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Post by redtele on Feb 1, 2022 7:15:30 GMT -7
After some tube-rolling a while back and reverting back to the OEM Tung-Sol tubes, I thought I was done with experimenting, but a post on here saying how they put a NOS rectifier in their Wreck and this getting the 'thumbs up' from the Doc got me thinking... NOS 5Y3 rectifiers are seemingly plentiful and cheap compared to EL84s and 12AX7s, so this was not an expensive experiment thankfully, so I bought a 1968 NOS JAN 5Y3WGTA rectifier tube made by Sylvania in the USA from eBay, and popped this into my amp before taking it to rehearsals yesterday. My amp was in the same rehearsal room in the same position, I was playing with the same other band mates who were using the same equipment, but for some reason my amp sounded quite mid heavy compared to before. The distortion was a bit fuzzy/fizzy, and it sounded like when the amp is played at super low volumes with the gain much higher than the master and there's that fizz, but I couldn't turn up the master any more to 'cure' this as I would have been too loud. I wasn't enjoying what I was hearing from the amp and my KOT pedal saved the day by providing all my distorted tones, where I usually prefer the amp's own distortion, and that's by a long shot. I have always understood that a rectifier either works or it doesn't, and there's no inherent sound or tone to them, so how comes my amp sounded like it had extra mid range with this NOS 5Y3 rectifier? I've used this amp quite a number of times but this is the first time I've ever experienced this and was unable to adjust the tone controls to dial it out, and as the rectifier swap was the only difference, it could only have been caused by this. I have put the JJ 5Y3S back in at home and it sounds better to me, back to how I like the amp to sound, but I won't know for sure until I get back into the rehearsal studio in a couple of weeks. Am I going mad? Does the JJ rectifier contribute to the tone in any way? Do I need to 'up my meds' ?
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Post by jhen86 (jordan) on Feb 1, 2022 12:51:17 GMT -7
There’s some truth and some misleading ideas to that. So youre right, but there are exceptions. The rectifier works or it doesn’t. This is true. If it functions then it will do its job. Unlike say a 6L6 that can have varying degrees of tone degradation over its lifespan. So they don’t shift their “tone” like a preamp or power tube during its life cycle per se.
But rectifiers do shape tone. Doc has talked about Chinese vs Russian 5AR4’s responding differently. The Chinese being a touch softer. A rectifier is creating what we call B+, or the high voltage DC that goes to your tubes and allows them to function. Two different 5Y3’s can create different voltages. I’ve measured this first hand. Especially with NOS vs current production. You can have a 20v difference which can affect a lot of things. Wattage, headroom, breakup, touch response. That added voltage can come across as brighter, faster, crispier, etc. On top of that the way a rec tube delivers that B+ can vary. Does it sag more than it “should” on paper, or less. The way the tube is manufactured can influence that too. Maybe not to the same degree as a power tube.
I’ve tested this in my M12. Perfect platform for that. Rectifiers do either work or not. But HOW they work affects tone.
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Post by redtele on Feb 1, 2022 13:19:24 GMT -7
Thanks for that informative reply jhen86 (jordan) and I have read around the subject how the B+ voltage can affect the amount of breakup an amp has, with new production and NOS rectifiers raising or lowering this respectively but not adding extra mid range or changing the tone per se. I wasn’t looking to change the sound but put the NOS tube in there for longevity and as a by-product I was kind of hoping that a NOS 5Y3 rectifier would lower the B+ voltage compared to a new production tube and bring on the distortion quicker, but it changed the character of the distortion and appeared to add mids, and I didn’t like the added fuzziness to the edges of the distortion, and if anything I perceived there to be less distortion at the same settings I was used to using. Maybe it was this one particular NOS tube, and maybe another one would have sounded better/different, maybe the wall voltage was different this day, maybe my strings were newer and this had an effect as it’s very hard to be 100% on the exact cause of this change but I honed in on the changed rectifier as that was the one definite change that I knew had taken place. I’m far from qualified to measure B+ voltages, so as long as the JJ rectifier lasts a fair amount of time then I’m happy to continue using this brand of tube as I know how it makes my amp sound, and that’s just how I like it!
