Is My Deluxe 5E3 “Normal”?

[syscokid]

I recently built a 5E3 to satisfy my curiosity of this old circuit. Prior to this build, I’ve never had any experience with any Tweed style amp. To develop a little foundation, I did a little bit of researching of the 5E3 on its history by watching and listening to various video and sound clips, and reading various online articles about this type of amp. A consensus of an undesirable feature of the 5E3 circuit is Blocking Distortion when pushed hard. My 5E3 build does NOT exhibit any blocking distortion at all, at any amp settings! Should I be concerned, or just shut up and play?

I’ve been plugging in guitars with vintage output single coils to guitars with moderate output humbuckers. From clean to fully cranked amp settings, with and without an attenuator. Tried signal boosting pedals like a Klon style overdrive and a Friedman Buxom Boost. All I’m getting is killer tones but none of that blocking distortion I was warned about!

Actually, I never did find a video or sound clip demonstrating a 5E3’s propensity for blocking distortion.

[cdemike]

Is the circuit stock 5E3 or are there grid stoppers either on the output tubes or on the phase inverter?

[LOUDthud]

Is the first preamp tube a 12AX7 or a 12AY7 ?

[syscokid]

Is the circuit stock 5E3 or are there grid stoppers either on the output tubes or on the phase inverter?

The circuit was first completed about four weeks ago and set up with stock values. Stock also means that there are 1.5k grid stoppers at the power tubes, though... I think? Even though the amp is not spitting out any blocking distortion, I temporarily added a switch with a 470k grid stopper for the PI just to hear what the amp will do with it. And honestly, at first I felt that there wasn't any difference by adding the resistor. But the following day with fresh ears, I feel like I'm hearing a touch of extra sweetness to the top end under heavy overdrive. Therefore, I have installed "permanently", the 470k grid stopper right at the pin.

Is the first preamp tube a 12AX7 or a 12AY7 ?

AY7...
Amps is in good company:
GE (JG) 12AY7
Sovtek 12AX7LPS
Pair of RCA 6V6GT
Sylvania 5Y3GT

[syscokid]

Voltages seem to be okay:

GeeDeluxe Voltages July '24.jpg

[brewdude]

Do you want it exhibit blocking distortion?

[syscokid]

Do you want it exhibit blocking distortion?

Not at all! But I was expecting it. I was under the impression that any 5E3 amp built with stock values will exhibit blocking distortion.

[Colossal]

Out of curiosity, what kind of transformers did you use?

[pdf64]

...
Not at all! But I was expecting it. I was under the impression that any 5E3 amp built with stock values will exhibit blocking distortion.

I suspect that most complaints of blocking distortion will correlate with use of a 12AX7 in V1 / the use of boost / fuzz pedals to heavily overdrive the 5E3.

[syscokid]

Out of curiosity, what kind of transformers did you use?

For the set of transformers, I did business with Tube Audio Supply. Trannies are made by Heyboer to TAS specs. The PT outputs 660v @ 120mA. OT specs are 8K primary and 8 ohm secondary.

https://www.tubeaudiosupply.com/collect ... r-usa-made

[cdemike]

...
Not at all! But I was expecting it. I was under the impression that any 5E3 amp built with stock values will exhibit blocking distortion.

I suspect that most complaints of blocking distortion will correlate with use of a 12AX7 in V1 / the use of boost / fuzz pedals to heavily overdrive the 5E3.

I agree. If you consider that 12AY7 is the first stage in the amp and that most reports of blocking distortion I've seen are in heavily overdriven amps, you're looking at apples and oranges. Your amp wide open sends roughly half as much signal to the second gain stage as an amp that has a 12AX7 in V1. The difference in mu will be offset some by the lower output impedance from a 12AY7, but it's a much lower gain tube than a 12AX7.

[psb962]

Even though the amp is not spitting out any blocking distortion, I temporarily added a switch with a 470k grid stopper for the PI just to hear what the amp will do with it. And honestly, at first I felt that there wasn't any difference by adding the resistor. But the following day with fresh ears, I feel like I'm hearing a touch of extra sweetness to the top end under heavy overdrive. Therefore, I have installed "permanently", the 470k grid stopper right at the pin.

If you have the 470k resistor mod on the grid of the PI then you wont get any blocking distortion. That's what the mod is for, it corrects a design oversight by Leo.

I did same mod when I built mine, and I haven't heard any blocking distortion either.