Treble pot turning volume down

DragonCrestPC

DragonCrestPC

Well-known member
I have Steven Hennings ( of Henning amplification ) Concept Plexrod 100. Amp sounds amazing but last night as i was playing it, i adjusted the treble pot and all of a sudden a huge volume loss happened. I did some research online and found alot of references to the treble cap being open/bad. I popped the amp open and located the cap ( he didn't have it mounted on the board rather attached to the pot) and am having a hard time locating the caps value online. Some places reference it as 47pf and others 4700pf. I have a bunch of ceramic caps of different values i just need to know what value this is. I also would like to know if i'm on the right track.
 

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First thing I would do is contact Steve, the builder of the amp and ask him as he would know and is super helpful.

If this is the treble cap in the tone stack it would typically be around 250pf-570pf for a Marshall style circuit, however how I read this cap is 680pf and have seen some modded circuits that use this size, not 68pf as that wouldn't make any sense in the tone stack.
 
68pF is an odd value for a tone stack treble cap. That cap reads 680pF I think. I have Henning's layout and it shows 470pF, which is typical. Unless you're talking about a different cap... Anyway, yeah 3kv is plenty.
 
jasonP said:
First thing I would do is contact Steve, the builder of the amp and ask him as he would know and is super helpful.

If this is the treble cap in the tone stack it would typically be around 250pf-570pf for a Marshall style circuit, however how I read this cap is 680pf and have seen some modded circuits that use this size, not 68pf as that wouldn't make any sense in the tone stack.
Click to expand...
https://www.mouser.com/ProductDetail/Xicon/140-153P9-680K?qs=yhJVdSeH8OvmOHaWQIxS8Q==
 
15kV was chosen for tone, not for actual voltage rating.

It’s 680pF not 68pF.

If you want the amp to sound somewhat different then roll the 3kV.

Ceramic caps go bad. It probably was bad from when it was soldered but just let go.
 
FourT6and2 said:
68pF is an odd value for a tone stack treble cap. That cap reads 680pF I think. I have Henning's layout and it shows 470pF, which is typical. Unless you're talking about a different cap... Anyway, yeah 3kv is plenty.
Click to expand...
It is that amp actually but a lot of that schematic is very different compared to his complete amp and contains boards/relays and values that are not listed on that schematic he published.
 
Last edited:

Henning Amplification​

February 24 2022
Well folks... it's been a hell of a ride, but I've decided to shutdown Henning Amplification. Supply chain issues have made it impossible to get the parts I need to build the high quality amps that you expect and I don't want to have to re-design things. Much thanks to all of the customers who have worked with me through the years.

It's 680pF.

I just called him.

This is the amp he later renamed "Cherry Bomb".
 
PLX said:

Henning Amplification​

February 24 2022
Well folks... it's been a hell of a ride, but I've decided to shutdown Henning Amplification. Supply chain issues have made it impossible to get the parts I need to build the high quality amps that you expect and I don't want to have to re-design things. Much thanks to all of the customers who have worked with me through the years.

It's 680pF.

I just called him.

This is the amp he later renamed "Cherry Bomb".
Click to expand...
Thank you good sir, yeah i LOVE this amp and can't believe he had to close his doors.
 
glpg80 said:
15kV was chosen for tone, not for actual voltage rating.

It’s 680pF not 68pF.

If you want the amp to sound somewhat different then roll the 3kV.

Ceramic caps go bad. It probably was bad from when it was soldered but just let go.
Click to expand...
If i may ask, how does the voltage change it's tone characteristics? i have a bunch of 680pf caps of different voltages and would love to know which direction to start with.
 
PLX said:

Henning Amplification​

February 24 2022
Well folks... it's been a hell of a ride, but I've decided to shutdown Henning Amplification. Supply chain issues have made it impossible to get the parts I need to build the high quality amps that you expect and I don't want to have to re-design things. Much thanks to all of the customers who have worked with me through the years.

It's 680pF.

I just called him.

This is the amp he later renamed "Cherry Bomb".
Click to expand...

That's unfortunate. And maybe things have changed since February, but I don't see any parts in this amp (or his others) that are hard to get or affected by supposed supply chain issues.
 
DragonCrestPC said:
I have Steven Hennings ( of Henning amplification ) Concept Plexrod 100. Amp sounds amazing but last night as i was playing it, i adjusted the treble pot and all of a sudden a huge volume loss happened. I did some research online and found alot of references to the treble cap being open/bad. I popped the amp open and located the cap ( he didn't have it mounted on the board rather attached to the pot) and am having a hard time locating the caps value online. Some places reference it as 47pf and others 4700pf. I have a bunch of ceramic caps of different values i just need to know what value this is. I also would like to know if i'm on the right track.
Click to expand...
He’s on Instagram, hit him up
 
Steve’s a good guy. I owned a cherry bomb a long time ago and although he wouldn’t release a schematic so I could mod it to my tastes, he helped tell me a few locations so I could try easily reversible things on it. Eventually it just didn’t have enough gain on tap for my needs and I sold it. The mods we discussed ended up being the v2 mods the amp came with later on stock.
 
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