New Rebel 30 Owner - Flabby Power Tube Saturation

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Cotton7

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New Rebel 30 owner and I cannot say enough about how cool this little amp is. However, I am experiencing some issues with nasty, flabby distortion (IMO)coming from the power tube distortion when cranking this little monster up at 1 watt. My prior experience with other amps that are way to loud (been playing semi-professionally for over 25 years) is that the power tube over drive is thick and rich in harmonic content with added sustain. My Rebel sounds absolutely awesome at bedroom volumes but, when I get the Power tubes pushing, the distortion just gets fuzzy/flubby/nasty. I've emailed Egnater Support a week ago. No response.

Here is what I've done to try and rectify this.... I started by replacing all of the power tubes. First I went with a set of JJ EL84s and a set of Mesa STR 417 6V6s. The saturation tone improved slightly but, still unacceptable. I switched power tubes again to Mullard EL84s and Tung Sol 6V6GTs. Again, a little better but still flabby when pushed. Ive tried biasing the tubes a little colder (35mVDC on each side) and a little hotter (45mVDC on each side) with each tube swap.

I then started rolling preamp tubes... The amp had stock EH 12ax7s in it which actually sounded pretty good. I replaced them all with Tung Sol 12ax7s. Ive been tube rolling different tubes every since from JJECC83s to Mesa 12AX7s to Penta Labs 12ax7s. Its still there.

The most notible change that I can pin point so far that helps this issue a little is switching the V5 position to a 12AT7. However, it somewhat sterilizes my tone at lower volumes. So I dont like it. Ive ordered NOS Phillips 5751 for the V5 PI position in hopes that it will provide the needed dynamics while cleaning up the power tube saturation issue.

My question is.... is this just the nature of this amp when the power tube section is pushed into overdrive? If yes, that is disappointing because this is one of the main reasons that I purchased this amp. The ability to get rich power tube distortion without making my ears bleed. I love my Boogie Mark IV as well and it sounds incredible in the rare chance that I can crank it up loud enough to push the power section on it without getting a ticket for disturbing the peace. :D

Any input will be greatly appreciated! I love the tones on the amp. I want to be able to crank up the power tubes in order to enhance those tones.
 
Cotton7":21wclgax said:
New Rebel 30 owner and I cannot say enough about how cool this little amp is. However, I am experiencing some issues with nasty, flabby distortion (IMO)coming from the power tube distortion when cranking this little monster up at 1 watt. My prior experience with other amps that are way to loud (been playing semi-professionally for over 25 years) is that the power tube over drive is thick and rich in harmonic content with added sustain. My Rebel sounds absolutely awesome at bedroom volumes but, when I get the Power tubes pushing, the distortion just gets fuzzy/flubby/nasty. I've emailed Egnater Support a week ago. No response.

Here is what I've done to try and rectify this.... I started by replacing all of the power tubes. First I went with a set of JJ EL84s and a set of Mesa STR 417 6V6s. The saturation tone improved slightly but, still unacceptable. I switched power tubes again to Mullard EL84s and Tung Sol 6V6GTs. Again, a little better but still flabby when pushed. Ive tried biasing the tubes a little colder (35mVDC on each side) and a little hotter (45mVDC on each side) with each tube swap.

I then started rolling preamp tubes... The amp had stock EH 12ax7s in it which actually sounded pretty good. I replaced them all with Tung Sol 12ax7s. Ive been tube rolling different tubes every since from JJECC83s to Mesa 12AX7s to Penta Labs 12ax7s. Its still there.

The most notible change that I can pin point so far that helps this issue a little is switching the V5 position to a 12AT7. However, it somewhat sterilizes my tone at lower volumes. So I dont like it. Ive ordered NOS Phillips 5751 for the V5 PI position in hopes that it will provide the needed dynamics while cleaning up the power tube saturation issue.

My question is.... is this just the nature of this amp when the power tube section is pushed into overdrive? If yes, that is disappointing because this is one of the main reasons that I purchased this amp. The ability to get rich power tube distortion without making my ears bleed. I love my Boogie Mark IV as well and it sounds incredible in the rare chance that I can crank it up loud enough to push the power section on it without getting a ticket for disturbing the peace. :D

Any input will be greatly appreciated! I love the tones on the amp. I want to be able to crank up the power tubes in order to enhance those tones.
Click to expand...

My R30 Head thru a 2x12 closed cab with V30's has never once sounded flabby imo - cranked at gig volume or not
That's with the stock tubes plus a replacement set recommended by Doug from www.dougstubes.com.
Never been a issue for me at any time and I've never even thought about it with this amp. I usually have bass dial at 11 oclock.
Sounds better to me the more it's cranked :thumbsup:
 
That is how I would think my amp would sound. So what you are saying is that there is something wrong with my amp. Agreed. Unfortunately, Egnater support has been completely unresponsive. I've emailed and called the emergency number off the website. No response and I was hung up on two in a row when attempting to call. I read online that there are no warranty repair shops in Austin and even if their were one, I understand it takes FOREVER for you amp to be fixed if it actually gets fixed.

I'm pretty bummed out about the Egnater support and I don't mind mentioning it to everyone I meet as I progress through the Guitar Center Battle of the Blues. Hope somebody responds to me before the finals on June 5th. I'll have keep telling everyone that the amp can sound great when it works but, if it doesn't, your screwed.
 
