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Mini A Board Run

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john65b

john65b

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Joined 2005
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Hello all, I have an irritating question to ask...just got my Aleph boards from Brian and have most of the parts for the Aleph 5 - all transistors, resistors, caps, 1200VA 28-0-28 torrid, four monster 56,000uF caps, chassis with heat sinks capable of dissipating 150w per sink, etc.

Now for the dumb question - I know the components of the Aleph 30 differ from the Aleph 5, but can I build an Aleph 30 and put the +/-34VDC rails on her to get the equivalent of the Aleph 5 (provided the components are good to go for the 35V)?

I like the fact that the Aleph 30 has a higher input impedance than the Aleph 5 (my tube pre is a bit highish 3k), and I have the schematic for the true Aleph 5 too, just believe the Aleph 30 at the higher rails may be a better bet..

Thanks in advance
 
mpmarino

mpmarino

Member
Joined 2004
john65b said:
Hello all, I have an irritating question to ask...just got my Aleph boards from Brian and have most of the parts for the Aleph 5 - all transistors, resistors, caps, 1200VA 28-0-28 torrid, four monster 56,000uF caps, chassis with heat sinks capable of dissipating 150w per sink, etc.

Now for the dumb question - I know the components of the Aleph 30 differ from the Aleph 5, but can I build an Aleph 30 and put the +/-34VDC rails on her to get the equivalent of the Aleph 5 (provided the components are good to go for the 35V)?

I like the fact that the Aleph 30 has a higher input impedance than the Aleph 5 (my tube pre is a bit highish 3k), and I have the schematic for the true Aleph 5 too, just believe the Aleph 30 at the higher rails may be a better bet..

Thanks in advance
Click to expand...


... so you wanna build an Aleph 60 with less output fets? I think that would be maaarvelous.
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
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jleaman said:
I wonder how hard it would be to track down a set of SMD version of the Output fet's, maybe something lower value, smaller package but also SMD, it would be cool to build a 5Watt version for headphones or tweeters :)


Jase
Click to expand...


just use IRF510 ; just imagine it as SMD part which you bought with uncut legs and screw tab

edit:

you'll never stop amazing me .......... :clown:
 
mpmarino

mpmarino

Member
Joined 2004
Well, since an A5 runs on 6 fets/ch, I think an A60 will as well - same rails.

I believe you may get a bit more distortion using less fets (NP said?), but an advantage to less fets is that you can run more bias per device on a given heatsink as well as less capacitance. Oh, and simpler construction using the boards you have with no mods - :D
 
john65b

john65b

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Joined 2005
Paid Member
At only 6, my output devices will run hotter at the A5 voltages - my guess around 32 (I read Sir Nelson likes to be around 25), and the A60 has 12 devices because they are designed a bit lower to 17 ish...

I guess if I use monster heatsink or active cooling, the hotter temp may not be an issue for the lesser # of devices.

I'll try it.

I just have to decide on the KSA-50 Krell Clone (99% done) or the Aleph 60 (got all parts).

Just waiting for the chassis/heatsink from China.
 
P

pchw

Member
Joined 2006
I also want to build an A5 using Brian's board. Can someone kindly email me the service manual? Sorry for pain in the butt, please pm me via the forum, I will reply with my email.
I have the spread sheet that lists the different parts between A30 and A5, but I am wondering where C6 of the A5 goes?

Thanks,
 
J

jleaman

Member
Joined 2002
plus.google.com/photos/104656656065604242634/albums/5725366675475046257?banner=pwa&gpsrc
pchw said:
I also want to build an A5 using Brian's board. Can someone kindly email me the service manual? Sorry for pain in the butt, please pm me via the forum, I will reply with my email.
I have the spread sheet that lists the different parts between A30 and A5, but I am wondering where C6 of the A5 goes?

Thanks,
Click to expand...

to keep it simple, use brians xcell sheet's.

the manual can be found at passdiy.com.
 
P

pchw

Member
Joined 2006
Hi Jase,

Passlabs only has the owner's manual. It doesn't have the schematic. The spread sheet specifies 99% of the A5 values except the C6 of A5. The comment says "680pf no position on pcb". If I had the schematic, I can p2p solder this cap to the board.

Thanks,
 
john65b

john65b

Member
Joined 2005
Paid Member
The service manuals are no longer on the pass site.

It took me a while, but I finally found the service manuals for the A2, A4, A5, A30 and A60 with their respective schematics.

Email me and I can forward.

I trust that I am not breaking any rules by offering them? Please let me know.

I assume they were taken down for a reason.
 
john65b

john65b

Member
Joined 2005
Paid Member
Hehe, both amps are wonderful.
Click to expand...


Hmm, that's just what I need, more decisions.

I actually finished a Rod Elliot P-101 amp biased quite a bit to into Class A - well 12 watts Class A - but sounds very impressive. The remaining watts (to 90 wpc) are in Class AB with +/-30V rails.

What I find a bit confusing is the Aleph type amps, a change from 8 ohm load to 4 ohm, increases the power, which is understandable, but on the Krell, the same change has a reduction in overall Class A output power (per the Class A spread sheet I downloaded off Krell Clone WIKI).

I must be missing something quite obvious. I am a bit of a tyro...
 
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