2023 Monkeymatic Whitney (Deluxe Reverb)
Moderators: pompeiisneaks, Colossal
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
Steve, my osc Rk is 3K3 (didn't have 2K7 on hand) and Rc is 25uF. And the three osc caps are all 0.02uF (I like the slower speed).
Also, where normal DR filtering is 32/16/16/16, mine is 47/22/22/22.
I'll try getting Rk closer to 2K7.
I may also try replacing the neon bulb with an LED.
Also, where normal DR filtering is 32/16/16/16, mine is 47/22/22/22.
I'll try getting Rk closer to 2K7.
I may also try replacing the neon bulb with an LED.
I build and repair tube amps. http://amps.monkeymatic.com
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Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
I don't think the roach is the problem. Sounds like your osc tube is starting but then dying. Might be helpful to replace the 3.3K/25µF cathode components with a 5mm red LED. This will give you a visual aid and it might just also fix the drop-out issue.
Might also help to use the standard Fender values for the osc caps, ie, .02, .01, .01. You can always modify later when it's running. Check the plate resistor too.
It would still be helpful if you post the layout.
Might also help to use the standard Fender values for the osc caps, ie, .02, .01, .01. You can always modify later when it's running. Check the plate resistor too.
It would still be helpful if you post the layout.
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
Schematic and layout attached.
Here's some weirdness to consider: Voltages on V5A are correct, but voltages on V5B are NOT, and they depend on whether vibrato is engaged or not. With vibrato NOT engaged, V5B anode is 410v and cathode is 0v. With vibrato engaged, anode drops to 406v and cathode rises to 5v (according to schematic, voltages should be 345/17). When I disengage vibrato, cathode voltage drops slowly from 5v to zero.
I don't see how the vibrato switch could affect whether V5B is conducting.
Here's some weirdness to consider: Voltages on V5A are correct, but voltages on V5B are NOT, and they depend on whether vibrato is engaged or not. With vibrato NOT engaged, V5B anode is 410v and cathode is 0v. With vibrato engaged, anode drops to 406v and cathode rises to 5v (according to schematic, voltages should be 345/17). When I disengage vibrato, cathode voltage drops slowly from 5v to zero.
I don't see how the vibrato switch could affect whether V5B is conducting.
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I build and repair tube amps. http://amps.monkeymatic.com
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
I checked the V5B plate resistor: 100K.
I replaced V5A cathode 2K7/25u with a red LED. When vibrato engaged, I get 1.5v across the LED. It visibly pulses for a moment, then fades, though voltage stays steady.
Will try replacing oscillator caps with schematic values.
I replaced V5A cathode 2K7/25u with a red LED. When vibrato engaged, I get 1.5v across the LED. It visibly pulses for a moment, then fades, though voltage stays steady.
Will try replacing oscillator caps with schematic values.
I build and repair tube amps. http://amps.monkeymatic.com
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
OK, Steve, stop worrying. I replaced C19/B and C19/C with 0.01u caps, and vibrato is working steadily now.
I build and repair tube amps. http://amps.monkeymatic.com
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Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
When the vib FS is off (or unplugged) a big negative voltage from the bias supply is sent through R21 and R20 to pin 2 (osc grid). This turns the oscillator triode off.
That big negative voltage is also sent through R21 and R19 to pin 7 (driver grid). This turns off the roach driver triode.
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
My first cathode LED failed after a few minutes. I installed a higher-current, 10mm red LED, and it has lasted 30 min so far.
Everything is sounding great. I recorded a quick demo. Channel 2, with Reverb and Vibrato, is pretty much stock, with the exception of the "slower vibrato" mod. Channel 1 has a three-way Mid switch: stock (6K8), boosted (~50K), and lifted tone stack. Playing thru a Jensen N12K, audio from iPhone's mic.
Everything is sounding great. I recorded a quick demo. Channel 2, with Reverb and Vibrato, is pretty much stock, with the exception of the "slower vibrato" mod. Channel 1 has a three-way Mid switch: stock (6K8), boosted (~50K), and lifted tone stack. Playing thru a Jensen N12K, audio from iPhone's mic.
I build and repair tube amps. http://amps.monkeymatic.com
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Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
Sounding good!
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Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
I was just on youtube listening to other amp and this popped up when I searched you trying to find another video..
SOUNDS AMAZING!!! Always great stuff!
SOUNDS AMAZING!!! Always great stuff!
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
That sounds amazing, Aaron. Did you use a 2-spring long tank? Speaker sounds great too!
Just plug it in, man.
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
The tank is three-spring, long springs, and SHORT decay...can you believe it? Sounds LONG to me.
I build and repair tube amps. http://amps.monkeymatic.com
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
Sounds great, just the right amount. Any more would be in the mush range if you ask me.
Just plug it in, man.
Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
Mojotone cabinet arrived, along with my faceplates from Indcom.graphics. The cabinet is excellent--fine attention to detail, edges, and glue. Really nice. Very happy with this sexy package.
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I build and repair tube amps. http://amps.monkeymatic.com
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Re: 2023 Monkeymatic Whitney (Deluxe Reverb)
You build some really nice looking amps.
- pompeiisneaks
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