Questions about the Aleph 5

[gabflo]

Could you give me more informations about :zen bablefish and jfet ?

 

[2 picoDumbs]

Could you give me more informations about :zen bablefish and jfet ?

http://www.diyaudio.com/forums/pass-labs/273318-about-possible-babelfish-j-interest.html

 

[gabflo]

2 picoDumbs
he look like great !!!
no match irfp150 , but how many watt for two irfp150 per chanel ?
Do you think I could use my transformers 2x35v?

 

[2 picoDumbs]

2 picoDumbs
he look like great !!!
no match irfp150 , but how many watt for two irfp150 per chanel ?
Do you think I could use my transformers 2x35v?

Pretty sure Zen Mod has output boards to allow for multiple pairs of output devices. You can basically build any powered version you want.
Send him a pm.

 

[gabflo]

I contacted him but no answer, I'll wait for his return and see for pcb. Thank you

 

[2 picoDumbs]

Here you go.

Finnaly , some graphical mishmash about Biggie version

attached pic as preview info , high resolution jpg and pdf on click

Do not mount Q10 , Q11 , R26, R27,R29 , R30

Mount (all of ) R31, R32 , R33 , R34 , R35 , R36

wire as shown

thick dia wires marked , medium dia wires marked , rest are thin

 

[Zen Mod]

I contacted him but no answer, I'll wait for his return and see for pcb. Thank you

I believe that I replied ........ yesterday, 08:55 PM

 

[gabflo]

Hello and sorry Zen Mod, I had not looked at my message.
actually evolved to the technoligie 5 and aleph is little to be more topical. I realized some years ago a hybrid amplifier class A based on irf 150, so I know the sound. I like the babelfish and his mount is tried and healthy.

I read the thread and I'm very interested. I do not have all my answers but I'll order a package.

A very fast for later

 

[gabflo]

Here you go.

And finally to complete my original idea, I realized the aleph 5. In 2016 the ZEN Mod !!!
PicoDumbs here are a few detected, measures for sets of irf 240, between 661 mV and 587 mV across resistors 1 ohm, 1.8A by rail. Speaker out 0,018 volts without load.
Do you think useful to install protection for speaker?
(some photos shortly)

 

[2 picoDumbs]

And finally to complete my original idea, I realized the aleph 5. In 2016 the ZEN Mod !!!
PicoDumbs here are a few detected, measures for sets of irf 240, between 661 mV and 587 mV across resistors 1 ohm, 1.8A by rail. Speaker out 0,018 volts without load.
Do you think useful to install protection for speaker?
(some photos shortly)

Come and join the ABFAB community. No need to install speaker protection.
You could test for voltage spikes/thumps across an 8 Ohm resistor at power on and power off before connecting you're precious speakers for the first time if you are worried.
Now take some pictures.

 

[ElectroNick]

Hi there,

I've been struggling with one channel of my A-5.
Can't get is stable at a acceptable offset level.
Left channel 7 mV, so good. But right channel gives me headaches....

Can it be that the power supply voltage is too high (36,5V on PCB) ?

 

[dungdochi1978]

Hi there,

I've been struggling with one channel of my A-5.
Can't get is stable at a acceptable offset level.
Left channel 7 mV, so good. But right channel gives me headaches....

Can it be that the power supply voltage is too high (36,5V on PCB) ?

Not high ( just lost power by heat ) .
Need check all values (R, voltage Zene ,..) make sure correct and matching mosfet again.

 

[res07njc]

Hi there,

I've been struggling with one channel of my A-5.
Can't get is stable at a acceptable offset level.
Left channel 7 mV, so good. But right channel gives me headaches....

Can it be that the power supply voltage is too high (36,5V on PCB) ?

Are you using a 500-1K pot above the diff pair current source to adjust this offset?

 

[ElectroNick]

Not high ( just lost power by heat ) .
Need check all values (R, voltage Zene ,..) make sure correct and matching mosfet again.

Because i had it at 35mV, i guess values are okay.
After testing i resoldered the components (at same location), and offset went up to 250 mV

Now checking for bad contacts. ( tapping on PCB gave some fluctuations).
This saga continues.....

Are you using a 500-1K pot above the diff pair current source to adjust this offset?

Because of one good channel, i'm confident it should work.
I should recheck/rematch the active components.

 

[ElectroNick]

Can it be a faulty transistor ?
I have less voltage on the top ZTX450, compared to the good channel.

Not enough gain on this device ?

 

[ElectroNick]

Headaches, just before Xmas....

Here are some measurements, replacing Q5 didn't help.... (Pass schematic part numbers)
First voltage is the good channel, second the bad one (200mV offset)

R11 : 5,35V & 5,39V
R14 : 4,73V & 4,67V
R17 : 24,8V & 25,0V
R18 : 7,9V & 7,8V
R19 : 11,7V & 11,7V

Q5(base) : 0,65V & 0,41V <=== ???
Q6(source) : 0.61V & 0.38V

Any suggstions what to check ?
I've replaced Q5 with types with different hFE, but that didn't help anything.

 

[ElectroNick]

Before desoldering Q6 to Q8, i changed R20 (with a wire) from Q6 to Q7 and later to Q8.
No effect, therefore i asume that Q6 to Q8 are not defect ?

Offset stays -200mV.

The question remains : why is the base of Q5 only 0,4volt. (Instead of 0,65 volt) ???
Please help....

 

[Zen Mod]

pictures ,maybe ?

 

[ElectroNick]

What pictures do you want ?

Btw : Boards are kk, the partnames i used are from the Pass schematics.

 

[Zen Mod]

any , which can bring some pop! in brain area