Search found 121 matches

by RB
Thu Feb 09, 2017 10:13 pm
Forum: Fender Discussion
Topic: AB763 KT88 Question
Replies: 11
Views: 1655

AB763 KT88 Question

I have a head that is basically a AB763 reverb only - 12AT7 PI - 2X6L6 OT is Classic Tone BFBassman 50watt 4K - PT is 200ma 320-0-320 with solid state rectifier. Heater spec is 5A so no problem with 2x12AXY 2x21AT7 and 2xKT66/6550 I am looking for the shortest path to a little more power/SPL - clean...
by RB
Mon Jan 02, 2017 7:07 pm
Forum: Dumble Discussion
Topic: High power Tweedle Dee.
Replies: 13
Views: 2024

Re: High power Tweedle Dee.

I have built/converted many Tweed Deluxes to big bottle amps. Tried all the OTs Mentioned (except MM) above and settled on the Tweed Pro/Super/Bandmaster 6k iron. 6L6,5881 and KT66 all sound amazing cathode biased. Fixed bias produces a little more power but some of the creamy quality disappears. I ...
by RB
Thu Sep 15, 2016 2:56 am
Forum: Technical Discussion
Topic: A mod/trix I never seen before
Replies: 20
Views: 3753

Re: A mod/trix I never seen before

When I pushed the submit button on my last post I thought I should have added where is martin manning when we need him?

Thanks so much for the clarification.

Randy
by RB
Wed Sep 14, 2016 10:20 pm
Forum: Technical Discussion
Topic: A mod/trix I never seen before
Replies: 20
Views: 3753

Re: A mod/trix I never seen before

When I think of feed back I understand that to be from an output to an input. This clearly bridges two outputs. I don't see how that constitutes feedback. It seems like it would create something like mixing/balancing/co-mingling of the two AC components. Would these signals be out of phase? I think ...
by RB
Wed Sep 14, 2016 3:24 am
Forum: Technical Discussion
Topic: A mod/trix I never seen before
Replies: 20
Views: 3753

trick??

I think he is referring to the silver mica between what appear to be the plate loads for the first two stages. just before the tone stack
by RB
Thu Jun 02, 2016 4:57 pm
Forum: Speakers and Cabinets
Topic: Cube 1936 = finger joint insanity
Replies: 10
Views: 3535

Wow

I think you should rename your post to "finger joint mastery".
Very kool cab.

Regards
Randy
by RB
Wed Jun 01, 2016 9:23 pm
Forum: Marshall Discussion
Topic: Buying a choke for JTM-45 build
Replies: 2
Views: 1283

Buying a choke for JTM-45 build

I am going to buy a PT and OT from Mag Components but am not sure which of their chokes to buy for the JTM. I would appreciate any and all suggestions.

Regards
Randy
by RB
Sat Feb 13, 2016 7:53 pm
Forum: Garage Talk
Topic: MOSFET heat sink connection
Replies: 2
Views: 849

Re: MOSFET heat sink connection

I always take an ohm meter and check the resistance between the leads and the back to check for continuity to determine if any pin is common with the back/sink portion of the device. Depending on the device type you would then chose to insulate it from the chassis or ground it.

Regards
RB
by RB
Thu Feb 11, 2016 8:29 pm
Forum: Garage Talk
Topic: I forget what I can't remember
Replies: 8
Views: 1181

Re: I forget what I can't remember

I just went over to the fender field guide site and checked out all the brown/blonde era schematics. They either have the 4 terminal/tapped treble pot or a Baxandall type tone circuit with the exception of the bass channel on the 6G6 amp. Actually its goes triode-bass-triode-treble-triode. Regards R...
by RB
Thu Feb 11, 2016 7:08 pm
Forum: Garage Talk
Topic: I forget what I can't remember
Replies: 8
Views: 1181

Re: I forget what I can't remember

The first thing that comes to mind is a Blonde Bassman 6G series

Regards
RB
by RB
Tue Feb 02, 2016 10:55 pm
Forum: Technical Discussion
Topic: Mystery amp
Replies: 5
Views: 881

Re: Mystery amp

Check this link out if you want a solid-state follower to work like a hollow-state follower.

http://milas.spb.ru/~kmg/irf_en.html

Regards
RB
by RB
Wed Jan 13, 2016 10:11 pm
Forum: Technical Discussion
Topic: PSA: Cheep Heyboer iron on eBay
Replies: 19
Views: 3379

Re: PSA: Cheep Heyboer iron on eBay

I bought a couple of the EL84/6V6 PTs. UPS tracking sez they will be here tomorrow. The shipper is 3rd Power Amplification. Check their web site out. Will be interesting to see if the transformers were mis-speced as suggested above. You can always call Heybore and get info based on their part/model ...
by RB
Thu Dec 17, 2015 10:53 pm
Forum: Technical Discussion
Topic: Smokin' Joe or mystery amp
Replies: 4
Views: 928

Re: Smokin' Joe or mystery amp

Check out Weber Speakers web site they had a kit by that name with similar topology. You should be able to get schematic and layout off the site.

Regards RB
by RB
Sat Jun 27, 2015 9:29 pm
Forum: Garage Talk
Topic: Ham Radio Question
Replies: 9
Views: 2063

Re: Ham Radio Question

I have been a ham since 1959. Have drifted in an out of the hobby all my life. What you have is what's was known as a sweep tube linear amp. This is a very cheep way of getting 250-500 watts PEP from a low drive device say <than 20 watts for cheap. There were many brands of these device's around and...
by RB
Mon May 18, 2015 7:16 pm
Forum: Marshall Discussion
Topic: Lower b+ plexi build
Replies: 32
Views: 10412

Re: Lower b+ plexi build

This is a great thread. I built an amp like Jana's but with 4X6V6 power section and I cant get it back from the guy I let try it. He decided he would use it on tour. I have a question for the low B+ gurus. What choke do you recommend with what filtering values? (assuming standard 2XEL34 power sectio...