Stolen Trademark Amplifier from Jim's Audio on EBAY - Page 10 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 3rd June 2012, 09:06 PM   #91
Jozua is offline Jozua  South Africa
diyAudio Member
 
Join Date: Aug 2003
Location: Cape Town
Hi

Check if the pcb works !

Jozua
  Reply With Quote
Old 16th June 2012, 04:13 AM   #92
spurlte is offline spurlte  United States
diyAudio Member
 
Join Date: Aug 2011
My gosh. No replys to Kaplaars #96 post. Dogs days of summer already?
  Reply With Quote
Old 16th June 2012, 07:53 AM   #93
diyAudio Member
 
Join Date: Nov 2004
Location: manila,PH
I recommend to mount the fans in the case so that fresh air can flow in and out of the tunnel. Class A amp can heat up quickly and aesthetics can be compromised in favor of long term reliability. See the original KSA 100mkII thread.
__________________
Pinoy ikaw ay pinoy... ipakita sa mundo... kung ano ang kaya mo...
  Reply With Quote
Old 16th June 2012, 10:43 AM   #94
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by spurlte View Post
My gosh. No replys to Kaplaars #96 post. Dogs days of summer already?
More likely that all the answers have been given before on this Forum, some many times.
__________________
regards Andrew T.
  Reply With Quote
Old 17th June 2012, 12:08 AM   #95
diyAudio Member
 
Kaplaars's Avatar
 
Join Date: Jul 2010
Location: Wageningen
Hi Guys,

Haha maybe David. But summer or not, replies or not Kaplaars is still @work ;-) !

Hmm, I've searched but could not find a checklist Andrew. Hope I did not overlooked a topic that explained it. Maybe I have to ask my questions again on the Dutch equivalent of this DIY-forum, or maybe someone can repeat the explanation because I am pretty curious. The basis of gaining knowledge is repeating knowledge so if someone wants to repeat, please do :-)

I red a few things about the zobel network. Great suggestion from AVWERK. It seems that this network will prevent instability due to the sometimes capacitive character of the loudspeakers. I hate smoking, I hate it even more if my Krell will smoke, so I have to prevent instability!

@Rolandong; that is exactely how I want to mount the fans :-) So push-pull principle. Noise will be far more less when I use two fans because noise is reduced quadratically with fanspeed. Have heard a lot of, sometimes very different, opinions about how to mount the cooling tunnels. I think I leave them the way they are. Please dont think I am stubborn, but I think this will be in my case the best solution. The tunnels are capable to dissipate at least 200W per channel with fans off (tested it with resistors mounted to them). But I am a little confused by now, because some people told me that I should use AC fans and not DC-fans because DC-fans would add distortion. Is there anything against DC-fans if I use brushless fans?

Have a little update, very busy at the moment so not very much progress. Lots of hours @lab (I now know everything about alcohol dehydrogenases... yay). But ontopic again Mr. Kaplaars; I've finished the PSU!!! I added very carefully current to the capacitors with a little stabilised PSU. I did this so the caps could reform their oxide layer back. I added a 1,2K resistor in series with the capacitor to limit current and added 25VDC to the caps. It was really cool to measure that the leakage current caused by the caps became smaller and smaller and the capacitors thus got better and better. After an hour the leakage current was only 3uA (it was 50uA). Very very good for electrolytic capacitors, but hey we don't want anything less than very very good.

Setup:
Click the image to open in full size.

When I measured that the capacitors were OK I mounted the capacitors to the chassis. I bought realy cool braided hose to cover the cables with. Is is really nice if I mag say so :-) Everytime when I search the internet for parts I am astonished by what there is to buy; there are so much nice parts around.

Mounted AC-cable:
Click the image to open in full size.

I also replaced the relays from the speaker protection. I've replaced them by Omron G2RL-1's. They should be a little bit better than the ones which came with the kit, and they were not realy expensive, so it was worth a try.

And how the amp is right now:
Click the image to open in full size.

To be continued.... :-)

Last edited by Kaplaars; 17th June 2012 at 12:10 AM.
  Reply With Quote
Old 17th June 2012, 09:31 AM   #96
Jozua is offline Jozua  South Africa
diyAudio Member
 
Join Date: Aug 2003
Location: Cape Town
Kaplaars

Looking very good except for my concerns re overheating - so be prepared for a possible desolder and rebuild w.r.t. output stage...

With the modern parts you are using I would not be surprised if your amp sounds better than the original.

