BUT! you have to be careful which version of the KSA-50 that you'd end up with. There are MANY variations of them. The later version will obviously outperform the earlier one as it has much later semicondictors. Re-furbishing one with original Krell parts could cost you more than just buying the parts to build your own! To not refurbish an original one without using Krell parts would only deterioate its value.
Nuttr... I'm glad that you have yours up now. Thay are quite good aren't they.......
.Mark
As to the group buy, I am happy to handle it and shipping Al's board from the U.S. to whomever wants them. I will also purchase extra boards for latecommers and to just keep them around for those that discover this thread down the road. We need to let the WIKI run for a while, say at least two weeks, and then place the board order. I am all for doing the output board as well and we could just use Brian GT's Aleph power supply board with this project but Brian has offered to do one that is Krell specific just for us.
Brian has given us space on his web site to uitilize for this project. Please send your project pictures and what ever else you'd like to contribute to that site thourgh its e-mail address.
http://www.diyamps.com/ksa/
On another note.... don't forget that this IS an expandable amp as to the power output. It can easily be built to be a KSA-100 , 100 watts pure class A, merely by adding more output devices(12), more heat sinking and larger power supplies. Although this thread is getting very long some of this was discussed earlier on.
Mark
Brian has given us space on his web site to uitilize for this project. Please send your project pictures and what ever else you'd like to contribute to that site thourgh its e-mail address.
http://www.diyamps.com/ksa/
On another note.... don't forget that this IS an expandable amp as to the power output. It can easily be built to be a KSA-100 , 100 watts pure class A, merely by adding more output devices(12), more heat sinking and larger power supplies. Although this thread is getting very long some of this was discussed earlier on.
Mark
Sorry,Mark.
Frankly, the nice thing about rebuilding is to take advantage of the mistakes the designer made, and availability of devices that are far superior to the original, available in production years.
(Mr d'Agostino made a couple, admitted i disliked each and every later date Krills, after the 50s and 100s)
These boards can be used with double output boards, and still be a KSA50, but with much higher bias. (see my wiki line)
I had an official warning by Hugo, GeWa, i am not commenting on the Ups and Downs !
Let me suffice by stating that NUTTR is Down under, it is nearly winter there, it is not more than fair that his are Up.
Frankly, the nice thing about rebuilding is to take advantage of the mistakes the designer made, and availability of devices that are far superior to the original, available in production years.
(Mr d'Agostino made a couple, admitted i disliked each and every later date Krills, after the 50s and 100s)
These boards can be used with double output boards, and still be a KSA50, but with much higher bias. (see my wiki line)
I had an official warning by Hugo, GeWa, i am not commenting on the Ups and Downs !
Let me suffice by stating that NUTTR is Down under, it is nearly winter there, it is not more than fair that his are Up.
still4given said:
Hey Terry,
Yeah they sure are the original boards mate!
I've had to relocate the drivers, but the pre drivers are fine, bias moved too..... this was so simple it isn't funny, no problem with fitting at all, i love the project and the amps sound fantastic IMHO! I'm running a LOT of bias (0.5v per output! .68ohm emitters, so a lot of current!!!) But i'm very very happy with the sound, just listening to a track i've heard hundreds of times and even my fiancee picked out new sounds we hadn't heard before!
I've got enough parts to get 3 channels up and running, leaving me with 2 more spare boards that i am going to build up with "low quality" parts and small heatsinks (maybe TO-3P devices?) and lower bias with 25v toroids
and i'll use those as rear surround amps, i'm that impressed with them!!! Probably run one power supply for the both rear channels I didn't use currently limiting at all, just left it out
Aaron
still4given said:
Not a problem at all Terry, when you are ready ask away! All the parts are right (from the spec sheets)... Don't bother with current limiting, just gives more board room
There's a few mods that MUST be done to the boards for the adjustment pots!!! Make sure this is done!I've asked stacks of questions along the way too
Dale resistors fit, JUST, you have to bend the pins in fairly hard!
I had no problem getting parts to fit...
Aaron
Parts lists, and construction guide is on the way and rather than here where it will get lost, it will be on the website.
