So I want to put some 12ay7s in my '57 Twin RI

[SinnerBoy61]

....but I'm not sure which slots they would go in...
Fender says that 3 of the 4 12ax7s can be substitued with 12ay7s, but which 3...

the first 3, or last 3?

I've included a picture


Thanks for your help

SB

[ne4tt]

Looking at the back, like your pic shows-

You would change the two tubes to the right of the power tubes. The Driver, and the Tone ckt.

Then select one of the other tubes to replace.
These amplify the guitar from the input jacks.

I haven't seen the reissue, but you should have two channels, 4 inputs, if it is true to the original 5D8 circuit.

[JohnnyCrash]

The one closest to the power tubes is your Phase Inverter. Leave that one as a 12AX7.

On the originals that was the ONLY 12AX7.

Right now, I'm building the little brother of that amp... the 5D8 "tweed Twin" circuit. It's only SLIGHTLY different:

It's cathode biased so it's got less headroom, but the tube compliment is supposed to be the same (too bad reissues don't use the tube types the originals were supposed to use). Mine's the famed "low watt" version of yours.

The 12AY7 is what is historically and schematically accurate. I don't understand Fender's weird Reissue tweaks except to say it MUST be for financial reasons.

Nice amp! Let us know how the tube swap sounds!!

[SinnerBoy61]

Originally Posted by ne4tt

I haven't seen the reissue, but you should have two channels, 4 inputs, if it is true to the original 5D8 circuit.

I do have two channels, and 4 inputs...but the circuit is the 5e8a I believe...

[SinnerBoy61]

Originally Posted by JohnnyCrash

The one closest to the power tubes is your Phase Inverter. Leave that one as a 12AX7.

On the originals that was the ONLY 12AX7.

Right now, I'm building the little brother of that amp... the 5D8 "tweed Twin" circuit. It's only SLIGHTLY different:

It's cathode biased so it's got less headroom, but the tube compliment is supposed to be the same (too bad reissues don't use the tube types the originals were supposed to use). Mine's the famed "low watt" version of yours.

The 12AY7 is what is historically and schematically accurate. I don't understand Fender's weird Reissue tweaks except to say it MUST be for financial reasons.

Nice amp! Let us know how the tube swap sounds!!

Well, the amp sounds killer as is..but..I would like to return it to orginal specs, just because. I also don't understand why they wouldn't put 12ay7s in it.

But, thanks a lot! =)
I'll let ya'll know how she goes.


SB

[JohnnyCrash]

Originally Posted by ne4tt

Looking at the back, like your pic shows-

You would change the two tubes to the right of the power tubes. The Driver, and the Tone ckt.

Then select one of the other tubes to replace.
These amplify the guitar from the input jacks.

I haven't seen the reissue, but you should have two channels, 4 inputs, if it is true to the original 5D8 circuit.

The '57 Reissue amp is actually the 5E8-A circuit, NOT the even lower powered, 5D8 circuit.

[Scott S]

Originally Posted by SinnerBoy61

Well, the amp sounds killer as is..but..I would like to return it to orginal specs, just because. I also don't understand why they wouldn't put 12ay7s in it.

I'm sure it's for financial reasons. 12AX7s are the highest-production tube of that family (thus the cheapest), and I think it's only recently that companies have been making good 12AY7s. To boot, a lot of players like the extra gain of 12AX7s.

At least Fender isn't trying to cover up which tubes would sound better in it: http://www.fender.com/products/searc...tno=8140500000

[JohnnyCrash]

Originally Posted by Scott S

I'm sure it's for financial reasons. 12AX7s are the highest-production tube of that family (thus the cheapest), and I think it's only recently that companies have been making good 12AY7s. To boot, a lot of players like the extra gain of 12AX7s.

At least Fender isn't trying to cover up which tubes would sound better in it: http://www.fender.com/products/searc...tno=8140500000

Don't get me wrong, I am not blaming them, just figuring if it was marketing or budgeting... players are always looking for more gain, I wondered if that's what Fender anticipated in this case.

I love Fender stuff, but I build my own amps now... which is WAY cheaper, but I completely understand them having to make money to stay afloat in this Korean Strat copy world we live in.

[Twangbanger]

I'd stick a 12ay7 in only one of the 2 channels. My heartland 5e3 has a 12ax7 PI, with a bright channel(more gain)12ax7 and a low gain (12ay7)channel. I love the low gain for all indoor mellow work and the 12ax7 channel for rock and blues.

After seeing these pics of the tweed twin and it's construction, I'm buying one!!!!!!

Or building one!

[SinnerBoy61]

So at volume seven, how much less gain would I have? Would it just be louder, clearer?

Never actually heard one of these with the 12ay7s in it...

Also, I read that...
"the #1 inputs are configured to route the signal to both amplifying stages (or grids) of the first two 12AX7s"

Does that mean I can swap one of the first two for a high gain/low gain channel type setup?

SB

[Twangbanger]

I'd need to see the schematic before I'd say which tube does what.

I have a fender and Traynor amp that doesn't follow the right to left tube layout that fender started back in the day, plus some amps use tubes for dual purposes. Say a driver circuit and a tone circuit.

[SinnerBoy61]

Does this work?
http://www.fender.com/support/amp_sc...Schematics.pdf



Thanks,
SB

[Dacious]

You'll probably find the amp goes a notch or two higher on the volume before breaking up. My 5E3 clone also produced a nicer clean going to RCA 6072s (12AY7s).

Fender probably went there as the only current production 12AY7 AFAIK is the EH.

[JohnnyCrash]

Originally Posted by SinnerBoy61

So at volume seven, how much less gain would I have? Would it just be louder, clearer?

Never actually heard one of these with the 12ay7s in it...

Also, I read that...
"the #1 inputs are configured to route the signal to both amplifying stages (or grids) of the first two 12AX7s"

Does that mean I can swap one of the first two for a high gain/low gain channel type setup?

SB

It's almost not a matter of headroom. It's also not just a matter of a "harder edge". It's kind of in between... it's subtle, but not.

It definitely aint gonna be like adding a good amount of dirt or anything like that.

Have I confused you yet :)

[Twangbanger]

Yeah, it looks as if V1 or the tube to the far right is for the normal channel and then v2 is the bright channel.

Stick a 12ay7 in the V1 position to see how you like it. They are great for blues and smooth sounding stuff.

My 52' Pro wass made for 6sc7's and it's hard to find good ones. After my amp revision, they just swapped out the sockets and put in 12ay7's. I bought the substitubes and stuck in a 12ax7 for the PI and a Mullard 12ax7 for one set of inputs and a Sylvania 12ay7 for the other set. I spend allot of my playing in the 12ax7 side, I love it's sound. I like playing through the 12ay7 side some. When I play(country) I want that tight, bright sound. Inside our house gig, I use the 12ay7 in my deluxe copy. It's smoother and gain isn't quit as high.

[Scott S]

I find the old schematics more pleasing to the eye. YMMV... http://www.ampwares.com/ffg/schem/twin_5e8-a_schem.gif

[SinnerBoy61]

So what does V3 do, and what would putting a 12ay7 in there do?

Thanks! =)
SB

[Jack Knife]

Just to mention...in that picture, the two tubes next to the power tubes are the rectifiers.

So, left to right you've got 2 power tubes, 2 rectifiers, 4 preamp tubes.

Just sayin...

[Twangbanger]

V3 looks to be a mixer circuit to feed the tone circuit. A 12ay7 would just drop the gain in this section as well.