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PRP 9372. $$$. https://www.prpinc.com/

Thanks Chuck! Hmmm that is something to consider isnt it?! that a clean blend may be a better choice after all. I do understand it could sound like ?. does the circuit invert the signal? Maybe Ill try a jfet buff n blend style blend instead. is there some way to limit the drive to prevent...

The OMF cuts too much bottom end for my liking with extended range guitars. Any ideas on how I can get more bottom end out of this circuit or can point out the filters to modify?

I did use that 1M value and felt I could discern no difference as chuck has already said.

At C2 my meter slowly climbs to 2000K and then stops/flashes back to zero when it reaches what I think is my meters max limit. I have “IC1” as the tlo71and “IC100” as the charge pump chip. I measured the tlo71 pin 7. ??‍♂️ black at opamp end was doing same thing as C2. red at opamp was 1487K...

those were still populated in the earlier pics. I can’t as of yet the forum forces me to resize them. This is “large”. I need to figure out better pics for sure. What you see are the empty pads from the component I removed. The pic was supposed to show the pads and traces are fully intact in...

I couldn’t seem to get any voltage reading on R6 on the bottom pcb pads or the top resistor legs. Happened to have another 220k here so I swapped it. Nope. Swapped C2, nothing. Reading about 3.4MV max if anything Pads of both inspected under magnification and photographed. Pics are not so...

Ok, noted. I edited the post for clarity in respect to the pinout. ?? I will get to this and report back my findings, thank you for your help again. ?

I don’t know. Hopefully he will chime in at some point, but it does work fine in the other build. this board has a built in charge pump which is how it reaches the higher voltages I mentioned earlier from a 9V supply.

Also using BC550 transistors as a substitute. Fortin again.

They are not polarized they are wima 4.7uf film caps. Chuck also advised those would be ok.

Nothing other than using wima film for the 1uf and 4.7uf caps. The other build sounds great. I don’t think the issue lies there.

Sorry I forgot to mention the 1M. I was told by Chuck D Bones in another thread that using Fortins’ 1M there was acceptable. As this was built alongside another identical build that operates perfectly, it is confirmed that value is fine.

A few more.

With my probe I started tracing the circuit (Blue dots ) are good clean signal. Once I hit the transitor/opamp area things are distorted (red dots). I noted the VCC and VREF voltages as well. (ignore red circle, was a previous marking.) any ideas?

Much to read, watch and respond to. Thank you to ALL of you in advance. I spent last night watching audio debug videos and learned to use my audio probe today. ? I am not a novice with my iron, I go VERY slowly and methodically. I have a folder on each build full of notes etc. obviously I am...

Ive got a pile of non working builds piling up. It seems for every one I get built another doesn’t work and I don’t know enough to get through them on my own. after an integral preamp I built today doesn’t work yet again I am pretty frustrated. My integral is farting and distorting. I reflowed...

That is what I am hoping that a larger trimmer value is all that is needed. The misbias at 18- 36 did sound a bit worse than 9.

I have run mine at 33-36V with an external charge pump. Sounds ok. Muxh louder. Caps are all 50V or higher. I previously tweaked trimmers by ear from the 4.5/half supply starting point at 9V. hmm had another look at this. Been tweaking for a while at different voltages. Even at 18V not all...