Friedman Depth and Thump controls

[Getupngiver]

Lately I've seen quite a few JJ100's and BE100's that have been modded by Friedman with added Depth and Thump knobs. Some of these amps have both. So question is: what is the difference between the Thump and Depth controls? For whatever reason I thought they were the same thing, just named differently.

 

[romanianreaper]

I'm probably way off on this but I thought "thump" was more about the low end and "Depth" was how the low mids can be adjusted.

 

[skullfxr]

I could be wrong but isn't depth a power amp altering control?

 

[scottosan]

Both do pretty much the same thing. Easy mod for a few dollars in parts

 

[Beandust]

I thought it was depth or thump as I've seen it. Which is like resonance.. the other is response* which is a power amp adjustment for feel/tone.. I didn't realize there were thump and a depth adjustment. But I could be wrong?

 

[fusedbrain]

Depth and thump are the same thing - variable resonance for controlling the low end. If there is a thump or freq SWITCH, it was probably to switch the cap value on the depth pot from the BE100 value to the JJ value.
Response is a variable negative feedback control, and affects the high end, and to a lesser extent, the feel of the amp. This can either be a pot or a switch like on the BE100 deluxe

 

[CornNutz]

Yeah, depth/thump/resonance same thing. Friedman typically uses a fixed depth, it's a 220k resistor, with a 4n7 paralled. The thump/depth control just replaces that 220k with a 1M pot. You can also parallel in a 2n2 cap (ala JJ, and Slax), this probably what the freq switch does on the BE100 deluxe.

 

[Getupngiver]

Thanks for all the replies! I was 99% sure they were the same thing but wanted to make sure

 

[RACKSYSTEMS]

It would be response ( variable negative feedback) and thump ( depth, resonance etc control) gives you more options to change the response of the power section of the amp.

 

[bhyatt1]

Sorry to necro-bump, but could I ask why the thump pot would be scratchy? Is this a bad cap or just something that goes with it, like some presence controls?

 

[LP Freak]

Sorry to necro-bump, but could I ask why the thump pot would be scratchy? Is this a bad cap or just something that goes with it, like some presence controls?

If the presence pot is scratchy it usually means there’s some stray voltage going to it. I don’t recall seeing this on a depth pot though. Maybe it’s just dirty

 

[glpg80]

Sorry to necro-bump, but could I ask why the thump pot would be scratchy? Is this a bad cap or just something that goes with it, like some presence controls?

The latter is correct if the presence is also scratchy.

 

[dead-pan]

Sorry to necro-bump, but could I ask why the thump pot would be scratchy? Is this a bad cap or just something that goes with it, like some presence controls?

Mine is quite a lot. My tech says it's due to the range of the dials. I wanted the most range. He says he can change it so they act normal but I will lose some range. No thanks.

 

[RedPlated]

It's normal for a presence pot to sound scratchy when it is turned. There is DC voltage on it, which is what you are hearing. Some amps add a resistor from the presence pot to ground to eliminate the DC scratch. But it affects the taper of the pot in a negative way, in my opinion. I always do my presence pots without that resistor. Much better taper. The scratchiness isn't hurting anything.

 

[glpg80]

I personally like the resistor in parallel to the presence pot.

Not only does it keep the phase inverter tail current off of the presence pot, if the presence pot wiper ever goes open as you turn it due to dust, the resistor in parallel guarantees a path to ground for the long tail pair should the pot fail in any way. Without the resistor, the inverter is reliant on the ground reference of the presence pot to the wiper.

I build for reliability as much as I do user preference. Personally I also hate DC on potentiometers so I’m a bit biased, pun intended.

 

[burger]

If you see two controls like a depth switch and a thump pot, the switch is switching in/out caps which set the frequency and the pot is controlling the level.

 

[bhyatt1]

The depth switch was added, myself... and I used a switch for the thump, as I don't like how much variation is there. I spend more time knob turning and less time playing with a pot. I have 2 values to switch between. My next step is to try and do the mods for the footswitchable JBE mode, with gain and volume for it. Any of you guys have pointers to the best way to work this. It's not overly complex but I wouldn't know the BEST way to do it. I haven't seen the inside of any JJs other than my own, so I have no idea how Dave handles that?
Also, I see that the fx loop seems to be connected to a relay on board (maybe just in the vicinity). Does this mean that the loop IS footswitchable?
Sorry for all the added content, lemme know if I should just start another thread.

 

[Giblesoqul2001]

The latter is correct if the presence is also scratchy.

I had a JJ jr. And my Presence made noise like a scratchy pot when I turned it. I emailed Dave and he replied rather quickly stating thats normal due to something or another (forgot what he said). However I then read the 2 page manual and it said “if you hear noise when turning the presence knob this is normal” then I felt a little stupid for emailing Dave.