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Post by rollyfoster on Mar 1, 2020 19:07:44 GMT -7
I know the Jetta is cathode biased, but does it employ any negative feedback? I’m trying to compare to the Plus. I realize they’re different circuits but they seem kind of similar in some ways.
Almost thinking about what it would be like to run them together.
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Post by simpleton on Mar 1, 2020 22:12:58 GMT -7
How does negative feedback vs no negative feedback differ in sound? I never really understood the difference.
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Post by rollyfoster on Mar 2, 2020 7:32:16 GMT -7
How does negative feedback vs no negative feedback differ in sound? I never really understood the difference. Generally speaking, IME non-NFB amps react differently to the guitar volume. It’s a more gradual change than an amp with a feedback loop where the transition from cleaner to dirtier is a little more abrupt...stays cleaner longer. The gain character is a little less “wild” and raw when there is NFB, kind of like it makes the amp behave itself a little more. NFB also tends to make an amp feel tighter because it’s damping speaker movement, which to me is more obvious than the differences in sound a lot of the time. Obviously amp topology can alter these things some but that’s my non-scientific explanation. |
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Post by simpleton on Mar 2, 2020 9:14:06 GMT -7
Thanks for the info! Maybe we’ll get an answer for your question as well.
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Post by DRZ on Mar 2, 2020 9:26:36 GMT -7
The Jetta has NO NFB.
Z
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Post by rollyfoster on Mar 2, 2020 15:08:13 GMT -7
Did that carry over from the ampeg or was it a decision you made in the design process? |
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Post by DRZ on Mar 2, 2020 17:25:50 GMT -7
All the JET amp iterations used NFB.
I decided not too, just a DR.Z thing.
Much bigger and open sound that way.
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Post by rollyfoster on Mar 6, 2020 20:39:14 GMT -7
All the JET amp iterations used NFB. I decided not too, just a DR.Z thing. Much bigger and open sound that way. You’re not lying. I just picked one up and it punched me in the nuts when I fired it up and the MV was at like 9 o’clock. My first Z amp. Lol. It’s a monster!!!!! |
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Post by Jaguarguy (Mike) on Mar 6, 2020 21:08:27 GMT -7
All the JET amp iterations used NFB. I decided not too, just a DR.Z thing. Much bigger and open sound that way. You’re not lying. I just picked one up and it punched me in the nuts when I fired it up and the MV was at like 9 o’clock. My first Z amp. Lol. It’s a monster!!!!! Probably won't be your last  |
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Post by simpleton on Mar 6, 2020 21:08:48 GMT -7
All the JET amp iterations used NFB. I decided not too, just a DR.Z thing. Much bigger and open sound that way. You’re not lying. I just picked one up and it punched me in the nuts when I fired it up and the MV was at like 9 o’clock. My first Z amp. Lol. It’s a monster!!!!! Low blow huh? Lol. |
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Post by rollyfoster on Mar 6, 2020 21:49:20 GMT -7
You’re not lying. I just picked one up and it punched me in the nuts when I fired it up and the MV was at like 9 o’clock. My first Z amp. Lol. It’s a monster!!!!! Probably won't be your last Well Technically it’s my second because I simultaneously tried a demo z-plus from sweetwater but the tubes are rattling like crazy and their customer service is amazingly pathetic in dealing with it so I’m sending it back. Too bad because I think I’d really like it and my plan was to run them together so I could have the bite of the plus and the body of the Jetta but I guess I’ll try a plus sometime later on. Getting one with the new LED boost would be cool, anyways. The Jetta is WAY thicker at comparative (low) volumes. The feel is super solid. It’s a fun amp. |
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Post by markT on Mar 7, 2020 5:59:48 GMT -7
Congrats rolly! I’m still loving mine several months in, becoming my favorite Z ever!....and that’s saying a lot!
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Post by buzzcrumhunger on Feb 16, 2021 20:44:35 GMT -7
Since this is already a techie question, sorta, I’ll ask here instead of making a new thread. After looking at the Jetta videos available online, I never see anyone move the tone knob in a demo. Is the Jetta tone “stack” like the Jet (i.e., like a 5f2 circuit), or is it more like the Carmen Ghia tone stack, which I love. Enquiring minds and all of that. Thanks!
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Post by perryr on Feb 16, 2021 22:47:16 GMT -7
I dont think the 5F2 has a tone knob? Jetta Tone and Volume layout is similar to the Ampeg. Driven by 1 side of a 12ax7, no recovery. Ghia is quite different.
The Jetta tone knob is effective, noon is neutral, between 10a and 2p covers most things. As you go beyond 2p it gets more aggressive and edgy at low input volume settings. But as you turn up the input volume the tone fattens up and with both input volume and tone full up it Rocks good.
When you turn the tone down, below 10a it gets Jazzy, not muddy. There is still some presence, especially at lower input volume settings (bright cap on input volume).
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