Questions about the Aleph 5

[KatieandDad]

The Aleph design creates a lot of internal heat. I know, I've got an Aleph 4. They tend to cook the capacitors. I've had to change all the big C's twice in 12 years, they are not cheap to replace.

 

[Zen Mod]

Capacitor in parallel to D5 (Z5 on original schematic) better NP or electrolytic?
Also, ina thread from Pass, he suggested to also put a capacitor in parallel to the other zener (Z1,Z2 and Z3,Z4) value between 1 and 4,7uF

point me to exact schematic you're speaking about

 

[DiegodB]

please refer to the attached schematic.


capacitor in parallel to all zener diodes

 

[DiegodB]

ZM,
in case a capacitor is put in parallel to Z5, Z1-Z2 and Z3-Z4 must it be electrolytic or non polarized?

thank you

 

[Zen Mod]

Z5 - OK , put 10uF elko

Z1-Z4 - whatever you put there , you'll make silencer instead of amplifier



(in short - don't do that!)

 

[DiegodB]

Thanks ZM!


also, concerning the power supply, would it be good to put a MKP capacitor (0.22-0.33uF) on the primary winding ot the tranny and two MKP (0.47-0.68uF) on each secondary winding?
I would not build a power supply with CRC or CLC filter


thank you again

 

[Zen Mod]

don't do that with xformer

find and read Quasimodo and Cheapomodo threads here

if you are not sure in what you're doing , better don't do anything

this table is good , but as semi-patch , not proper one , made after adequate test:

 

[DiegodB]

ok ZM!
maybe better to buy the soft start board together with the speaker protection one from the diyaudio store.

 

[DiegodB]

Quick question about the power mosfet positioning on the heatsink:


better to place them horizontal or vertical, see pictures


thank you

 

[DiegodB]

Hello ZM,


PCB development is in progress, I finally decided for the traditional 2 layers!


question about the output devices (IRFP240):


- the original design has 3 paralleled devices while the modified M10 has 4 in parallel. is there any advantage to have 4 instead of 3?


- power transformer output voltage question, would it be possible to have 2x26Vac as secondary?
- 26x1.41=36.7 - 1.4 =35.3Vdc
the original A5 asks for ±34Vdc voltage rails. don't think an addition volt and a half would be a pain.


thank you

 

[Zen Mod]

more output pairs , if you don't change anything - more heat and more grunt on 4R speakers

don't forget to alter current sense resistor group , according to number of mosfets .... in fact - that's already done on that schm you posted

for 34Vdc rails , compute AC as DC/1.25

so around 28Vac

1.41 is for lightly or non- loaded rectification/filter

 

[DiegodB]

As usual, thank you ZM!


very helpful

 

[Chamberman]

Hello Diegod,

I just noticed your questions about Aleph 5 and thought I'd add my two cents because I built a set of amps similar to what you're investigating.

I built a pair of Aleph 5 mono's with 4 outputs instead of the normal sets of 3. I've biased them up a bit and have them at 600mA per device on 33VDC rails. I'm using an Antek 500VA - 25V X 2 transformer in each mono amp. My incoming AC voltage is a bit high here at 125VAC so I get a little bump on the rails of my amps. If it was more normal at 115 -120VAC then my DC rails would be < 32VDC.

I recently went through the amps and installed SJ313's for the diff pairs and cleaned a few other problems up. I posted some info about the amps with some measurements here.

 

[DiegodB]

Hello ZM,


as per your suggestion to have the possibility to trim the bias, is the attached circuit correct?


The 221K resistor replaced by the R150K - POT100K - R150K


is the POT correctly connected?




thank you

 

[Zen Mod]

better like this

 

[DiegodB]

Thanks!