2019 Monkeymatic Pinnacle #3 (using HRD2ODS Rev B PCB)

[rootz]

I can see why the bright caps would make the amp overly bright. Master pot placement after the relay isn't standard BM practice, right? So you had two masters with bright caps after each other. I can't see many other clues to the brightness in the schematic. C37 and C38 maybe, increasing these would certainly give you more low end, but might not help with fizzies. Tube selection?

[xtian]

No, the MV here is placed like #183.

I replaced C41, a 33n Panasonic film cap that I had on hand, with a 22n Mallory 150 cap, and the OD sounds better. The transition into distortion is smoother.

I might like more bass in the OD channel. C37 and C38 are good targets. Thank you.

[JD0x0]

I think this one is amazing! Not your typical Dumble clone build (not that I don't like those though).

I can't really see what circuit I'm looking at. This is an HRM with 2n2 before lean gain and 1uF on the V2b cathode?
By the looks of it you already turned the treble in the HRM down low, say 10 'o clock, right? I think you did the right thing ditching those bright caps. I imagine the HRM is a pretty bright amp by it's nature without those caps.

At this point, our circuit is a hybrid. Mostly #183 and BluesMaster. Lou just posted the schematic, if you want a look, PAGE 15 of this thread: https://ampgarage.com/forum/viewtopic.php?f=4&t=32646

Looks good, I seem to really like the sound of the BM biasing on the cleans. I don't seem to get along with bright caps, with the acceptation of one over the clean channel volume (on a switch of course). My theory is that having the bright caps later in the circuit sounds too peaky and harsh because after the Master, you don't have much clipping, compression, or low pass filters to smooth anything out, plus you have the presence circuit accentuating highs in the poweramp already. Whereas, when you have the bright cap early in the circuit, it can go through preamp stages to compress some of the frequencies, and the snubbers tend to take off the nasty stuff, on the OD, so it sounds a bit more usable.
I think every amp I've owned I've had to clip the bright cap off the master. It doesn't compensate for the fletcher munson curve at lower volume and seems to add too many highs at very low settings. Perhaps one day I'll experiment with a series resistor on the bypass cap.

[pompeiisneaks]

glad to hear your's worked well, now I'll go cry in my beer I'm still going with the idea that Ive got a component wrong somewhere that's pushing hte V1 gain a bit too high. I'll be able to do some more troubleshooting this weekend.

~Phil

[xtian]

I made further refinements to the OD tone, by removing the treble peaking circuit (R13/C35), changing C37 coupling cap to 0.047u, and replacing both V2 cathode bypass caps C36 and C38 with 25uF.

[norburybrook]

I made further refinements to the OD tone, by removing the treble peaking circuit (R13/C35), changing C37 coupling cap to 0.047u, and replacing both V2 cathode bypass caps C36 and C38 with 25uF.

more Bottom end ?


M

[JazzGuitarGimp]

glad to hear your's worked well, now I'll go cry in my beer I'm still going with the idea that Ive got a component wrong somewhere that's pushing hte V1 gain a bit too high. I'll be able to do some more troubleshooting this weekend.

~Phil

Hang in there, Phil. There are a lot of astute builders on this forum. We’ll figure it out.

[rootz]

47n and 25uF on V2 And not fart city?? OD entrance is like #102 now?

[xtian]

47n and 25uF on V2 And not fart city?? OD entrance is like #102 now?

Nobody farting, except me...

[xtian]

Faceplate arrived, all pretty.

IMG_E3364.JPG

IMG_3356.jpg

Late mod: I added a 150K/3W resistor from B+5 to ground, to simulate the voltage drop of the missing FET input. Can't be sure it made a difference in sound, but everything is playing very nicely right now.

[drew]

I like the bright/brighter switch. You should add a secret control whereby if you tap the monkey 7 times in less than 3 seconds (like enabling the developer options on an Android phone), it puts you into “none more bright” mode.

[xtian]

I like the bright/brighter switch. You should add a secret control whereby if you tap the monkey 7 times in less than 3 seconds (like enabling the developer options on an Android phone), it puts you into “none more bright” mode.

I like your idea. But that would be overkill, since I already have the hidden "Frogger" Easter egg.

[xtian]

I have four ODS builds in the house: ODSLite, ODS#183, Pinnacle#1 (Lou's RevA PCB in Fender HRD), and Pinnacle#3 (Lou's RevB PCB in Carvin X100). The OD channel on the Lite defines GLORY, and causes the other three to hang their heads in shame. The Lite has no HRM stack, but all three others do. This prompted me to remove the HRM stack in one, then eventually all three.

My main complaints about the amps with HRM are EQ and character of distortion. First, the OD EQ is radically different from the clean (hard cut to bass, big boost in mids); where I prefer a similar EQ curve to clean with a minor cut to bass. And the transition, in OD mode, from clean to distorted as achieved by playing at varied volumes, should be smooth, seamless and musicial; where I was hearing an abrupt, ugly onset of distortion.

I got much closer to my ideal in Pinnacle#3 with the following mods to remove the HRM stack and tailor the EQ:

lifted R23,24 and added jumper on P2 — removes HRM stack
C37 -> 10n and C40 -> 5n — allows closer to full bandwitdh
added ~300p caps, anode-to-cathode, on V2a,b — tames fizz when distorted
re-installed treble peaker C35+R13 and re-installed MV bright cap C33 — adds needed articulation and clarity
re-installed and then REMOVED OD Level bright cap C43 — too much treble

450v plates, 30mA per EL34

[donvan]

added ~300p caps, anode-to-cathode, on V2a,b — tames fizz when distorted
re-installed treble peaker C32+R13 and re-installed MV bright cap C33 — adds needed articulation and clarity

Very interesting information. Thanks for posting it!

For my 183 circuit I also had an issue with OD fizz and like you I tamed with anode to cathode caps. I used 250pF.
For me the fizz was ONLY an issue in OD with single coil strat pickups. Humbuckers were fine. The trade off of this mod in my opinion is that with humbuckers in OD mode, the harmonics are tamed just a tiny bit. But still, I am happy with it.

2 questions:
-What type of guitar/pickups were you experiencing OD fizz with?
-When you say you re-installed treble peaker C32+R13 did you really mean C35+R13?

Thanks,
Don

[xtian]

-What type of guitar/pickups were you experiencing OD fizz with?

Both.

-When you say you re-installed treble peaker C32+R13 did you really mean C35+R13?

Yes, thank you. Edited to reflect C35+R13 is the treble peaker.