mojotom wrote: ↑Wed Apr 28, 2021 4:35 pm
Marcus 250k Send pot and 25u on the cathode of the reverb tube can help.
A long three spring reverb tank too (9AB2C1B).
Tom, I've got a vintage USA Acusonics Tank I pulled from the donor peavey amp along with the transformers it's a sweet reverb tank, better than any new one I've heard .
I'll give those tweaks a try though.
I presume you mean the send Cathode with the 2k2 resistor? I would imagine that will let a whole lot more bass through, yes?
I can put the 68k (1M) resistor back in now as well and remove the pot now it's all as it should be.
I'm thinking of adding a FET as well as I have a JFET and a board here in a box of stuff. Would I need to use a relay to get this on a Foot switch?
Ah yes, I remember now the Peavey donor amp and tank.
For sure way better sounding than the new ones.
Yes 25u on the 2K2 cathode, AT7 (a good NOS CV is not that expensive) and 250k 30% send pot.
Not really an issue with bass on the Reverb part of the amp (small caps anyway), at least for me. Felt like a slight level increase, still got to push both send and return higher now with the mod too.
neskor wrote: ↑Thu Apr 29, 2021 9:44 am
I just tried to put 25uF on cathode of 12AT7, but that didn't work quite well, too dark for me.
Interesting;
have you got the bright cap on the send though?
I notice on one of the layouts/schematics that some have a 10uF there and a 1k resistor. That's for a 5751. I have an AT7 as well which I think is the equivalent of the 5751 no?
I've just revisited my original build thread.
It's interesting that as soon as I powered up I said it was too quiet. There was a whole raft of discussions here and on the facebook amp builders group about the voltage divider when actually it is the mixer resistors that are the issue. I wonder where the error come from, if it is indeed and error, or if the amp Taylor was inside did indeed have a 120k there by mistake or perhaps an experiment.
whatever it is was, I'm glad someone here :Ryan C? or who ever it was found this out and I'm eternally grateful to them.
Yup - I poked around a real JM sig and had a few tips/pictures from friends who acquired post-Mayer amps which I added the corrections to (crudely) in the drawing I made up. I cannot wait to build a fresh JM Sig using this information Summer project. I'm super happy there are good results with this change! It's also entirely possible others here came to their own independent conclusion earlier (Martin?)
Here is the 1:1 size signal board and a slight adaptation supply board of a real JM sig that you can upload to Hoffman Amps to have them made up for ya.
Ryan thanks again for the info and also to Marcus and everyone else for experimenting.
Ryan, in the amps you saw were the 226K resistors Draloric LCA type or RN60D type? I assume Draloric based on how they are depicted in your layout.
I am going to make these changes too even though I am pretty happy as is with the reverb mix and overall loudness of the amp (since I play at home only). I also plan to adjust my dropping string to get the preamp voltages in line. Interesting that my power amp voltages are right on for the custom wind 10% lower voltage PT two rock used, but other voltages are high.
dbharris wrote: ↑Thu Apr 29, 2021 2:08 pm
Ryan thanks again for the info and also to Marcus and everyone else for experimenting.
Ryan, in the amps you saw were the 226K resistors Draloric LCA type or RN60D type? I assume Draloric based on how they are depicted in your layout.
I am going to make these changes too even though I am pretty happy as is with the reverb mix and overall loudness of the amp (since I play at home only). I also plan to adjust my dropping string to get the preamp voltages in line. Interesting that my power amp voltages are right on for the custom wind 10% lower voltage PT two rock used, but other voltages are high.
Thanks!
-Dan
Dan,
I found the changes made the amp feel not only louder and where it should be gain/level wise but it seemed to tighten/balance everything up as well and really come together nicely as a whole. Not sure why but I'm pleased it did.
I put the 25uf in the send cathode in today along with a 250k pot. A subtle difference. I also put the 68k resistor back in at the 1m divider node as I had a pot there before to up the gain, this is no longer needed.
dbharris wrote: ↑Thu Apr 29, 2021 2:08 pm
Ryan thanks again for the info and also to Marcus and everyone else for experimenting.
Ryan, in the amps you saw were the 226K resistors Draloric LCA type or RN60D type? I assume Draloric based on how they are depicted in your layout.
I am going to make these changes too even though I am pretty happy as is with the reverb mix and overall loudness of the amp (since I play at home only). I also plan to adjust my dropping string to get the preamp voltages in line. Interesting that my power amp voltages are right on for the custom wind 10% lower voltage PT two rock used, but other voltages are high.
Thanks!
-Dan
Hey Dan! That resistor was Draloric. I found the reverb was quieter coming from 130k to 226k however when I played the amp at stage volumes and the head cab sitting on top of my speaker cab, the reverb came alive perfectly. Maybe at bedroom volumes it would be best sitting at 130k or similar?
