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Old 1st February 2005, 03:31 AM   #611
tmblack is offline tmblack  United Kingdom
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Anyone build the Krell clone yet?
Too late to buy boards I guess.
Also strongly considerly the Leach V4.5 amp.

Will the Krell work in class AB til proper transformer can be bought?

Tom
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Old 1st February 2005, 03:49 AM   #612
NUTTTR is offline NUTTTR  Australia
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Quote:
Originally posted by tmblack
Anyone build the Krell clone yet?
Too late to buy boards I guess.
Also strongly considerly the Leach V4.5 amp.

Will the Krell work in class AB til proper transformer can be bought?

Tom


No one i know of yet, no boards!!!
I'm still waiting on cap's and toroids and casing!

It will work ok in class a/b, just lower the amount of bias used... you can still have class a for the first watt or two... What transformer do you have to use for it?
Aaron

[edit - i think a lot of people bought spare boards, so there may be some for later? depends if they want to sell!]
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Old 1st February 2005, 03:26 PM   #613
troystg is offline troystg  United States
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Quote:
Originally posted by NUTTTR

No one i know of yet, no boards!!!

Hi-

The GB of boards will hopefully arrive Wednesday or Thursday. I hope to get them out on Saturday or Monday.

Has anyone gathered the parts necessary (except boards of course) to complete theirs?

And please post pictures of the completed amps here when finished.
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Old 1st February 2005, 04:41 PM   #614
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Default got parts?

ooo, me, me, I have...

I decided a while ago to make at least a couple of channels of all the 'classic' amps, been collecting parts ever since, hence the 'sculpture'. I recently traded for heatsinks and finally bought a stack of toroids from parts express, they are approx. 500va, and delivered, ended up costing $12 each, so I bought 10. I had to rewind one for the aleph, the default secondaries of 40-20-0-20-40 weren't cutting it, now it's 30-0, 30-0...much better.

So far I've built an aleph50, next will be the ksa50, then perhaps a quad 405, not sure after that, maybe a naim nap250...

So far the aleph50 has cost me ~$75, everything included, though it's not finished mechanically...might have to buy some metal extrusions to complete the case.

Stuart
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Old 1st February 2005, 04:45 PM   #615
troystg is offline troystg  United States
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Stuart-

Don't lose your camera again under that pile and take a few pictures if you don't mind.

I am curious to see which one you end up preferring.
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Old 1st February 2005, 04:45 PM   #616
MikeW is offline MikeW  United States
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What's an Aleph 50?
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Old 1st February 2005, 04:47 PM   #617
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Default pi filters

In case anyone was unsure just how good a pi filter can be...

For each polarity I built the PSU filter using a 2.7mh iron core, 16gauge choke between a pair of 68000uF caps, the ripple at 6amps is less than 10mv, DC voltage loss from the choke is about a volt...

Duncans psu simulator is absolutely great in this regard, every voltage and current I could check was as close as the tolerance of the components would allow, it's a great piece of software.

Stuart
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Old 1st February 2005, 04:53 PM   #618
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Default whats an aleph50

Ah, yes, good question...it's an aleph that puts out 50w per channel into 8 and 100w into 4. It is also the largest stereo aleph I can build using the heatsinks I have. It idles at about 300w, and uses 4 heatsinks as the sides of the cuboid case, and runs about 32c above ambient. I shamelessly copied the 'borg' look passlabs used.

Stuart
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Old 1st February 2005, 05:08 PM   #619
troystg is offline troystg  United States
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Default Re: pi filters

Quote:
Originally posted by Stuart Easson
For each polarity I built the PSU filter using a 2.7mh iron core, 16gauge choke between a pair of 68000uF caps, the ripple at 6amps is less than 10mv, DC voltage loss from the choke is about a volt... Stuart

What size x-former did you use, and did you have any problems with inrush current?

I am planning a similar supply but 20,000uF first, coil, then 30,000uF for each channel x 3... I will use a single 1kV -1.2kV toroid but am concerned about inrush current from the 60kuF caps before the coils.

Any comments welcome.
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Old 1st February 2005, 05:16 PM   #620
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Default inrush current...

I was worried about it at first, but after simulating, then building it wasn't a problem. The toroid I'm using is ~500va, smaller than yours, but the caps are larger. When I plug the transformer into the power, the lights blink, but they do that whether the caps are attached or not...I've read it's the core having to achieve a certain flux density before the emf from the transformer can inhibit the incoming current.

Originally I was going to use a pair of the transformers, but thus far a single seems to be able to do the trick, after it was rewound to get more current and less voltage.

Stuart
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