[ScornDefeat]

Dimensions are approx 340mm width, 320mm length; Same dimensions as the C2029 conditioner (they can be stacked if desired). Weight of approx 32lbs or so.

Truly appreciate it! One more annoying question; do you know the height of BH+ at its tallest point (feet to top of transformers)?

The location where I'd put BH+ is a little height limited, as you can see from the below photo, which is what's driving my inquiry. I'd also need to add a little support to that shelf to support 30+ lbs, well worth it

 

[A2029]

Truly appreciate it! One more annoying question; do you know the height of BH+ at its tallest point (feet to top of transformers)?

The location where I'd put BH+ is a little height limited, as you can see from the below photo, which is what's driving my inquiry. I'd also need to add a little support to that shelf to support 30+ lbs, well worth it

Very cool setup! I like the look of the floating shelves with all your gear!

I believe around 240mm to the top of transformers, but 250mm or so to top of tubes (6AS7s are slightly taller than the transformer covers). If you want to use tube socket adapters (e.g. to use EL34/KT88/etc. family as power tubes), you may want to account for an extra 20-30mm for those. So ~280mm height total. A bunch of optional switch choices for the rear of the amp as well, so best to have easy access to look at the amp rear to toggle switches.

 

[ScornDefeat]

Very cool setup! I like the look of the floating shelves with all your gear!

I believe around 240mm to the top of transformers, but 250mm or so to top of tubes (6AS7s are slightly taller than the transformer covers). If you want to use tube socket adapters (e.g. to use EL34/KT88/etc. family as power tubes), you may want to account for an extra 20-30mm for those. So ~280mm height total. A bunch of optional switch choices for the rear of the amp as well, so best to have easy access to look at the amp rear to toggle switches.

Thank you! Transformed a spare room into a "library room" and put custom floating shelves across all the walls....had to carve out a little nook for a listening area, of course with the C2029 proudly displayed in the chain

Good news is I have about 300mm clearance where the tubes would be, not as good news is around 220-250mm on where I would anticipate the transformers may be.

Appreciate the measurements and insights, will reach out to you via PM to further discuss as I'd love to find a way to make it work and jump in the queue.

 

[Zachik]

Dimensions are approx 340mm width, 320mm length; Same dimensions as the C2029 conditioner (they can be stacked if desired). Weight of approx 32lbs or so.

Cool - a portable amp

I've been working on another amp design in the shadows for a long while that I hope to release very soon.

Interesting...

 

[Isaacc7]

Things are getting weird over here... Tried the 6AS7G (Chatham) as a driver in the Blue Halo+. I also used a pair of 6AS7G (Chatham) as power tubes. Order of operations went like this:

1. Blue halo mode: This sounds pretty good! A little looser and more spacious perhaps when compared to "normal" driver tubes. Bass quality/quantity is still solid. Overall clarity remains good as well. I could enjoy this... but why? It's not "better" than running the more common driver tubes. I have to turn the volume wayyy up to ~3-4 o'clock to achieve normal levels.
2. BH+ w/ CCS: Much thinner sounding. Less bass quantity/worse quality. Veiled and far less enjoyable.
3. BH+ w/ RES: Even more veiled and flatter. No redeeming qualities. The least "euphonic" I've ever heard this amp. Like if someone took an amazing etch-a-sketch drawing and started shaking it up. Or a detailed pencil drawing and started smudging it up with their finger tips. This is taking things in the wrong direction.

I tried pre-out BH+ w/ RES > DSHA-3FN and the difference was much more noticeable than the tube roll in my previous post. Fuller, smoother, rounder sound with noticeably less clarity.

Possible conclusions:

1. Power tubes (particularly 6AS7G) are not great drivers (Duh?)... Even in BH mode where it still sounds pretty good: Just because you can, doesn't mean you should. Especially since power tubes have much lower typical lifespan.
2. Blue Halo mode does an amazing job at taking not-great driver tubes and making them sound pretty awesome.

The adapter can also be used with other types of power tubes (6BL7/6BX7/6080/5998) so might be fun to try a few different variants some other time, esp. with BH mode.

I have tried 6as7 as drivers in my amp as well. Had similar results. I think the problem is that the gain is just too low.

