my amp is at 75w / pair IRFp9240, 240. They don't seem to be overstressed by it. If I moved the rails to 50v from 40 I would add another pair.
This amp reminds me of the 3 transistor CFA amp I made for the car late 80's. It has a 353 op amp servo and drives IRF530,9530 outputs. It had it's origins in a 1979 Sanyo radio and consists of a 2N5401 7ma current source, 2N5551 VAS and 2N5401 current feedback level shifter. That amp sounded fantastic and was incredibly fast.
KSA992, KSC1845 are better transistors so it may work even better with those
This amp reminds me of the 3 transistor CFA amp I made for the car late 80's. It has a 353 op amp servo and drives IRF530,9530 outputs. It had it's origins in a 1979 Sanyo radio and consists of a 2N5401 7ma current source, 2N5551 VAS and 2N5401 current feedback level shifter. That amp sounded fantastic and was incredibly fast.
KSA992, KSC1845 are better transistors so it may work even better with those
IMHO the beginning design should be a total of 4 output devices then move up to 6 or 8. The design by Alex has room for 8 devices...I have his layout 6 file for that design that he shared with me. IT IS NOT DONE. Thanks, Cost is 100 with shipping for it's size for 5 boards from PCBway.
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If you mean 4P + 4N, ok. If not, remember some can always forget to populate all of them if they want less power. The contrary would be difficult.
Some not so good news. Starting from version in post #428 I was hoping for a production ready candidate. After familiarization it seems we have taken a step backwards and the design has lost its tolerance to device variation.
What doesn't help is a messy schematic. There is a reason that standard industrial practice is to separate BOM info into a separate doc.
I was hoping to run the front end from +/- 25V. It should have taken a few resistor changes to achieve this. However the design collapses when the rails go below 41V. Gut feeling is that this is isn't the one. Additional analysis welcome. Maybe I made a mistake extracting the front end. If some one could cross check with #428 for introduced errors that would be great, as I have now spent many hours attempting to resolve issues. Also would someone volunteer to tidy the .asc file so that it is readable with adequate space for pertinent notes?
What doesn't help is a messy schematic. There is a reason that standard industrial practice is to separate BOM info into a separate doc.
I was hoping to run the front end from +/- 25V. It should have taken a few resistor changes to achieve this. However the design collapses when the rails go below 41V. Gut feeling is that this is isn't the one. Additional analysis welcome. Maybe I made a mistake extracting the front end. If some one could cross check with #428 for introduced errors that would be great, as I have now spent many hours attempting to resolve issues. Also would someone volunteer to tidy the .asc file so that it is readable with adequate space for pertinent notes?
Different people pay different amounts of attention to small details. Maybe you are discovering that the early "design contributors" focused more upon the Big Picture rather than the small details. If that's your conclusion, it may suggest that plenty of design work remains to be done, with or without members who have been banned.
As a reality check earlier front end designs were subject to voltage reduction. With a couple of resistor changes they worked fine. In general, if designs have constant current sources and are robust, they should scale.
I don't feel confident in the last iteration so I am just going to pick an earlier one and try to salvage something from this effort.
I don't feel confident in the last iteration so I am just going to pick an earlier one and try to salvage something from this effort.
I immediately identified Tounesol as being Esperado because of a language mistake both made, using the same French word "tension" instead of the English word "voltage". No other French-speaking guy here made this mistake.
After a lot of back tracking, we were in a position for a first test at posts #278, #279 to establish a base level. Standard development protocol mandates this as Terry Demol reiterated. So I suggest picking up from here. The stage before the driver stage has been added so that DC conditions can be evaluated with feedback.
Performing due diligence on the latest iteration is not an option from my standpoint. Others may want to pursue that route.
The version here seems to scale to PSU voltage by varying one resistor, giving an indication that a viable configuration is a possibility. A typical +/- 30V bench supply can be used. I suggest to minimize effort and cost, that a through-hole component on perf board can be constructed. This is just a toe in the water with a few pots to adjust to set operating point when devices are swapped. The idea is to get a handful of 2N5401/2N5551 and simply rotate their position to check how the operating point varies. Tempco can be investigated as well.
I will leave it up to Krisfr on how he wants to proceed.
Performing due diligence on the latest iteration is not an option from my standpoint. Others may want to pursue that route.
The version here seems to scale to PSU voltage by varying one resistor, giving an indication that a viable configuration is a possibility. A typical +/- 30V bench supply can be used. I suggest to minimize effort and cost, that a through-hole component on perf board can be constructed. This is just a toe in the water with a few pots to adjust to set operating point when devices are swapped. The idea is to get a handful of 2N5401/2N5551 and simply rotate their position to check how the operating point varies. Tempco can be investigated as well.
I will leave it up to Krisfr on how he wants to proceed.
R11-R12 & R21-R22 = 0Ω. Don't you understood why they are here ?
That is your expectation. +-25V is an other amp.
R3 R4 limit the collector voltage. this seems to play a role for the good clipping behavior. With Power supply of+-75V. not +-25 !!!
The #428 schematic seems to allow a lot of iterations and options just by changing values and components on the same printed board, including your last version that could be build on it.
Tournesol explained it was the purpose.
Please, don't try to break, ruin or confuse his work: make your own personal version if you like and call-it an other name.
What i find the strangest in your attitude is the DMMT pairs were your idea. And that solved the "tolerance" problem.
I doubt your version to behave so good on distortion+Clipping+VAS tempco.
Even if the #428 will require some little adaptations on the bench depending of the devices used.
Once a printed board will be available, it will be time for all of us to show our results and improvements. But, please, give this amp a chance.
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And the Queen of England, while you're at it.
I was new on this forum: What a welcome ! (I don't know who you are or what I did to you.)
Well, for several reasons, I was interested in this amp that was referred to me by a friend, reason of my registration here.
As Tournesol used the "ultimate" protection of Esperado (which has a website) instead of a conventional servo, I think they had probably communicated and so I can find a way to reach them directly by Email.
Both Esperado and Tournesol offered a lot of work and innovative ideas. Both banned ? Two people here offered to design a PCB, but nothing after several months and not a word... it is a pity.
I will build and tune this amp and publish my results ... elsewhere: I do not accept this kind of personal attack.
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The username "Tournesol" was banned on 17 February 2020. The username "Soulthern" was registered on 28 February 2020.
I wonder if the IP Addresses, saved & logged on each of their posts, happen to be similar. Will have to buy a DIYA moderator some beers to find out, next time I meet with her.
I wonder if the IP Addresses, saved & logged on each of their posts, happen to be similar. Will have to buy a DIYA moderator some beers to find out, next time I meet with her.
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