El84 questions

[isaac]

Hey guys,
I have a few questions on EL84's.
First, how do they sound in fixed bias config, instead of cathode bias?
Second, Is there a way to make them sound a little thicker and less glassy like a 6l6?
I want to build a Tweed bandmaster with el84's, but Want to check on some of the options.
Thanks,
-Isaac

[booj]

First, how do they sound in fixed bias config, instead of cathode bias?
Second, Is there a way to make them sound a little thicker and less glassy like a 6l6?Mesa's use EL34's in fixed bias mode, but I don't know how to compare that to anything else. It's a pretty subjective matter. I guess if I had to say something it would be they might sound "tighter"

I thought 6L6's were supposed to be glassy sounding. Again it's all subjective. No clue on how to help you.

[isaac]

I meant make the 84's a little less chimey (?) Since it seems to me that 6l6's have a thicker more thumping (?) tone. (not great adjectives, hope you get what I mean...) Whereas el84's have a chimey sparkly kinda raw (when cranked) tone. They all sound great, its just some projects are nice with slightly varied tones. Whatever the case, as I have barely any experience with 6l6's, the deal is, I want to basically build an amp that usually has two 6l6's but I want it with 84's as I have those chassis handy, and transformers that should work, handy, and so I don't blow my face off, so I'm trying to think if I can get 6l6-ish tones by messing with a couple components. I guess the power tubes don't change the tone as much until completely cranked and clipping. Obviously, one might be smoother, or rawnchy, or chimey, that they add a slight tone variation, but at low volumes most power tubes don't make as much difference as adding another 12ax7 or something. I guess I should actually start the project, see how I like it, then mess with stuff.

[cyclone]

I build 20 watt heads of my own design in fixed bias. I run the plate voltage at around 378 at 20-22 cathode current into 7k ohms opt primary. Neg bias is 16 to 19.5 volts, tube dependent. I wouldn't say the tube has a "tone" per se, but I will say that if you drive them too hard, they sound harsh. So, don't it doesn't seem to be confined to one kind or brand of el84/6bq5, including the 6p14p variants. I'd say most output tubes (or preamp tubes or fets or transistors) sound like a big bag of ass when driven with a square wave or an input signal thats just too much for the device. Use interstage attenuation!

It doesn't take a huge drive (13.45 volts ac or something) to drive el84's to their max, often, people put too much drive signal into them and it ruins the sound of the amp.

[isaac]

Yea, I guess my biggest question is that, how would it sound to build an EL84 power stage instead of 6l6's, in most basic Fender style amps. I have to use noval sockets, so I'm just afraid that my amp will sound too different by then. The idea for me is, build a tweed bandmaster (5e7) but with el84's, like in a marshall 18watt 1974x, or ac15. That kind of idea. That way it won't blow your face off when you achieve drive tones. And yea, I actually have 412plate voltage on my 84's on one of my 18W, How do you think that would sound with this design. It sounds good there, just...

[frus]

btw, there are 6BW6 tubes, that are very similar to 6V6's

[jimboyogi]

Another idea. If you are looking to build a Fender style amp using EL84s, how about the 6G9 Tremolux?

The 5G9 used 6V6s, the 6G9 used EL84s (labelled 6BQ5 in the Fender drawings), and then the 6G9-A went to 6L6s. From what I can tell on the schematics, the only iron changes between the 6G9 and the 6G9-A was the choke code, not the PT or OT codes. According to the schematic, the EL84 plates are running at 400V, screens at 398V! Bias voltage at -22.5V.

I've always wondered how the 6G9 would sound, how about you build one and tell me. Or at least record some samples!

[isaac]

I want to build a 5e7 Bandmaster, but I thought I had heard that one of the tremolux's had el84's. So thanks for that confirmation. ;-) I would be using Marshall 18W trannys, and the basic power amp design of them too. I could do Fixed bias if I wanted also, versus cathode bias, but just an idea. If I do get around to starting this project soon, I will definitely tell how it sounds. ;-) That 6bw6 is definitely cool, but I'm trying to use standard tube-styles, (12a*7's El*4's, 6*6's, those kind of standard) Great idea though. I never knew there was a noval tube that was likeunto a 6v6. I wonder if there is one that is similar to a 6l6 or EL34 (I guess the EL tubes sound similar just power differences, oh well). I'm not sure if you can fit a tube that big into something small enough to go noval, but it'd be cool. ;-)

[isaac]

Hey I started the project today, and I decided just to build it just as it should be (mostly, small differences here and there) Anyway, Instead of el84's I took the 18W chassis I had, stuck it in my father's old excello milling machine and made the tube socket holes larger. I then proceeded to use a set of 36W marshall transformers instead of 18W. Man that mill makes that chassis look as if it were designed and built that way originally. ;-) So amazingly wonderful that thing is... ;-) And hey funny coincidence, I was at my local GC on Sunday after church, and I saw a vintage tweed tremolux. It was awesome. Didn't play it though. I believe it was the model right after the el84 one. It had 6l6's I think. May have been 6v6's but I didn't look too hard. Funny thing, whoever sold it to GC flipped the back panel around... so you could see the inside of the amp through the holes that are usually tube heat vents (at least I think that's what they are usually for). I guess that's a horrible thing as the inside gets INCREDIBLY dirty quickly that way, but I could see inside, and as a amp guy, that was cool. They wanted $3499 for it. Was in good condition, though. ;-)

[isaac]

I finished the project a while back but never really reported on it, I built it exactly as it should be except SS rectifier, and the 36W marshall trannys, but the transformers are in the correct spec so they dont matter, plus my OT has 4, 8, and 16 ohm taps. ;-) Anyway, it sounds awesome and I love it. I posted another thread regarding the tones I was getting and some possible mod options but for now Its staying stock, thanks guys.