ideas for Beefing up Traynor YBA-1

Hebaton

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What would be the effect of installing a 47uf bypass cap on the v2a resistor ( in a Marshall type amp ) ? I tried .68 and did not like the result, abit..fizzy" for lack of a better description. there was earlier brakeup and grind but not in a pleasing way at least to my ear.

Can I play with values in that position and if so, what would be a "range" to try ?

Thanks !
 

Pete Farrington

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What would be the effect of installing a 47uf bypass cap on the v2a resistor ( in a Marshall type amp ) ?
Try whatever you like; no damage can be caused, as long as it has sufficient voltage rating.
Note that Marshall have made and continue to make a wide variety of amp models, each often with design variants over time.
Hence 'V2A of a Marshall type amp' is a very unsuitable way to identify what you're truly asking about, and may well lead to confusion and wasted time and effort on everyone's part.
 

_Steve

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What would be the effect of installing a 47uf bypass cap on the v2a resistor ( in a Marshall type amp ) ? I tried .68 and did not like the result, abit..fizzy" for lack of a better description. there was earlier brakeup and grind but not in a pleasing way at least to my ear.

Can I play with values in that position and if so, what would be a "range" to try ?

Thanks !

For less fizz, you can try NO bypass cap
 

Hebaton

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O.K. let's try to be more specific. THis was an early 70's Traynor YBA-1. the tone stack has been mdified to JTM45 values and the v1 acthodes have been split with pexi values ( 820/220 and 2k7/.68 )

THe amp has the most beautifull cleans you can dream off ( to my taste ) but I would like it to breakup a bit quicker and carry a little grind ( again for lack of a better term )
Is this less prone to confusion ?
 

Hebaton

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Also, that V2a resistor is currently 820 ohms, should I try something else there ?
 

_Steve

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O.K. let's try to be more specific. THis was an early 70's Traynor YBA-1. the tone stack has been mdified to JTM45 values and the v1 acthodes have been split with pexi values ( 820/220 and 2k7/.68 )

THe amp has the most beautifull cleans you can dream off ( to my taste ) but I would like it to breakup a bit quicker and carry a little grind ( again for lack of a better term )
Is this less prone to confusion ?

V2a is the front of a DCCF. Its common to be fizzy here when bypassed. You can try bootstrapping the stage to get more gain without the fizz. More info at the bottom of this page: The Valve Wizard - Ive never tried it myself though.
 

_Steve

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O.K. let's try to be more specific. THis was an early 70's Traynor YBA-1. the tone stack has been mdified to JTM45 values and the v1 acthodes have been split with pexi values ( 820/220 and 2k7/.68 )

THe amp has the most beautifull cleans you can dream off ( to my taste ) but I would like it to breakup a bit quicker and carry a little grind ( again for lack of a better term )
Is this less prone to confusion ?

And to directly answer your question the 'range' of caps you could try there is typically .1 - 330uF. All will be fizzy as fizz is high-frequency and bypass caps are high-pass filters.
 

Pete Farrington

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So there’s no master vol of any kind?
If there’s no master vol, it’s the output valves that will largely define the clipping / overdrive behaviour.
Those amps sound great, but rather different, with either beam or suppressor grid pentodes.
So what output valves? eg type, manufacturer, current or vintage production.
Set for what anode or cathode current at idle?
 
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thetragichero

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also adjusting the phase inverter to more "marshall" values would be helpful. if i remember correctly some of them came with incredibly small (47k? something like that) grid resistors on either side of the phase inverter
also a more descriptive thread topic is likely to elicit more traffic
 

Hebaton

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Thanks for that hint on the grid resistors, I'll look those up. Robinette also talks about switchable NFB is that worth investigating ? the Iron only has an 8 ohm tap I believe. I may also try the "tone stack bypass" seems to me that woul provide a boost ...
Thread title o guess cannot be changed now. I'll do better next time
 

FleshOnGear

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Thanks for that hint on the grid resistors, I'll look those up. Robinette also talks about switchable NFB is that worth investigating ? the Iron only has an 8 ohm tap I believe. I may also try the "tone stack bypass" seems to me that woul provide a boost ...
Thread title o guess cannot be changed now. I'll do better next time
You can click on “thread tools” at the top of the thread and it will give you a link to edit the title.

I have a YBA-1A, and there are a few places where that model can be modded for more gain. Your YBA-1 potentially can be modded the same ways, depending on the version you have.

1) Change mixer resistors from 100k to 470k

2) Change phase inverter grid resistors from 47k to 1M

3) Change bias feed resistors to 220k

Early versions of the YBA have 1M grid resistors on the PI, and 220k bias feed resistors.
 

Hebaton

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PI grid resistors are 1M already. mixer resistors seem to be 270K. can you help me locating the "bias feed resistors" sorry to expose my incompetance ...
 


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