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Old 4th August 2012, 10:03 PM   #261
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Haha wel let's say I don't go on a vacation this year A good estimate of the costs right now is about 600 euro's. Especially the details cost a lot of money, to be fair, more than I budgetted. I have been very lucky with buying surplus parts. But there are a few things that you have to buy new. When buying things new it will cost you almost instantly twice as much.

When I build something I want to do it perfect the first time, so even every screw, nut and bolt has to be perfect. I have to admit I spended quite a bit of money at buying iron hardware like screws, bolts and nuts. But that is a but due I buy in large quantity, when I need 10 bolts, I buy 100. I like to have some stock

Also the engraved plates were not cheap, even with some discount that I got. But I have to say, I think they the plates are very cool, the engraving company did a fantastic job, so well spended And last but not least cabling of the beast costed quite a lot of money, especially all the connectors. Potential builders must not underestimate the costs of the details... I did haha. I thought the cabinet and transformers would be the lionshare of the costs, but actually cables and iron hardware costed the most. You can build it cheaper by ignoring details, but how often do you make a project like this. I want it to last and like I said it has to be perfect

And offcourse another part of the build that costs money is buying measuring equipment and tools like a holesaw and so on.. This costs are not added to the 600 euro's estimate

Expensive for a dog-poor student, haha nah it is not that bad I over egaggerate a bit haha, but expensive for a student? To be fair....offcourse a bit, but I think I've did a great job with keeping expenses as low as possible, I think building one when you have to buy all the parts for less money is going to be very hard. So it could be worse :-) Worth it? EVERY PENNY Would do it without questioning it again

By the way, I bought some bigger 12 cm fans. I thought the Nidec fans were quiet..... till I heard or actually did not hear these ones, even at full speed just no audible sound! That is great, I will replace the Nidecs. I was thinking of mounting two 12 cm fans underneath the tunnel cooler. There are ventilation holes underneath the cabinet, so fresh air can enter easily. Also warm air can go easy out of the cabinet due to the ventilarion holes on top. Since the fans are almost inaudible, adding two more would not be a real problem. But I have to think of a nice solution of mounting the fans underneat the tunnel coolers. Will be continued
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Last edited by Kaplaars; 4th August 2012 at 10:07 PM.
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Old 4th August 2012, 11:30 PM   #262
Jozua is offline Jozua  South Africa
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Kaplaars

Your costing is very low.

Many prospective KSA100 clone builders started with good intentions but their projects failed due to the hidden costs.

You might just restart my KSA100 clone project... I have all the parts except the transformers. The pcb's are already buildt up.

Regards

Jozua

Last edited by Jozua; 4th August 2012 at 11:32 PM.
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Old 5th August 2012, 12:19 AM   #263
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Yeah, it is a shame so much projects fail here and there. From reading some topics here and there I noticed people are with great spirit when starting the project but there actually aren't much big DIY amps that reach the finishline. I think people also underestimate the amount of work it takes and knowledge you sometimes need. I am lucky that I have the ability to absorb knowledge relatively fast, but things can get pretty complicated. This is actually the first big amplifier I've build. So needed to read quite a bit of literature and spammed this forum (and other fora's) quite a lot with asking questions . I am glad it all worked out.

My project had a bit of delay too, not due financial problems, but mere time problems. Was very busy with my study so the amp had not an high priority (don't want to delay my study, that will cost you the equivalent of building a few of these amps. The Dutch governent will even give you a fine of 3000 euro's when you delay more than one year with your bachelor or master study @university ). Luckaly I earned all study points for this year, so VACATION And I have to say when I start something I want to finish too

You really should Jozua ! I am sure you won't regret it. Is it actually duable to build a 100W class A amplifier in South Africa? I can imagine you will need pretty big heatsinks due to the ambient temperatures over there. When it is 30 degrees here it is for some people almost unbearable hot, especially the elderly have some problems to adopt. Can't almost imagine how temperatures in South Africa feel. But to be fair, I almost want to say global warming is good, how cool would it be to have a palm tree in your garden IN HOLLAND I like high temperatures far more than cold temperatures, I really hate winter here But now I am going way offtopic.
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Old 5th August 2012, 06:16 PM   #264
neychi is offline neychi  Croatia
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I finally started working on my toy
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Old 5th August 2012, 10:59 PM   #265
spurlte is offline spurlte  United States
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Default Nice soft-start.

Quote:
Originally Posted by neychi View Post
I finally started working on my toy
Every inner-child should have a Toy. Now, why is there a soft-start specifically for toroidal transformers? Just want to know the possible reason for it--FYI, if there is one. Neychi, how far along are you with the project? David
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Old 6th August 2012, 02:37 AM   #266
spurlte is offline spurlte  United States
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Default Warming up the Caps

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Originally Posted by Kaplaars View Post
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. How much current did you apply to warm up the capacitors? I have a chance to buy an old variable, triple output, +-32volt/1A power supply. Would 1A be enough to reform the Caps?

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.... :-)
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Old 6th August 2012, 05:26 PM   #267
neychi is offline neychi  Croatia
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Quote:
Originally Posted by spurlte View Post
Every inner-child should have a Toy. Now, why is there a soft-start specifically for toroidal transformers? Just want to know the possible reason for it--FYI, if there is one. Neychi, how far along are you with the project? David
Yes David I agree with you


There's no specific soft start for toroidal transformers, but they are used more often than laminated E-l type for diy. Also, toroidal transformer has a higher inrush current (up to 50 times greater than the nominal current) compared to laminated E-I, becouse they have no gap in magnetic flux.
For this reason, a soft start is required for toroidal transformers ≥500VA.

I am waiting for some metal parts to be finished because I’ve changed something in the construction. Then I will take them to the anodizing. If all goes well, soon will be assembling.
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Last edited by neychi; 6th August 2012 at 05:28 PM.
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Old 6th August 2012, 08:29 PM   #268
spurlte is offline spurlte  United States
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Default anodizing

Quote:
Originally Posted by neychi View Post
Yes David I agree with you


There's no specific soft start for toroidal transformers, but they are used more often than laminated E-l type for diy. Also, toroidal transformer has a higher inrush current (up to 50 times greater than the nominal current) compared to laminated E-I, becouse they have no gap in magnetic flux.
For this reason, a soft start is required for toroidal transformers ≥500VA.

I am waiting for some metal parts to be finished because Iíve changed something in the construction. Then I will take them to the anodizing. If all goes well, soon will be assembling.
Why anodize? Is this for aluminum? I quess this is why Kaplaars used a copper bar for the smoother caps connections. I went to a scrap yard today and found some similar heat sinks for the output drivers. I wish someone could explain about why some are using "live" heatsinks for the TO-3s and how to get by without using such "live" setup. I will post a photo of these heatsinks ASAP.
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Old 6th August 2012, 08:52 PM   #269
Jozua is offline Jozua  South Africa
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Hi

I am looking for a spare set of tunnel heatsinks.

Please let me know if you have any for sale?

Thanks

Jozua
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Old 7th August 2012, 08:23 AM   #270
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Jozua, I use tunnel heat sinks from Semicron. Call Ivan at 031 463 3245 they will cut to length and surface them.
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