I haven't been on this forum long but I can tell already, that if a good project exists, the compulsion to make it better is right behind. With that in mind, how about the hi-end GC with input buffer and ps regulation? I know I'm gonna do one like that. I don't have them, but Pedja has some pretty spiffy designs that he is willing to let the DIY folks use for a group order type project like Brian's.
Brian said he might (and I'll stress might) be able to help with the pcb design, and Pedja might also be willing. But the project needs someone to organize a group specification/buy ala Brian GT. Any interest/takers?
Sheldon
Brian said he might (and I'll stress might) be able to help with the pcb design, and Pedja might also be willing. But the project needs someone to organize a group specification/buy ala Brian GT. Any interest/takers?
Sheldon
Well, I'm too much of a noobie to take on a group buy... But I am interested in this project! I had been thinking after reading the other regulated power supply thread that it would be pretty dang nifty if someone put out a matching red PCB for the power supply regulators!
agent.5 said:
I'm thinking of one myself. The JFET circuit Pedja has described looks like it would be pretty easy to convert to low voltage tube use ala Rasmussen's JTLi, though I don't know enough to supply the details. My guess is that most here would want the JFET version, but the same board might be useful for either.
Sheldon
i think it will be wise not to include a buffer on the amp pcb - many people will use several amps for biamp or triamping there system, and therefor only need one buffer........imho...😉
i send sheldon a ready pcb file and he is "authorized" to use it as he likes.
it is made for lm3886 and the regs are lt1083 with trimpots for V adj. there is also a dc - null trimpot. the two full bridges are made for IR hfa08tb60 and likes. and there is space for one cerafine 10000uF/63 / channel.
as you see, its a complete amplifier pcb - just ad a transformer and go.......
it is made for lm3886 and the regs are lt1083 with trimpots for V adj. there is also a dc - null trimpot. the two full bridges are made for IR hfa08tb60 and likes. and there is space for one cerafine 10000uF/63 / channel.
as you see, its a complete amplifier pcb - just ad a transformer and go.......
sheldon
.....to open the file, you have to have protel dxp installed.
i think briangt uses protel - perhaps he can help.
.....to open the file, you have to have protel dxp installed.
i think briangt uses protel - perhaps he can help.
tbla said:i send sheldon a ready pcb file and he is "authorized" to use it as he likes.
it is made for lm3886 and the regs are lt1083 with trimpots for V adj. there is also a dc - null trimpot. the two full bridges are made for IR hfa08tb60 and likes. and there is space for one cerafine 10000uF/63 / channel.
as you see, its a complete amplifier pcb - just ad a transformer and go.......
Thanks,
Anyone want to take a stab? I don't have the experience to do it. I do agree that separate boards for a buffer and reg. seem best. Then one can do basic GC, or various deluxe versions.
Sheldon
Yes, if it is meant like a possible addition to the existing amps, it is probably better to make regulators and buffers independently of each other.
First, it should be determined what regulators will be used (if 3-pin ICs, then the same board can serve both for LM338 and LT1083/1084). Then it should be defined how the heatsinking will be done. The designing of the board for this purpose then shouldn’t be that difficult and I may try to help with this part (but can’t deal with anything else at the moment).
As about the buffers you see in my site, and because of the power-up thump, only the simpler buffer can be implemented straightforward, and this assumes you do not use high-efficiency speakers. The MOSFET cascoded JFET buffer has the power-up thump that must be solved by the additional means.
Pedja
First, it should be determined what regulators will be used (if 3-pin ICs, then the same board can serve both for LM338 and LT1083/1084). Then it should be defined how the heatsinking will be done. The designing of the board for this purpose then shouldn’t be that difficult and I may try to help with this part (but can’t deal with anything else at the moment).
As about the buffers you see in my site, and because of the power-up thump, only the simpler buffer can be implemented straightforward, and this assumes you do not use high-efficiency speakers. The MOSFET cascoded JFET buffer has the power-up thump that must be solved by the additional means.
Pedja
Yup, separate boards, so some can use chips and some tube buffer. Also so you can easily try it with only power supply or only buffer.
Of course they could be made on one board and scored to snap as Brian did.
Of course they could be made on one board and scored to snap as Brian did.
Pedja said:
If you use the LM3886 or the LM4780 instead of the LM3875, you can use the muting circuit for a small delay at power-up.😉
...use LM3876 🙂
The mute of LM3886 works really good. Smooth startup , completely thump or clickfree.
I'll the guess the only way to get a quiet power on is to use a speaker relay.
The mute of LM3886 works really good. Smooth startup , completely thump or clickfree.
I'll the guess the only way to get a quiet power on is to use a speaker relay.
The power-on thump is definitely an issue.
I've built a veroboarded prototype based on Pedjas buffer design 🙂 which exhibits a very loud thud through my speakers 😱. I'm planning on building a final version (on PCBs) with the chip regulators. To stop the thump I'm going to use a seperate transformer and regulators for the buffer stage and use the slow start circuit for the regulators on the 3875s.
I did wonder about using a chip with muting but have always felt that thay must compromise sound to some degree - relays are also out for this reason.
I'm hoping to start building PCBs in next week or two - would love to see any ideas people have for designs. My preference is to keep the regulators on the same board as the chip to minimise distance and wiring/connections. May also include the buffer circuit on the same board.
BTW Pedjas GC sounds absolutely fantastic - MANY THANKS PEDJA
cheers
Dickie
I've built a veroboarded prototype based on Pedjas buffer design 🙂 which exhibits a very loud thud through my speakers 😱. I'm planning on building a final version (on PCBs) with the chip regulators. To stop the thump I'm going to use a seperate transformer and regulators for the buffer stage and use the slow start circuit for the regulators on the 3875s.
I did wonder about using a chip with muting but have always felt that thay must compromise sound to some degree - relays are also out for this reason.
I'm hoping to start building PCBs in next week or two - would love to see any ideas people have for designs. My preference is to keep the regulators on the same board as the chip to minimise distance and wiring/connections. May also include the buffer circuit on the same board.
BTW Pedjas GC sounds absolutely fantastic - MANY THANKS PEDJA
cheers
Dickie
My personal opinion about this, is that LM3875 and 3876 is exactly the same chip but with the exception of a maybe laser burned resistor. The 3875 has it and 3876 has it removed. Therefore the mute function is harmless. This is only a statement from me but it would be interesting if anyone can pick this in a double blind testdickiegeorge said:
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