Rewiring the PAB switch to 10thtx's example brought the tone circuit to life, now all controls function with good range. I've done a little work on the cab for this new amp, photos to follow.
Thanks again for your help and advice
Search found 182 matches
- Mon Dec 01, 2014 5:27 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
- Wed Nov 26, 2014 10:55 pm
- Forum: Technical Discussion
- Topic: So, what's wrong with Switchcraft and JJ?
- Replies: 10
- Views: 1484
So, what's wrong with Switchcraft and JJ?
I like Switchcraft jacks and plugs. I like JJ tubes, I find them to be more consistent than other current manufacture tubes (admittedly, that's not saying that much, but they work well for me).
- Mon Nov 24, 2014 10:31 pm
- Forum: Dumble Discussion
- Topic: Bonamassa's Dumble's for sale
- Replies: 16
- Views: 3914
Re: Bonamassa's Dumble's for sale
Where's my checkbook
- Thu Nov 20, 2014 4:44 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Wow, that's a lot different than Mat's 86 special or the other variations of the 101HRM preamp layouts I've seen, you completely eleminate the two 20M resistors? Sorry for being a noob about it, this is my first experience with a PAB switch. Thanks for your help and patience.
- Wed Nov 19, 2014 4:23 pm
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
New Question: Mat mentioned in the original 86 Special thread that the tone circuit did not work correctly. I built mine to his layout and it does not work either. The Bright. Mid and PAB switchs seem to work correctly. So.... can you take a look at the layout and schematic and recommend a fix? I se...
- Sat Nov 15, 2014 8:19 pm
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
SUCCESS! Robert was right, I tracked back through the OD drive wiring and discovered two wires were reversed. Once corrected, the OD channel has nice, sweet sustain. It sounds great with a little delay. Thanks everyone for your input, especially Robert. Now I'll try a version with 2 EL-84s, double s...
- Fri Nov 14, 2014 6:54 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
That's interesting. I think you are right about the schematic, but... I have it wired like the layout which has the grid (pin 9) going to a 150k resistor and then to the middle (wiper) lug of the Drive pot.
- Thu Nov 13, 2014 10:40 pm
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Check out the sound files for the post SE EL84 Mini ODS PTP, this is the sort of overdrive I was expecting from this similar circuit.
- Sat Nov 08, 2014 3:00 pm
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Yes, these are the voltages I used to compare with my amp in the previous post. They seem to be close enough to me, I don't see that the original amp (meaning Mat's) has "substantially higher voltages". 10thth, didn't you build one of these circuits?
- Sat Nov 08, 2014 1:13 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Compared to the posted voltages, my amp is with in a few volts (on the low side). The first value is the posted voltage, the 2nd value is my amp Point A: 263v/257v Point B: 257v/ 247v Point C: 261v/ 250v Point D: 259v/ 240v EF86 voltages: bias: .8v/.86v Grid: 51v/50v Plate: 105v/ 118v This circuit d...
- Fri Nov 07, 2014 4:34 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Agreed, I checked the 820r, 82k & 820k first thing, all correct.
- Fri Nov 07, 2014 12:26 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Dang, it's not the tube. I checked the component values for the EF-86 stage. the bias and plate voltages match those listed on the schematic.
Now I think it's gonna be one of those embarrassing ah-ha things.....
I'm still looking.....
Now I think it's gonna be one of those embarrassing ah-ha things.....
I'm still looking.....
- Wed Nov 05, 2014 4:58 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Yes, indeed the OD channel stops working with the EF-86 is removed BUT after confirming that the channel switching is wired correctly and that the OD channel controls (level, drive and tone) all work correctly, I discovered that even though the filament circuit is supplying power to the EF-86, the t...
- Tue Nov 04, 2014 8:04 pm
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
Re: New EF86 Special build
Thanks, Here's the schematic and layout I built too (with the effects loop omitted). I agree that it sounds like the 12AX7 stage and the EF-86 stage are working independent of each other. I'm going to the check the channel switch wiring to see if there is an error there. The sound files that Mat pos...
- Tue Nov 04, 2014 5:09 am
- Forum: Dumble Discussion
- Topic: New EF86 Special build
- Replies: 40
- Views: 12730
New EF86 Special build
I've just constructed an EF86 Special using Mat's layout, schematic and BOM, The B+ voltages measure about 8 to 10 volts low but the amp sounds very nice. The issue is, the OD side is just about a clean as the clean side, there is no significant over-driven tone to speak of. Both channels are plenty...