
NewReligion
Active member
All feedback welcomed Good, Bad & Ugly.
David...♫
David...♫
crankyrayhanky":3crnq0ze said:Dig it!
Sounds killer
V2a":xngterzf said:Please consider this constructive criticism.
I think the video shows some misunderstanding of the basis for Friedman's signature sound, or at least the PT20's sound. It does not come from one "filter circuit" (which I presume is an interstage voltage divider with bright bypass cap) or "neutering circuit". If you don't already have a signal generator and oscilloscope, I suggest that you get these tools to help visualize what an amp is doing. I also suggest you think a bit more about circulating currents as opposed to just voltages and filter cutoffs. These will give you a better understanding of what an amp is actually doing and perhaps even why the designer of the amp made certain decisions. A builder could copy an amp from a schematic and still not end up with what the designer intended. This is particularly true of Friedman amps.
And as a checky parenthetical comment, I don't think you need a serial number for changing three parts and adding a clipping circuit![]()
V2a":2i12q5vn said:You are reading a bit too much into my post, NR. I did not imply that what you did led to instability etc. (although now that you alerted me to an added NFB loop, I hope you calculated open- and closed-loop gains of the PI, output tubes, and OT; without doing that, instability is quite possible).
I didn't actually say you were a novice, but that's probably fair to say - especially when people like Dave Friedman are the yardstick. As you said, modding the PT gave you a great learning experience. BTW - EL84s were designed to drive a speaker with a much smaller input signal so that people could build and sell radios with fewer preamp tubes (and also stock only 9-pin sockets). Hence 84s can sound harsh, not only with NFB (there are cures for that) but also with multi-stage preamps. Some builders (Bruce Collins of Mission Amps being one that comes to mind) refer to distorted EL84 sounds as a can of buzzing bees. Dave did a good job of keeping those bees at bay. There are many other tricks that can be applied too.
V2a":2e3ozi3q said:You asked for input and you got it. You said you had a thick skin, and then you lash out again and again. It's clear from your posts that you are insecure and need to praise. Not a thick skin at all.
In short - you are the new Billy Blades without the run on sentences (but certainly run-on posts).
V2a":2vgy9ora said:NBB - you are loosing the battle with your own sanity, my friend. The three-resistor comment appears in the last sentence of my unedited first post.
You make lots of wrong assumptions about the people with which you interact online, mainly because you are only interested in yourself and don't take the time to get to know others. If you ever want to get together to see who has the sharper mind, just let me know!
CrazyNutz":12bttmve said:Sounding good.
@V2a You were pretty cocky in your criticism. Really unnecessary, seems like you were trying to start an intellectual challenge? The guy is learning, and quite frankly most of the stuff he's done sound pretty damn good. A good ear, determination, with some technical knowledge is all most the great amp builders needed to produce some of the best sounding amps. It's not all about being super technical.
fusedbrain":3q2fv7d4 said:WTF happened there![]()
It's too bad this thread has kinda "gone off the rails" so to speak, as I thought the modded amp sounded quite good, and I typically find the contributions to the forum from both V2A and NR to be of value and informative.
It would have been nice to have more of a discussion about the mods, the clipping circuit, the issues arising from adding NFB to an EL84 amp etc...
This is supposed to be the "Tech Corner" forum after all....
Oh well.... such is life on the interwebs in 2019![]()
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Mailman1971":32iesjbj said:Fight the good fight David!
Your mod sounded great![]()