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Post subject: Rebel 20 Question for 63Supro
Posted: Sat Jan 03, 2015 6:29 pm
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Question directed at 63Supro because I know he owns one of these amplifiers but if anyone else has info please feel free to respond.

I would like to try swapping the preamp tube in my Rebel 20 but while the Egnator manual does have a diagram depicting the tube layout that diagram does not identify which sockets are which. The pic shown here is one I altered using Photoshop and I put labels V1, V2 & V3 in the locations where I suspect they reside but my searches of the internet cannot confirm or deny this. Do you have any info on these locations?

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 12:37 am
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FWIW

http://www.egnateramps.com/download/Rebel20TubeChart.pdf

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 2:22 am
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Thank you!

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 3:13 am
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So this brings up a new question. I have an older Tung-Sol 12AT7 which is known to be microphonic. Just out of curiosity I tried it in all three sockets and it only makes an audible howling in the socket I originally suspected was V1. In that socket is also the only place where I notice slightly reduced volume and grind. Can that be right?

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 7:56 am
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That makes sense, you call it V1 and they call it V2, either way it's the first tube in the signal path. Why they would call the first tube in the signal path V2 is beyond me.

I do know for sure that some of Egnater's tube chart labeling differs from what is labeled on the circuit boards, and there is discussion on the Egnater forum of incorrect tube charts.

Maybe you should post in the enemy forum and double check. :lol:

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 9:43 am
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OK. Thanks, Shimmi. I'm glad I wasn't imagining things.

Note to interested Rebel owners:
This amp seems almost impervious to tube changes. I have never met an amplifier that produced tonal changes as small as this one when swapping tubes.

My amp came equipped with:

3 - Sovtek 12AX7WA
2 - JJ EL84
2 - Jj 6V6GT

In place of the 6V6 I tried

NOS JAN Phillips 6V6GTA (black plates) (USA)
NOS JAN Sylvania 6V6GTY (black plates) (USA)
NOS JAN RCA 6V6GTY (black plates) (USA)
Genalex Gold Lion 6V6GT (grey) (Russia)

None made a lick of difference that I could hear and I think I have a pretty critical ear.
I can usually appreciate the difference a good tube can make.
The JJs went back in.

I have fewer alternate choices on hand in EL84, just one pair of Sovtek and one pair of Tung-Sol with the same apparent lack of any significant tonal change. The JJs went back in but before I am done I may decide to leave the Sovteks in there instead as I normally like JJs better and would rather preserve those. I usually set the blend knob to heavily favour the 6V6s anyway, typically around 9 o'clock.

In the real V1 (first in chain) I tried:

Genalex Gold Lion ECC83/B759 (Russia)
MesaBoogie 12AX7A (Russia)

Both those tubes appear to be identical and possibly rebranded from the same source. Both seemed just a pinch brighter and looser than the stock JJs. I expected this but I expected there to be a more significant difference. I had to really listen. It's actually the reason I started this thread in the first place. I was pretty sure I knew which socket was V1 but the insignificance of the swaps made me doubt it. That's also the reason I tried the microphonic AT7 in all three sockets.

I also tried:

RCA 12AT7 (USA)

Electro~Harmonix 12AY7 (Russia)

Tung-Sol 12AX7 (Russia)
JJ ECC83S (Russia)

Those last three tubes (not the RCA) also appear to be identical and possibly rebranded from the same source but a different tube than the first two. Both of these AX7s were just ever so slightly warmer and tighter than the stock Sovteks but nothing like the difference you might expect. The real surprise came when I tried the AT7 and the AY7. The AT7 sounded pretty much like an AX7 with nowhere near the loss of volume and gain I have seen in other amps and the AY7 was actually the best sounding tube of the bunch. I started this quest to try to lose a little of the hair and get a little more cream. The AY7 was the only tube that did that for me and what I mean is it did it ever so slightly and in all honesty I am used to an AY7 producing a greater loss of volume and grind.

I would say that for anyone wishing to alter the tone of their Rebel 20 a speaker change is the only real avenue. Tube swaps likely won't produce the results you would expect. I do admit that I did not adjust the the bias trim-pots for the power tubes and will likely try tweaking them just a touch to see what comes of it. The lack of any initial improvement caused me to lose interest in trying to tweak my better tubes.

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 10:53 am
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The EH, TS and JJ are all definitely very different tubes. The TS and EH are from the same factory, Reflector in Saratov, and the JJ is from a completely different factory in Slovakia.

As you probably know, Mesa tests and relabels tubes from various factories just like GT does, so any particular Mesa tube could be the same tube as any particular GT. Mesa and GT both use various Russian and Chinese brands, including EH, Sovtek, JJ, Shuguang, and others.

