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Old 21st October 2013, 04:27 PM   #311
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Thanks guys. Yes, went through the treatments. So far NED but left with neuropathy and no saliva. Big wake up call. The days we have are a gift and numbered. I plan to make the best of them. I do this for fun. I am learning as I go. It has been great meeting all you fine folks too. That is the best part of this hobby.

Blessings, Terry
I have to say that I enjoy watching your work Terry. I know Andrew wants good to all of us. His advices helped many members here. Bu his style is distinctive little bit.
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Old 21st October 2013, 06:44 PM   #312
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Hi Guys,

Didn't mean to cast a dim light. Thanks for all the well wishes. I have 4 amps right now that need cases. I need to get to the metal supply house and get some more materials. I hope to get these finished up before I start another but I'm not promising anything.

I'm really hoping to get this one done so I can listen to it properly. I listened to the single channel for a couple hours yesterday and it just seemed to sound better and better as it burned in.

Blessings, Terry
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Old 21st October 2013, 07:18 PM   #313
AKN is offline AKN  Sweden
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Hi Terry,

+1 health wish from me.
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Old 21st October 2013, 07:46 PM   #314
Bigun is offline Bigun  Canada
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Originally Posted by still4given View Post
I hope to get these finished up before I start another but I'm not promising anything.
I suffer from that problem too !

Have you started to look at playing with valves (vacuum tubes) yet ?
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Old 21st October 2013, 08:34 PM   #315
PauloPT is offline PauloPT  Portugal
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Hi Terry,

Health wishes from me too and lots of fun with your builds!
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Old 21st October 2013, 09:19 PM   #316
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I suffer from that problem too !

Have you started to look at playing with valves (vacuum tubes) yet ?
My son keeps after me to build him a tube guitar amp.

Thanks again for all the well wishes.

Blessings, Terry
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Old 23rd October 2013, 08:52 PM   #317
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OK, so I have a blown output. An IRFP9240 to be exact. Rather than order another matched quad, I just ordered some IRFP9240 devices which means I will need to match them myself. My question is will using this circuit for the P-channel device work well enough to match them for this amp? I think Nelson suggests a 2k2 for the resistor.

Click the image to open in full size.

How close in voltage do they need to be to be considered a good match?

Thanks, Terry
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Old 23rd October 2013, 09:24 PM   #318
PauloPT is offline PauloPT  Portugal
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Hi Terry,

10mV Vgs is close enough.

You can always do a differential matching like I did. See the pic.
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File Type: gif Differencial Mosfet Matching.gif (2.6 KB, 502 views)
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Old 23rd October 2013, 11:14 PM   #319
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I was able to match a pair but now it seems I have a problem with the other 2 as well. they are not shorted but I'm reading about 30R between the source and the gate. Going to have too pull them and see what's up with that. I'll get back to you.

Thanks, Terry
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Old 29th October 2013, 10:35 PM   #320
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I received the replacement parts this morning. I have been listening to it for a couple hours now. This is a very good sounding amp. It is slightly darker sounding than the VSSA but not in a bad way. I have been A/B'ing them for a while and it is very subtle but there is just a slight difference. The GB150 is lovely on female voices. I am looking forward to listening to it for a few days.

One thing I did want to ask is the bias setting. I know I had something to work from but I can't find it. I checked the side I had working and it was set at 240mA per rail so I set this side at that too but I don't know it that is right. The outputs are running at about 56C mounted to my test heatsink. I know Nelson uses these output in his Class A amps so I would guess that is OK but I would like to have the amp operating where Greg intended so if any of you know the proper way to set the bias I would appreciate hearing from you.

Blessings, Terry

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