Regards

Jozua
  Reply With Quote
Old 17th June 2012, 12:04 PM   #97
diyAudio Member
 
Kaplaars's Avatar
 
Join Date: Jul 2010
Location: Wageningen
Thanks Jozua! That is a concern which I share with you. I try to keep the build as modular as possible, so that in case of failure the amplifier is relatively easy to disassemble. That is why I used for example cable clips at the side pannel instead of tiewraps and faston plugs instead of soldering the wires directly to the bridge rectifiers. From the other hand I have to assemble the tunnel coolers with a lot of bolts, they weigh a lot. So dissassembling the tunnel coolers will not be an easy task.

I realy hope so! I have never heard the original Krell KSA-100. Would be fun to compare it to an original KSA-100.
  Reply With Quote
Old 17th June 2012, 01:36 PM   #98
Jozua is offline Jozua  South Africa
diyAudio Member
 
Join Date: Aug 2003
Location: Cape Town
Kaplaars

I have the KSA 100 mk1 and mk 2. Subjectively the mk2 is more mellow wheras the mk 1 seems more dynamic in my system.

With my KSA 50 clone top notch resistors (Ricken)were used and subjectively I seem to imagine it having slightly more detail.

When I find some good looking heatsinks, or a KSA 100 box or a spare set of heat tunnels my clone 100 will proceed.

Consider yourself very lucky with your costing. This is a very expensive amp to build.

Regards

J
  Reply With Quote
Old 17th June 2012, 04:30 PM   #99
AVWERK is offline AVWERK  United States
diyAudio Member
 
Join Date: Jan 2004
Location: So Calif.
The AC vs DC fan debate is just that a debate. I used both styles because of the ..debate...
Having built 6 Krell monoblocks that use both types, I can not reliably tell a difference switched in or out that it does anything negative to the soundstage or on the scope for that matter.
The zobel is cheap insurance. Bedini never used them thinking I assume it does something negative to the sound. I smoked a 150 mk2 without anything connected to the outputs while changing components and then the phone rang....magic smoke from the distance? It oscillated itself out of exsistance

When you do power up you can use the light bulb method. I haven,t done that but it is excellent.
When I power up I ramp my Variac fairly quickly to about 1/3rd to get the trannies to switch while looking at the DVM set in the milivolt
range hung on the outputs. You can place a 2nd DVM across a emitter also.
Then I wait about 3 seconds while sweating like a dog with knees vibrating, nail bitting..the whole package.. A few beers might help here BTW!
If I haven,t had a heart attack yet and can observe the DVM coming down into the milivolt range then I can start slowly increasing the Variac while looking at both DVM,s and adjusting bias along the road ahead..

My variac gets stiff fairly easily if something is wacked and that why light bulb method is a better item to asist.
If you get this far you need to sit with it awhile and keep an eye, actually both eyes on everything.

Regards
David
  Reply With Quote
Old 17th June 2012, 05:31 PM   #100
diyAudio Member
 
Kaplaars's Avatar
 
Join Date: Jul 2010
Location: Wageningen
Haha yeah I was pretty lucky with obtaining parts Jozua. There are so much details that cost money. For example I had to order all wires, terminal rings, cable clips ed for the amp, costed me another 50 euro's! Bought that stuff new which makes the parts far more expensive than second handed parts. But OK it's great quality cable which can withstand 180 degrees of temperature. No beer this week, but cables instead ;-)

WOW 6 monoblocks! How turned your clones out David? Do you have pictures of yours?

Great to hear I can still use the DC fans. I've bought pretty good ones from Nidec (Beta V). They are dead silence, you realy can't hear them. I am thinking of building PWM-control, but.... I've heard PWM-control was not sane because of distortion. Hope that is a fable too!

Great suggestion. I always use the lightbulb method to start old tube radio's (I collect them) which havent been used for years. This way you can see very fast if something is wrong. The mains electrolytic capacitor has this way also an opurtunity to form it's oxide layer a bit slower back.

Hahaha, will some Russian water, or in other words Vodka also do? ;-)

Okay David, will do, I will slowly increase voltage with my variac hoping it does not go kaboom. I've build my variac in a cabinet and added a fuse of 3A together with a VAC- and ampère meter. This fuse has proven it's value, had once a radio which was completely short circuit. Luckily for me the fuse blew which prevented further damage. I will also measure voltage across the outputs and emitters carefully. Do you attach a dummyload and maybe an oscilloscope to the outputs aswell when you are measuring across the outputs?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Jim's Audio F5 power supply board Hikari1 Pass Labs 35 4th December 2013 10:41 PM
Jim's Audio Goldmund Telos 390 clone Tyimo Solid State 9 5th March 2013 02:28 AM
Jim's Audio F5 referenced kit. HiVi Guy Pass Labs 21 22nd November 2012 10:24 AM
Stolen items? kctess5 Multi-Way 14 23rd February 2012 10:02 PM


New To Site? Need Help?

All times are GMT. The time now is 11:00 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2