5E3-taming the volume

[Slim66]

So, I built my 1st 5E3. I used P-TGP-002 PT and a Hammond 1750-H OT. The 1st filter cap is 33uf, and the power tube cathode resistor is a 10w, along with a 50v power tube bypass cap. The rest of the circuit is standard.
Going into a Celestion G12M 65 watt speaker, this thing is too loud with the volume at 1. Also, like most 5E3's, it starts grinding at @2, and just keeps getting more grindy after that.

What can I do to tame it a bit?

Thanks,

Slim

[Stevem]

There are numerous things you can do, some will effect the sound and some will not.

Let me start off with two questions.

Is your V1 tube a12AY7, or a 12AX7?

On pin 1 and 6 please report back on what you have for D.C. Voltage on them.

PS.

You do have a volume control on the guitar right?

[jabguit]

First thing I'd do is ensure a 12AY7 is in V1. Fender used these for a reason. A 12AX7 provides so much gain that the volume control becomes a "fuzz" control. Replacing V1 with a 12AY7 (assuming you have a 12AX7 in there now) would help. Another thing is the V2 phase splitter, which is actually a gain stage into a concertina or cathodyne phase splitter. Replacing this with a 7247 (12DW7) tidies things up a little, not as much as the first suggestion. The first section of the 12DW7 is equivalent to a 12AX7 whereas the second section is equivalent to a 12AU7 - much less gain.

Another thing that can be done is change the coupling caps from 100nF to something smaller - like 22nF, which will drop some sub-bass out of the signal. The effect here is a slight tightening of the bass and general cleaning up the tone.

I'd try these 3 things and see how you like the tone. They certainly are easily reversible.


cheers,

[Slim66]

Thanks,

I'm a little confused about the 12DW7. Do you want the lower gain half for the phase inverter, or the second preamp section? Because there is version of the tube with the sections reversed.

Slim

[sluckey]

I'm a little confused about the 12DW7. Do you want the lower gain half for the phase inverter, or the second preamp section? Because there is version of the tube with the sections reversed.

For the 12DW7 use the low gain triode (pins 1,2,3) for the phase inverter. All 12DW7s are the same.

Yes, there is a similar tube that has the triodes reversed. It is called an ECC823.

https://www.tubedepot.com/products/jj-e ... acuum-tube

[Slim66]

That's what's confusing. On this annotated fender layout (attached), it shows pins 1,2,3 as the preamp side. Unless I'm reading it wrong?

Slim

[xtian]

This amp is cathode biased, which means adding a VVR is pretty simple. See post #4: https://ampgarage.com/forum/viewtopic.php?f=6&t=28653

[sluckey]

That's what's confusing. On this annotated fender layout (attached), it shows pins 1,2,3 as the preamp side. Unless I'm reading it wrong?

You're reading correctly. That was Fender's choice. And because of Fender's choice you will lose a lot of gain if you plug in a 12DW7. Now if losing gain is what you are after, then go for it. But if you want to maintain the same gain structure, don't use a 12DW7. Use the ECC823 instead.

I don't see any advantage in using a low gain triode in the phase inverter position because the gain of that PI is always less than one. A 12AX7 PI is quite capable of driving 6V6s. But if you were driving 6550s you would want the increased current capability of the ECC823.

[Mark]

That's what's confusing. On this annotated fender layout (attached), it shows pins 1,2,3 as the preamp side. Unless I'm reading it wrong?

You're reading correctly. That was Fender's choice. And because of Fender's choice you will lose a lot of gain if you plug in a 12DW7. Now if losing gain is what you are after, then go for it. But if you want to maintain the same gain structure, don't use a 12DW7. Use the ECC823 instead.

I don't see any advantage in using a low gain triode in the phase inverter position because the gain of that PI is always less than one. A 12AX7 PI is quite capable of driving 6V6s. But if you were driving 6550s you would want the increased current capability of the ECC823.

Good post.
I had considered using a ECC823 in the hope of providing more regulated signal to the 6V6, in the hope that during forward conduction of the 6V6 the crossover distortion wouldn’t be as bad. I may have it all wrong of course.

[Mark]

This is a possibility perhaps. Using 6K6’s, this is from Google Gemini.

While 6V6 and 6K6 vacuum tubes share the same octal base and pinout, they have completely different power ratings and sonic profiles.

6V6s are built for higher power and headroom. 6K6s offer lower output and highly aggressive mids, making them popular for mellowing out bright amps or studio recording.

Plate Dissipation: The 6V6 is rated for up to 14 Watts, whereas the 6K6 is rated for 8.5 Watts.

Voltage Limits: 6V6 tubes can typically handle significantly higher plate voltages without burning out.

Tone & Breakup: 6V6s are known for sweet highs, rich low-end, and a progressive, chimey breakup. 6K6s are true pentodes that compress earlier and yield highly aggressive, "Marshally" mid-range frequencies when pushed.

Can You Swap Them?

