Aleph 5, change of sound ?

[ElectroNick]

Hi,

After a few years, i wanted to change my bulky stereo A5 into a set of mono amps. The large stereo version was so heavy, i couldn't lift it.
Also it is not practical......

So i decided to start collecting stuff for making the mono chassis.
New heatsinking, new transformers, new capacitors, etc, etc.

But after a few listening hours i get the feeling, i'm missing the punch in the bass. I think the stereo chassis did it better.
Although i think the specs should be better, it sounds not better....

Stereo version :
1 x 800 VA transformer
6 x 68000uF caps (3 per rail)
Low offset (after tweaking with R11 (221ohm))
1 x Heatsink(0,1K/W) (temperature was good, no burning hands...

Mono version :
1 x 600 VA transformer
4 x 68000uF caps (2 per rail)
again low offset
2 x Heatsink(0,2K/W) temperature was lower

I wired the 3 transistors with 14 AWG wire to the opposing heatsink.
That should be enough, right ?

I'm affraid that bending the legs of the output devices again might break them, so therefore i try to get help on the forum.
Maybe i made a mistake, don't know....

Anybody ideas about the change of sound ?

regards,
Nick

 

[Zen Mod]

same rails voltage ?

don't bother with reasons for different sound , try adjusting Aleph AC gain to your liking

 

[ElectroNick]

Yes, railvoltage is the same.

 

[Andersonix]

Are your gate blocker resistors close to the output transistors?

 

[ElectroNick]

Nope, they are on the PCB.
So, about 20cm wire between them.

 

[Andersonix]

http://www.diyaudio.com/forums/pass...-vs-gate-stopper-jfet-inputs.html#post5332375

A recent reminder to place the gate blocker ON the transistor pin.
"Resistor/s located some distance away from the Gate leadout with long traces/leads will add some inductance to the Gate lead and can make de-bugging of problems later in the build more difficult to find/analyse. "
(Thanks AndrewT)

 

[Juntuin]

Nope, they are on the PCB.
So, about 20cm wire between them.

As others stated, move resistors to relocated transistor pins and replace their places on pcb with jumpers.

 

[ElectroNick]

Wow, moved the resistors direct on the output devices.
It’s really better now.

Will start listening this week to see if it is like the old setup.

Thanks for now !

Regards,
Nick

 

[Andersonix]

Really?!

 

[ElectroNick]

It’s not as if a loudness button was suddenly switched on....
There’s a subtle difference.

More people have output devices devided on multiple heatsinks, so i don’t suspect the wires. They’re thicker than the PCB traces.

If i’m not convinced, i might switch back to the old situation. But that’s the ultimate step. 😕

 

[Juntuin]

Did you noticed any diffirence between temperatures of heatsinks before and after gate blocker resistors relocation?

 

[ElectroNick]

No. But i only listened for a short period (night time...)

But the mono versions are much cooler than the stereo version.
Altough the K/W should about be the same.