closest 6L6 circuit to 5E3-like tone?

[oldmica]

Hey, all! First post, but I've been lurking for ages (and really appreciate the breadth of knowledge and positive vibes).

So here's my current project: I have a couple pairs of RCA blackplate 6L6GB, and want to build my brother (and myself) a pair of amps that are higher powered versions of the 5E3. I have some organ chassis' here that are 5U4 rectified, cathode biased 6L6 designs. I've also read that a 6L6GB supposedly sounds somewhat like a 6V6.

Has anyone here been down this road already? I'll share the build details in this thread. Any help/suggestions/criticism will be gratefully appreciated.

(edit: the 5e5 is similar, so that would be a likely starting point)

[Stevem]

They do not sound like a 6V6 to me , and I have all 3 of them in black plate plate versions!
It's just that they are a 19 watt tube and not 30.
Any similar tones and feel comes from the cathode bias and the weak power supplies that most Fender 6V6 powered amps of that era had!

Most organ amps do not have much plate voltage , and a 5U4 is going to but about 50 to 60 volts off of that so if you want a higher powered amp then a 5E3 you might concider using a 5AR4 recto tube, but you can use / audition both in the amp if you use power supply filters with a high enough voltage rating.

On this same note if you want your filters to live a long life then try to get them to rated for 50 volts more then they will ever see.

[sluckey]

Basically all you need to do is just build the stock 5E3 but use a PT and OT rated for 6L6s. You may be interested in this...

http://store.marshamps.com/product_info ... cts_id=492

or this...

http://www.ceriatone.com/american-classics-5x3/

Or just search for Neil Young 5E3. Lot's of info available.

[didit]

Hey, all! First post, but I've been lurking for ages (and really appreciate the breadth of knowledge and positive vibes).

Good start for fun, if crazy, trip.

So here's my current project: I have a couple pairs of RCA blackplate 6L6GB, and want to build my brother (and myself) a pair of amps that are higher powered versions of the 5E3. I have some organ chassis' here that are 5U4 rectified, cathode biased 6L6 designs. I've also read that a 6L6GB supposedly sounds somewhat like a 6V6.

I'll reenforce SteveM's comment. Audition your tubes in a 6V6 cathode-biased "50s" era amp with sufficient extra filament juice for 6L6. Perhaps better, also with a bit more primary current on tap and use 5AR4/GZ34 or silicon rectification to raise the plates a bit, and you will hear distinct differences.

Has anyone here been down this road already? I'll share the build details in this thread. Any help/suggestions/criticism will be gratefully appreciated.

Years ago, yes. That road well-travelled, building a 5E3 clone using one of Bruce Collins' Mission Amp kits. He provided hefty power and output transformers that enabled and encourages using 6L6. Make a long story short, to my particular peculiar tastes, tweed deluxe is an uninteresting one-trick design. Following advice, took fork in the road and ended up at tweed Tremol-less. That is, the 5E9a without the tremolo. To my ears & appetites this was more. More flexible and more sonically pleasing in any given setting. Even when chasing an elusive Neil Young howl.

Reenforcing SLuckey's comment, you could model from any number of hefty 5E3 designs. Roughly, keep the preamp from 5E3 and work it into the PI+power of a 5E5 as you posited in the "PS".

Best .. Ian

[stelligan]

Look for a Tweed Pro or a ProLuxe type amp...

I recently built a straight 5E3 board with 33uf filters, Bassman like PT and Tweed Pro OT. Like the 5X3 Sluckey referenced above in a way. Sounds great. Pretty loud at breakup but cleans sound groovy...

BigD.JPG

Oops - I guess it was 16uf filters and some monkey business at V1 + 5881s

[oldmica]

Many thanks! This is all really great information.

My brother is the impetus behind this. He bought a Hammond AO29 chassis that was modded into a 5E3, and wants the same kind of tone - just louder. I'm willing to send him more than one chassis (he's about 1500 miles away so I'll need to ship these), with some different builds. I don't think he's heard/played a tweed circuit other than the 5E3.

Another option (assuming the filament and B+ current budget): a quad of 6v6?

5E5, with a 5E3 preamp and 5AR4 rectifier is getting built for certain.

Thinking about a VVR, with a sag control.

