Hi Z,
just as well you came along after the KSA50 Klone was near finished, but not yet dead.
The 100mk2 design is nearly finished.
Debugging is progressing.
A GB will start soon, but since I am not in the design loop, I can make no promises on what soon means.
The Wiki is already up and gathering interest.
Get on board.
just as well you came along after the KSA50 Klone was near finished, but not yet dead.
The 100mk2 design is nearly finished.
Debugging is progressing.
A GB will start soon, but since I am not in the design loop, I can make no promises on what soon means.
The Wiki is already up and gathering interest.
Get on board.
HI
I would like to ask for some help about KSA -100 transformer .
I would like to order transformer from Plitron but I don't have any idea what size would be good for these amp .
For the KSA-50 I have 30-0-30V 1KVA . I think the KSA-100 need something bigger ??
Would you please let me know so I can go on with the order .
I will have to wait 6 weeks on the transformer if I order now ..
Regards
Please let me know when the GB is on and who collecting the payment foer the PC Boards .
I would like to ask for some help about KSA -100 transformer .
I would like to order transformer from Plitron but I don't have any idea what size would be good for these amp .
For the KSA-50 I have 30-0-30V 1KVA . I think the KSA-100 need something bigger ??
Would you please let me know so I can go on with the order .
I will have to wait 6 weeks on the transformer if I order now ..
Regards
Please let me know when the GB is on and who collecting the payment foer the PC Boards .
Thanks Mark
I think I will have to go with one transformer for both channel .I don't have enough room for two transformer .
Or I will go with one transformer but separate secondary for the two channel.
In that case I guess I need around 2KVA or something.
What would happen if use two transformer and I stock them on the top of each other or if they are close to each other .
The enclosure for the amp inside measure 10x12 inch and 15 tall .
It is possible to use only one power supp for the two channel with out degrade the sound ?
Regards
I think I will have to go with one transformer for both channel .I don't have enough room for two transformer .
Or I will go with one transformer but separate secondary for the two channel.
In that case I guess I need around 2KVA or something.
What would happen if use two transformer and I stock them on the top of each other or if they are close to each other .
The enclosure for the amp inside measure 10x12 inch and 15 tall .
It is possible to use only one power supp for the two channel with out degrade the sound ?
Regards
Yes, 2-1KVA toroids are just a little taller than one 2KVA unit. So stacking them with a rubber pad in between each toroid might work out. I originally did this in my KSA-50...stacked two 500VA toroids but later on I bought a single 1.2KVA toroid with dual secondary through surplus that I replaced them with.
Mark
Mark
Four secondaries are an excellent way to go for ClassAB and probably OK for a ClassA as well.gaborbela said:
There will be a small amount of crosstalk between channels but much less than with a shared pair of secondaries and both these will be less than a shared PSU. If you call these levels of goodness from 1 (monoblock) to 4 (shared PSU) then your proposal is level 2.
With 2kVA the transformer regulation will be slightly better.
I would ask the supplier to aim for good regulation AND 2kVA for the slight extra cost. The two gauge increase in wire diameter for both the primary and secondaries will be miniscule compared to the core and production set-up costs.
I am planning an 8inch cube (internal) for a monoblock. Your proposed size is enormous, even for two channel.
A stereo KSA100 Klone will always suffer from the same Krell problem - getting rid of the HEAT.
Monoblock and 2ft long cables will be much better for eliminating compromises. Just my opinion.
The larger toroid is much better!! Its also larger in KVA than the other two combined by about 1/3. The low end became much tighter and cleaner. This difference was heard at one of the Pass Shoot Outs by other as well, not just myself. The other toroids were those cheap Chineese toroids sold on E-BAY though.....
Mark
Mark
Hi Mark,
Do you agree?
Or, do you really believe that the cheap Far Eastern transformers were that bad?
Did you try to compare the regulation of the 500VA and 1200VA?
Remember, I am trying to find the recipe to "guarantee" our builders that renowned Krell BASS.
this sounds like an advert for using a combined transformer with separate PSUs in a stereo amplifier rather than monoblocks.
Do you agree?
Or, do you really believe that the cheap Far Eastern transformers were that bad?
Did you try to compare the regulation of the 500VA and 1200VA?
Remember, I am trying to find the recipe to "guarantee" our builders that renowned Krell BASS.
Andrew,
I think part of it was the Chineese toroids and also that the larger toroid is not going to run out of steam in this amp no matter what. Rail voltages would sag a couple of volts with the two seperate toroids but barely at all with the larger single unit. Regulation is very tight. I think the single unit is just a higher quality toroid. It came surplus from a Minnesota company that makes high end gear but I can't remember their name.
Mark
I think part of it was the Chineese toroids and also that the larger toroid is not going to run out of steam in this amp no matter what. Rail voltages would sag a couple of volts with the two seperate toroids but barely at all with the larger single unit. Regulation is very tight. I think the single unit is just a higher quality toroid. It came surplus from a Minnesota company that makes high end gear but I can't remember their name.
