Aleph J illustrated build guide

[Zen Mod]

that means entire Aleph CCS control mechanismus is bootstrapped to output

meaning - it is swinging along with output node , R25/R26/C2 node - way above upper rail , keeping working parameters (almost) unchanged

 

[Bobsburger]

I think you're talking about C3. C2 is the bootstrap capacitor.

 

[Bobsburger]

Yes but why does it have to be so big? In spice the distortion goes down with a sane capacitor value and it brings down the amount of AC current diverting into the cap as well.

 

[Zen Mod]

wrong

 

[Bobsburger]

Can you explain?

 

[Zen Mod]

if you're talking about C2 (bootstrap cap) - you need to think about lowest frequencies ....

if you're talking about C3 (Aleph CCS modulation path) - you need to think about lowest frequencies

 

[Bobsburger]

The time constant between C2 and R25/R26 is 0.4/0.2 hertz. Lowest frequency of interest should be 20hz. What am I not understanding?

 

[Zen Mod]

and what's phase shift , when you take cap good for 20Hz , not lower ?

 

[Bobsburger]

Don't know, I know little about phase shifts and their effects

 

[Zen Mod]

irrelevant - just remember that , to avoid phase twisting , you need to calc RC constants pretty low

that's good for start , until you really learn what's phase shift/twist

 

[Bobsburger]

Okay thanks for the advice

 

[krivium]

Hello, Bobsburger capacitors modify phase up to one decade past the determined fc. Thats a reason you sometines see way higher capacity that you would allow for your target audio fc.

 

[manniraj]

something is fishy

do what I said in #1894

I got my Aleph J singing today after about couple of weeks and thanks to all guiding me on the issues. The issue was with couple of mosfets damaged because of the heat not being dissipated to the heat sinks. Those mosfets were no properly mounted on the heat sink and hence got damaged. So ordered matched mosfets again and had to wait for some weeks and I received them last week and replaced all the 4 mosfets with proper mounting of new heat sink holes/tapped. This time I used hex screws rather than the usual star screws for mosfet mounting.

I set the bias to 400mv and the heat sinks are manageable and hot to the touch. I think I will not go beyond 400mv bias as the heat sinks may not manage with our tropical climate. Managed to get 0.1mv dc offset on both the channels and after playing for more than couple of hours the offset drifted around 4 to 5mv otherwise pretty stable. The hottest amp build so far

Thanks

 

[biju55]

I got my Aleph J singing today after about couple of weeks and thanks to all guiding me on the issues. The issue was with couple of mosfets damaged because of the heat not being dissipated to the heat sinks. Those mosfets were no properly mounted on the heat sink and hence got damaged. So ordered matched mosfets again and had to wait for some weeks and I received them last week and replaced all the 4 mosfets with proper mounting of new heat sink holes/tapped. This time I used hex screws rather than the usual star screws for mosfet mounting.



I set the bias to 400mv and the heat sinks are manageable and hot to the touch. I think I will not go beyond 400mv bias as the heat sinks may not manage with our tropical climate. Managed to get 0.1mv dc offset on both the channels and after playing for more than couple of hours the offset drifted around 4 to 5mv otherwise pretty stable. The hottest amp build so far



Thanks

Congratulations [emoji3]


Sent from my iPhone using Tapatalk

 

[gadut]

I got my Aleph J singing today

Upload your 'porn' here, share the glory

 

[Zen Mod]

yup

no porn , no trust

 

[manniraj]

Ok here you go

 

[Zen Mod]

finally proper use of ML case

 

[6L6]

Wonderful!! Well done!!

 

[ColinA]

You can never have too many blue LEDs!