Mr. Pass

[thylantyr]

Mr. Pass,

Have you ever designed an amplifier output stage where
you used current sharing resistors, one per transistor,
plus a diode in parallel with each resistor ?

What is the pros/cons of said design ?

[Nelson Pass]

Not without some resistance in series with each diode also -
we have to avoid current hogging.

Generally when you put diodes in parallel with emitter/source
resistors, you are looking to limit the forward drop at high
currents and/or have more resistance for bias stability at lower
currents. I used something like this about 35 years ago, and
I'm aware that it also appeared in the HP "Barney Oliver" amplifier.

[thylantyr]

Thanks for the info.

This came up on another forum as certain car audio amplifiers
from two established manufacturers use this scheme. I don't
know who else at the moment. I never saw it done before.

The two manufacturers are Soundstream and Genesis.
In 2003, I asked if you did designs for Soundstream in
the early days -> yes

but I didn't see that scheme implemented in those original
amplifiers, as I saw some gut pictures.

Further researched showed that Wade Stewart had a hand
in later Soundstream products, then later Gordon Taylor's
Genesis products had this scheme.

Another internet search shows Wade having this business.
http://www.stewartaudio.com/

I guess I wanted to also see if he uses this scheme in the pro
audio amps he makes.

This scheme is almost akin to a fingerprint because the idea
seem so esoteric. If someone were to copy a design, they'd
copy the fingerprint unbeknownst to them that it's very unique,
implying they took the idea from someone else.

The 'who copied who' question got raised.

While that isn't that important, I was more interested in know
why this scheme would be used.

[clwong168]

I am a happy owner of X600. I have few suggestions to made:

To get sound as natural as possible and extension as wide as possible, I found to do the few things will help:

1. losing the nuts on all the Transformers and hand tighten it without any force.

2. Loosing all the cable ties

3. Remove all the Plastic cable heatshrinks and replaced with vinyl electrical tape but loosely binded.

The reason to do all these : To release any undue stress on the amp.

Your commends please,

clwong168

[juma]

Of course, loose nuts are always major improvement, it relieves the stress completely.

P.S.
When I say "loose nuts" I mean relaxed screwing.

[clwong168]

There is another cheap way to improve my x600 Amp: The Power supply cable of X600.
All Power Cables offer in the market are heavily shielded and are tightly wrapped with Heatshrink and the wires are screwed tightly. I removed all the Heatshrink, throw away all the nuts/screws of the terminal and using silver solder to weld the wires to the terminal instead. It will improve the sound quality.

[Babowana]

Originally posted by clwong168


I am a happy owner of X600. I have few suggestions to made:

To get sound as natural as possible and extension as wide as possible, I found to do the few things will help:

1. losing the nuts on all the Transformers and hand tighten it without any force.

2. Loosing all the cable ties

3. Remove all the Plastic cable heatshrinks and replaced with vinyl electrical tape but loosely binded.

The reason to do all these : To release any undue stress on the amp.

Your commends please,

clwong168

Reading this, I really don't know where is the border line between the seriousness and the joke . . .

[Netlist]

It is highly unlikely that a mod like this would improve the sound.
On top, I need to categorize it as very dangerous.

/Hugo

[thylantyr]

The X600 sound improvements are now on revision 2.0

[clwong168]

I put forward my findings in this forum to share. I am not joking.
It cost you nothing to try it. To loosing the nut on Transformer is easiest way to try, you can revert back if you do not like the sound. (Beware not to loose too much that the nut come out of the Transform. It will be difficult to fix back the nut)

I do not post here to joke but sharing. If you do not tried before, you should not give comments. How Do you know?

The principle behind what I am doing are to release any stress in the amp in ordere to get better sound quality.