Direct substitution depends heavily on the specific amplifier:Putting 6K6s in a 6V6 amp: Some players swap 6V6s for 6K6s to tame treble bite (like in Fender Reverb units) or to achieve earlier, softer distortion at lower volumes.

However, because the 6K6 has a lower maximum plate voltage, doing this without circuit modifications can shorten the tube's lifespan or result in component failure if the amp runs too hot.

Putting 6V6s in a 6K6 amp: This is generally not recommended. A 6K6 amplifier (such as vintage radios or specific hi-fi gear) often runs at lower voltages. Dropping a 6V6 in won't damage the tube, but you will likely experience bias issues, incorrect load lines, and virtually no increase in output volume.

MORE AI content.

Dropping 6K6 power tubes into a Fender Tweed Deluxe (5E3 circuit) is a classic "secret weapon" modification for studio players who want earlier breakup at lower volumes.

Because the 5E3 is cathode-biased, it is highly accommodating to this swap. However, there are critical electronic and sonic changes you need to know before you plug them in.

Electronic Safety & Voltages

The Cathode Bias Advantage: The Fender Tweed Deluxe is a cathode-biased, plug-and-play circuit. This means you do not need to adjust a bias pot when changing tubes. The amp will automatically bias the 6K6s.

Plate Voltages: Vintage and accurately replicated 5E3 circuits usually run their 6V6 plates around 340V to 360V. While this technically exceeds the historic 315V rating of a 6K6 datasheet, vintage New Old Stock (NOS) 6K6 tubes are incredibly rugged and easily handle these voltages in a Tweed circuit.

Impedance Mismatch: A 5E3 output transformer expects an 8k ohm primary load from 6V6s. 6K6s technically prefer a higher impedance load line (around 12k ohms).

This mismatch won't damage the amp, but it causes the power section to lose efficiency, reducing your output power from 12 Watts down to roughly 6 to 8 Watts.

The Sonic Result

Aggressive Mid-Range Crunch: Because 6K6s are true pentodes rather than beam tetrodes like 6V6s, they exhibit a much rowdier, aggressive mid-range bark when overdriven. It pushes the 5E3 into "mini-Marshall" territory.

Instant Compression & "Sag": The already loose, spongy, and heavily compressing nature of the Tweed Deluxe becomes even more pronounced.

Power tube distortion happens early on the volume dial, turning into a thick, woolly fuzz at higher settings.

Zero Clean Headroom: If you rely on your guitar volume knob to clean up your tone, you will find it much harder to do with 6K6s.
The amp will remain dirty even at very low volume settings.

Best Practices for the SwapUse NOS Only: Do not try this with modern production tubes if you manage to find any. Use rugged vintage NOS 6K6GT tubes (RCA, Sylvania, GE, etc.), which are still relatively cheap and can handle the voltage abuse.

Watch out for Reissues: If you are using a modern digital or high-voltage PCB variant of the Tweed Deluxe rather than a true 5E3 Hand-Wired Circuit, verify the internal plate voltages first, as excessive voltage will burn out a 6K6 quickly.

Here are some of the links from the AI search:

https://www.diyaudio.com/community/thre ... k6.250415/

https://www.aggh.net/discussion/index.php?topic=22832.0

https://www.tdpri.com/threads/6k6-and-5 ... um=organic

https://antiqueradios.com/forums/viewtopic.php?t=100348

https://el34world.com/Forum/index.php?topic=11880.0

https://forum.seymourduncan.com/threads ... es.190208/

It also mentions a You Tube videos by D Lab.

https://www.youtube.com/watch?v=i4qlgZHMTI0&t=2

I haven’t posted in a while so I might be over compensating. It did occur to me that the 6K6 might be a good fit for the Tweedle Dee version of a 5E3 with a lower rail of course.

[Fischerman]

Easiest improvement imo is to lift the ground on the cathode cap for that second gain stage. I used a pull-pot for one the 1M pots. I simply added an extra 15k resistor between cathode cap and ground and then bypassed that resistor with the switch.

[jbrew73]

So, I built my 1st 5E3. I used P-TGP-002 PT and a Hammond 1750-H OT. The 1st filter cap is 33uf, and the power tube cathode resistor is a 10w, along with a 50v power tube bypass cap. The rest of the circuit is standard.
Going into a Celestion G12M 65 watt speaker, this thing is too loud with the volume at 1. Also, like most 5E3's, it starts grinding at @2, and just keeps getting more grindy after that.

What can I do to tame it a bit?

Thanks,

Slim

Did you use linear or log volume pots?
I worked on a 5e3 clone recently that had a bad pot so I replaced both volumes with alpha 1m log pots. The volume controls were smooth and came up gradually as I expected. I can’t remember at what point the amp started to grind but it definitely was not on 2.

[Mark]

I had been previously working on an 5E3 and I found that I was using input two to get better clean tones. The amp has a lot of gain even using a 12AY7. In the end I put a LaMar master volume in the amp and it worked well.