I am working 6 long days a week at the moment, and so have very little time. Like this, I can pop in from work to add the odd comment, but I can't really do much else.
With the interest in the output board, it looks like I have to get that sorted as well...
I am working 6 long days a week at the moment, and so have very little time. Like this, I can pop in from work to add the odd comment, but I can't really do much else.
With the interest in the output board, it looks like I have to get that sorted as well...
Well, then it isn't really a Krell anymore then is it except for the name plate? The fact that it is a Krell is what helps to hold its value, as does Threshold and Pass stuff. There are few other products that can claim this..... most amps of this era were worth a mere pittance just a year or two after birth.... any KSA-50 modded by other than Krell would also just be worth just a meer pittance. IN this case these amps are going for sometimes 2/3 of the original selling price.
What you are looking for really is just a chassis in which to build a Krell.... why not take some nice chassis with garbage inside....ARC solid state stuff comes to mind.... nice chassis but really bad solid state designs.... These can sometimes be had for next to nothing.
There were not all that many KSA50's built anyway so one ought to consider them a tad odd when they do pop up..... Keep them as they are.
Mark
Yea, that was my point. Actually though if the Krell factory made any upgrades to a KSA-50 it could actually increase its value slightly. Having them do those upgrades however would cost more than to just build your own clone. I will leave the originals to collectors and for those that cannot build their own clone. Really, its a shame that Dan doesn't still make these amps today....
Mark
Mark
jacco vermeulen said:
Ha jacco,
I can always count on you to put a smile on my face.
My problem right now is that I have a couple of amps that I can't seem to find the promlem with. It's making me crazy. I need to set them aside and work on something else for a while. One of the members here was selling his boards so I bought a couple. I probably should have read all the way trough this thread before I bought them but I didn't. Seems as though there are a few things that need to be changed to make them right so I guess I will have my work cut out for but If they sound as good as everyone says I suppose it will be worth it. NOt sure where I'm going to get the proper transformers but I'll keep my eyes open.
NUTTTR,
Thanks for advice. Looking forward to learning from you.
Blessings, Terry
pinkmouse said:Parts lists, and construction guide is on the way and rather than here where it will get lost, it will be on the website.
I am working 6 long days a week at the moment, and so have very little time. Like this, I can pop in from work to add the odd comment, but I can't really do much else.
With the interest in the output board, it looks like I have to get that sorted as well...
Thanks Al.
I think I should also give a thanks to BrainGT, Mark, Jens and Jan who have all contributed much to this. Surely without them this would just be a long thread with nothing more than a schematic and a few folks who have the skill to roll their own.
With the kind dedication of the above, it looks like we're all going to get a chance to order a Krell clone.
I take my hat off to your generosity for the community.
I need a little help with the KSA boards from ACD and Jens. Aside from the hacking and slashing of the traces under the pots are there any other trace rework issues?
IS there any reaon R144, D305 and D306 have been left off the BOM?
Are there any Practical, less vague values I could use for the RB, RV & RE resistors on the output boards?
How do I calculate the required values without a Degree in advanced Mathematic Theory?
Why is the BOM for the output boards calling out RE1 to RB3, is this a typo?
Thanks in advance for anyone's help.
Regards
Anthony
PS. Al I hope the documentaion you are preparing is a tad more, hummmm... Idiot friendly
IS there any reaon R144, D305 and D306 have been left off the BOM?
Are there any Practical, less vague values I could use for the RB, RV & RE resistors on the output boards?
How do I calculate the required values without a Degree in advanced Mathematic Theory?
Why is the BOM for the output boards calling out RE1 to RB3, is this a typo?
Thanks in advance for anyone's help.
Regards
Anthony
PS. Al I hope the documentaion you are preparing is a tad more, hummmm... Idiot friendly
Coulomb said:Al I hope the documentaion you are preparing is a tad more, hummmm... Idiot friendly
Well, it's going to be written by one, if that helps!
Right, a few quick answers for the things I can remember. RE can be anything from 0.1 to 0.68 Ohm, 5W should be plenty. RB, between 0 and 10Ohm.
I'll check the other things later, but I am at work at the moment, so will have to squeeze it in when no-one is looking...
