Search found 182 matches
- Mon Dec 18, 2023 5:07 pm
- Forum: Technical Discussion
- Topic: EH 6v6's in a JTM45?
- Replies: 8
- Views: 4947
Re: EH 6v6's in a JTM45?
Well not likely since your power transformer will need to supply 1.200 more amps of heater current since a 5881 pulls .900 amps and a 34 needs 1.500 amps. Also pin 1 needs to be jumped to to pin 8 and a 34 will need about 8 volts less bias voltage which may be out of range of your bias pot without ...
- Mon Dec 18, 2023 4:06 pm
- Forum: Technical Discussion
- Topic: EH 6v6's in a JTM45?
- Replies: 8
- Views: 4947
Re: EH 6v6's in a JTM45?
Primary impedance is 6k6. What about EL34's?martin manning wrote: ↑Mon Dec 18, 2023 2:46 pm You should be ok. The B+ will drop with the current draw. Just bias them conservatively. What primary impedance do you have?
- Mon Dec 18, 2023 2:04 pm
- Forum: Technical Discussion
- Topic: EH 6v6's in a JTM45?
- Replies: 8
- Views: 4947
Re: EH 6v6's in a JTM45?
Sorry, I meant 457v.
- Mon Dec 18, 2023 3:32 am
- Forum: Technical Discussion
- Topic: EH 6v6's in a JTM45?
- Replies: 8
- Views: 4947
EH 6v6's in a JTM45?
I'm building a JTM45. Well technically a Dirty Shirley, but the power section is a JTM45. I'm ready to power it up, but the 5881 tubes that I ordered won't arrive until late this week. I've gone through all the initial testing with the GZ34 rectifier tube and 3 preamp tubes installed. It's reading a...
- Sat Dec 09, 2023 1:27 am
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
- Fri Dec 08, 2023 7:45 pm
- Forum: Technical Discussion
- Topic: OT primaries and heater wire proximity
- Replies: 2
- Views: 1569
OT primaries and heater wire proximity
Is it OK to have the OT primaries right near the heater wires? Would this cause any issues?
- Wed Dec 06, 2023 4:28 pm
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
Well, I finished rebuilding it back to Express specs. I don't know, maybe I just don't jive with this circuit. There's something about the frequencies that I'm just not liking. I'm not sure if it's something in the midrange or the treble frequencies. Could be my cabinet, which is a Suhr 2x12 with a ...
- Mon Dec 04, 2023 3:41 am
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
And you said you made it foot switchable?Reeltarded wrote: ↑Sun Dec 03, 2023 11:16 pm Try it on either or any, but it is a good place. You can moderate it and hammer the amp gain or volume for a huge array of textures.
- Sun Dec 03, 2023 10:27 pm
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
Ahh ok, that makes sense. Would you do that on the 2nd stage?Reeltarded wrote: ↑Sun Dec 03, 2023 8:35 pm The ground end.. to a pot that goes to ground. It just increases the cathode value on the stage, like if 1k5 then 26k5 total at full rotation with 25k pot.
- Sun Dec 03, 2023 4:08 pm
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
Maybe I'm just dumb but I'm not sure what you mean by cathode tail.Reeltarded wrote: ↑Sun Dec 03, 2023 7:14 am So, you simply add 25k pot on cathode tail to ground. It is that simple and you dial in how much fire overall.
- Sun Dec 03, 2023 3:23 am
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
Yeah, can you explain that variable cathode tail thing?Reeltarded wrote: ↑Sun Dec 03, 2023 3:10 am It is rarely something worth doing. That variable cathode tail I described is hundreds of times more useful for a similar but better action with infinite degrees.
- Sun Dec 03, 2023 1:49 am
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
Silver micas have a reputation for one in many being shit. Possible. FLY the switch wires ALL THE WAY to the deck of the headbox. That situation is not great, there are also some safety reasons to use the Farady coil instead of shield there depending on wire prep and voltage capacity. I'm probably ...
- Sun Dec 03, 2023 1:16 am
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
I found a pic I took before I started ripping it apart. Ignore my attempt at the split load switch, and the few component additions. That was my attempt at converting the preamp to a Komet 60. That odd noise was happening before and after those changes.
- Sat Dec 02, 2023 11:55 pm
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
Yeah, I think so. I liked the Komet 60 sound, but it's not all that different from a few of my Marshall type amps.Littlewyan wrote: ↑Sat Dec 02, 2023 11:51 pm It’s normal to hear some sound without a speaker. I think it comes from the OT.
Use Silver Mica, don’t use Ceramic.
Are you rebuilding it as an Express again?
- Sat Dec 02, 2023 8:54 pm
- Forum: Trainwreck Discussion
- Topic: Weird note decay - Express build
- Replies: 41
- Views: 18180
Re: Weird note decay - Express build
What type of caps are recommended for the treble cap and the bright caps? Right now I'm using mica. Would ceramic be better?