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/13 RSA23 derived from what circuit?

jcat5503

Member
Messages
1,252
I have heard that the RSA23's are derived from the Marshall 18 watt circuits. It uses a 5879 pre amp tube instead of the ef86 I know. And kt88's instead of dual el84's.

Does anyone know if this is true or not? If no what circuit is it some what based off of?

I know where an 18 watt TMB is that Id like to modify to be similar to the /13 if it's possible

thanks!
 

roknfnrol

Gold Supporting Member
Messages
6,670
I have heard that the RSA23's are derived from the Marshall 18 watt circuits. It uses a 5879 pre amp tube instead of the ef86 I know. And kt88's instead of dual el84's.

Does anyone know if this is true or not? If no what circuit is it some what based off of?

I know where an 18 watt TMB is that Id like to modify to be similar to the /13 if it's possible

thanks!
It might have some 18 watt roots but I'm betting it is an original design. Also, I don't think Marshall 18 watters used an EF86 front end (although AC15s did).
 

jcat5503

Member
Messages
1,252
Oh okay. Yeahh I'll contact him

I'm guesing the ef86 is just a popular mod to the 18watters?
 

bettset

Member
Messages
4,269
the amp was made for his friend--rusty anderson. he plays with mccartney. good company :munch
 

gtrfinder

Silver Supporting Member
Messages
3,720
I'm neither a vintage amp expert or an expert on Fred's business line, however I do think I can help by clarifying a few things.
The 5879 tube is only associated with Channel 2 (or the non TMB channel of the amp). Channel 1 is all 12ax7's. I think almost all of the Divided By 13's with a second channel like this have a 5879 in there, so it is not exclusive to this amp.
I owned the single channel version of the RSA23 for about a year and did not find it similar to any 18 watt Marshall I have ever played. To me it sounded very big, agressive, and loud. I don't think you could modify an 18 watt (EL84 based amp) to sound like an RSA23.
 

bettset

Member
Messages
4,269
i think the rsa23 is a blend of marshall & vox tones the way it's described on his site. the above post can clarify better since he owned one. i have the ftr37. mine has the 5879 tube for channel 2. that channel has vox/marshall tones to some degree. the other channel is fenderish. it is a 6v6 tube amp. i don't know if fred uses the ef86 at all in any of his amps. mine can get very loud too--great for outdoor stages. i can go to 1/2 power. i believe it when he says the rsa 23 is loud. rusty i think still uses the rsa31 live--it is powerful too. the rsa23 may be a tamer version of the 31--but still potent :munch
 
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626
Fred said the 23 was modeled after a marshall major -he cold biased the tubes,what he said on the phone when he was just releasing them.....
 
Messages
2,537
Fred said the 23 was modeled after a marshall major -he cold biased the tubes,what he said on the phone when he was just releasing them.....
Yes Marshall Major, straight from Fred. He is proud of this amp, and thinks it has something very special going on. While it can take other tubes (6L6, EL34, KT66) he feels that the KT88's really do something special in this amp.
 

cbfurg

Member
Messages
414
all i know is that i played a single channel 23 down at rock block in nashville and that amp still haunts me to this day.
 




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