[Beefy]

So if the bias reduces as temperature increases should I not use it for long listening sessions?

No, not at all, you're over-analyzing it. There's just nothing to be gained by waiting for warmup or from leaving it turned on, except wasted electricity.

 

[eswng679]

I actually left mine on all weekend. Barely got warm. Still room temperature. Not sure if that had any effect on the sound but it didn't seem to hurt anything. Not sure if the Rebel sounds dry to me but it seems more open sounding compared with the Jot 2.

Perhaps dry may not be the best term. Synergy was the word I was looking for. The Rebel didn't jive as well with my library vs. Jot 2.
Hope you like the Rebel more as time goes on.

 

[hottyson]

So I just got the Rebel Amp. Traded my Jot 2 for it. Pairing the Rebel with my Bifrost 2 connected to my Mac via USB. Comparing with my Feliks Audio Echo Mk2. The verdict is still inconclusive. Listening with my Aeolus. Definitely sounds more open (brighter?) than my Echo Mk2 and Jot 2 (to my remembrance). Seems more revealing as well which can be good or bad depending on the song being played or headphones used. Gonna try my HD6XX next. Also going from low to medium gain is a big jump in volume.

For those two headphones I find the Jotunheim 2 the better amplifier to pair with over the RebelAmp.
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My Schiit Jotunheim 2 paired with Aeolus actually sounds really good when the gain switch is set to low gain. However, my Rebel Audio RebelAmp paired with Aeolus sounds a little bit dull and a little bit too polite. When pairing amplifiers for the Aeolus, I would not recommend the RebelAmp.
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Pairing my Sennheiser Massdrop HD6XX my Schiit Jotunheim 2 sounds pretty decent as long as it is connected to the balanced headphone output of the Jotunheim 2. I also find this Jotunheim 2/HD6XX combo superior to the unexciting veiled performance of the HD6XX when paired with the RebelAmp. When pairing amplifiers for the HD6XX, I would not recommend the RebelAmp.

 

[hottyson]

Perhaps dry may not be the best term. Synergy was the word I was looking for. The Rebel didn't jive as well with my library vs. Jot 2.
Hope you like the Rebel more as time goes on.

I find this surprising considering you have two HifiMan headphones. While my Jotunheim 2 does sound wonderful with my HifiMan planar dynamic headphones, the Rebel Audio RebelAmp is superior to my ears all of the time with HifiMan headphones.
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This just goes to show that people can have drastically opposing tastes and subjective preferences.

 

[MacMan31]

For those two headphones I find the Jotunheim 2 the better amplifier to pair with over the RebelAmp.
.
My Schiit Jotunheim 2 paired with Aeolus actually sounds really good when the gain switch is set to low gain. However, my Rebel Audio RebelAmp paired with Aeolus sounds a little bit dull and a little bit too polite. When pairing amplifiers for the Aeolus, I would not recommend the RebelAmp.
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Pairing my Sennheiser Massdrop HD6XX my Schiit Jotunheim 2 sounds pretty decent as long as it is connected to the balanced headphone output of the Jotunheim 2. I also find this Jotunheim 2/HD6XX combo superior to the unexciting veiled performance of the HD6XX when paired with the RebelAmp. When pairing amplifiers for the HD6XX, I would not recommend the RebelAmp.

So basically I should have kept my Jot 2. On certain songs with the Rebel (such as the last track on the Avengers movie score) I found the instruments to sound distant. I don't mean it was a wide sound stage. It just sounded like certain instruments were further away compared to how they sound on other amps.

 

[Plieb]

So this has been a trip but after nearly a week I think I can have a take on this.

First off, build quality is great. From Kharkiv, Ukraine, a city in part known its tank factory, this thing looks like its built there. Its surprisingly not as heavy as I thought, but it's nonetheless a solid, minimalist industrial piece of kit. The Back in Black paintjob is nice, has a bit of metallic flake in it and fits well on my desk. Do I regret not getting the sexy green? Eh, not really. It's big, that it blends is probably a good thing.

Knob feels good and weighty, pot is smoother than anything I own but there's a slight scratchiness to it which you dont notice it in the actual sound. Its satisfying to roll. Pre-out switch is a bit stiff and honestly would have preferred something else for switches if I *have* to nitpick but it all does the job just fine and for a minimalist build it works.

As for sound, this thing needs burn in. It craves it. It's straight up not good out the box. Let it settle. At first I thought it was harsh and had typed out some thoughts finding it had an uncomfortable tone on the highs to the point of being a no go for longer listening sessions. The bass was stronger than my tube amp but it was ultimately sounding like a poor-man's version of my Schiit Valhalla where it just wasn't doing anything better or meaningfully different. Buyers remorse set in. 24 hours later it was a total 180 and having given it the weekend to just play with and enjoy I can confidently say everything I hated about it is gone.

This is a tubey sounding amp. It's warm, it's buttery, it has powerful bass and smooth highs. The bass can be a bit blown out at times with my current EQ settings (which I'm trying not to change so I can A/B test a bit at the moment), and its a bit deep but without definition. Without my EQs going if I had to pick I think this is the best 'stock' amp I have right now. On the whole playing with this has had me listening to and rediscovering music like I just bought the weirdest set of vintage tubes. I mean really, this thing is not natural or neutral, it's *very* flavored, it makes my Valhalla (with 50s Brimar tubes) sound neutral.

