S.I.R. 100W SuperLead Schematic pt. II

[CoffeeTones]

Sounds great. Can also tell it's got a nice feel / bounce.

[BRMSlash]

with 510p's on mixer and treble cap:
http://sclk.co/s7ta53

[BRMSlash]

I stiffened up a couple of the preamp B+ caps and repositioned the mic slightly. Thanks for the cap suggestions CoffeeTones.
http://sclk.co/s7taq2

[CoffeeTones]

Yep, that was a major tonal change for such a component change. I believe that your previous arrangement was better in tone but had less sustain. What is your opinion?

[BRMSlash]

The major tonal change was due to bringing the mic a touch closer to get a bit more grit and attack that I had a few clips ago before one of my kids knocked the mic stand out of place. The larger filter caps did give a slightly more high gain sound, while not making it too stiff. The new caps aren't burnt in so that may make a slight difference too. Maybe I'll drop the first stage back to 8u to sweeten it up a touch.

Also any thoughts on how to get rid of that slight low frequency octave effect I've got going on when I play Estranged?

[CoffeeTones]

Also any thoughts on how to get rid of that slight low frequency octave effect I've got going on when I play Estranged?

I hate to say it, because you just put new ones in, but it could be mica caps. Maybe change the fizz cap to ceramic and see what happens. Which type .0022uF is parallel to the 470k? I'd also try raising the .0022uF coupling cap.

I've used polypropylene and ceramic on the peakers before. Mixing the types can be useful. Look for COG, NPO or X7R ceramics.

I like wire wound screen resistors and carbon film on everything else. Not that I'm opposed to metal film. I just don't trust the CC resistors. If you want to hear something simple and surprising, put a 100k metal oxide in place of the 100k carbon film, cathode follower, load resistor. Metal film may have a similar effect as well, but metal oxide definitely has an effect. I was surprised, due to that resistor leading to ground.

You might also try changing the NFB a little bit.

[CoffeeTones]

Do you think it may be the new mic position?

[rockgod212]

I think its el34's vs. 6550's, switch to 6550's and it should be gone. el34's always have that weird middy tone to me.

Do you think it may be the new mic position?

[CoffeeTones]

He has 6CA7. The mids were not in question but I get what you are saying. He asked about the low frequency octave effect in his playing of Estranged. Low mids maybe.
http://sclk.co/s7taq2

[BRMSlash]

It's not the mic position as the effect is even more pronounced in the room. I haven't touched the fizz cap for years, so I don't think that'd be it. I guess the new mica's could be a possibility. I'm using a ceramic 2n2 over the 470k. I can't see why I'd need to increase the 2n2 coupling cap as I don't need any more bass. I'm starting to sense I'm intentionally being given bad advise. Maybe I should release my spec and be done with it.
I've returned everything back to normal http://sclk.co/s7tb6f

[CoffeeTones]

I'm starting to sense I'm intentionally being given bad advise. Maybe I should release my spec and be done with it.
I've returned everything back to normal

Man, I hope that is not directed at me, but just in case... You already shared your spec with me and I only gave suggestions because you asked and it's your choice to try them or not. I also posted that your previous arrangement sounded better. You DO HAVE one of the top 3 or 4, best sounding AFD specs on this forum. I have no intention nor anything to gain by misleading you or anyone here. I have no idea of what you have or have not recently changed, so if a suggestion doesn't fit, don't try it.

* I suggested the fizz cap because it is easy to change and it is not one of your new / hard to source 510pF caps.
* I suggested the .0022uF coupling change because .0022uF creates a strange low mid effect to my ears. I have posted that way before now.
* Mica caps can create what Larry calls a "howling wolf effect". Ceramic also create a strange effect, especially as a coupling cap, to my ears. Polypropylene and Polyester don't seem to do that.
* I stated that I don't trust CC resistors and like wire wound screen resistors, and will add that I really don't like MO anywhere in an amp but maybe early in the power supply. You don't have to agree or change because I have that opinion.
* I suggested a slight NFB change because it can have some interesting effects, even in 10k or less increments.

I'm highly interested in knowing what resolves the "low frequency octave effect" you are experiencing. That's why I posted so many ideas, as I was thinking about it and studying your schematic. There is absolutely no intent to mislead you, coming from me.

[BRMSlash]

OK, thanks for the reply. That makes more sense now.

[herbvis]

Also any thoughts on how to get rid of that slight low frequency octave effect I've got going on when I play Estranged?

Is this occurring at certain points of your recording, or is it consistent all the way through? What is a good time stamp to hear what you are hearing.

[BRMSlash]

OK, so I swapped out the 2n2 over 470p with a 715p orange drop. No good, the amp lost its grit and attack. The octave thing was still there. So put back the ceramic.

Swapped out the 510p mica's for 470p ceramics and the amp still sounded decent, but the octave thing is still there. I'm wondering if it's maybe not the amp, but my guitar feeding back internally or something.

Swapped out the 12k metal oxide in the B+ with a 15k carbon film. Doesn't appear to be any significant changes in tone, just a slight drop in headroom due to the value change.

Here's a clip with the 470p ceramics. http://sclk.co/s7tbby
I only notice the octave effect during estranged. It can be most notably heard in this clip at 2:45, the first note of estranged.

[CoffeeTones]

I'm beginning to think it is speaker cone cry, but If you want to, see what a .01uF sounds like when you clip it in parallel to the .0022uF coupler.

From Weber's website -
"Context: I replaced that speaker because it had too much cone cry.
Description: As the speaker cone is vibrated by the voice coil, it can generate frequencies of its own that may be strong enough to be audible along with the intended note or signal from the musical instrument. These notes or tones may or may not be harmonically related to the intended note, and in some cases may be either higher or lower in frequency than the intended note. This usually means that the voice coil is driving the cone so hard that it is overcoming any damping and is essentially out of control. Sometimes manufacturers use huge magnets and loose spiders so they can win the 'sensitivity ratings' contest, but the result is a system that is difficult to control. Edge yowl is the term used to describe sounds that occur when the surround resonates, imparts energy back into the cone, and generates tones and notes that may or may not be harmonically related to the intended note. "