Search found 77 matches
- Mon Jun 15, 2020 8:14 pm
- Forum: Fender Discussion
- Topic: Blackvibe has left the building
- Replies: 4
- Views: 3570
Re: Blackvibe has left the building
Congrats Phil on getting the Blackvibe up and running. I'm very happy to hear it is being gigged on a regular basis.
- Sat Mar 02, 2019 8:38 pm
- Forum: Fender Discussion
- Topic: Single Channel, No Reverb, No tremolo AB763 Amp Design
- Replies: 11
- Views: 3306
Re: Single Channel, No Reverb, No tremolo AB763 Amp Design
The mixing resistor was left in because it affects the phase inverter's overdrive tone. It's there to keep the tone as close to standard AB763 as possible. Thanks for pointing out the missing schematic label for the bias balance pot but it is labeled as a 25KL pot in the layout. I'll update the sche...
- Sat Mar 02, 2019 7:03 pm
- Forum: Fender Discussion
- Topic: Single Channel, No Reverb, No tremolo AB763 Amp Design
- Replies: 11
- Views: 3306
Single Channel, No Reverb, No tremolo AB763 Amp Design
I know this has been done before but here's my take on an easy to build, normal channel only, no reverb, no tremolo AB763 blackface amplifier. There is a 2x6L6 and 2x6V6 version along with a 1 watt micro version that uses the AB763 preamp and phase inverter but feeds a single 12AU7 push-pull power t...
- Sat Mar 02, 2019 5:27 pm
- Forum: Technical Discussion
- Topic: Adding Presence Control to Deluxe Reverb
- Replies: 23
- Views: 7216
Re: Adding Presence Control to Deluxe Reverb
Here's one way to add a presence control to a blackface/silverface amp. It uses the 5F6A Bassman presence control and the amp's NFB & PI Tail resistors are adjusted to compensate for the presence circuit's added resistance. https://robrobinette.com/AB763_Modifications.htm#Presence_Control https://ro...
- Tue Jul 21, 2015 1:31 am
- Forum: Fender Discussion
- Topic: KT66 power tubes in Hotrod Deville
- Replies: 19
- Views: 3939
Re: KT66 power tubes in Hotrod Deville
This is fixed bias isn't it? Then the cathode is basically at 0V (well 10's of mV through the 1 ohm resistor). You are right, it is fixed bias so there is no difference between plate voltage and plate-to-cathode voltage. Sorry about that OP. With a fixed bias Class AB amp like yours most people use...
- Tue Jul 21, 2015 12:58 am
- Forum: Fender Discussion
- Topic: KT66 power tubes in Hotrod Deville
- Replies: 19
- Views: 3939
Re: KT66 power tubes in Hotrod Deville
The simplest way to do it is to put the multimeter red probe on the plate pin and the black probe on the cathode probe and the measured voltage is the plate-to-cathode voltage with no math involved. You can measure the cathode voltage direct at the cathode pin to ground or from the tube side of the ...
- Mon Jul 20, 2015 5:21 pm
- Forum: Fender Discussion
- Topic: KT66 power tubes in Hotrod Deville
- Replies: 19
- Views: 3939
Re: KT66 power tubes in Hotrod Deville
You should also use the plate voltage - cathode voltage for your "plate voltage" in the dissipation calculations so that will drop your dissipation % too.
I have a tube bias calculator webpage that's pretty easy to use: https://robrobinette.com/Tube_Bias_Calculator.htm
I have a tube bias calculator webpage that's pretty easy to use: https://robrobinette.com/Tube_Bias_Calculator.htm
- Mon Jul 06, 2015 4:46 pm
- Forum: Fender Discussion
- Topic: Simple obvious effective Bassman tweak
- Replies: 9
- Views: 3385
Re: Simple obvious effective Bassman tweak
sliberty, I did something similar in this modded version of the Deluxe Micro:
[img1377]https://robrobinette.com/images/Guitar/ ... ematic.png[/img]
[img1377]https://robrobinette.com/images/Guitar/ ... ematic.png[/img]
- Mon Jul 06, 2015 12:41 pm
- Forum: Fender Discussion
- Topic: Simple obvious effective Bassman tweak
- Replies: 9
- Views: 3385
Re: Simple obvious effective Bassman tweak
My 5F6A mod web page.martin manning wrote:Rob, what is the source for the quote above?
- Mon Jul 06, 2015 12:03 pm
- Forum: Fender Discussion
- Topic: Simple obvious effective Bassman tweak
- Replies: 9
- Views: 3385
Re: Simple obvious effective Bassman tweak
This is my 5F6A tweed Bassman "Lead" channel mod. It uses the Marshall 1987 first preamp cap and cathode resistor values. With this mod there's a real difference between the standard Normal and Bright channels. [img:400:752]https://robrobinette.com/images/Guitar/Bassman/Bassman_Lead_Channel.png[/img...
- Thu Jul 02, 2015 11:30 pm
- Forum: Fender Discussion
- Topic: Google Malware Warning for The Amp Garage
- Replies: 2
- Views: 1189
Re: Google Malware Warning for The Amp Garage
Thanks Martin.
- Thu Jul 02, 2015 3:36 pm
- Forum: Fender Discussion
- Topic: Google Malware Warning for The Amp Garage
- Replies: 2
- Views: 1189
Google Malware Warning for The Amp Garage
Am I the only one getting a warning from Google that there's malware on the site? I have to click on the ominous "visit the unsafe site" link to see any content here.
- Thu Jul 02, 2015 3:34 pm
- Forum: Fender Discussion
- Topic: I Can't Stop! Check My Attempt?
- Replies: 21
- Views: 4476
Re: I Can't Stop! Check My Attempt?
I just noticed the 6G3 schematic doesn't show a cathode resistor. The standard would be a 250 ohm 5 watt.
- Wed Jul 01, 2015 5:14 pm
- Forum: Fender Discussion
- Topic: I Can't Stop! Check My Attempt?
- Replies: 21
- Views: 4476
Re: I Can't Stop! Check My Attempt?
Zep, I prefer the 6G3's long tail pair phase inverter for its own overdrive tone and the much larger voltage swing to push the power tubes to full overdrive. You can always use a solid state inverter in the 6G3. Since you're using one input the 6G3's first grid stopper should be 33k (like the Prince...
- Fri Jun 26, 2015 4:03 am
- Forum: Fender Discussion
- Topic: 5F1 Bus Grounding: where to ground speaker out?
- Replies: 6
- Views: 1888
Re: 5F1 Bus Grounding: where to ground speaker out?
The black 'ground' wire from the output transformer secondary should be grounded at the speaker jack's sleeve (ground) terminal.
I would ground the variable NFB pot to the preamp bus. That's where the 5F6A Bassman's Presence control is grounded.
I would ground the variable NFB pot to the preamp bus. That's where the 5F6A Bassman's Presence control is grounded.