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Post by jhen86 (jordan) on Feb 1, 2022 14:07:25 GMT -7
Hard for me to give any further insight on your specific situation or what you heard, but I don’t question you heard differences. Could just be that tube?! But as you said, if you can find some different NOS or current production 5Y3’s to try for cheap, it’d be a fun and worthwhile experiment.
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Post by adam on Feb 1, 2022 16:53:42 GMT -7
I think I remember Z mentioning in one of the AMA videos that they absolutely can and does affect the tone of the amp. Don't quote me on that though.
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Post by smolder on Feb 2, 2022 14:42:52 GMT -7
My father always said that a rectifier does not impact tone. Though through bias and sag or lack there of, the sound of the amp may change. His point… the ac signal path of the amp does not go through the rectifier. He was a particularly exacting engineer.
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Post by jhen86 (jordan) on Feb 2, 2022 19:46:54 GMT -7
My father always said that a rectifier does not impact tone. Though through bias and sag or lack there of, the sound of the amp may change. His point… the ac signal path of the amp does not go through the rectifier. He was a particularly exacting engineer. Yeah that’s where the gray area lies. It seems that tone in your statement is being defined as something exclusive to the ac signal path. I understand your Dad’s perspective but we all know that everything affects tone. Including many things outside the ac signal path. I see your point though and don’t disagree. I guess we have to come to a starting definition of “tone” together.
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Post by premiumplus (Dave) on Feb 3, 2022 6:55:01 GMT -7
It's true that the signal doesn't go through the rectifier tube, but the rectifier tube is responsible for the DC voltage that the amp operates on. So when the amp is cranked and you hit a big power chord, the rectifier's DC output is going to drop under demand, depending on the ability of the tube to deliver it's specified output current. As the DC voltage rises and falls depending on the amplifier's need, the tone will change. It's the reason that notes "Bloom" or "Sag" with a tube rectifier.
I guess it does depend on your definition of "tone" but I can envision a situation where a rectifier tube is at the edge of it's life and doesn't hold up like it should. Different DC voltages are key to how an amp stage operates, so that rectifier needs to be a steady, reliable power source for the amp. After all, the amplifier's primary job is to modulate a DC voltage into an AC signal that tracks the input signal, and drive a speaker with that voltage. It all starts with the rectifier.
If I had the OP's amp on my bench I'd measure the B+ voltage with different rectifier tubes, and under operating conditions. I'd run a signal into it and look at the B+ with a scope and see what it does under load.
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Post by sharkboy on Feb 3, 2022 8:52:07 GMT -7
I see this as others are describing it. It isn’t supposed to affect tone, but there are differences in resistance/capacitance/impedance across most of them and the amount of stored energy in the circuit, due to even subtle differences in tubes. The available current heavily affects bass and definition, thereby potentially affecting midrange and even treble. This translates to easily perceived differences between rectifiers in extreme cases.
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Post by redtele on Feb 3, 2022 9:47:06 GMT -7
Thanks sharkboy it’s good to know I’m (probably) not going mad! I get that some days your rig sounds awesome, and then another day using exactly the same equipment and settings, you can’t seem to dial in a decent tone, but as I purposely changed something in my amp then this raised my suspicions and thought I could possibly learn something here. I put the original JJ back in the following day, and when I played through the amp at home I think it improved and the tone was back to how it sounded before, so I’ll test it at my next rehearsal session at full volume and see if ‘my sound’ is back. I have a Bendix 5Y3 that is meant to be a very stout and efficient rectifier tube, so maybe I can experiment with this, or maybe I should learn my lesson and leave well alone as if it ain’t broke then don’t fix it!!!
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