Thanks Rick! Yeah, I totally get it and appreciate the help. I should've checked it before posting.
Here is the revised schematic and footprints PDF. Hopefully, this should be good.
Here is the revised schematic and footprints PDF. Hopefully, this should be good.
Are all the resistors rated 1/4 W unless otherwise noted ?
I’m used to building power amp...
Thanks
Eric
I’m used to building power amp...
Thanks
Eric
There is space on the board for 1W fir all resistors. The 100 ohm in the PS must be 1W. All others can be 1/4 W. But let me confirm.
Big resistors sound better. If 1 watt are available that is what I am ordering.
In a fit of obsession I have decided to use a 50 uF PP for C102. Will use a 0.47 uF as a bypass or maybe one of ZM's 1uF yellow caps.
I know I have asked this before but things have changed since then - I am going to use this with a TDV style amp using THF51s - does one really need a 10uF output cap feeding another 10uF cap at the input of the amplifier? Would like to use the money for other things and figure one less cap would be a good thing.
I remember there was a good reason for the input cap on the line stage but is the input cap for the TDV amplifier redundant with the line stage having an output cap?
All advice and counsel is appreciated.
In a fit of obsession I have decided to use a 50 uF PP for C102. Will use a 0.47 uF as a bypass or maybe one of ZM's 1uF yellow caps.
I know I have asked this before but things have changed since then - I am going to use this with a TDV style amp using THF51s - does one really need a 10uF output cap feeding another 10uF cap at the input of the amplifier? Would like to use the money for other things and figure one less cap would be a good thing.
I remember there was a good reason for the input cap on the line stage but is the input cap for the TDV amplifier redundant with the line stage having an output cap?
All advice and counsel is appreciated.
Seems like 50uf/50v Radial caps are tough to get from Digikey or Mouser with the footprint suggested. Any alternatives like 47uf or 56uf is fine for C102,202?
Thanks
Thanks
or maybe integrate PushPul mosfets directly in series with the ccs (mu follower) like Juma did in this amp?I am working on exactly that. New chassis parts ordered. But will wrap-up the GB first.
I want to run it with a choke, otherwise the dissipation requirments get quite large, though still very much within the capability of monoblock 3U or 4U. George is taking a different approach with high voltage and low current and a trafo as the load. Should be fun both ways
That looks like a PP output stage and is different from the SCG topology, which is single-ended. The SCG also has an N- and P-channel device but the sound goes from the gate to source of the bottom device and then comes out the drain of the top one.
You can drop the input cap on the TDV amp without any consequence, assuming you are building the one in Post 26. Don’t drop the cap at the output of the SCG pre. But you can reduce the size. I have used 1 uF without problem in the past. Smaller values roll off the low end.
Check out this high pass calculator on Digikey:
https://www.digikey.com/en/resource...sion-calculator-low-pass-and-high-pass-filter
There is 47k on the output on the pre, which will be in parallel with the input of the next stage. If that is TDV, then you are driving 10k. The two in parallel gives about 8k. The output cap and 8k form a high pass filter. Using 1 uF, I get 20 Hz as yhe -3db point, which means roll off will begin before that. Doubling it to 2 uF gives 10 Hz. More than enough.
Thanks very much for that.
I remember an article in the publication (Audio Update) of an interesting audio retailer in San Diego by the name of AUDIO DIMENSIONS - a dealer owned by a tweaker extraordinaire = one of their tricks was getting rid of redundant coupling capacitors. This was in the late '70's/early '80's.
Of course, all sorts of nirvana were promised for the removal but I simply like the idea of simplicity and saving the cost of additional large capacitors. Even the smaller value good ones are large in size.
Neither of my amplifiers and CGS stages will be asked to reproduce the low bass so I was going to use smaller in capacity caps - smaller still for the above 400 Hz pair.
I am attempting a compilation of suggestions made in this thread which I will submit for your approval.
Take care,
I remember an article in the publication (Audio Update) of an interesting audio retailer in San Diego by the name of AUDIO DIMENSIONS - a dealer owned by a tweaker extraordinaire = one of their tricks was getting rid of redundant coupling capacitors. This was in the late '70's/early '80's.
Of course, all sorts of nirvana were promised for the removal but I simply like the idea of simplicity and saving the cost of additional large capacitors. Even the smaller value good ones are large in size.
Neither of my amplifiers and CGS stages will be asked to reproduce the low bass so I was going to use smaller in capacity caps - smaller still for the above 400 Hz pair.
I am attempting a compilation of suggestions made in this thread which I will submit for your approval.
Take care,
That’s great! The 10 uF is there to ensure the pre can drive anything without losing low end. But of course you can play with it 🙂
The input 10 uF can be lowered too. Even 1 uF will work fine there.
The input 10 uF can be lowered too. Even 1 uF will work fine there.
R11, R12, and Rsch1 are really the only ones with somewhat moderate dissipation.
PCBs are here!!!
I have payment from nearly everyone. Will PM the remaining parties and get started on packing things up and getting the mailing details in order.
I have payment from nearly everyone. Will PM the remaining parties and get started on packing things up and getting the mailing details in order.
Not sure what happened. Your name is not on the list. If there is one that becomes available, I’ll let you know. Other folks have also PM’ed me about PCBs, so there’s a few ahead of you in the queue. Maybe I can do another run of 10 and get everyone else who wants one.
Attached is the annotated BOM (unzip to get the Excel file). It has notes for key parts and Mouser links. I marked "critical part" for parts that have a significant impact on sound.
Last week was very busy at work. Making progress this week and should definitely start shipping out next weekend.
Last week was very busy at work. Making progress this week and should definitely start shipping out next weekend.
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