My rebel 30 also had nasty lows on the OD channel,the bias was way cold at 16vdc and 36vdc so crossover distortion is a bad thing,it destroyed my lows on that channel,its not doing that now at 45vdc on both sides.
Funny my clean channel seemed way better than ch 2.
 
My rebel 30 also had nasty lows on the OD channel,the bias was way cold at 16vdc and 36vdc so crossover distortion is a bad thing,it destroyed my lows on that channel,its not doing that now at 45vdc on both sides.
Funny my clean channel seemed way better than ch 2.
 
Thank you for the tip. I've biased it hot. It doesn't sound like crossover distortion. It sounds like blocking distortion with the volume dropping down and then jumping back up. That means its probably a resistor or an issue with one of the caps. I'm not going to go any further than the bias inside the amp.

Sounds awesome at lower volumes. Just wish I could crank the power section for some cool power tube breakup.
 
I would put a sovtek 12ax7 balanced into the phase inverter,some amps hate certain PI tubes and it shows in
distortion.
Those tubes have smooth distortion but you may notice the watts down to 1 could be the culprit. preamp starved.
Ive noticed Cotton has done everything else i think,dont overlook the PI after just trying a 12at7.
Ive put the same Mullards in as you did and the tungsol 6v6gt tubes and rebias to 45vdc on both sides and the nasty tearing sound on picked lower notes are gone.
My tubes are- v1 stock ruby,v2 tungsol gold pin,v3 tungsol GP,v4 ruby 12ax7 HGac7 tube,v5 stock ruby with a sovtek 12ax7lps balanced on the way.
My amp had a similar nasty distortion at low volume using overdrive ch. No issues now. The Bias was cyro cold. fixed now
Also consider the SS rectifiers,there overstrong new,then the amp smooths out the attack especially in the lower frequenceys.
Cotton i would let it play and try the retubed Phase Inverter ,and try another speaker too !
Youve done every darn reasonable thing possible allmost except those i mentioned,your speaker isnt broke in and the bass is pitiful until there relaxed as a break in does.
Odd that your sound description in the nasty distortion was as if i wrote it ,as mine had that nasty sound in the stronger lows.
Also check your house hold voltage,mine is 119v now,but runs 125v sometimes ?
I say run that amp more and see if your caps and resistors drift as they do anyway.
I luv this amp now,the rebel 20 is retubed and fabulous,fantastic sounding on slide guitar.
Cotton where would a Gold Lion 12ax7 be best in the rebel 30 V2 ? Is that the OD stack begining .
 
Thickwood, thanks a ton for the great information. I completely agree that there could be something up with the PI. I popped that 12AT7 in there and the issues seemed to disappear. However, I lost some tone and lots of if. That PI position us VERY important and is responsible for a lot of that power tube mojo that we all love. I also picked up a NOS Phillips 5751 graded for extra low noise and tested at 95/95 on each side (pretty hot for a 5751). Sitil dropped out on channel 2 when cranking the amp past 2 o'clock ONLY on the 6V6 side. EL84 side works beautifully.

I tooled around a bit more last night and adjust the bias to run hot just for the fun of it. I set the EL84s to 50mVDC and the 6V6s at 52mVDC. Sounds awesome. Didn't fix my issue and i probably just cut the life of the power tubes in half but, it's all good. :)

I am going to go ahead and pick up a 12AX7LPS for the PI. I've read many good things about them in that position.

The V2 position is the post volume gain stage on Channel 1. The hotter bias settings have really warmed up that channel and with the NOS RCA 12AX7A short grey plate in V1 keeping the amp quiet and smooth, I can really crank up the volume on that channel for some great blues tones. I love the tone. V3 is the second and third gain stage of channel 2. I've rolled all all the prior mentioned tubes into that spot while keeping the beautiful RCA NOS in the 1st gain stage. Didn't fix it. I then started playing with V4 (which is the FX loop buffer) just in case. Didn't help.

I've deducted that it has to be blocking distortion on the 6V6 side just because I am having absolutely 0 issues with the EL84 side. When the volume drops on the 6v6 side, it sounds like someone threw a blanket over the amp and bass is horribly flabby. It will only last a couple of seconds and then pick back up. Then it repeats. I was frustrated one day and just kept on playing through it. It eventually ended up staying at the dropped, flabby volume 100% of the time. I turned the volume back down to about noon and it was gone.

I love this amp. At this point, I am more frustrated with Egnater support (or lack there of). I can live with the issue and work around it but, the amp is only a couple of months old. This shouldn't be happening.

Thanks again for the great info. All great stuff. I'll let you know how it goes with the 12AX7LPS.
 
Correction (haven't had my morning coffee yet). V2 is the second and third gain stage in ch2. I described v3 in the prior post. I quit look at them as v1 v2 etc. now I just know that the one closest to the input is my input gain and the one beside it at the front of the amp is the second stage of ch1.
 
Hi Cotton, considering all you have done to make sure the tubes and bias are correct I would consider the problem might be power sag, that is to say the power supply may be struggling to keep up with the 6V6's. this certainly makes sense considering it works at lower volume which of course requires less power. Maybe something to think about anyway.

Cheers
 
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