A30 hardware

[Buhl]

We all love hardware......at least I do - this is some of the goodies that I have found 2.hand for use in my upcoming A30....

Trafo: 2x25 volts, 800 VA - can be wired to 2x23 - and will lose about 4 volts in 1ohm / 50 watt powerresistors

Heatsinks: big, unused, got the for free from a friend whos company didnt need them in production (Thnx Peter !)

What do you guess I could sink with one of those - 100 watt ?

[Buhl]

Heatsink from the top......

[Buhl]

Heatsink from the side.....

[Stabist]

Those heatsinks remind me to Classe amps ...

I doubt 1 peace is enough for 100W - if cutted on half - then you will easilly dissipate 100W on that new pair ...

[steenoe]

Nice heatsink Fat bodyplate, very nice.
If you have 4 of those, you can make a monster amp chassis
Did you consider a Aleph 5, with those 25V secondaries?

Steen.

[Buhl]

Cutting the heatsing in half ? - so I have to halves, that makes double width, but half the higth ? - The area will be the same, ABOUT 4600cm2 each - so I dont see how cutting them could make them better ?

Steen - I first got the PC board for A30, then ran across the trafo - I know its to large, so mabye ill get a 2x20 volt, but this was very cheap, and since I would like to burn a couple of volts in an CRC (got some nifty power resistors for mounting on heat sink...)

But, the original A5 used 3 transistors pr. side, just like the A30, sure it should be able to handle 27-28 volts instead of 25 ?? I plan to lose 4 volts in the supply resistor.....

I have 6 of the heatsinks, and mabye 4 more, if I pursuade my friend that he'll never get to use his, and I should build him a GC instead ;-)

But I also have 4 pcs. of Zen 4 channels lying, along with two puwersupplys, so a balanced Z4 should also be build....

And then theres the pearl phono that Im struggeling with - it has some hum when turned up, mabye some grounding problem....

Cheers !
Hans

[Stabist]

Buhl - believe me - just check the K/W curve in datasheets for heatsinks - after some height - for an average heatsink at arround 150mm - the curve becomes very flat - eg - a popular Fisher SK56 - at 100mm height - K/W is around 0,40, at 150 arround 0,32 and at 200mm 0,29

So cutting one SK56/200 into 2 100mm ones - you have 0,28K/W vs 0,4K/W//2-->0,2K/W ...

Is there really no difference??

[steenoe]

But, the original A5 used 3 transistors pr. side, just like the A30

You might be able to tweak the A30 PCB's into an Aleph 5, If you wanted to, that is
Stabist is right about the dissipation,IMO. But what a shame to cut those nice big heatsinks in half.
Did you make a GND connection to the PU arm, on your Pearl?

Steen.

[Buhl]

Oh my god - time flies....4½ years since I started on this A30 project....it is almost to embarrising....

Chose to follow your advice Stabist, and cut the sinks - had it done at a local machineshop that also cut the 4mm panels - they did not do a very good job on the sinks - however, each sink has a nice looking side that I can use as top side Even though they also managed to scratch the "nice" looking side

Attached a couple of pics fra about 3 weeks ago - right now the case is painted, circuits mounted, and I am in the process of wireing it up...more to come....

/Buhl

[Buhl]

Damn.....almost a year more went by.....Got my self into a lot of trouble - got almost everything wired up when I discovered that my transformers (4x150VA EI Cores) buzzed like a jigsawe at full rpm. Tried rubber insulation - did'nt work - tried more rubber insulation - did'nt work. Builded a mains filter from scratch - did'nt work - cut all wires in anger and threw the EI's to h... - found a large 750 Toroid from a local manufacturer, installed it, wired everything up (I know - test before you do this) - and it blew all fuses that I had - bought a finished soft start module (The biggest DIY sin...?) - it still blew fuses - found out I had the secondaries wired up wrong (I did not have make that mistake on the EI's - they provided the correct voltage )

So - ten months and a lot of cursing and frustration later....It is beginning to look like something.....