Mark
Attachments
transformer
Mark,
That looks a lot like the surplus bell canto x-formers that somebody on the forum sold a few months back. If it is, that is what I purchased my my '50. Do you happen to know the 'code' for the different leads. I could probably figure it out, but it would be nice to have a check so I don't hurt something or someone.
Cheers,
Ryan
Mark,
That looks a lot like the surplus bell canto x-formers that somebody on the forum sold a few months back. If it is, that is what I purchased my my '50. Do you happen to know the 'code' for the different leads. I could probably figure it out, but it would be nice to have a check so I don't hurt something or someone.
Cheers,
Ryan
I agree with Ryan, Mark. That does look like the Bel Canto surplus transformer.
I may have missed your post, Mark, but didn't you also hook up that huge black transformer as well? Wasn't that a Plitron transformer? And has anybody heard recently from Victoria Magnetics? Their website is up, but I didn't get any email response. But that doesn't say much, as I bought transformers from him for my Aleph 3 build, and the only way to really get hold of him was by telephone. For USA buyers, he should also be considered for a group buy if he was willing to cut us a deal.
http://www.victoriamagnetics.com/
As well as Edcor Transformers
http://edcorusa.com/
Now the heat producing amps are coming into their own for those of us that are living in the northern latitudes. My Eico ST-40 kept my bedroom warm and cozy for last night's listening.
I may have missed your post, Mark, but didn't you also hook up that huge black transformer as well? Wasn't that a Plitron transformer? And has anybody heard recently from Victoria Magnetics? Their website is up, but I didn't get any email response. But that doesn't say much, as I bought transformers from him for my Aleph 3 build, and the only way to really get hold of him was by telephone. For USA buyers, he should also be considered for a group buy if he was willing to cut us a deal.
http://www.victoriamagnetics.com/
As well as Edcor Transformers
http://edcorusa.com/
Now the heat producing amps are coming into their own for those of us that are living in the northern latitudes. My Eico ST-40 kept my bedroom warm and cozy for last night's listening.
Yes, It is from Bel-Canto and it is an AVEMVCO toroid. No, the big black one is from a Crest amp and has strange windings. Am almost done building up the KSA-100 power supply with the 2KVA Plitron toroid from the scrapped out AB systems 6 chan. amp.
I
I will check later today or tommrrow to see what the color is and post it back here.
Mark
I
I will check later today or tommrrow to see what the color is and post it back here.
Mark
The new supply temp wired into the 100 chassis. The bottom end is alot tighter than it was with the old Cerwin Vega tranny and only 10K mfd. There is now 56K mfd per rail plus the 2KVA toroid. I will add some .1's across each 56K when time permits. Still running it up on the variac when I start it... I have a delay relay and 10 ohm inush limiting resistor mounted in series with the toroid primary but need to breadboard a small 24 volt supply for the relay... perhaps tommrrow.
Mark
Mark
Attachments
100nF's across the 56k's so far from the amp are unlikely to offer any improvement - in fact they can cause high-Q resonant circuits that can even deteriorate performance. The frequencies addressed by the 100nF's are very high and of little consequence situated so far away
Much better would be to place them on the board itself, that's why I made ample provision for them. On the board they must be accompanied with at least 100uF or the small capacitance and highish Q of the 100nF's are likely to cause a resonant circuit from the DC wire inductance.
In short: stuff the pads with all the flavours and varieties of PSU caps on the board, that's what they're there for. And while you're at it you could perhaps experiment with decoupling the front-end and/or driver stage with resistors and/or lossy chokes. An easy starting point would be to replace the jumpers with 10ohm resistors and listen for any perceivable difference, once again only with a substantial amount of subsequent capacitance. present. The entire front-end draws only 35mA per rail, so with 100ohms the front-end voltage will only be 3.5V lower. At rated bias the drivers draw just under 80mA per rail, which will obviously increase according to load and input amplitude.
Since the current draw of the front-end is very low and essentially constant within 1mA irrespective of signal or load, a series resistor will work well, while the drivers may gain from an inductor or very small series resistor. Naturally a proper regulated supply for at least the front-end will yield the best performance, but the passive filtering is cheap and easily and will already provide some ripple attennuation.
Much better would be to place them on the board itself, that's why I made ample provision for them. On the board they must be accompanied with at least 100uF or the small capacitance and highish Q of the 100nF's are likely to cause a resonant circuit from the DC wire inductance.
In short: stuff the pads with all the flavours and varieties of PSU caps on the board, that's what they're there for. And while you're at it you could perhaps experiment with decoupling the front-end and/or driver stage with resistors and/or lossy chokes. An easy starting point would be to replace the jumpers with 10ohm resistors and listen for any perceivable difference, once again only with a substantial amount of subsequent capacitance. present. The entire front-end draws only 35mA per rail, so with 100ohms the front-end voltage will only be 3.5V lower. At rated bias the drivers draw just under 80mA per rail, which will obviously increase according to load and input amplitude.
Since the current draw of the front-end is very low and essentially constant within 1mA irrespective of signal or load, a series resistor will work well, while the drivers may gain from an inductor or very small series resistor. Naturally a proper regulated supply for at least the front-end will yield the best performance, but the passive filtering is cheap and easily and will already provide some ripple attennuation.