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Old 19th February 2013, 03:58 AM   #1821
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Default Distortion Meter

Me too !! One of those nice Audio Precision rigs would be a nice birthday present, but my wife thinks its a dumb idea !!
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Old 19th February 2013, 04:01 AM   #1822
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She feels the same way about the new 'Vette (make mine a Z51 in silver....)
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Old 19th February 2013, 04:37 AM   #1823
6L6 is offline 6L6  United States
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You can get used first gen AP rigs for about a grand. (Although you need an old windows machine to run it...)

This looks fantastically interesting -- QA400 Audio Analyzer And it's only $200!!!!

Vette? A '70 or '71would be great, but honestly any chrome-bumpered Mako would be fine.
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Old 19th February 2013, 01:22 PM   #1824
poli is offline poli  Germany
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Hi guys,
thanks a lot for all your answers! I will check out the MOS-FET and the other ZTX450 transistors. Yes, I have a jumper in place for R15.

One more question:
Did you have problems in adjusting voltage between R16 and R17 with P1 to 0V DC? I find it very difficult, I am having drift to +- 0.3 V - is that normal?

Thanks
Poli
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Old 19th February 2013, 02:05 PM   #1825
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Hi Poli ,

that drift is within spec ....

I checked my VDC and all good ,but I do have a short fall where I need 10mA
I'm getting .03 mA

Rich
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Old 19th February 2013, 02:34 PM   #1826
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Quote:
Originally Posted by poli View Post
Hi guys,

One more question:
Did you have problems in adjusting voltage between R16 and R17 with P1 to 0V DC? I find it very difficult, I am having drift to +- 0.3 V - is that normal?

Thanks
Poli
300 mv seems high. I would think you could get under +/- 15 mv.
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Old 19th February 2013, 04:20 PM   #1827
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Originally Posted by richluvsound View Post
Hi Wellerman ,

was this post to me or Poli ?
To poli, but maybe it is of some use to you too
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Old 19th February 2013, 04:24 PM   #1828
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Quote:
Originally Posted by bnorrish View Post
What clued you that ZVP3310 was bad? Did you measure ~ 10 mA current going into per Wayne's voltages diagram?

I used 10R instead of 10K on R7, R8 and R10. I think I get carried away stuffing all the 10Rs. After replacing them, found out that Q1 and Q3 were bad. Waiting for an order of ZTX450s. I only ordered 10.
Well,actually a post by someone having a bad ZVP. Voltages around mine were ok, but I thought I'd try to replace it anyway and fortunately that worked.
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Old 19th February 2013, 05:18 PM   #1829
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Quote:
Originally Posted by poli View Post
Hi guys,
thanks a lot for all your answers! I will check out the MOS-FET and the other ZTX450 transistors. Yes, I have a jumper in place for R15.

One more question:
Did you have problems in adjusting voltage between R16 and R17 with P1 to 0V DC? I find it very difficult, I am having drift to +- 0.3 V - is that normal?

Thanks
Poli
My voltages drift too. I replaced my dmm as it drifted in the mV range with the leads not connected. But even with the new one (Metrel 9040) the voltage drifts. I also noticed that it takes some time before the readings stabilise a bit. When connected I might get a few 100 mV or even over 1V, which then continually decreases to more normal voltages. I can get it to drift between 30mV with occasional peaks around 60mV. Also P1 is quite sensitive around the 0V point. Just a tiny bit of adjusting might get the voltage from say 80mV to -50mV.

What I do now is to let the Pearl II warm up for at least an hour, then conect the dmm and watch the voltage for quite some time, ocasionally adjusting P1 until I've got the feeling that I get satisfactory readings.
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Old 19th February 2013, 05:33 PM   #1830
Salas is offline Salas  Greece
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Looks like a Brymen OEM meter possibly, which is a good thing.
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