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Old 18th January 2009, 03:13 PM   #7831
john65b is online now john65b  United States
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Whoops, I will correct ASAP.
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Old 18th January 2009, 04:32 PM   #7832
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Default @neychi

extremely fugly!

extremely!

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Old 18th January 2009, 06:27 PM   #7833
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MODERATOR - please delete both of my posts above - I need to find my server to post the pics...

In the meantime, the real page is

here


Thanks
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Old 23rd January 2009, 10:42 PM   #7834
john65b is online now john65b  United States
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Finally,

I picked up this chassis a few months ago...pretty banged up, but was relatively cheap. Chassis came only with Power Supply Board/Caps.

Power Supply - four 68,000uF @ 100VDC Philips caps with four 35A Rectifiers...Have no need for the Power Supply, as my rails are just under 40VDC..(for sale if anyone is interested)

Here for more info on the Power Supply...

Krell KSA300 Power Supply Board

Anyway, still haven't decided what I will do to the chassis. Powder coat? Sandblast entire chassis? She is pretty banged up...TONS on room inside. As far as heatsinking capability, if good for a KSA300, maybe .05 C/W??

Click the image to open in full size.

TOP VIEW

Click the image to open in full size.

SIDE VIEW - note the scratches...

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BACK VIEW - I have the other Binding Post - just not on the chassis

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FRONT VIEW - The Starter board (?) was not included - just have a clear window...

Click the image to open in full size.

CURRENT KSA-50 CHASSIS - thanks again Stuart!

Click the image to open in full size.

The amp is on a rolling flower pot holder from Menards I bought for $6. Works great for moving around amps.
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Old 24th January 2009, 08:38 AM   #7835
AndrewT is offline AndrewT  Scotland
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what is KSA300?
This Krell chassis will not do more than KSA100 dissipation (100W + 100W in ClassA). It might even get too hot for that.
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Old 24th January 2009, 01:03 PM   #7836
john65b is online now john65b  United States
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The sinks on the KSA300 are at least double the length of a KSA100. If you look at a top view of a KSA100 you will see what I mean.

Another question. The Pinkmouse KSA50 amp I have runs at 39V rails, 6 pairs output devices per channel (2SA1943/2SC5200) and 1 Amp per device (R64 emitter resistor and voltage across it is 640mv).

Now the KSA50/100/150 etc are their Class A power into 8 ohms, and half of that rating into 4 ohms.

Then my amp, as it is indicated above, would be equivalent to a KSA144, correct (72 wpc into 4 ohms class A)? It calculates out to about 230 watts per channel out the sinks by the way....now the sinks I have now seem to do fine (I can hold my hand on the sinks for quite some time, so must be under 60C), but was thinking of putting the amp into the KSA300 chassis someday, as it should have plenty of heatsink reserves....
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Old 24th January 2009, 02:04 PM   #7837
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If you see the KSA100s top view here, the chassis is easily about 1/2 the length of the KSA300s...

Click the image to open in full size.
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Old 24th January 2009, 02:27 PM   #7838
AndrewT is offline AndrewT  Scotland
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6pairs of output devices, each passing 1A of bias current comes to 6A of total bias current, Pq~468W. Have I interpreted your description correctly?
Maximum ClassA output current is 12A from a 6A bias push pull amplifier.

Your +-39Vdc supply rails will give about 72W all in ClassA into 8r0 and makes it equivalent to KSA72 if there were such a beast.
But your one will do 138W in ClassA into 4r0. I suppose you could call that equivalent to a KSA138/4

It will also do 250W into 2ohms 60degree phase angle if Tc can be held below 77degC. But that is a big ask if it is dissipating 468W per channel. First guess tells me that each channel will need 0.06C/W of heatsink. Each of those triplets would need to be 0.18C/W. They aren't.

That pic is not a KSA100.
It is probably a ClassAB stereo amplifier.
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Old 24th January 2009, 03:24 PM   #7839
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Andrew,

The pic is a KSA100s, not the KSA100 (sorry) - I guess it is the stepped bias version of the KSA100...I believe the bias isn't high all the time (like the non-stepped KSAs) on the stepped bias Krells, allowing for lesser sinks??

OK, so the KSA50 is 50wpc Class A into 8 ohms (25 into 4 ohms) which seems to be the convention on naming the Krell KSA series, so I guess what I have is a KSA138 equivalent?? Interesting.

I think the Krell KSA100s (like the pic I attached) has 8 pairs output devices and stepped bias...that would be around .31A/device?? Was it kept that low for reliability reasons? Am I pushing mine a bit hard at 1 Amp each?

BTW - my speakers on this amp are 4 ohm Magnepan MGIIIa...
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Old 24th January 2009, 05:28 PM   #7840
AndrewT is offline AndrewT  Scotland
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The KSA50 has 2pair of 250W devices and dissipates about 148W
The KSA100 has 4pair of 250W devices and dissipates about 270W
Your 6pair of 150W devices is dissipating about 468W.

Do you see the cooling problem?
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