krell SOLD: FS: Krell KSA 150 Power Amp

[srms]

Item: Krell KSA 150 (Class A) Poweramp
Location: Currently in Canberra - Can drop to Melbourne
Price: $1650
Item Condition: Good
Reason for selling: Raising funds for preamp repair
Payment Method: Pickup Canberra or delivery to Melbourne - Cash, Paypal, EFT
Extra Info: (no boxes or factory packing) 

 I have owned the KSA-150 for the past 13 years and it has operated faultlessly in that period. It hasn't seen much use in the past 5 years as I purchased it's big brother the FPB-600 and have been using that as my main power amp. I have powered up the 150 and run it for a few hours to make sure it is still operating correctly and really was surprised at how good it sounds. It is a beast of an amp and will pretty much drive anything (as Krells are known for)

 

The amp has never been serviced or had the caps changed (I know some will ask that question)

 

I have recently had my preamp repaired and upgraded which has been an expensive exercise, so I am selling off some gear that I really don't use much to fund the repair (hence the sale of the KSA-150)

 

The amp is currently in Canberra on loan to a friend, so if someone in Canberra is interested transport would be very easy.  I'll be picking up the amp this Sunday and taking it home to NE Victoria (near Albury). I can provide free transport to Melbourne next Tuesday or Wednesday.

 

Shipping to other places is not really an option as the amp is very heavy and I don't have any suitable packing. There is no Pack and Send within 2 hours of my home and you would have to donate a kidney to have something like this shipped via P+S.

 

I have attached images that my friend was kind enough to take for me last night.

 

 

Pictures:

KSA150250_MAN.pdf

[Qwertyqaz]

That’s a Class A amp, you cannot get one at that price.

I payed over  twice for a 200 Watt version.

[frednork]

Oh my!!!!

[Mendes]

This must be a delight on those cold Canberra nights warming up the room.......

[vandunga3]

 Pm sent!

[Soundscape]

@djb

Edited December 16, 2017 by Dave O)))

[eman]

@dor

[gonefishing999]

@ghost4man you need this

[srms]

Thanks for all the PM's about the amp. Clearly it was too cheap! Anyway its now sold. I'll update the add when I have access to a computer.

[Lowfi-tech]

Beautiful amp. Clearly way too cheap!

[georgehifi]

  On 16/12/2017 at 2:02 AM, Qwertyqaz said:

That’s a Class A amp, you cannot get one at that price.

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No sorry, it's only Class-A up to around 25w into 8ohms, then it shifts into Class-B

But still an excellent buy for $1650

Cheers George

Edited December 16, 2017 by georgehifi

[Wimbo]

If it had been recapped, then close to $3000. Seeing it hasnt, to recap one of these should be around a $1000 plus.

If you can do the job and have the time, great buy. Same if you know someone that will do the job cheap.

http://liquidaudio.com.au/class-a-amplifiers-krell-ksa-150/

[Wimbo]

  On 16/12/2017 at 10:58 PM, georgehifi said:

No sorry, it's only Class-A up to around 25w into 8ohms, then it shifts into Class-B

 

Cheers George

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So, the 150 watts is its RMS power value?

[georgehifi]

Wimbo"So, the 150 watts is its RMS power value?"

 

 

It should be really classed as a Class A/B amp.

This amp the first 25w is class-A into 8ohms, and into 4ohms it's 12.5w Class-A

Then it's switches to Class-B up to 150w into 8ohms or even higher as Krell always understate their wattage inro 8homs.

 

 

The only pure Class-A from that era were the KSA-50, KSA-100 and the KSA-100 monoblocks, these had no heatsinks but internal chimney heatsinks that were fan forced cooled.

 

Cheers George

 

 

 

 

  

 

 

Edited December 17, 2017 by georgehifi

[Wimbo]

  On 17/12/2017 at 12:03 AM, georgehifi said:

It should be really classed as a Class A/B amp.

The only pure Class-A from that era were the KSA-50, KSA-100 and the KSA-100 monoblocks, these had no heatsinks but internal chimney heatsinks that were fan forced cooled.

 

First 25w is class-A into 8ohms, and into 4ohms it's only 12.5w Class-A

 

Then it's switches to Class-B up to 150w into 8ohms or even higher as Krell always understate their wattage inro 8homs.

 

Cheers George

 

 

 

 

  

 

 

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The big thing about the 150 is that it could drive a 1 Ohm load to 1200 watts.

[Qwertyqaz]

  On 16/12/2017 at 10:58 PM, georgehifi said:

No sorry, it's only Class-A up to around 25w into 8ohms, then it shifts into Class-B

But still an excellent buy for $1650

Cheers George

Expand  

I don’t think that’s right. Anything that you can refer that says so.

[georgehifi]

  On 16/12/2017 at 11:07 PM, Wimbo said:

  On 17/12/2017 at 12:08 AM, Wimbo said:

The big thing about the 150 is that it could drive a 1 Ohm load to 1200 watts.

