choke mod for 5e3

[martin]

I`d like to try to add a choke to my 5e3 but can anyone tell me
wich one to use? Will simply any choke labeled 3H do or are there
any more variables (ohmage or whatever) to concern?

I`d get one from Bruce with no worries if i lived nearby but sadly I´m on the other side of the planet so...

[Bruce / Mission Amps]

Where on the other side of the planet?
Yes, a 3Hy to 5Hy @ 50-60ma choke is all you need.
You'll need to rewire the sockets with a Fendery 6L6 power tube layout using 470 ohm to 1000 ohm screen resistors on the socket lugs and a rebias of the power tubes as they will draw too much idle current with a choke instead of the 5K resistor.

[sjhust]

What would happen if you used both the choke and the 5K?

steven

[galibier_numero_un]

What would happen if you used both the choke and the 5K?
steven

I've found that decreasing the DCR anywhere in an audio circuit tends to impart a livlier more "see-through" sound.

By leaving the resistor in line with the choke, my guess is that you would "sit on" the dynamics and transparency. IOW, you wouldn't get the full benefit of replacing the resistor with the choke. More isn't always more

Note that I've never tried this combination, so reality may conflict with theory

Cheers,
Thom

[martin]

Where on the other side of the planet?
In Estonia

Question for those who have added a choke for 5e3:
Roughly how much does the value of the 250 ohm cathode resistor
need to be risen in order to get the bias back to where it should be?

[flythair1]

Hello Ampage Community!,

I have a scratch built 5E3 that I used a 10H choke with and I did not do any modifications yet but it seems to play very nicely as it is. Bruce, I'm looking at a shemo for your "Tweedy Deluxe" (latest date is Oct 2004). With the choke installed, where do the 470-1k screen resistors go, pin 4 to ground on the 6V6's? I'll check the current and probably raise the value of the cathode resistor?? Can an adjustable bias be installed in this circuit? If so where?
I used an old DuKane PA head for the platform for the 5E3 circuit. The DuKane was near mint when I found it. I used the transformers & sockets but that's about all. It fired right up and only needed minor tweeking. This was my first build but before I got this amp running I built a P1eX AX84 project. All scratch built with a salvaged chassis & trannies & some odds and ends. That one turned out neat also.
Thanks!!

Scott

[Bruce / Mission Amps]

When I do the choke mod I rewire the power tube sockets like Fender did on their 6L6 amps...
1500 ohm grid stopper resistor from lug 1 to 5 and the new 470-1000 ohm screen resistor from lug 4 to 6.
The screen voltage is fed from lug 6 to lug 6 of the other tube and from there, on to the eyelet board at the preamp side of the old screen node, where he old 4700-5100 ohm resistor, use to be, ...but of course a choke there instead now.
I'd still use a NOS 5Y3 gt rectifier and use no less then 270 ohms for the cathode resistor but I bet a 330 to 360 ohm would work very well.

[barfoden]

When I do the choke mod I rewire the power tube sockets like Fender did on their 6L6 amps...
1500 ohm grid stopper resistor from lug 1 to 5 and the new 470-1000 ohm screen resistor from lug 4 to 6.
The screen voltage is fed from lug 6 to lug 6 of the other tube and from there, on to the eyelet board at the preamp side of the old screen node, where he old 4700-5100 ohm resistor, use to be, ...but of course a choke there instead now.
I'd still use a NOS 5Y3 gt rectifier and use no less then 270 ohms for the cathode resistor but I bet a 330 to 360 ohm would work very well.

This choke mod on a 5e3 looks very interesting... I always wondered how much current is sourced in a hot cathode biased PP amp like a 5e3 from idle to high transients.
In a true single ended class A amp there is no difference from idle and pumping music through it.. Current might actually get slightly lower when played..
I heard a skilled amp builder on youtube play his Dearmond R15T clone on youtube,,, very nice amp.. He used the largest 6.6K deluxe reverb OT from classictone but used a GZ34 rectifier instead of the schematic 5y3, but compensated by using a 100mA transformer with 275VAC secondary to get around the 340V B+ like the original ..

That amp is close to a 5e3 but it works well with humbucker equipped guitar and has less raspy, flubbing break up....

Interesting is it that the amp has no grid resistor on the 6V6GT tuebs...
Differences between this and a 5e3 is lower voltages (330V on the 6v6 plates) which equals cooler bias with the 250r resistor, lower value screen dropping resistor (2.7K vs 5K), and finally 0.047µf couplers in the power stage, a 0.01µf on the bright/tremolo channel preamp, 0.047µf on the normal channel. A 12ax7 in V1 with 350r volume pots and lower gain on the V2 (12ax7) by omitting the bypass cap... Finally more filtering on the 6v6 plates.. (40µf in the schematic which sounds a bit disturbing with the normal 22µf practice on a 5y3 rectifier)...
And larger stronger transformers... THe OT size looks more like something you would find in a 40W 6l6 amp from fender...

I even saw a original Dearmond R15T on ebay for mucho dollars... Instead of the probably dead 10-15-40µf multi-cap can the previous owner had put modern single capacitors in there... 10µf preamp,,22µf 6v6gt screen, and wait for it 47µf cap feed from a vintage 5y3 rectifier on the 6v6GT plates.....47µf main filter on a vintage RCA 5y3 rectifier seems like a stupid thing to do.. If you go modern a 33µf is max in my book...