Death of Zen 15 watt Power Amplifier

[shaan]

Hi guys. Sorry, I was out for some time due to serious net connection failure. How've you been?

Originally Posted by kp93300

I noted 2 minor problems :
1) I notice that it is very sensitive to switches of power supply in other parts of the house. There is a rather obvious thump audible through the speaker.

An extra resistor should solve it. See the attachment. 1K right after the input cap.

2)The bias current fluctuates between 1.5 amp to 1.8 amp.Input V is 22 V to 23 V
Hi, Shaan is there anyway of stabilising these?

Yup. Zeners. Only one per channel. An 18V zener would be best.

Steps:- 1K resistor from positive rail to zener negative lead. Zener positive lead goes to ground. Disconnect VR from positive rail and connect the pin to zener negative lead. Done.

Cheers.

[kp93300]

Hi all,
More listening impressions through a 93db/1w/m open baffle speakers and powered subwoofer.

It has the signature of JLH 69 but everything is more. More extended bass, more smooth vocals and more extended high.

The timbre of piano is very , very good .

The ambient retrieval is also better. Big drums are protrayed well with the perception of the skin being hit and very nice reverberation of the sound around the recording studio.
Vocal are more detailed and sound very human .

It is more holographic. 3D and sound stage is lifesize with a walk through sensation. This is the most impressive aspect .

Hope to start on the cap multiplier power supply soon.

Shaan
Thanks for the reply. See the attached drawing.
Is this the correct wiring ? I was thinking of retaining the VR in the circuit and regulated the V in the + and _ power supply rail before the amp. In this way you can still adjust the Iq


You are right, I am over the moon !

thank once again

kp93300

[shaan]

Originally Posted by kp93300

Hi all,
More listening impressions through a 93db/1w/m open baffle speakers and powered subwoofer.

It has the signature of JLH 69 but everything is more. More extended bass, more smooth vocals and more extended high.

The timbre of piano is very , very good .

The ambient retrieval is also better. Big drums are protrayed well with the perception of the skin being hit and very nice reverberation of the sound around the recording studio.
Vocal are more detailed and sound very human .

It is more holographic. 3D and sound stage is lifesize with a walk through sensation. This is the most impressive aspect .

You've got very sensitive ears.

Hope to start on the cap multiplier power supply soon.

DOZ will be happy with a simple CRC filter with 33000uF+0.5ohm(5watt)+33000uF in both rails of the power supply. Cap multiplier is still welcome though.

Shaan
Thanks for the reply. See the attached drawing.
Is this the correct wiring ? I was thinking of retaining the VR in the circuit and regulated the V in the + and _ power supply rail before the amp. In this way you can still adjust the Iq.

The VR is essential part of the circuit. What I meant in my last post is to disconnect only the VR pin that goes to + rail; not the whole VR from the board. See the attachment.

You are right, I am over the moon!

kp93300

It was just a matter of time. Enjoy your moonwalk.
Cheers.

[shaan]

Originally Posted by lizhi3amorphous

why no anyone talk to me?
I ma engineer of Anhui Lizhi Soft magnetic Material Co.,Ltd in China

maybe I can solve your questions
we have amorphous cutting cores ,common magnetic chokes ,PFC reactor that can solve your since wave of power inverters or modified sine wave power inverters

lizhi, it seems you don't know the forum rules, didn't read/understand the first post of this thread, don't care what we are talking about, and are here for advertising purpose.
You are posting wrong things in the wrong place. Please do not post anything off-topic, otherwise I will have to report your activities to the moderators.

[kp93300]

Originally Posted by lizhi3amorphous

why no anyone talk to me?
I ma engineer of Anhui Lizhi Soft magnetic Material Co.,Ltd in China

maybe I can solve your questions
we have amorphous cutting cores ,common magnetic chokes ,PFC reactor that can solve your since wave of power inverters or modified sine wave power inverters

Hi lizhi3amorphous
Sorry you feel that way .
I feel intimated by your credentials !
My electronic knowledge is limited to what I learn from this forum and people like Shaan.

I am willing to learn any suggestions from you to improve my audio experience and diy knowledge.

thanks
kp93300

[shaan]

So the direct coupled version has been confirmed okay as well as the normal cap coupled DOZ. I was wondering whether the direct coupled one would do the same in other diyer's case as it did for me. Let us see who's the next happy guy to have built a DOZ himself.

cheers...

[kp93300]

I add the zener described in post 103 and Iq is much more stable --between 1.7 to 1.8 amp depending on ambient temp.
There is added benefit as the output transistor temp is more predictable --between 50 to 55 deg c in non air con room with ambient temp of about 30 deg c.

One channel when into oscillation last night and thanks for the speaker protection unit
After trouble shooting for 2 hours notice a poorly soldered resistor .

Still having a honey moon with the amp:

regards

kp93300

[shaan]

Originally Posted by kp93300

I add the zener described in post 103 and Iq is much more stable --between 1.7 to 1.8 amp depending on ambient temp.
There is added benefit as the output transistor temp is more predictable --between 50 to 55 deg c in non air con room with ambient temp of about 30 deg c.

That's good to know.

One channel when into oscillation last night and thanks for the speaker protection unit.

I wasn't that lucky. Lost a speaker a couple of months ago due to current source oscillation in the JLH modern version.

Still having a honey moon with the amp:

regards

kp93300

LOL.

[kp93300]

Hi
Last weekend one of my friend who owns audioresearch reference series gear and SF Ellipsa speaker comment very positively on the sound of the amp.
I hope more will build it .

Shaan,
Are there any other trans with better spec than TIP 3055 ?
My output tran is off board and easy to swap
Eager to milk the maximum out of this circuit !

thanks

kp93300

[shaan]

Originally Posted by kp93300

Shaan,
Are there any other trans with better spec than TIP 3055 ?

kp93300

TIP3055 = Good choice(Standard).

TIP35C = Better choice(monster with 25A collector current! WHOA!).

MJL21194 = GREAT choice(LARGE TO264 body, better dissipation, 4MHz, perfect).

2SC5200/MJL3281 = Best choice(Bloody fast BJTs with close to perfect characteristics; BUT thermally unstable and might introduce parasitic oscillation. )

cheers.