[tubeswell]

... Another option (assuming the filament and B+ current budget): a quad of 6v6?...

Yep - that will sound more like a 6V6 amp than a 6L6 amp for sure, but you will still want a PT and OT that is rated for 2 x 6L6 (because the heater draw and the power output will be the same). And you'll want a beefier rectifier (than the 5Y3GT typically found in 50s 6V6 amps).

[oldmica]

That sounds almost too easy:

6V6: .45 A heater current draw
6L6: .9 A

Pair of 6L6: 1.8A
Quad of 6V6: 1.8A

I have a stepped drill bit for the additional holes, as well.

[tubeswell]

You'll also find that the reflected load for 4 x 6V6s in p-p is about the same as for 2 x 6L6s in p-p.

And the OT power rating.

Which adds up to using a PT and OT designed for a pair of 6L6s.

FWIW - Some companies (like Heyboer) offer p-p OTs for 2 x 6L6 in two size/power ratings (with one being slightly smaller 40W rated OT). The smaller 2 x 6L6 OTs would be ideal for 4 x 6V6s IMHO.

e.g.:
https://www.tedweber.com/hy404248

https://www.tedweber.com/hy022848

[oldmica]

Fantastic. Thank you!

The organ OTs are all purpose-built for a specific output impedance, and my brother wants at least 8 and 4 ohms outputs, so the 40w one you've posted is ideal.

I'll build it up and debug it using the old organ OT, then swap it out.

[Bear]

A different animal, but for lower voltage, cathode biased 6L6Bs, I would look into the 5B6 Bassman, which isn't quite a 5E3 but is closer to that sort of amp than a 5F6A. The Little Walter amps that were in vogue a few years back were 5B6 based, and some folks here got into DIY-ing them, so some searching will give you ideas.

[brewdude]

I have an amp with 4x 6V6 or 2x 6L6.
I used an AC30 style OT w/ 4K primary.
I built it with cathode bias such that one push/pull pair uses one cathode resistor and capacitor and the other pair another resistor and capacitor.
It can also run a pair of 6V6’s (w/OT secondary mismatch) dependent on which sockets are used.

[oldmica]

@Bear: thank you and I'll definitely look into the 5B6!

@brewdude: that's pretty much exactly where I'm going. The only things I'll need are power supply caps, a VVR (or components to make it) and an output transformer with 4/8/16 secondaries. I have some decent, new coupling caps and signal & dropping resistors. It is really amazing how many good parts are in these chassis.

Two questions remaining:

would the stock 5E3 phase inverter have enough juice to drive a quad of 6v6, without a significant tonal impact?

would there be a significant tone difference, or feel difference, if I was to drop B+ using a dropping resistor, rather than using a zener or VVR? I think I know (zener/VVR preferred, and that's what I'm going to use) but simply curious!

[tubeswell]

...would the stock 5E3 phase inverter have enough juice to drive a quad of 6v6, without a significant tonal impact?

The stock 5E3 cathodyne inverter should be perfectly adequate. It has a relatively low output impedance so it shouldn't have any problem driving 4 x 6V6 without any signal deterioration

...would there be a significant tone difference, or feel difference, if I was to drop B+ using a dropping resistor, rather than using a zener or VVR? I think I know (zener/VVR preferred, and that's what I'm going to use) but simply curious!

I'd wait until you built it first and then see if you need voltage reduction. YMMV. The 4 x 6V6s will tend to pull the B+ down more than 2 x 6V6s, and so until you get it fired up, its going to be a guessing game.

[oldmica]

^^

I was also thinking that I don't know the power transformer's designed secondary voltage, nor whether it will change because of modern wall voltages.

I'm going to approach it in the following manner:

retain the dropping resistor network, but replace the existing electrolytic caps,
check the value, then retain the existing cathode resistor (removing any bypass cap),
ground the grids through the existing power tube resistors,
light bulb check it with no tubes,
put a not-so-important pair of 6L6GB or GC in there, and not populate the PI or preamp sockets,
variac it up, in a dark-ish room, using my eyes & a digital thermometer to check the plates (I think 200 degrees means too hot)
and check the voltages at B+ and B+1

I think this is a valid approach (I couldn't think of anything else).