How will this sound and feel ?

Hebaton

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I am looking at Traynor YBA-1 variations and one version has 1K5/125uf on V1A and V1B
How would this change behaviour as opposed to plexi values ( currently in there )
 

Hebaton

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will no one please me here ?
those are cathode bypass values of course

thanks
 

thetragichero

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also sometimes you have to wait more than four hours for a reply
next time maybe do some googling and see if you can't find out for yourself in the interim?
 

Hebaton

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Thank you, and thank you for taming my inpatience somewhat.
I did search but, I guess I'm not so good at it. Waht I found did not seem very clear to me.
That asaid, AM-I to stand 1K5 wothout bypass cap in frequesnt in fenders ? Is tha what you are saying ?
 

Pete Farrington

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https://www.ampbooks.com/mobile/amplifier-calculators/cathode-capacitor/calculator/

don't need to go nearly as high as 125uf. 1k5 cathode resistors with 100k plate resistors is just about dead center biased. used in a whole swarm of fender amps
I understand this calculator to be more accurate, it’s a nice user interface and uses the gold standard formula from RDH4
http://bmamps.com/CapCal.html

1K5 wothout bypass cap in frequesnt in fenders ?
No, Fender typically use a 25 or 22uF bypass cap.
 

Hebaton

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reverted to original values. May do the same to tone stack.
I have decided to make this just the best clean amp possible.
any clues towards that goal would be appreciated. I originally asked a tech to make it as close as possible to a JTM45 but that never really worked so her I am.

curently driving KT66 power tubes. should I stay with those o go back to EL34 type ?
 
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Stephen H

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I would stick with the kt66's, bit more clean headroom... maybe (I'm no expert in anything, just a monkey.)
 

Pete Farrington

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I would stick with the kt66's, bit more clean headroom... maybe
Depending on how you define 'clean headroom', that seems more like probably not to me.

They probably won't reach overdrive until the vol control is turned higher. But that's due to the power stage almost certainly having a somewhat lower gain with them.

I think most versions of YBA-1 are intended for EL34 / 6CA7 with their OT having a primary impedance around 3k4, so that valve type should put out more power into that than KT66 are likely to.

But beam pentodes (KT66, 6L6) can sound and respond a bit differently to suppressor grid pentodes (EL34), so try both and go with your preference.

Personally, when I tried a YBA-1 with both EL34 and 6L6GC (all Winged C), at band sound levels, the amp seemed punchier and 'bigger' with 6L6GC, even though on the bench, the clean power outputs with either were about the same.
The owner wanted to use it as a clean pedal platform, so stuck with 6L6GC.
 
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thetragichero

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i've switched both yba-1 and yba-1a to 6550s (adjustable bias, lowered bias feed resistor values) with good results. especially the yba-1a which uses two 6ca7 for a quoted 80 or 90 watts. runs em hot enough that it came with a fan. maybe okay with the mullards that came in it but i would imagine murder on modern production tubes!
 


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