Well if your PT is good then your PT is good! It is odd you had some higher voltages in some parts of th circuit. Sounds like you're pretty happy overall! ¯\_(ツ)_/¯
dbharris wrote: ↑Thu Apr 29, 2021 2:08 pm
Ryan thanks again for the info and also to Marcus and everyone else for experimenting.
Ryan, in the amps you saw were the 226K resistors Draloric LCA type or RN60D type? I assume Draloric based on how they are depicted in your layout.
I am going to make these changes too even though I am pretty happy as is with the reverb mix and overall loudness of the amp (since I play at home only). I also plan to adjust my dropping string to get the preamp voltages in line. Interesting that my power amp voltages are right on for the custom wind 10% lower voltage PT two rock used, but other voltages are high.
Thanks!
-Dan
Hey Dan! That resistor was Draloric. I found the reverb was quieter coming from 130k to 226k however when I played the amp at stage volumes and the head cab sitting on top of my speaker cab, the reverb came alive perfectly. Maybe at bedroom volumes it would be best sitting at 130k or similar?
Well if your PT is good then your PT is good! It is odd you had some higher voltages in some parts of th circuit. Sounds like you're pretty happy overall! ¯\_(ツ)_/¯
Ryan,
the reverb is quieter because the dry signal is a lot louder in comparison that was the missing link in this whole story for me.
I have silicone rings around my 4 output tubes because at stage volume , sat on the 2x12 cab the tubes were rattling... they're good now.
I've just been looking at the two rock classic reverb sig and that 68k/1M voltage divider is on a switch for gain staging . I think that's what got me to put a POT on the back.
perhaps i should revisit this with a 3 way switch.
I cant remember what the 2 rock values were for this though, any one have any ideas?
I've just been looking at the two rock classic reverb sig and that 68k/1M voltage divider is on a switch for gain staging . I think that's what got me to put a POT on the back.
perhaps i should revisit this with a 3 way switch.
I cant remember what the 2 rock values were for this though, any one have any ideas?
M
I use a similar switch on these amps Marcus. The switch I use places it in series with another 68 k resistor so I get a total of about 140k with switch engaged. We found these values work well to give a nice little boost in volume. You may even prefer less.
One interesting thing we discovered is that when the amp is turned up loud with the 2x68k resistors the clean headroom was actually a little less than when running with a 68K resistor. So even though we were louder with 2x68k, clean headroom was greater with 68K.
Our test was done with a 50 watt version .
I think this is why Two rock preferred the 68K value.
dbharris wrote: ↑Thu Apr 29, 2021 2:08 pm
Ryan thanks again for the info and also to Marcus and everyone else for experimenting.
Ryan, in the amps you saw were the 226K resistors Draloric LCA type or RN60D type? I assume Draloric based on how they are depicted in your layout.
I am going to make these changes too even though I am pretty happy as is with the reverb mix and overall loudness of the amp (since I play at home only). I also plan to adjust my dropping string to get the preamp voltages in line. Interesting that my power amp voltages are right on for the custom wind 10% lower voltage PT two rock used, but other voltages are high.
Thanks!
-Dan
Hey Dan! That resistor was Draloric. I found the reverb was quieter coming from 130k to 226k however when I played the amp at stage volumes and the head cab sitting on top of my speaker cab, the reverb came alive perfectly. Maybe at bedroom volumes it would be best sitting at 130k or similar?
Well if your PT is good then your PT is good! It is odd you had some higher voltages in some parts of th circuit. Sounds like you're pretty happy overall! ¯\_(ツ)_/¯
Ryan,
the reverb is quieter because the dry signal is a lot louder in comparison that was the missing link in this whole story for me.
I have silicone rings around my 4 output tubes because at stage volume , sat on the 2x12 cab the tubes were rattling... they're good now.
m
Wow! What a great day(s) at TAG! Between this report and the SSS #002 findings from the team on that project, we're kicking butt! Now only if we can confirm UL taps or not on the Dumbleland....
well after finally sorting it I decided I had to recover the cloth the match the 2x12 vintage G12-65 cab
so I did,
IMG_20210502_140433-01.jpeg
Also here's a clip of the amp. all guitar parts done with the same 50's strat with custom shop texas special pickups. the one with more hair (0:30 sec) is the amp with the dirty switches on-so no NFB, recorded with my Captor X into a 4x12 I think. The clean guitar is into the matching cab, with a ribbon and 57. The pad sounds are also the same guitar and 2x12 using my H9 and a POG 2
it's a sweet reverb tank, better than any new one I've heard .
Summer project. I'm super happy there are good results with this change! It's also entirely possible others here came to their own independent conclusion earlier (Martin?)
they're good now.
