Converting Krell KSA 80B to KMA 160

NealW · 14th November 2008, 07:39 PM

Have got the opportunity to add another KSA 80B to my the one I already own but am only interested if I could convert it to a KMA 160 (to have a pair of monoblocks). I thought it wouldn't be a big deal and I have someone who has worked on my KSA 80B but he never did this conversion back in the day. The krell guys say it is difficult because there was a kit of parts that needed to be added. Has anyone done this and can they give us some guidence.

by the way i love this amp have been comparing it to a wyred 4 sound amp that is creating a buzz on the net and prefer the krell.

lineup · 16th November 2008, 05:37 AM

there should be some members that could advice you
I have seen several topics dealing with Krell amplifiers etc.
And been many done Krell 50/100 clones

NealW · 17th November 2008, 02:01 PM

thanks yes in fact there is a thread on a conversion/ rebuild of a kma 160 back to ksa 80. of course i require the opposite and the amp is working fine so no other issues are at stake. of course i'm hoping some of the south african members reply then i may be able to contact them directly. as a newbee i'm not allowed to email members directly.

jacco vermeulen · 17th November 2008, 04:17 PM

Quote:

Originally posted by NealW
no other issues are at stake.

No transformer swapping ?

NealW · 18th November 2008, 02:50 PM

just mean the amp is in working order. are you saying the transformers need to come out in making the swap from ksa 80 to kma 160???

jacco vermeulen · 19th November 2008, 04:32 PM

Measure the loaded voltage level on the rails of your 80B, multiplied by 2 if you put two secondaries in series is how much power ?
Secondaries in series still have the same current rating, but a power amp with twice the output power requires at least twice the current.
A conversion of a '90s stereo KSA-250 to a monaural MDA-500 required an exchange of the (very very large) transformer.

jwb · 18th December 2008, 04:22 AM

You do not need to exchange the transformer to convert the KSA-80 to KMA-160. They are the same. You do, however, need to do some things.

1: You need to remove the input board on the left side (obviously).

2: There is a jumper wire on the protection board on the rear of the amplifier. It is dead center in the middle of the board, near the bottom, and about the size of a staple. Yours will be missing. You should install that jumper.

3: You need to fabricate a cable to carry the signal from the right rear driver to the left rear driver. This will have the same orange, brown, and gray wires that already connect the driver boards, but it will cross the amplifier from right to left, instead of running front to back. You can see this wire in my photo. It is the one that is disconnected on one side:

4: After you do all that, you must adjust the pots on the top edge of the input board for bias level and DC offset! Very important!

Good luck!

jwb · 18th December 2008, 04:26 AM

To make it more clear I have indicated the needed wire with orange arrows.

Jovi Perry · 10th February 2011, 01:40 AM

Dear JWB

I am going to get a Krell KSA 80 in this weekend and planning to convert it into KMA 160 for my center speaker. Would you mind reposting the images again? By the way, I also need to add a XLR connector for true balance input for the amp, any suggestions for the parts?

Thanks in advance.

Regards
Jovi

14th November 2008, 07:39 PM	#1
NealW diyAudio Member Join Date: Nov 2008	Converting Krell KSA 80B to KMA 160 Have got the opportunity to add another KSA 80B to my the one I already own but am only interested if I could convert it to a KMA 160 (to have a pair of monoblocks). I thought it wouldn't be a big deal and I have someone who has worked on my KSA 80B but he never did this conversion back in the day. The krell guys say it is difficult because there was a kit of parts that needed to be added. Has anyone done this and can they give us some guidence. by the way i love this amp have been comparing it to a wyred 4 sound amp that is creating a buzz on the net and prefer the krell.

16th November 2008, 05:37 AM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	there should be some members that could advice you I have seen several topics dealing with Krell amplifiers etc. And been many done Krell 50/100 clones __________________ lineup

19th November 2008, 04:32 PM	#6
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, just under Rotterdam	Measure the loaded voltage level on the rails of your 80B, multiplied by 2 if you put two secondaries in series is how much power ? Secondaries in series still have the same current rating, but a power amp with twice the output power requires at least twice the current. A conversion of a '90s stereo KSA-250 to a monaural MDA-500 required an exchange of the (very very large) transformer. __________________ Looks like Sponge Bob has killed another thread.

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17th November 2008, 02:01 PM	#3
NealW diyAudio Member Join Date: Nov 2008	thanks yes in fact there is a thread on a conversion/ rebuild of a kma 160 back to ksa 80. of course i require the opposite and the amp is working fine so no other issues are at stake. of course i'm hoping some of the south african members reply then i may be able to contact them directly. as a newbee i'm not allowed to email members directly.

18th November 2008, 02:50 PM	#5
NealW diyAudio Member Join Date: Nov 2008	just mean the amp is in working order. are you saying the transformers need to come out in making the swap from ksa 80 to kma 160???

18th December 2008, 04:22 AM	#7
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	You do not need to exchange the transformer to convert the KSA-80 to KMA-160. They are the same. You do, however, need to do some things. 1: You need to remove the input board on the left side (obviously). 2: There is a jumper wire on the protection board on the rear of the amplifier. It is dead center in the middle of the board, near the bottom, and about the size of a staple. Yours will be missing. You should install that jumper. 3: You need to fabricate a cable to carry the signal from the right rear driver to the left rear driver. This will have the same orange, brown, and gray wires that already connect the driver boards, but it will cross the amplifier from right to left, instead of running front to back. You can see this wire in my photo. It is the one that is disconnected on one side: 4: After you do all that, you must adjust the pots on the top edge of the input board for bias level and DC offset! Very important! Good luck!

18th December 2008, 04:26 AM	#8
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	To make it more clear I have indicated the needed wire with orange arrows.

10th February 2011, 01:40 AM	#9
Jovi Perry diyAudio Member Join Date: Feb 2011 Location: Hong Kong	Dear JWB I am going to get a Krell KSA 80 in this weekend and planning to convert it into KMA 160 for my center speaker. Would you mind reposting the images again? By the way, I also need to add a XLR connector for true balance input for the amp, any suggestions for the parts? Thanks in advance. Regards Jovi

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