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Post by eggman on Aug 20, 2022 7:47:44 GMT -7
Howdy, This old man wants to know about Post phase inverter master volume and its effect on amp tone. 1. If say, a Dr. Z Jetta were made without PPIMV and compared to a stock Jetta in a blind test-particularly with the Master volume knob all the way to 10, is it likely one could hear a difference? 2. When being overdriven (With the master volume knob on 10 and no pedals) are we hearing the output tubes being overdriven to the same degree we will hear a Carmen Ghia's output tubes being overdriven? I'm thinking of pretty much any current Dr. Z amp with PPIMV here. Thanks in advance. As many here on the forum know, I have an acquired distaste for Master volume since buying my first combo amp with that feature in my teen years in 1980. The Carmen Ghia is fantastic, but you all know this
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Post by LT on Aug 22, 2022 14:21:13 GMT -7
I don't know the technical answer to your questions, but I've never had a MV as well designed as Doc's. To my ears, it almost is like a fader on a mixing desk. It simply changes the loudness, and does not affect tone (IMO). The Level control on the Cure is an example of this.....brilliant!
MV's have changed a LOT since 1980. I've had MV amps where you had to re-balance the Input and MV if you wanted more or less overall volume, so I know what you're talking about.
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Post by Don A on Aug 22, 2022 15:15:41 GMT -7
I don't know the exact PPIMV that's in the Jetta, but a PPIMV can can be exactly the same as the components it replaces, just variable. When turned to 10, the electrons don't know the difference.
There are a lot of different PPIMV schemes out there. Some sound transparent when turned all the way up, but don't sound great turned down. Some sound great turned down but are not totally transparent when turned all the way up. Some sound great turned up or down. Some sound bad, either way! And pre phase inverter masters (prevalent in the '80s) have their own uses and sounds.
From what I've seen in Dr. Z amps, the PPIMV is tuned specifically for the amp model and works really well whether turned down or turned way up.
My Dr. Z Cure has two types of masters in it and it's a learning experience tweaking them!
Like Lou said, master volume controls have come a long way since the '80s. You should give it a try.
BTW, what master volume amp did you have in 1980? We can probably let you know if it had a pre or post phase inverter master and if it was considered bad or awesome in its day.
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Post by premiumplus (Dave) on Aug 22, 2022 17:24:15 GMT -7
A properly implemented PPIMV would be electrically transparent when set on '10' or full output volume. I can't detect any change in tone, either on my bench or onstage.
Any time you start throttling back the output tube drive (and obviously the signal level to your speakers), you begin to alter the amp's tone; it's unavoidable. But Doc's PPIMV circuits work better than any others out there.
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Post by nick0 on Aug 22, 2022 17:39:50 GMT -7
1. If you're running a Jetta wide open, you're not going to be hearing much of anything for very long! Jettas are LOUD! Hahaha. But I have no idea what a non master volume Jetta would sound like. Interesting question though.
2. Everything changes with volume. Even the way you hear things will change. You just have to let your ears guide you.
I will say that the ppimv mods that I have had done by Dr Z seem to improve the amp's tone. I'm sure part of that is the fact that i can push the preamp more at tolerable volumes. But it sounds better to me!
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Post by eggman on Aug 23, 2022 7:28:11 GMT -7
Howdy,
Thanks very much for the informed replies on a subject foreign to this purist.
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