Tubes? Speaker? Other?

[rutledj]

I built a deluxe reverb clone. Low hum, low noise, but the amp just sounds way too ... punchy is the word that comes to mind. I'm referring more about the initial note attack. It sounds kinda hard for lack of a better word. I'm using an ET65 speaker. Amp is biased around 20 ma. I'm using tung sol 12AX7s and JJ 6V6s.

Any suggestions as a way to mellow the initial note attack? Not really sure how else to describe it. It isn't harsh as a lot of people complain about these amps.

Open to any suggestions.

[pdf64]

That’s a high sensitivity speaker, nearly 100dB @ 1W I think.
Maybe try it with a small magnet, lower sensitivity type.

What’s the winding resistance of the HT secondary, eg between pins 4&6 of the rectifier? Transformer manufacturers seem to overlook / ignore that it’s beneficial and expected for them to include sufficient resistance in vintage type PTs, intended for valve rectifiers.
Customers expect a cool running transformer I suppose.
External resistance can be added.

But bear in mind that these are stage amps, were probably intended to have a punchy response at high outputs.

[martin manning]

What is the plate voltage? What rectifier are you using?

[rutledj]

Using a 5U4 rectifier. Plates around 460-470v. Not sure about the OT winding. It is a classic tone model.

[martin manning]

Your plate voltage is quite high. It should be more like 400-420V.

[Vintagelove]

I built a deluxe reverb clone. Low hum, low noise, but the amp just sounds way too ... punchy is the word that comes to mind. I'm referring more about the initial note attack. It sounds kinda hard for lack of a better word. I'm using an ET65 speaker. Amp is biased around 20 ma. I'm using tung sol 12AX7s and JJ 6V6s.

Any suggestions as a way to mellow the initial note attack? Not really sure how else to describe it. It isn't harsh as a lot of people complain about these amps.

Open to any suggestions.

Try a sag resistor.

That being said, you may want to look at the voltages mentioned earlier. Lastly, this is very subjective, but I never cared for the et65, but if you like the tone, it’s not part of your current issue.

[pdf64]

Using a 5U4 rectifier. Plates around 460-470v. Not sure about the OT winding. It is a classic tone model.

What’s your actual measured mains and heater VAC?

[Stevem]

In terms of note attack, are you playing with a pick, and if so are referring to pluck of the note while the pick attack is still part of the sound or are we talking about when a note is just ringing out?

[rutledj]

I have 717v on PT secondary with 124v wall voltage. Heater 6.7v. Plate voltage is 440v

[martin manning]

Do you have any way to reduce the AC input voltage to see if that gets it closer to where you want it? A Variac for example, or lacking that you could use a 120V to 12V transformer.

[Guy77]

I built a deluxe reverb clone. Low hum, low noise, but the amp just sounds way too ... punchy is the word that comes to mind. I'm referring more about the initial note attack. It sounds kinda hard for lack of a better word. I'm using an ET65 speaker. Amp is biased around 20 ma. I'm using tung sol 12AX7s and JJ 6V6s.

Any suggestions as a way to mellow the initial note attack? Not really sure how else to describe it. It isn't harsh as a lot of people complain about these amps.

Open to any suggestions.

Yes plate voltage too high here. I built a 6v6 push pull amp recently with JJs and with a lower B+ (400v) and it did not experience the symptoms you described. I ran them at 450v in the same amp and it experienced those issues (kinda hard). Yes the JJs can with stand higher B+ than other 6v6 but it comes with a change in tone I discovered.
I ran them at 375V B+ in another amp JJ 6v6 amp and they were a dream!
I think you will be happier with a transformer with a lower B+.

Cheers

Guy

[bepone]

too high voltage can be easily overtaken with 6L6 tubes, plugged in to check. power transformer will survive 5 min of 6L6's.

under "other" category, can be :

1. material and thickness of the front baffle (i have built some combos from 3/4" ply, all sides, and they never sound specially good, and they had this hard sound, too fast attack - EL84s on normal voltage - 310V). changed many speakers in combo but problem was present on all. so with time i have changed front baffle to 1/2" and there was significant imporvement of this "hard" sound.

2. also sometimes i felt this "too punchy sound" with some experimental output transformers, so i replace them for some others and sound became "slower", more normal. this i will on the magnetic properties of the core, hysteresis curve.

3. too much metal films resisters everywhere, "slow down" with carbon film and carbon comps in signal passages, sometimes anodes too.

[didit]

Hello --

Recommend following the advice from pdf64 to add resistance into primary before the rectifier. Here's an old post where I'd explored this topic at some length. A pair of suitable value 1W MF resistors in series, with perhaps a third between the center-tap ground yields happy changes to power supply dynamics.

Two BFDRs

Best .. Ian

[rutledj]

I used two 5 watt 250 ohm resistors in line with the PT HV wires. Knocked the voltage down to about 410v. Improved the sound some but still has that hard punchy character to it.

I had an Eminence alessandro GA-SC64 speaker (although for 16 ohms) that I also tried. Didn't really change the sound that much.

I'm wondering if bepone is on to something about the cabinet. Mine is made from 3/4" walnut along with a 3/4" oak plywood baffle.

[bepone]

i rarely found voltage problems like people stated here to produce hard sound. my problems were mostly related to speaker cabs in general, and their dimensions, wood type etc. there is a video online where one guy produced zillion cabinets and in everyone had different sound. speaker cab actually is extension of the speaker, and it is making the sound. it is more important than an amp!

on good speaker box, also tranzistor amp will have excellent sound, tested by myself on one excellent 4x12" soldano cab. but on bad speaker cab also the best amp will produce shitty sound. you cannot fix that with electronics.

in the speaker cab design is the essential thing to make it good. i'm now on mixed 1/2" ply for the front baffle and 3/4" of pine for externals and it is satisfying