to be loud!!
Will require a Master Volume.

Checked some voltages
Unloaded B+ is 450V
And filaments 6.9 V
What choke would you recommend?

Want to switch from clean to mean with relays ala Dumble.
Do I need to think of cascading? Maybe enough gain already?
Effects Loop to add delay pre PI
Rocka and Jazz on the clean
Bright switch on the mean channel

Any other tweaks to recommend?
I am excited!

Cheers and thanks for all the info you brought already!

Fred.

Fred, did you get this one wired up? I noticed the 79 Deluxe OD thread yesterday and to answer your cascade question I think that amp has the answer.

Yes. It will be a MONSTER version of your fantastic Tweedle. It seems that thread says the normal channel is a switchable cascade.

[bepone]

It just started spitting?

it was at the beggining during build, and then some time nothing, and now again. incredible! 50 yrs old amp revenge!

[bepone]

After tweaking like crazy all morning, adding RC elements, separating decoupling the tube halves, changng pot, raising the wires in the air.. all what should stop osc - nothing. V1a stopping with LF osc only when i disconnect V1b!

Now im quitting , mazbe i ll rebuild all, but at the end i was changing amplitude in freq. gene and i saw miracle! And tragedy in the same time

[bepone]

here are oscillograms, output from V1b anode (so after cascade), when amplitude is changed on V1a g1 input:

input 1Vpp 400 Hz (all ok)

SCR02.PNG

input lowered to 250mVpp (all ok)

SCR01.PNG

input lowered to 100mVpp (oscillation started 2 frequencies present, 400Hz is modulating 16Hz carrier)

SCR04.PNG

-------------------------

it is volume dependant, great, need to use only hi output pickups, and play only loud! stage amp!

[Reeltarded]

I thought about it for a long time.

No idea.. unless it is downstream instead of expected upstream.. hmm. Potential ground issue towards PI.. it becomes overwhelmed by potential toward input.

It's a theory. Careful not to create a new creation. Whoa. haha

[fred.violleau]

I am going in!

16993279505335954937282762255603.jpg

100 watts is going to be loud!!
Will require a Master Volume.

Checked some voltages
Unloaded B+ is 450V
And filaments 6.9 V
What choke would you recommend?

Want to switch from clean to mean with relays ala Dumble.
Do I need to think of cascading? Maybe enough gain already?
Effects Loop to add delay pre PI
Rocka and Jazz on the clean
Bright switch on the mean channel

Any other tweaks to recommend?
I am excited!

Cheers and thanks for all the info you brought already!

Fred.

Fred, did you get this one wired up? I noticed the 79 Deluxe OD thread yesterday and to answer your cascade question I think that amp has the answer.

Yes. It will be a MONSTER version of your fantastic Tweedle. It seems that thread says the normal channel is a switchable cascade.

Cleaned the Bassman chassis, put some components aside for a future build. Been busy working on the layout (I like to plan things).

Got a few questions on the schematic posted by Bepone vs Aaron's original, mostly on the 4th stage of the drive channel, on Aaron's schematic there is a 45k resistor going into the coupling cap and then into another 45k resistor, when on bepone's schematic, it seems to be closer to the original JCM800 with 0.005uf coupling cap going into the 470k divider resistors. I don't have a simulator to see what frequencies these two setup would affect. can one of you elaborate on this ?

PXL_20231218_211012184.jpg

Bepone have you tried to replace V1 socket ? It seemed you had trouble with it during the build.

I should start assembling in the coming days, will keep you posted.

Fred