Search found 152 matches

by larsvictor
Mon Sep 27, 2021 1:21 pm
Forum: Dumble Discussion
Topic: Corrupted PT
Replies: 16
Views: 1956

Re: Corrupted PT

Hello Oddvar, since it seems that your location is Europe you might have a look at this polish supplier: https://amptone.pl/p/273/2443/power-transformer-pt50l150-50w-laydown-amptone-power-transformers.html This one has more or less Dumble ODS 50W specs. It has an extra 12VAC secondary for the relays...
by larsvictor
Mon Sep 27, 2021 8:32 am
Forum: Dumble Discussion
Topic: My take on an SSS
Replies: 104
Views: 44432

Re: My take on an SSS

Hi,

Thanks to everyone who reviewed the schematics. I tried to fix all the errors you mentioned.
The current versions are here and in the "editable D-style schematics" -section.

Thanks
Lars
by larsvictor
Tue Dec 25, 2018 9:06 am
Forum: Dumble Discussion
Topic: My Dumble hrm needs help . Please.
Replies: 49
Views: 6040

Re: My Dumble hrm needs help . Please.

HRM50-MK2.jpg
Is this your Amp? Any modifications?

Lars
by larsvictor
Sun Dec 23, 2018 6:46 pm
Forum: Dumble Discussion
Topic: My Dumble hrm needs help . Please.
Replies: 49
Views: 6040

Re: My Dumble hrm needs help . Please.

An Issue with the relay? Does it really switch? Is there a change in volume between clean channel and overdrive?

Lars
by larsvictor
Fri Oct 27, 2017 5:06 am
Forum: Dumble Discussion
Topic: SSS #004
Replies: 37
Views: 8427

Re: SSS #004

Regarding the gut shot. Seems that this one does not have the cf driver tube in the poweramp section. Just a "normal" PI.

Lars
by larsvictor
Tue May 23, 2017 7:19 pm
Forum: Dumble Discussion
Topic: Dumble video/sound clip reference, real Dumbles only please
Replies: 381
Views: 337910

Re: Dumble video/sound clip reference, real Dumbles only please

Found this one on a website of a recording studio in Germany. Could be an early silverplate ODS somewhere around #028-039. Only a few information about this amp is available on the site: Company: (Alexander) Dumble Model : Overdrive Special Year: 1979 Export Model Added Reverb Accent switch converte...
by larsvictor
Wed Mar 29, 2017 7:42 pm
Forum: Dumble Discussion
Topic: 2nd Gen hybrid
Replies: 97
Views: 16813

Re: 2nd Gen hybrid

Wow, Erwin. That one looks great ! I love it.
Lars
by larsvictor
Tue Mar 28, 2017 4:43 am
Forum: Dumble Discussion
Topic: SSS#002 low voltage in original drawing
Replies: 39
Views: 6061

Re: SSS#002 low voltage in original drawing

Thank you, guys!

Yes, the EVM 12L is already mounted.

Lars
by larsvictor
Sun Mar 12, 2017 6:06 pm
Forum: Dumble Discussion
Topic: Alternate power supply for SSS driver stage
Replies: 28
Views: 4852

Re: Alternate power supply for SSS driver stage

The new circuit works fine: B+ for the plates is +198 VDC, grids of the CF have -50.3 VDC and Cathodes -48.6. Less stress for the tube with ~250V plate to cathode. PT somehow delivered higher voltages than I expected (+/- 206 VDC without load). I had to adjust the values of the resistors in the bias...
by larsvictor
Sat Mar 11, 2017 7:23 pm
Forum: Dumble Discussion
Topic: SSS#002 low voltage in original drawing
Replies: 39
Views: 6061

Re: SSS#002 low voltage in original drawing

Working on the cabinet...
by larsvictor
Fri Mar 10, 2017 10:34 am
Forum: Dumble Discussion
Topic: SSS Cathode Follower and Bias Voltage in a 50W Fender Bassman Converted to Vibroverb
Replies: 32
Views: 4474

Re: SSS Cathode Follower and Bias Voltage in a 50W Fender Bassman Converted to Vibroverb

Marcusw, thanks for the information concerning the high and low filter section. I compared your schematic to the sss_002_revision_7-174-781 ("may contain errors-schematic") and to the original drawing of SSS #002 from Japan there are indeed minor differences. Your understanding of that network makes...
by larsvictor
Wed Mar 08, 2017 5:50 am
Forum: Dumble Discussion
Topic: Steel String Singer 002 Build - 60Hz Hum - SOLVED
Replies: 27
Views: 3316

Re: Steel String Singer 002 Build - 60Hz Hum - HELP!

The artificial center tap of the heater winding is located near the pilot light? It could be a problem with the additional FET circuit. I had the same thing when I tried to build a 9 VDC power supply for stomp boxes in an amp using the heater winding. When I engaged the effect, I had this terrible h...
by larsvictor
Sun Mar 05, 2017 2:21 pm
Forum: Dumble Discussion
Topic: Alternate power supply for SSS driver stage
Replies: 28
Views: 4852

Re: Alternate power supply for SSS driver stage

Ok, Martin. I´m convinced. :D
Build this tiny board for the +/- 160VDC CF-power supply. Curious wether it makes a difference soundwise.

Lars
by larsvictor
Wed Mar 01, 2017 7:14 pm
Forum: Dumble Discussion
Topic: Alternate power supply for SSS driver stage
Replies: 28
Views: 4852

Re: Alternate power supply for SSS driver stage

Martin, can you explain why the entrance of your cf driver has a different design ? (compared to the published #002 cf driver circuit). In your schematic the grid leak resistors are 470k ( 1M in #002) and you have 220k grid stoppers (#002 has no grid stoppers there). I do understand the 100k for the...