Aleph 4 to Aleph 5 modification?

[Alois]

Referring to my previous threat http://www.diyaudio.com/forums/showthread.php?s=&threadid=4158 I have made the following modifications to my Aleph 4:

- doubled heat sink capacity
- included 2 x 12 V low noise Pabst fans operating at 9V DC


The temperature has reduced to 65 C without the fans and 58 C if I have them turned on . I am still not satisfied to the extent that 65C is still quite hot and the fans can be heard at the listening position. I came across the article The Zen Variations – Part 3 “Active Supply Regulation” of Mr. Nelson Pass and consider converting my Aleph 4 into an Aleph 5. I would like to use the active supply regulation in order to reduce the rail voltage from +-48 to the requested +-34 without the need of changing my existing toroids. I do not really need the 100W of the Aleph 4 design and heat dissipation would go down from 500W to 300W what could easily be handled by my current heat sinks without using additional fans.

Since I love the sound of my current Aleph 4 the question really is what would happen. Does anybody have some experience comparing the 4 with the 5 and dares to make a statement? Will it be a side grade or downgrade? How will the active supply regulation influence the sound?

Furthermore the active supply regulation will generate some heat as well. The question is how much?

Regards,

Alois

 

[Nelson Pass]

Alas, the regulators will also heat up, and the dissipation
will tend to stay constant.

Try an inductor in series with the AC line. This will drop
your voltage and even improve your power factor. Start
with 1 or 2 mH and see what you get.

Heavy duty inductor only! Iron core with 5 or 6 amp rms
rating.

 

[Alois]

THANK YOU VERY MUCH NELSON PASS

It really is an honor to get a respond from you. Indeed I am thinking to convert my aleph 4 into an aleph 5.

Will the performance and sonic character change/suffer?

Any vote is highly appreciated

Regards,
Alois

 

[promitheus]

Doesn´t look bad at all. Very cool...or hot is better ?

 

[mefinnis]

Very nice!

The very problems you are experiencing were the basis of my choice to replace my A4 with an A5 as a permanent amp.

Question: Would another practical method for dropping the AC line-in be to use a capacitor divider network?

Regards, Mark

 

[Alois]

Thank you Mark!

It was actually your description of building your Aleph 4 that made me curious and inspired me! I have used the layout of your PCB. Thank you!!

Being a newbie and this my first amplifier that I have built I have very basic knowledge in electronics. Sorry, but I don't now what a capacitor divider network is? Could you please teach me a lesson?

Furthermore I still would like to know the sound difference between the 4 and the 5 before I start. Did you allready have the possibility to compare them?

Regards,

Alois

 

[woody]

One of the easiest ways to drop your voltage is to use a {buck or
bost } transformer. This is a transformer whose secondary is added or subtracted to the line voltage going to your power
supply transformer. Say a transformer with 30vac output wired
out of phase with the line voltage would yield 115vac- 30vac =85vac into your amps powersupply so your rail voltages would
be ~25% less. In general it is best not to run a transformer above it's rated input voltage but they seem to be ok at lower
input voltages/

Regards, Bob12345678 AKA Woody