Aleph 5 Running (Pic)

Jye · 6th February 2005, 11:42 PM

Hello all...

Finally got the caps for my Aleph 5 and powered it up 9am Saturday morning. Surprise surprise no sparks flames or smoke. After a couple of minutes everything heated up evenly and I measured the following voltages:
LEFT R14 4.52V, R11 5.32V Z5 9.06V, C7 4.46V and the output resistors 0.629, 0.605 and 0.542V and DC offset 8.5mV.
Right R14 4.54V, R11 5.25V Z5 9.06V, C7 4.59V and the output resistors 0.603, 0.611 and 0.659V and DC offset 4.3mV. After 1 hour and 10 hours of play these values had not changed by more than 10mV.
Power supply is CRC with 30,000uF (Will be 40,000 when I get the final 2 caps from back order), 2 1 ohm resistors in parallel and 40,000uF per rail. The voltage before and after the resistors are 38.1 and 36.3V so I am thinking of increasing the resistance the bring the voltage down to 34V and to try and reduce a bit of the hum that you can hear from about 1m away, and reduce the temp since the thermal switches cut in twice (it probable didn't help that it was 35C over the weekend

)

I wouldn’t like to comment on the sound yet as I have it running through a crappy pot I had lying around for some sort of volume control.

Finally but not least I would like to thank Mr Pass for this wonderful amp and Mark for his helpful website and PCB design and of course anyone who has answered my questions on this site

Will post a final pic when the case is properly finished.

PS a few more pics on my so called website

Cheers
Jye

jleaman · 7th February 2005, 06:17 AM

Looks good.. link broken.. here though.

http://www.users.on.net/%7emefinnis/passlabs/aleph5.htm

csmith · 7th February 2005, 06:29 AM

Wow, cool.

It looks nearly as good in the picture as it does when I saw it in person on the weekend.

Taco · 7th February 2005, 06:33 AM

Wow, nice metalwork! About the hum, you say you've used a crappy pot. Maybe an external grounding problem?

george a · 7th February 2005, 06:52 AM

Hi Jye

well done and congrats.
Looks like you've used the same heatsinks I ended up going for...

Mine in FINALLY going, not without some assistance from Mark (I pinched his Variac)
My thermal cutouts are about 3-4cm from the mosfets and have not cut in yet with a heat rise over ambient of 37deg. (measured between fins near fets)

Voltages similar to yours excepting offset which is a bit higher.

I hope you are as happy with yours as I am with mine..
Cheers.

Jye · 7th February 2005, 07:13 AM

Thanks for the comments guys.

Taco I think the hum is the same problem most people have with their power supplies, but I could be wrong. Will have a look around with a CRO soon and see.

George you say yours rises 37C above ambient temp....well on the week end that would put mine just over 70C since we had 35C all weekend up here in Brisbane

As for the sound, when get some sort of decent preamp I will comment BUT I will say I can hear an improvement in the bottom end.

I didnt have a Variac so I just bit my lip and turned it on and all was good

Jye

7th February 2005, 06:52 AM	#5
george a diyAudio Member Join Date: May 2002 Location: oz	Hi Jye well done and congrats. Looks like you've used the same heatsinks I ended up going for... Mine in FINALLY going, not without some assistance from Mark (I pinched his Variac) My thermal cutouts are about 3-4cm from the mosfets and have not cut in yet with a heat rise over ambient of 37deg. (measured between fins near fets) Voltages similar to yours excepting offset which is a bit higher. I hope you are as happy with yours as I am with mine.. Cheers. __________________ george a

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7th February 2005, 06:17 AM	#2
jleaman Banned Join Date: Apr 2002	Looks good.. link broken.. here though. http://www.users.on.net/%7emefinnis/passlabs/aleph5.htm

7th February 2005, 06:29 AM	#3
csmith diyAudio Member Join Date: Aug 2004 Location: somewhere	Wow, cool. It looks nearly as good in the picture as it does when I saw it in person on the weekend.

7th February 2005, 06:33 AM	#4
Taco diyAudio Member Join Date: Nov 2002 Location: Place in the Netherlands	Wow, nice metalwork! About the hum, you say you've used a crappy pot. Maybe an external grounding problem?

7th February 2005, 07:13 AM	#6
Jye diyAudio Member Join Date: Aug 2003 Location: Brisbane, Australia	Thanks for the comments guys. Taco I think the hum is the same problem most people have with their power supplies, but I could be wrong. Will have a look around with a CRO soon and see. George you say yours rises 37C above ambient temp....well on the week end that would put mine just over 70C since we had 35C all weekend up here in Brisbane As for the sound, when get some sort of decent preamp I will comment BUT I will say I can hear an improvement in the bottom end. I didnt have a Variac so I just bit my lip and turned it on and all was good Jye