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Yes, it will drive 1ohm, but at not 1200w. It's impossible to double wattage for each halving of impedance load because of the losses, if it did it would be doing the equivalent of "perpetual motion". But it could do 60% - 80% of doubling. 

 

Cheers George

[georgehifi]

  On 17/12/2017 at 12:13 AM, Qwertyqaz said:

I don’t think that’s right. Anything that you can refer that says so.

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Afraid so, here's it's bigger brother the KSA-250 same amp little more Class-A a lot more Class-B.

 

Stereophile measurments of the KSA-250.

"Looking inside the KSA-250, the emitters of the 12 pairs per channel of output-stage transistors appear to standing on series resistors of nominal 1 ohm value. The average voltage drop across these resistors was 110.5mV, implying a standing bias for each of 110.5mA; ie, a total of 1.33A.
This will give a maximum power for true class-A operation into 8 ohms of 28.5W (14.5dBW) rather than 250W."

 

https://www.stereophile.com/content/krell-ksa-250-power-amplifier-when-class-class

 

Cheers george

Edited December 17, 2017 by georgehifi

[Wimbo]

  On 17/12/2017 at 12:15 AM, georgehifi said:

Yes, it will drive 1ohm, but at not 1200w. It's impossible to double wattage for each halving of impedance load because of the losses, if it did it would be doing the equivalent of "perpetual motion". But it could do 60% - 80% of doubling. 

 

Cheers George

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This is the 250 measured by JA, https://www.stereophile.com/content/krell-ksa-250-power-amplifier-measurements

[Wimbo]

  On 17/12/2017 at 12:21 AM, georgehifi said:

Afraid so, here's it's bigger brother the KSA-250 same amp little more Class-A a lot more Class-B.

 

Stereophile measurments of the KSA-250.

"Looking inside the KSA-250, the emitters of the 12 pairs per channel of output-stage transistors appear to standing on series resistors of nominal 1 ohm value. The average voltage drop across these resistors was 110.5mV, implying a standing bias for each of 110.5mA; ie, a total of 1.33A.
This will give a maximum power for true class-A operation into 8 ohms of 28.5W (14.5dBW) rather than 250W."

 

https://www.stereophile.com/content/krell-ksa-250-power-amplifier-when-class-class

 

Cheers george

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Lol, just got back from Macca's, we are quoting the same measurements.

[georgehifi]

  On 17/12/2017 at 12:34 AM, Wimbo said:

This is the 250 measured by JA, https://www.stereophile.com/content/krell-ksa-250-power-amplifier-measurements

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Yes and they are fine measurements, but nothing said here about the amount of Class-A bias

 

You have to go to the bottom of the page and go to his link on this same amp "When is Class-A Class-A"

 

In there he states " This will give a maximum power for true class-A operation into 8 ohms of 28.5W (14.5dBW) rather than 250W."

 

Cheers George

[Wimbo]

  On 17/12/2017 at 12:39 AM, georgehifi said:

Yes and they are fine measurements, but nothing said here about the amount of Class-A bias

 

You have to go to the bottom of the page and go to his link on this same amp "When is Class-A Class-A"

 

In there he states " This will give a maximum power for true class-A operation into 8 ohms of 28.5W (14.5dBW) rather than 250W."

 

Cheers George

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I know that. I'm talking about the 1200 watts in to 1 ohm.

I remember once when Len was on the otherside in the Mall, late one night one of the salesmen set up a couple of MDA300's with Duntech Sovereigns. He was using that single cabled Krell cable and because it was late, go the wiring wrong. He shorted both sides of the Krells with the stuff and both turned on.

[georgehifi]

  On 17/12/2017 at 12:47 AM, Wimbo said:

I know that. I'm talking about 

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Simply sorry you don't, if it does give 1200w into 1ohm, it much more than 150w into 8ohms.

 

A Krell amp will not double for each halving of load impedance starting at 8ohm all the way to  1ohm, no amp can it's impossible, and if you were told this by Lenny or one of his team, they were told that by Krell who are lying.

There is a common practice among some power amp makers to "under quote" the 8ohm wattage so the 4ohm looks to be doubling, but they won't give the 2ohm  or 1ohm as doubled if they give them at all.

 

You see this happening very much on Stereophile tests, where the manufacturer states in thier specs  "150w into 8ohm and it can double into 4ohm at 300w" then Stereophile test it and finds it can actually do 200w into 8ohm, but still only 300w into 4ohm.

This is almost false advertising or good marketing.

 

Cheers George 

Edited December 17, 2017 by georgehifi

[georgehifi]

Here are the tested specs on the bigger KSA-250.

 

325W into 8 ohms

635W into 4 ohms

1000W into 2 ohms

1548W into 1 ohm
 

Very good results, but hardly doubling all the way.

 

Cheers George

[Qwertyqaz]

What about the S version amps.