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 11:30 am
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I understand that. The only reason I began looking at the tubes beyond the labels was because of the way they seemed to make so little difference. That was when I noticed two slightly different types of construction and two slightly different sounds, at least with this amp, anyway.

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Sun Jan 04, 2015 9:50 pm
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BMW-KTM wrote:
I understand that. The only reason I began looking at the tubes beyond the labels was because of the way they seemed to make so little difference. That was when I noticed two slightly different types of construction and two slightly different sounds, at least with this amp, anyway.


BMW, sorry about that. I've been working on that Marshall 18 watt clone the past few days. From what I remember that tube chart Lou gave you is correct. The only thing I ever did to mine was to put a 5751 in V1 to tweak back the gain a bit. With the Tube Mix and Watts circuitry in the Rebel 20, I could see why it would be hard to notice a huge difference in the tone. Did you check the bias when you changed the power tubes? Each set of power tubes has it's own bias trim pots and are biased separately. I've tweaked the bias a little and did get some tonal variation. I like the Rebel 20, but since I started building my own, it gets a little less use. This new one I'm working on might push me to sell it. I've never had an issue with it and like the way it sounds, but I'm thinking about running the 5e3 and the 18 watt clone with my A/B/Y box. The Rebel 20 has a lot of features that affect the tone, it's not a simple amp. It took me a little while to learn the amps sonic pallet. Even when you run the Tube Mix at noon, you get a pretty nice volume bump, and messing with the Watts dial changes the headroom. It's crazy stuff.

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Mon Jan 05, 2015 10:18 am
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I like my Rebel clean but I'd like to lose a little of the hair when it's pushed. The tight switch helps a bit but it also changes the EQ slightly, removing some of the lows and it's not enough of a change for my taste. I don't have any issues with how much gain it has, just the kind of gain it has. My experiment with preamp tube swaps showed me little to no change so I am going to try another speaker swap. I am in the same boat as you. I like the amp much better than the BJ it replaced but it's still not getting much use. It just never became my "go to" amp for low power use. If the speaker swap doesn't satisfy me I may decide to sell.

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Mon Jan 05, 2015 11:01 am
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BMW-KTM wrote:
I like my Rebel clean but I'd like to lose a little of the hair when it's pushed. The tight switch helps a bit but it also changes the EQ slightly, removing some of the lows and it's not enough of a change for my taste. I don't have any issues with how much gain it has, just the kind of gain it has. My experiment with preamp tube swaps showed me little to no change so I am going to try another speaker swap. I am in the same boat as you. I like the amp much better than the BJ it replaced but it's still not getting much use. It just never became my "go to" amp for low power use. If the speaker swap doesn't satisfy me I may decide to sell.


I run mine with two Egnater 112 cabs loaded with 80 watt Celestion Elite 80's. The cab is actually really nice. I like the way way the amp sounds and it works for me, but there's something about my 5e3 that just kills. I never like the Blues Jr or even the Pro Jr. Just too boxy sounding for my taste. They sound okay through an extension cab. If I were you, I'd dump it if you're not happy with it. I'm pretty much done with Fender's new offerings. I'll either build them myself or go vintage. Egnater came out with a Rebel 20 MK2 that they claim has better transformers, upgraded PCB's and a couple other goodies like more gain. I haven't tried one. I know they had a serious problem with transformers. Mine's fine, but I bought mine pretty early in production. The boards in mine are fine too. Could be like everyone else including Fender, went to cheaper production methods to increase profits. It's a shame. I had really high hopes for Egnater. Once you get a reputation for poor customer service and poor reliability it spells serious trouble. I still like Jet City amps, which are designed by Mike Soldano and VHT amps too. but like I said, I think I'll just keep building what I want. For lower power for now I use my 5e3. I have a Weber 12A125A alnico in it and it just a great sounding amp.

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Post subject: Re: Rebel 20 Question for 63Supro
Posted: Mon Jan 05, 2015 7:20 pm
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I think perhaps I will try running a couple of different amps through those cabinets and see if it's the amp or the cabs that don't please me when pushed. I do like the amp's clean tones. It was the clean tone that initially won me over but it's overdriven tones are a little too hairy and abrasive for me. Those overdriven tones are still preferable to me than the BJ it replaced, BillM mods and all. Too boxy and honky. I kept hearing Felix Unger in my head playing that amp. Tony Randal doing that nasal honking thing he always did that drove Oscar up the wall. As it sits now, the Rebel is close to where I want it but not quite.

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