Fixed to Cathode Bias On The Fly

[eschertron]

Sticking a pentode somewhere upnfront usually doesn't hurt, either!

Justin

A bump for this; I'd think any small-signal pentode near the end of the preamp would be a good "SE amp" emulator, when overdriven giving the raw, asymmetrical clipping typical of a 5W amp. Exactly like an EL84? well, probably not exactly, but it'll produce a similar effect, and a few tone-shaping components might make it presentable.

[g1]

I want to "Like" what you wrote but I don't see an icon anywhere to do that.

In the lower right area of a post there should be "like" in blue right above the multi-quote button.
If the person has a 'sig', it will be above the signature line.

[Chuck H]

Exactly like an EL84? well, probably not exactly,..

But then, an el84 run into a resistor doesn't sound the same as an el84 run into a speaker. Maybe a different, small signal pentode into a resistive load would actually sound MORE similar to the proto amp than an el84 into the resistive load.?. There's still the way the el84 responds to the specific drive voltage too. A different pentode would also be different in this regard for better or worse.

[Chuck H]

In the lower right area of a post there should be "like" in blue right above the multi-quote button.
If the person has a 'sig', it will be above the signature line.

It's not always there. In fact I didn't have the "like" option just a minute ago, but it reappeared after I had to reload the page because "reply with quote" only gave me half of your post and no end quote *^$(&@$%^&* When THAT happens I have right click "reply with quote" and then "open in a new tab" to make it work. There are many here that find the forum hitchy with their OS.

[The Dude]

My experience is that it takes a moment after a post is put up for the like button to appear. If you happen to be viewing the post immediately after it was put up, the like button may not yet be there. If you refresh the page or come back in a minute, it will be there.

[Justin Thomas]

Oh, I don't ever run my amps into an attenuator - I just build tiny ( <25W) amps. But in all seriousness, I add those crappy old "noisy" OT-driven Line Outs to my amps - that way, I get every bit of the amp except the speaker. Which, not to diminish its importance in any way, but at least the amp is always running into a reactive load, and any line signal gets everything... And you know, I've never had anyone complain about my OT line out signal being noisy... Well, usually they mute me in the house, anyway. Mission accomplished.

@ eschertron: I usually use an EF86 right up front. But there's a couple Matchlesses that use one later on. Might experiment with some others as I use up my donor chassis. I'll say this - EF86 - Volume - Tone- 1/2 12AX7 - Cathodyne - 2xEL34 was a HOLY $#!+BALLS Distortion Machine!

Justin

[Chuck H]

I've never had anyone complain about my OT line out signal being noisy... Well, usually they mute me in the house, anyway. Mission accomplished.

[Mike Sulzer]

Yes, this is true. It's greatly exaggerating the usual gain change that you get in the transition from class A to class B (sometimes called 'gm doubling').

I think it's one of the 'nicer' sounding distortions. It also gives a kind of compression - relatively higher output when you play soft and relatively less output when you play more aggressively. (Just my opinion! Others can and will disagree. )

Malcom, I tried it, and I like it. No need to use fixed bias. Thanks. I have never liked bypassed cathode biasing for a push pull output stage because the consequences, although not severe, are just so complicated. This is just nice simple compression. Considering trying it in an EL34 amp; you would have to dissipate a considerable amount more power, and you would lose a significant amount of output power, but so what?