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-   -   ZV7-T questions: (http://www.diyaudio.com/forums/pass-labs/145334-zv7-t-questions.html)

Dura 5th June 2009 02:35 AM

ZV7-T questions:
 
-I've been trying to figure out the individual dissipation in the ZV7-T circuit. This is what I have come up with so far: The voltage across the .5ohm resistor is 3V which with help from Ohm's law gives 6A total bias to the circuit, which at 30V gives 180W total. At 16% efficiency and 180W total this gives 30W output. The .5ohm resistor dissipates 20W which gives 130W left over. Approximately 50W is dissipated in each transistor in the differential pair and 30W in the CCS transistor. I am not sure if/how much the inductive loading transformer dissipates. Does this seem correct?

-Am I correct that it is not crucial in a differential amp if the transistors are matched? I plan on running the differential pair transistors in parallel. I know Mr. Pass stated in the original SOZ article that you didn't have to match them.

-When driving the SOZ unbalanced do you need to keep the gate resistors the same value or can it be omitted on one side since it is just grounded anyway?

-Does it mater if the .5ohm stabilizing resistor on the CCS transistor is inductive? I know Mr. Pass mentioned that for the original SOZ resistors it didn't matter if they where inductive but I thought this "stabilizing" resistor may be more critical.

-Will it work if a winding from a 1kVA transformer (about 1H) is used in a pi-network with capacitors? I am wondering if it would limit the current.

Brock

carpenter 6th June 2009 06:07 AM

I'm using the primary windings from an 1800 v/a transformer in a pi network and it supplies 15 volts/20 amps to my follower amp with no problems.

carpenter 6th June 2009 06:09 AM

I used wire wound resistors in my ZV7-T with good results.

Nelson Pass 6th June 2009 07:27 PM

Re: ZV7-T questions:
 
Quote:

Originally posted by Dura
-Am I correct that it is not crucial in a differential amp if the transistors are matched? I plan on running the differential pair transistors in parallel. I know Mr. Pass stated in the original SOZ article that you didn't have to match them.

-When driving the SOZ unbalanced do you need to keep the gate resistors the same value or can it be omitted on one side since it is just grounded anyway?

-Does it mater if the .5ohm stabilizing resistor on the CCS transistor is inductive? I know Mr. Pass mentioned that for the original SOZ resistors it didn't matter if they where inductive but I thought this "stabilizing" resistor may be more critical.

-Will it work if a winding from a 1kVA transformer (about 1H) is used in a pi-network with capacitors? I am wondering if it would limit the current.

1) It is not crucial, but it is helpful, particularly in keeping a low
DC differential offset voltage on the speaker.

2) Do not omit the Gate resistors or it will take off into oscillation.

3) Inductive is OK if it's not a lot. It will reduce high frequency
response depending on the amount.

4) The transformer is likely to saturate from the DC. Better to use
air core or open steel core inductors rated at high DC current.

:cool:

carpenter 6th June 2009 08:54 PM

Quote:

Originally posted by carpenter
I'm using the primary windings from an 1800 v/a transformer in a pi network and it supplies 15 volts/20 amps to my follower amp with no problems.

Incorrect, sorry. I'm using the 7mH SECONDARIES of this transformer. I hear nothing unusual, and there is no hum at the speakers.

carpenter 6th June 2009 08:57 PM

I used Dale RH-50 50W 0.5 ohm resistors. Highs were good. Inductance appears to 0.012 mH.


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