Search found 90 matches
- Thu May 06, 2021 4:47 pm
- Forum: Marshall Discussion
- Topic: Marshall Standby switch deletion and bias tap design
- Replies: 25
- Views: 4133
Re: Marshall Standby switch deletion and bias tap design
The preamp and phase inverter filter caps in marshalls are only rated for 350v to 500v (depending on the amp). In many cases you risk blowing these caps unless you use the standby switch. For example, a 100JH has 600VDC across the standby switch, while the phase inverter cap is only rated for 450v....
- Wed Feb 01, 2017 7:32 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
Reverb should go through some kind of effects loop, I use an interrupt type passive loop to drive reverb and delay. Sounds good. It is going through a loop (a slightly modified version of the one in Merlin's book). Reverb sounds perfect, but 15W means not a lot of headroom so reverb gets compressed...
- Wed Feb 01, 2017 7:30 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
56k on the 8 ohm tapLittlewyan wrote:Is that 56K on the 16Ohm tap?
The amp sounds good!
Thanks
- Wed Feb 01, 2017 2:56 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
Newer demo with more tweaks (including the smaller NFB resistor)
https://www.youtube.com/watch?v=3bWiXUqG_5A&t=361s
Starting to sound pretty good IMHO
Having never owned an amp that made less than 50W before (save for my 8W JCM8 which is more of a toy), it takes some adaptation
https://www.youtube.com/watch?v=3bWiXUqG_5A&t=361s
Starting to sound pretty good IMHO
Having never owned an amp that made less than 50W before (save for my 8W JCM8 which is more of a toy), it takes some adaptation
- Mon Jan 30, 2017 1:41 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
Ah cool glad you sorted it. Does the presence control work well? If not you might want to consider changing the NFB resistor to 82K as at the moment you don't have much feedback with that 100K. Sounds good though :). I struggle to get a clean tone with my 20W Master Volume amp when the gain and mas...
- Sun Jan 29, 2017 4:36 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
Ah cool glad you sorted it. Does the presence control work well? If not you might want to consider changing the NFB resistor to 82K as at the moment you don't have much feedback with that 100K. Sounds good though :). I struggle to get a clean tone with my 20W Master Volume amp when the gain and mas...
- Fri Jan 27, 2017 4:01 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
Changing the voltage divider to 470k/22k pretty much fixed the loop's volume drop. Also, swapped a smaller coupling cap in the lead channel (0.0033uF), and experimented with a 12AY7 for more clean range
https://www.youtube.com/watch?v=Jn6mz9ROHDY
https://www.youtube.com/watch?v=Jn6mz9ROHDY
- Wed Jan 25, 2017 9:28 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Re: Demo of my cathode-biased tube-rectified 6V6 Plexi
Nice amp man :). Good tone. I've never seen a low power switch like that before, thats pretty cool! Maybe try changing it to a triode/pentode switch so it keeps the distortion at a lower volume. It will change the tone but you might like it. With regards to the Effects Loop, try setting it up how S...
- Wed Jan 25, 2017 8:58 pm
- Forum: Marshall Discussion
- Topic: Demo of my cathode-biased tube-rectified 6V6 Plexi
- Replies: 11
- Views: 2982
Demo of my cathode-biased tube-rectified 6V6 Plexi
https://www.youtube.com/watch?v=tF9a8yhygy4 I did a complete video log of the build if anyone is curious. It's built entirely from scratch: https://www.youtube.com/playlist?list=PLqC_WjyYCKZHSq071HgWoueuDdyoHHHWm There's a schematic and description on my website of what it WILL be when it's complete...
- Fri Oct 07, 2016 12:21 pm
- Forum: Marshall Discussion
- Topic: kt66 in a stock 18watt?
- Replies: 7
- Views: 1564
Re: kt66 in a stock 18watt?
6V6 yes, KT66 no
- Tue Oct 04, 2016 12:44 pm
- Forum: Vox/Hiwatt Discussion
- Topic: Morgan AC20 layout or schematic
- Replies: 12
- Views: 11546
Re: Morgan AC20 layout or schematic
Interesting. So my analysis wasn't too far off. The EF86 is not triode-strapped (that didn't make much sense too, but I'm no EF86 specialist), and the switch also switches B+ (turning off the unused tube, and sending the signal through the same coupling caps, which explains why the coupling cap sele...
- Thu Sep 29, 2016 2:54 pm
- Forum: Vox/Hiwatt Discussion
- Topic: Morgan AC20 layout or schematic
- Replies: 12
- Views: 11546
Re: Morgan AC20 layout or schematic
If you MUST copy that amp, there are some very clear gut shots if you Google for it, you can clearly make out the circuit and read most cap and resistor values. Looks like a pretty basic AC15-type circuit, with a switch to select an EF86 or 12AX7 preamp tube, and a neat little VVR control on its own...
- Tue Sep 27, 2016 11:11 am
- Forum: Marshall Discussion
- Topic: Anderton '64 reissue JTM145 - any info?
- Replies: 442
- Views: 121216
Re: Anderton '64 reissue JTM145 - any info?
So did anyone ever figure out how the JTM145 offers two volume knobs? It sounds QUITE different from the JTM1, I doubt it's just a JTM1 with a full tone stack. Here's my theory: one of the designers gave some clues about the JTM1 and JCM1 on another forum, and one trick they used on the JCM1 is to h...
- Sun Sep 25, 2016 12:53 pm
- Forum: Technical Discussion
- Topic: Calling Supro experts: which version of the 1624T to build?
- Replies: 4
- Views: 2264
Re: Calling Supro experts: which version of the 1624T to build?
I guess I figured out why the change in tremolo circuit: the original one had the Intensity control as a plate load, aka it had B+ on it. It'll work (Alpha 24mm pots are rated for 500V), but it's not ideal.
So I guess I'll stick with the 2 triode tremolo (which keeps DC off the pots)
So I guess I'll stick with the 2 triode tremolo (which keeps DC off the pots)
- Fri Sep 23, 2016 4:57 pm
- Forum: Technical Discussion
- Topic: Calling Supro experts: which version of the 1624T to build?
- Replies: 4
- Views: 2264
Re: Calling Supro experts: which version of the 1624T to build?
No expert by any means but always on the edge of getting one of Ken's 24 kits to see what tones would/could be available. Not sure how close it is to a dual tone http://tubeamplifierparts.com/amp-kits/supro-amp-kits.html#! D It's pretty much exactly a 60's Dual Tone (the 2nd schematic I shared): ht...