I recently used the red light treatment for a couple of headphone amps using cheapo dual dissimilar triodes originally intended for vertical oscillator/amplifier service. I did a parafeed amp using strings of parallel GaAsP LEDs for output stage, and a basic 2-stage SE amp using GaP green LEDs for bias on the output stage. Both sound nice, and will be appearing at this year's Burning Amp.
LR8N3 will get you part way there:
http://ww1.microchip.com/downloads/en/DeviceDoc/20005399B.pdf
it will only handle 0.75W is inexpensive TO-92, so I have used a power BJT (BU208A).
I have a couple of questions... I'm on page 39 reading the thread and it's already pretty overwhelming.
Is there any way of keeping the benefits from the diode bias, but without the LEDs? I'm not worried about the cost of the LED, but It's going to be awfully bright, and all those LED are going to take up a fair amount of space. And having to construct a separate PCB just for this purpose...
Let's just say it would be awesome if there was a way to shrink this down to size and loose the landing lights. I'm afraid the control tower over at the neighboring airport would complain.
And secondly, I'm curious if people have managed to get everything modeled properly in Spice? I'm trying to get a sim running but I'm only getting 6W or something from the speaker terminals. My guess, is I'm missing something essential... Lol.
I am a complete no0b after all, hoping to begin building my first tube amp soon.
Is there any way of keeping the benefits from the diode bias, but without the LEDs? I'm not worried about the cost of the LED, but It's going to be awfully bright, and all those LED are going to take up a fair amount of space. And having to construct a separate PCB just for this purpose...
Let's just say it would be awesome if there was a way to shrink this down to size and loose the landing lights. I'm afraid the control tower over at the neighboring airport would complain.
And secondly, I'm curious if people have managed to get everything modeled properly in Spice? I'm trying to get a sim running but I'm only getting 6W or something from the speaker terminals. My guess, is I'm missing something essential... Lol.
I am a complete no0b after all, hoping to begin building my first tube amp soon.
Keep the LED internal in the chassis. Less light. Also, having the LED has a nice side effect as they get much brighter during clipping.
When one considers that the whole point of the project IS the LED bias, it makes sense to just go with it, get everything operating properly, then try to find a substitute that works as well.
When one considers that the whole point of the project IS the LED bias, it makes sense to just go with it, get everything operating properly, then try to find a substitute that works as well.
The spice situation is more frustrating.
Since I don't have the experience to lean on, it's difficult to know if I'm doing something really wrong, or if everything is ok. I just like to first run the models before taking the plunge...
Post your .asc file so we can have a look at what you've done.
I’ll start my own thread when I know enough to ask the right questions, and I’ll be sure to post it then. I realized that having the wrong diode model was giving me problems... My project is relying heavily on RLD for inspiration, but it’ll be quite a bastard. I always end up mixing and matching for some reason, lol. It wouldn’t be right to pollute this thread with detailed talk about it.
The idea is basically going as simple as possible...
I had been planning a RLD and I still may but what I have done is to RLD-ize an Eico ST40 by adding led arrays and screen regulation. The state of the eico was such that I can’t make a reasonable comparison but I am pretty happy with it.
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I really enjoy this RLD amp. It performs well. I sometimes like to play loud. And
this amp can.
I just fell for this approach, the way Stuart desgn this amp. Atleast for me it
was a new way to use penthode's.
I don't claim to have `Golden Ears´ I'm an old man. But I know when it sounds good.
Rolf.
this amp can.
I just fell for this approach, the way Stuart desgn this amp. Atleast for me it
was a new way to use penthode's.
I don't claim to have `Golden Ears´ I'm an old man. But I know when it sounds good.
Rolf.