OT impedance and break up relationship

[Randall]

To button this up (as far as I am concerned) I swapped out the OT with the exact proper model and year, and I think it sounds like a great BF Super Reverb should sound. I know... I didn't go searching for break up with a scope, etc, but in this one case I am going to buck the current tide of opinion. I have the advantage of knowing this guy. He is not technical. His complaint that it breaks up too fast, could be anything from his pedal set up to the original CTS speakers (which we cannot measure). I am confident this amp is working as it should with the correct OT. I am not one to chase my tail too much when my instincts tell me not to. I got 39 clean watts thru the input to the speaker with the mismatched OT/load, so I'm good with that. Some here with bigger brains than mine will have something to say about that, but in this case I'm done.

I believe this is my stop gents, have a pleasant day. Thank you as always for your input.

[Justin Thomas]

Given that every other spec in a Fender is +/-20%, I'm willing to accept a +/-20% tolerance in power output, too...

Justin

[Justin Thomas]

B-b-b-b-b-but ..... Stevie Ray did! (cue synchronized group face-palm now)

Off Topic a Bit, about BF/SF tone: Since you brought it up... having played a few BF and lots of SF amps, I associate the sound of SF amps with SRV more than BF. I know, I know, what the amps looked like... But I think a few SF amps of the appropriate speakers get you there for the rest of us who DON'T have his hands...

I kind of associate BF tone more with hard rock than blues. SF (& Tweed) more with the smooth blues - not so much how much "distortion," but overall character. Just me... I like Browns, myself...

Justin

[cjenrick]

note that you will have less breakup when using the normal channel as you have one less gain stage,
also check to see if there is a 12AT7a in the PI slot.

Kendrick Mods: (most opposite to reducing breakup)

1. disconnect feedback resistor for more gain and richer harmonics
2. increase gain and dynamic response by switching PI to 12AX7a
3. thicken up sound by replacing PI feed cap to .02 uf
4. improve and open up dynamic response by using individual cathode resistors for V1/V2
5. improve low end by increasing value of first stage bypass caps to 250 uf / 6 v.
6. improve fidelity by reducing 68K input jack resistance
7. improve fidelity and gain of one channel by moving wire from 220K PI input resistor to other side of resistor and unsoldering the other wire for the other channel and insulating it with tape.
8. improve volume and punch by changing to solid state rectifiers
9. dramatically improve fidelity of vibrato channel by disconnecting yellow wire to top of intensity control. (this will disable vibrato function)
10. improve tone and sweetness by replacing speakers - stock speakers are not that great.

[bob p]

40 years later amp designs have evolved quite a bit. Looking back from 2017 Gerald Weber's recommendations seem quaint.

[Justin Thomas]

Especially #5, to me... I don't know ho me who thinks the cathode bypass caps in any vintage Fender need to be BIGGER! Especially if we're trying to improve low end. Maybe if you keep the volume on "2?" But usually Fenders are more than sufficiently bottom-ended.

I would think #4 does allow for more tweakable control and voicing among individual channels... And for #10, I think the recommendation was to use KENDRICK speakers? though to be fair, I didn't really hear ant complaints from the few I heard used them...

Justin

[bob p]

Especially #5, to me... I don't know ho me who thinks the cathode bypass caps in any vintage Fender need to be BIGGER!

pedal steelers and keyboardists? they tend to love amps like the Super Twin Reverb that has that big "wooly" sounding 750uF cap in the first stage.

[Justin Thomas]

Fair enough, but I also tend to not exactly put the Super Twin squarely in the "Classic" or "Vintage Fender" category... IIRC, neither do you, Bob! I tend to take them as "something completely different."
I remember struggling to dial in enough Bass on my Super Twin to match my BF Bassman. I found the Super Twin to be more in line with the eq of a modern amp than with a vintage Fender. Or maybe it was malfunctioning. It certainly took pedals better. But damn if some neodymium speakers woulda been nice.
I would still argue that 90% of us are always trying to get the wool OUT of our Fenders... while playing dirty.



Justin

[cjenrick]

mods moot>

[dstrat]

wow, signal to noise anyone?

[bob p]

there's a guy who doesn't know what kind of tone he's looking for.

[g1]

I guess you would need some kind of 'foot extender' or stilt to run that pedal board?

[Leo_Gnardo]

I guess you would need some kind of 'foot extender' or stilt to run that pedal board?

How about a couple of pedalboard assistants to dance the Floppy Boot Stomp, trained to hit the appropriate switches on cue.

More to the point, that guy badly needs a big Bradshaw (or one of his competitors) switching rack. Or two. But that takes away from the pedalboard spectacle. Heck that one's even bigger & more impractical than Eric Johnson's "barn door."

All that's lacking is a Rick Nielsen 5-neck guitar to complete the circus.

[Gnobuddy]

Super Twin Reverb that has that big "wooly" sounding 750uF cap in the first stage.

750 uF cathode bypass cap? No kidding? Someone at Fender must have either got ten thousand 750 uF caps for free, or got their cathode bypass calculations a few orders of magnitude wrong.

A 750 uF cathode bypass cap on half a 7025 (triode) will get you a frequency response flat down to a fraction of a hertz. It cannot possibly do anything beneficial for the sound of a guitar (no notes below 82 Hz), and is begging for massive blocking distortion and subsonic thumps and bumps from guitar handling noise. It sounds like either a complete design mistake, or sheer idiocy, really.

-Gnobuddy

[Gnobuddy]

...that guy badly needs a big Bradshaw

I suspect the huge pedalboard is an attempt to compensate for, erm, his small Bradshaw.

-Gnobuddy