coinmaster
1000+ Head-Fier
Higher impedances will be easier loads and give less supply ripple.
Get caps specifically designed for handling ripple.This talk about the PSU needing more capacitance for ripple current handling is interesting as on the first page it was stated that the PSU would be kind of overkill already as it is so I've only replaced the PSU output caps with the super fast 400uf 400v DCL Wimas.
But wouldn't it be quite possible to replace the four 1000uf 200v caps with bigger ones that would be specifically designed for ripple current handling, and what would be the highest sensible capacitance that could be used here? Are there some other specific components around/in the PSU that would suffer from overcurrent with a capacitance too high?
No we cannot place any cathode cap on that driver tube. Sorry that was another brain fart,Yes, I just feel that if the cathode film cap upgrade can be that much better than what is there atm it might be worth jettisoning the CCS .
I believe coinmaster was referring to stock implementation.This talk about the PSU needing more capacitance for ripple current handling is interesting as on the first page it was stated that the PSU would be kind of overkill already as it is so I've only replaced the PSU output caps with the super fast 400uf 400v DCL Wimas
I think the dual regulation transistors with all the extra beefed up caps, with also the increased decoupling film caps already placed in this mod thread have taken care of ripple,Caps designed for handling ripple are just caps with lower ESR and better heat handling. If you want high regulation with caps you need a ton of capacitance and a low enough ESR so that capacitance isn't stifled.
You could use a capacitance multiplier which would require just a single resistor and transistor added to each cap. But you would need to adjust some values in the supply to ensure there is enough voltage headroom or it will produce ugly ripple at the output.
Haha... x2... again! We've been out of this for too long LOL . Don't know about you but I can't imagine what I was thinking. I know perfectly well I have the CCS on the driver stage anode/cathode, and the cathode bypass cap on the power stage cathode, it's not that difficult... , even without a schematic... but for some reason I assumed that the cathode bypass went on the gain stage .No we cannot place any cathode cap on that driver tube. Sorry that was another brain fart,
Sounds like alotta effort for unkown performance gains.Following on from the work of CopperFox, and... brain farts excepting... I have a plan. I'm thinking of relaxing the restrictions that a compact version of the amp has and go with a chassis extension using heatsink plates, easily done and that would allow some of the huge film caps that according to members here should give the amp a boost in speed, and with that sharper bass, a weak point with the amp, and improving soundstage as well. So probably the 400uF Wimas for PSU which makes a ratio of around 3:1 film to lytic cap, seems reasonable. And up the power decoupling caps to about 100uF Wima. CopperFox already verified this. Which leaves cathode and WCF caps.
For cathode and WCF caps we need to take account of the cutoff on the rest of the frequency response, but also we need to have good power handling.
So for cathode caps, going from the cathode bypass calculator which is based on the mathematical formulae, probably starting at around 100uF to 500uF, figures for lytics. So for films around 50-200uF sounds about right. We will need to watch for oscillations for the higher values.
For WCF caps Maxx noted what Redge said on page 1 that half the current of the WCF push/pull design, comes from the cathode caps. Therefore the other half must come from the WCF caps? Anyway it looks like they could do with being uprated so maybe try around 1uF and possibly upwards to see the effect on the power drain, and taking account of oscillations of course here also. We may have overlooked the importance of the WCF caps before now as Maxx said.
So all of this should maximise the liveliness of the amp to a new level. I seem to remember coin, along with Redge, threw out the old chassis with his "alfresco workbench" version of the amp way back at the beginning of the thread!
How's that for a brain fart.. a huge one at that .
I will let the prospect ferment in my brain for a while before doing it . If I do I might as well go the whole hog, you're probably right but might be interesting to try faster caps for PSU, I don't know. Anyway I do'nt intend to do anything more exotic as coin suggested like rebuilding the PSU for example, too much pain and maybe not enough gain, the LD already sounds pretty good to me, good enough anyway.Sounds like alotta effort for unkown performance gains.
I'm not bothering with PSU, because as coin stated, the balance design cancels PSU ripple, plus I already have film caps as decoupling..
I'm only looking to change up my cathode caps and WCF caps.
Appreciate it!Well, as I said. I can build a PCB for people here of the idealized version of the mk6 where all of the theoretical flaws are already solved without changing the functional design structure (It will still act as a WCF, just without the downsides).
I'd share the schematic but I won't bother unless I decide to build it. Don't want the asian lurkers stealin it off me for nothing.
But as I said, I'll need some expressed interest for me to go out of my way.
The issue is the idealized version of the input stage requires twice the number of triodes, so it would need a new chassis and wouldn't be compatible with the existing one.
I could order a custom chassis from china but again, not worth it unless enough people are interested.
Considering the B.O.M and the time I would probably need to sell it for at least $800 if I populate the board and buy all the parts. Maybe less if I can get the expected B.O.M lower.
But I would need to order in batch to keep the cost down, so a minimum of 5 people would need to be interested.