Zetex ZTX853/953 Upgrade

[Deleted]

juke
This is old stuff that is out of date, and Mike has had far too much on his plate to update it.
I drew attention to it because of the huge wealth of information that Mike has put there.
e.g. many members would want to have the schematic for their X-CAN V2.
Many of the services may no longer be available. Best to send Mike a PM if you want any specific information.
SandyK

[canjunkie]

Ah yes, that seems so long ago.

[dejanm]

Well, I was thinking lately about this heating phenomena of X-Can V2: why they are running cooler after updates ? If they are running cooler ... but I think yes.

This is a story that I came out with ...

What I know for certain (because I measured it) is that the regulated voltage after all the changes I made in PSU is higher than it was before for a couple of Volts. I am not sure whether exchanged ZTX transistors have something to do with that but that is one possibility. I will have to look more carefully into this regulator in order to understand better what has been changed.

This higher voltage drives output transistors (working in class A) which have a certian dissipation value. Therefore, higher voltage means smaller current that they provide at the output. That practically means that by putting new parts, larger elkos etc. in PSU increases a voltage and decreases the output current. Decrease of the current means also less power to the headphones but it also means less heating of all transistors involved.

Does this story makes sense ?

This unit still has enough power though to drive my Grado's (30 ohm) without any problems. So no issues in this department ...

[Deleted]

Does this story makes sense ?

NO ! At least not the bit about the higher voltage and less current. The voltage that is slightly higher, is it the B+ for the valves, or the voltage for the Class A solid state output ? If it is the B+ supply, a couple of extra volts is going to make very little difference.

SandyK

[dejanm]

SandyK,

I am talking about Vcc voltage supplying collector of output Darlington (Q106 on the schematic provided here).

[Deleted]

dejanm
Are you saying that the nominal 24V rail has increased to something like 26V ?
If so , I would suggest that if it has only increased after the fitting of the new ZTXs, and returns to the correct value when the originals are refitted, that the modification was ill conceived.
The regulated output voltage should remain the same after modification.There may be other changes needed in the PSU to rectify the situation, if these devices are used. It's hard to be more specific without a PSU schematic.
SandyK
P.S. I should have looked at the schematic ! I have been preoccupied with a new Samsung 24" HD monitor.

[PinkFloyd]

Nov 3, 2008 23:49:35 GMT @canjunkie said:

Ah yes, that seems so long ago.

Seems like years...... I too joined this forum after looking at that wonderful website

[Deleted]

I've joined the club here.

The Zetex are in, music playing. Only basic kit where i am now, so no actual impressions.

Thanks to Canjunkie for the how to and supplying these (and other parts I was having trouble sourcing).

I'm looking forward to plugging in at home

[Deleted]

Ok, I left the unit bedding in all evening at work.

Took it home, plugged in and let the other kit warm up. It must have been about 12:30 at night.

At 5:00 this morning my wife suggested it may be time for bed!

So, safe to say I was enjoying what I heard, plus I stayed on the K701 all that time, first time, I've always eventually switched to the HD600 on the xcan before.

I think the most stand-out improvement was on recordings where the mid-range info is a bit "fuddled", now being rather easier to hear the detail with a better flow, plus the sound seemed to a come a tad further away from the head than before.

I would could conclude that the improvement is more than subtle, closer to pretty impressive for just 2 components!

( to clarify my Xcan has improved valves, the elna kit upgrade, alps pot, Little Pinkie and now the Zetecs )