Percussive drums & guitars cut through bass like a machine gun into a mountain of Jell-O. It's a flavor, it's not neutral, but it's ultra satisfying. Longer listening sessions are very nice. Put on some heavy metal and the smoothness means I can crank the volume higher without blowing my ears out (see: volume scaling below) or put on some electronic music to zone out to and let the bass and rich lower tones wash me away.

Volume scales nicely with this mix, and I find myself using high gain on older (pre loudness war) tracks, and it plays nice on recordings with deep dynamic range. The whole "use high gain for planars and low for Sennheisers" or whatever lines I hear from some reviews is nonsense. Low gain is too low to listen to on my 300ohm headphones for a lot of tracks, so I'm usually on medium the majority of the time.

**Anyway, enough rambling. Amp good. Amp smooth. Fake super tube in metal box from tank town.**



(all thoughts based on an HD800 w/ Bifrost 2 & Lokius and impressions were in contrast to set tuning and performance of my retubed Valhalla which I deem to be 'ideal'. Nothing was done neutrally or analytically)

Yes i had same experience. Corse sound prior to break in. Then all is great.

 

[Meridian7]

No, not at all, you're over-analyzing it. There's just nothing to be gained by waiting for warmup or from leaving it turned on, except wasted electricity.

Hi Beefy,
Do you have hands on rebelamp experience? I ask this because my rebelamp enjoys a warmup of aprox 30 - 45 mins to reach it best sound performance, before that it's good though, but after that it's even better.

 

[Meridian7]

Q to other rebelamp users:
I found the high gain to sound more open / detailed than low gain. Do you agree?

 

[hottyson]

Q to other rebelamp users:
I found the high gain to sound more open / detailed than low gain. Do you agree?

I tried to listen to the differences of low and high gain and my answer is, I think that maybe you're right. Based on my quick five minute comparison, I would have to pick the high gain as having a brighter sound compared to low gain. However, the distinction in brightness between the two gain levels is minute. The difference might just might be in my mind. The difference is not night and day like the Schiit Jotunheim 2 high and low gain. On the Jotunheim 2 they are each like listening to two different amplifiers. Here on the Rebel Audio RebelAmp they are very similar or perhaps even the same. I would have to put more listening forth to come to a definitive conclusion.

 

[Beefy]

Hi Beefy,
Do you have hands on rebelamp experience? I ask this because my rebelamp enjoys a warmup of aprox 30 - 45 mins to reach it best sound performance, before that it's good though, but after that it's even better.

The Rebel's circuit is the AMB M3, but with dual rail PSU and no buffered ground. It's an amp I built myself and have owned for 14 years. There is no significant improvement with warmup, except perhaps between your ears.

 

[Lvivske]

Q to other rebelamp users:
I found the high gain to sound more open / detailed than low gain. Do you agree?

yup. more voltage / gain = boosting the signal detail. You may also hear noise in your system become emphasized as well.

likely also depends on headphone impedance

personally i keep it on low because i find it smoother, which suits my desktop better since I'm usually focused on other stuff

 

[Beefy]

yup. more voltage / gain = boosting the signal detail. You may also hear noise in your system become emphasized as well.

likely also depends on headphone impedance

personally i keep it on low because i find it smoother, which suits my desktop better since I'm usually focused on other stuff

That's.... not how this works. Consider a low gain of 2x where the volume pot passes 1/2 the input the signal to generate a particular volume. To achieve the same volume at a gain of 5x, the volume pot would only pass 1/5 the input signal.

The noise from the source, and the amplification of detail, should end up exactly the same.

Where high and low gain might sound different, it is generally related to negative feedback. At higher gain, the amount of negative feedback being applied is a little less, and there's a case to be made that less negative feedback can sound better. It might also depend on how well the feedback loop is compensated at different gains, which can alter the slew properties - basically, changing gain might alter overshoot versus undershoot on very fast transients.

 

[Lvivske]

The noise from the source, and the amplification of detail, should end up exactly the same.

Should, but we're talking minute stuff here.

 

[Plieb]

Assuredly brain burn in. There's really nothing in the design that burns in. And the design is universally accepted to sound better at higher bias, and bias reduces as temperature increases.

Yes its funny. I noticed that it sounds a bit dry after leaving amp on for more than a day or so. Have tried it many times going from turning it off at end of day to keeping it on for a week. Sound loses some of its richness and impact when constantly on.
Edit ...
Im wrong again. Using with different dac and amp bass actually gets a bit tighter with smoother high end and a bit more detail when amp is left on. Amp temperature never gets more than warm.

 

[Meridian7]

The Rebel's circuit is the AMB M3, but with dual rail PSU and no buffered ground. It's an amp I built myself and have owned for 14 years. There is no significant improvement with warmup, except perhaps between your ears.

I read: no rebelamp experience, you had something along the lines.

I suppose you were not able to notice the difference in cold vs nominal operating temp in your particular complete setup compared to mine. That looks more plausible to me than resorting the dead horse beating psychology argument.

Secondly you're probably right, albeit techy inclined, that you do not know whatever could play a roll in warming up the rebelamp. No clock crystal temp depending jitter etc.. I see that. Then there's only my experience in my setup situation telling, it does to a modest extend.

Thirdly, we all differ in sensitivity to touch, taste/palatte, sight, and hearing, this is imho not to be overlooked.