A30 hardware

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 ?
 

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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
 
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??
 
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
 

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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.....
 

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Here is one more picture - where she is playing sweet music with her friends: Pearl Phono and Balanced Zen linestage. Sound is really good - definetly Class A character with very "liquid" or easy sound - especially in the middle. This is very similar to the Zen4 I build earlier, but unlike the Zen, the Aleph is much more "extended" in the frequency outer ends - highs are better, and lows are also stronger, and more defined. Low end definition is still however not the strongest side of this amp I think. The soundstage is more laid back than with the popular Gain Clones - however, the sound seems to have more ambience to it - more room details. The difference between vinyl and CD's are larger than ever before with this amp - possibly due to the good reproduction of weak ambience sounds??
Also - it sounds like a really large amp - not stressed or collapsing when played loud (I have Snell E/III which is an relatively easy drive though!)

My only problem is a slight 50Hz hum which troubles me. I have floating grounds, which means that my grounds are not common betwean the cannels and also not connected to the chassis (tried this, but no change). PSU ground, Speaker Ground and GND on the A30 board meet at a star point for each channel - signal ground is run directly to the RCA/XLR. Think it may be stray field introduced?

Anyway, big thanks to Nelson for sharing this design, and also to Peter D for his very, very nice PCBs! - also Steen for sharing some of his matched mosfets!!!

/Hans
 

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