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Post by backwardsman on Jan 26, 2008 19:17:46 GMT -7
OK, I know the two sides of the 12ax7 phase inverter in my Maz38 Sr should be "balanced". I currently have a JJ in that slot that was purchased new as "balanced for a phase inverter." Now my question is this....I have a NOS Mullard which measures 1350 on one side and 1400 on the other--is that considered close enough? Or should it be closer?
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Post by dixiechicken on Jan 27, 2008 5:07:34 GMT -7
Ask Myles that qustion - or Doc himself - they could probably help out better than just about anyone else.
Cheers: Dixiechicken!
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Post by myles on Jan 27, 2008 15:53:01 GMT -7
OK, I know the two sides of the 12ax7 phase inverter in my Maz38 Sr should be "balanced". I currently have a JJ in that slot that was purchased new as "balanced for a phase inverter." Now my question is this....I have a NOS Mullard which measures 1350 on one side and 1400 on the other--is that considered close enough? Or should it be closer? I normally match phase inverters on a few points and not just TC. I actually curve trace them. You can have a tube with the same TC on each side yet have totally different gain on each side if their plate resistance is not equal which is usually the case. But matching TC is better than nothing. The VTV tester is great at matching as it actually plays the two sides of the tube against each other and that is as good as it gets without going the curve tracing route. Tubes that have been "matched" on the VTV tester generally trace perfectly and the VTV tester is a heck of a lot smaller and cheaper than a Tektronix 570 curve tracer.
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Post by backwardsman on Jan 27, 2008 18:08:28 GMT -7
Thank you Myles. As a follow up, (since I don't have access to a VTV tester or a curve tracer), can you tell me what the "typical" results will be if the phase inverter is not well balanced. I'm just thinking if I use this Mullard 12ax7, what will be the expected audio clues, if any, to a bad choice....Thanks again, you've been very helpful to the is entire forum!!
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Post by myles on Jan 28, 2008 10:12:32 GMT -7
Thank you Myles. As a follow up, (since I don't have access to a VTV tester or a curve tracer), can you tell me what the "typical" results will be if the phase inverter is not well balanced. I'm just thinking if I use this Mullard 12ax7, what will be the expected audio clues, if any, to a bad choice....Thanks again, you've been very helpful to the is entire forum!! I have an entire section on my website on this subject.
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