RealAmpsAreDead
Member
Can you tell me what kind of inductor you would use?
Depth Control - Different Capacitor / Different Range & Feel
FourT6and2
Well-known member
My Mako Dorado has some sort of depth control in addition to the normal Depth. Looks like a small transformer/inductor added for that. It definitely adds the thump. Sounds like an active/powered sub-bass control. If you hooked it up to a crossover and powered woofer it would rattle the fillings out of your neighbor's teeth.
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ClintN667
Well-known member
Alex Catlow helped me with some mods on an Evolve ST1 based build and I can't remember exactly what I did but I screwed up the depth mod and took me several days to figure it out. Ah now I remember, I had used Ceriatone Iron and had reversed the OT leads on the power tubes. Anyway I couldn't tell any sound differences and a few people told me that I would need to get the volume up before it would be apparent... blah blah.. once I corrected the OT connections it was very noticeable and awesome.
The NFB control on the KSR PA50 is why it's one of my favorite power amps. I would actually rather have that control over a resonance and presence
The NFB control on the KSR PA50 is why it's one of my favorite power amps. I would actually rather have that control over a resonance and presence
CrystalSky
Well-known member
RealAmpsAreDead
Member
I got an Ceriatone Plexi and an Origin 20 modded to his Eternal Classic with a foot switchable Solo Boost - still don't know why not every amp has one.... It goes from clean, to plexi to high gain (not to the insane amount, what is good). Awesome amps now with a great working master volume.
7704A
Well-known member
Ah yeah, Johan Segeborn did a video with that, as well as an interview or two with him. Seems like a cool dude.. Sad to hear about the goop though, -5 respect.
BesaMoogie
Well-known member
Uhh, another active Swiss guy on RT. Grüezi!
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paulyc
Well-known member
Great thread !
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paulyc
Well-known member
Care to share that JCA 20 full spec ??? Love that amp…
psychodave
Well-known member
I shared it here years ago. Only one forum member actually took the time to build it.
The thread should be around somewhere here. I might have removed some pics since I caught wind some modder might have been selling the mods as his. I never got confirmation though.
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paulyc
Well-known member
Crazynuts did one for me, but I don’t think it has an inductor in the NFB circuit. Is that a later revision or just an experiment ?
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paulyc
Well-known member
I’d love to have some examples of using an inductor in this way, and what type/part number/source could be used.
psychodave
Well-known member
I use a regular 1 meg .003uf/39k resistor depth circuit in my JCA20.
I was just pointing out that a lot can be done in the NFB/depth circuit.
CrystalSky
Well-known member
Could you please check out my question above?
psychodave
Well-known member
Use a pedal to tighten up a SLO, unless you want to get into some heavy modifications in the preamp section. Adding a depth pot just adds in more bottom end. There is no “taking away” effect of the depth pot unless you focus the values on mid range. At that point I really don’t know how it would sound since all of the amps I have modded have had a lot of midrange already and I wanted to add more bottom end.
CrystalSky
Well-known member
No, I would never want to mess up mine. It is has somewhat of a sentimental value to me.
I was just thinking if I should have ordered it with that Depth mod back then or not. But since it only adds bass, it doesn’t look like it would have been a good idea.
If I get ultrarich, I will buy a BAD version to experiment on
VaporDemon
Member
Question regarding depth caps, I’ve seen schematics for some amps where two smaller value caps were used in parallel to arrive at the desired value instead of one cap and I’m curious if this changes the tone or if it’s more just a parts availability thing? I’ve also seen this in a tone stack on some amps again not sure what the audible difference would be if any. I’m interested to experiment with this either way but thought maybe someone would know.
FourT6and2
Well-known member
It's most likely a parts availability thing. i.e. the builder had a bunch of 1,000pF caps and nothing else. OR... I had one infamous modder tell me he did that on purpose so when he saw other people doing the exact same thing with the same values, he knew they copied him. Almost like a signature of sorts. But that's incredibly egotistical and paranoid. So I don't really buy it. More likely parts availability.
acceptance
Well-known member
For the laymen, how does what’s being discussed here relate to this?
RedPlated
Well-known member
That's the most basic depth control out there. 1 meg pot with a .0047uF cap across it. Then out to the NFB tap.
The .1uF cap is just blocking DC so the depth pot isn't scratchy. It WILL affect the tone, though. That .1uF is blocking very low frequencies so they won't be canceled out. I've tested this a lot. It does add low end. If you want to get silly, put a .0022uF cap there. See what it does...