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Old 28th October 2004, 03:11 PM   #111
K-amps is offline K-amps  United States
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Quote:
Originally posted by AuroraB
30V supply is too low, - 50W into 8 ohms is 28,2V peak. 35 V is minimum in my opinion, but then of course idle dissipation increases as supply goes up.

K-amps... your calcs are OK, but the combined 1.8-2 A idle will flow through both halves... theoretical minimum idle will be 2,5A for 50W into 8 ohms in true class A, which makes my toroids just about good for a 50W amp, as the trafo is spec'ed at full load. Obviously, a larger trafo would make for a stiffer supply voltage, but at a cost,- price....
Maybe the frontand should be ragulated ?? any thoughts ??

ACD, - which design voltage was used for the driver section ??? Are the component values true to the original, except for the transistors ??
Agreed, Also a class-A amp loaded rails at 30v are much stiffer than a class-AB PSU with the same 30v voltage. (This ofcourse assumes the PSU is designed according to dissipation requirements).

Also to get 50w from 30vdc, you will need a huge trafo... 800VA to 1kva otherwise you will not get 50 watts.

It's possible, but I'd rather have rails of 42-45v and have some headroom... don't like clipping too much here...

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Old 28th October 2004, 03:26 PM   #112
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Quote:
Originally posted by K-amps


Agreed, Also a class-A amp loaded rails at 30v are much stiffer than a class-AB PSU with the same 30v voltage. (This ofcourse assumes the PSU is designed according to dissipation requirements).

Also to get 50w from 30vdc, you will need a huge trafo... 800VA to 1kva otherwise you will not get 50 watts.

It's possible, but I'd rather have rails of 42-45v and have some headroom... don't like clipping too much here...

As I said, I'm not expecting 50W from 30V, just something smaller but similar sound. Call it a KSA-25 if you like. I also mentioned that I realised that the driver might have to stay at 45V, that I was prepared to try just reducing the volts to the output stage.

AuroraB implied that even in the original KSA-50 the drivers and output might not be the same rails - can anyone confirm what the driver stages require?

I don't understand 'Also to get 50w from 30vdc, you will need a huge trafo... 800VA to 1kva otherwise you will not get 50 watts.', not that it matters because I'm not trying to get 50W.

Apologies if it looks like I'm hi-jacking the thread (cloning the KSA-50); should I move it to a new topic called 'baby KSA' ?

btw...I am right in thinking that this is a class-A amplifier...?
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Old 28th October 2004, 03:31 PM   #113
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Attached you find the schematic whichs I got from Bra (the threadstarter)
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File Type: jpg krell ksa-50 mk ll original schematic_2.jpg (79.8 KB, 5109 views)
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Old 28th October 2004, 03:34 PM   #114
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The components list the schematic whichs I got from Bra
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File Type: jpg ampli krell - componenti.jpg (69.2 KB, 4818 views)
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Old 28th October 2004, 03:38 PM   #115
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And the revised schematic (thanks Bremen)
Attached Files
File Type: pdf krell-clone_ksa-50_1-4.pdf (23.3 KB, 1257 views)
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Old 28th October 2004, 03:40 PM   #116
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and silk print (thanks again Bremen)
Attached Files
File Type: pdf krell-clone_ksa-50_ii_silk.pdf (48.0 KB, 1565 views)
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Old 28th October 2004, 03:42 PM   #117
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I haven't been looking at it in the last days, as I was waiting for mods from you guys
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Old 8th November 2004, 07:40 AM   #118
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Default Delay

Hello all,
Sorry for the delay, but I have had a major crash on my network
.

The good thing is, that I had back-up's of all files

I hope to publish the final layout at the end of this week
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Old 15th November 2004, 04:18 PM   #119
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Wink Hello All

Sorry for the delay

Here is an updated layout of the KSA-50
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File Type: pdf krell-clone_ksa-50_ii_complete.pdf (77.6 KB, 1904 views)
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Old 15th November 2004, 07:23 PM   #120
wim is offline wim  Netherlands
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I am following this tread from the beginning. Very interesting!!

What do you think. Can it become a subject for a groupbuy? (PCB only, or PCB+components).
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