5G9 Tremolux questions! Calling Tweed gurus!

[Herzog]

Hi guys,

I'm pulling together parts for a 5G9 tremolux build and am a little stumped as to what pot types to use, particularly in the tremolo circuit.

Here's the layout, no clues here!

http://www.thevintagesound.com/ffg/sche ... layout.gif

What do you guys reckon? I've seen 5E3 layouts with linear pots for VVT and later AA763 layouts with reverse audio pots for speed and depth but can't dig anything up about tweed trem pots.

[wyatt]

Schematic trumps layout...

http://www.thevintagesound.com/ffg/sche ... _schem.gif

IIRC, the Speed pot is a reverse audio an the Depth is linear.

[Herzog]

Thanks Wyatt,

So you reckon it's linear for VVT, speed is RA and depth is linear?

[M Fowler]

250kA

[Herzog]

Thanks!

[wyatt]

VVT would probably be 1M Audio, like on a 5E3.

[Herzog]

Thanks again Wyatt,

I think that's me set then.

[Herzog]

So I got some NOS AB resistors and, as expected, they are very drifty, anything above 220k is measuring at 10% or more above tolerance, the 1megs are measuring at minimum 13% above.

Should I take the trouble to source closer tolerance resistors or build with the drifty ones?

Also, the closest RA pot I could get is 3m not 2m. I can parallel a resistor to get 2m but wondered what practical difference it would make?

[sluckey]

Should I take the trouble to source closer tolerance resistors or build with the drifty ones?

I would. The CCs will likely contribute some noise, hiss, or crackles. I've switched to metal film with good results.

Also, the closest RA pot I could get is 3m not 2m. I can parallel a resistor to get 2m but wondered what practical difference it would make?

3M will be fine. It will allow the speed to be a bit slower on one end of rotation but still keep the same fast speed on the other end of rotation.

[ToneMerc]

So I got some NOS AB resistors and, as expected, they are very drifty, anything above 220k is measuring at 10% or more above tolerance, the 1megs are measuring at minimum 13% above.

Should I take the trouble to source closer tolerance resistors or build with the drifty ones?

Also, the closest RA pot I could get is 3m not 2m. I can parallel a resistor to get 2m but wondered what practical difference it would make?

Are they truly drifty or did you get 10% tolerance resistors?

TM

[Herzog]

I've a mixture of 5% and 10%. The 1meg 10% are furthest out, the closest to tolerance being 1,132m. The 220k are measuring from 246k upwards.

So I guess close to the 10% but certainly higher

[Herzog]

I would. The CCs will likely contribute some noise, hiss, or crackles. I've switched to metal film with good results.

Do you use metal film in tweed builds? I'm looking potentially at using metal films in select spots in the amp to keep the noise down.

3M will be fine. It will allow the speed to be a bit slower on one end of rotation but still keep the same fast speed on the other end of rotation.

Perfect, I'm a sucker for slow rolling trem, thanks for this.

[ToneMerc]

I've a mixture of 5% and 10%. The 1meg 10% are furthest out, the closest to tolerance being 1,132m. The 220k are measuring from 246k upwards.

So I guess close to the 10% but certainly higher

Honestly, I would be worried more about the having closer voltages and some period correct GE preamp glass than chasing 3% on a high value CC resistor. When Leo was ordering 20K CC resistors at time, do think his assemblers were culling the tighter tolerance values or just pulling them out of a bin, cranking these things out. I been in some these old Fenders which still sound great, but have resistor values outside their tolerance and most likely some of these resistors were out tolerance 60yrs ago. My point is that having a CC resistor a little high is not necessarily a deal breaker.

I look at the entire build specs in context.

TM

[Herzog]

Thanks man, this was my gut reaction too but thought I'd reach out for more experienced views.

[AcornHouse]

Part of the tweed sound is a less than hifi approach. Carbon comps, cathode bias, etc...
Weren't the original resistors used by Leo only 20% tolerance? When I was getting my '54 Deluxe checked out, we decided to leave any resistors that were within 20%. It sounds great.