 

[A2029]

Another interesting thing that can happen if you run some types of low gain, high wattage tubes (e.g. 6AS7) as driver into another power tube (6AS7 as output power tube) is distortion cancellation or additive effects. I.e. 6AS7's as drivers are already pretty high distortion tubes when compared to 6J5s and other small signal, high(er) gain tubes. When you combine the 6AS7 driver with with the added distortion of the second stage 6AS7s it can either cancel their distortion or add to it, and cause some weird (good or bad) effects depending on the tubes.

A while back in some countries there were certain amp designers that developed a following for using power tubes to drive power tubes. I believe Japan was at the forefront of that movement, but I can't remember the name of the designer who became most known for building tube amps with a large power tube driver fed into the same large power output tube.

Edit: Remembered it was the late Susumu Sakuma that you can read about here: https://www.jacmusic.com/kits/amp/gm70/GM70-index.html

 

[Isaacc7]

Another interesting thing that can happen if you run some types of low gain, high wattage tubes (e.g. 6AS7) as driver into another power tube (6AS7 as output power tube) is distortion cancellation or additive effects. I.e. 6AS7's as drivers are already pretty high distortion tubes when compared to 6J5s and other small signal, high(er) gain tubes. When you combine the 6AS7 driver with with the added distortion of the second stage 6AS7s it can either cancel their distortion or add to it, and cause some weird (good or bad) effects depending on the tubes.

A while back in some countries there were certain amp designers that developed a following for using power tubes to drive power tubes. I believe Japan was at the forefront of that movement, but I can't remember the name of the designer who became most known for building tube amps with a large power tube driver fed into the same large power output tube.

Edit: Remembered it was the late Susumu Sakuma that you can read about here: https://www.jacmusic.com/kits/amp/gm70/GM70-index.html

Broskie‘s Tubecad Journal is the first place I had heard of it https://www.tubecad.com/articles_2001/Inv_Dist_Cancellation/index.html

I’ve heard a lot of systems in my day but I’ve never heard an amp that uses that technique. Could be interesting. I’ve also seen the hypothesis that because speaker drivers’ distortion tends to be 2nd harmonic, it’s possible that SE amps with (realatively) high 2nd harmonics could also do a kind of distortion cancellation. Flipping the polarity of the speaker wires could potentially give different results if that were true. It could also give engineers an explanation as to why so many people prefer high distortion amps, the system is actually more accurate! Lol.

 

[Isaacc7]

Tube rolling journey chronicles continue. I have been trying out the 6J7 -> 6J5 adapters made by 1101 Audio. These adapters are very high quality. I think they are nicer than any other adapter I have tried (including ones made by a certain head-fi'er).

First up: EF37A

After trying 4 different tubes with the signature "Mullard Red" coating, I found only 1 to be silent, 2 to have noticeable noise floor, and 1 to be totally dead. Bummer. Fortunately I had this gray coated NOS pair that are dead silent.

Sounding very nice! Smooth and detailed with great soundstage. Remind me of some of my favorite L63.

Next up: KTZ63!

Having some fun playing with the new iPhone 15 Pro camera settings/lighting:

I have gotten some great results from the KTZ41 as a driver. Well, I did eventually. You can read about my initial frustration with them on the 6j5 thread. Initially they gave me a big diffuse sound no matter what output tube I used. It wasn’t a bad sound necessarily but not what I was looking for. I eventually posted that I was going to give up on them. Some time later I returned to I them and I got a very different sound. Now when paired with tubes like the vt60a I get a much more balanced sound with really seductive midrange. In theory the KTZ41 is just a 4v ktz63 but I haven’t been able to dig up much on them. Since each draw 1.5 amps I haven’t been recommending them to folks in general lol.

 

[Isaacc7]

After several attempts, I finally passed the quiz on the operation, and got permission from Mischa to fire Solar Flare up!
In its new home in my rack, and running with 45 Globe tubes driven by 12AU7 tubes in SET mode with Resistor Load (a.k.a. Orange mode):



Driving my Grado GH2 (SPL 1mW: 99.8 dB, Nominal Impedance: 32 ohms), testing for noise:
* 2-stage mode and high gain, closing my eyes and listening carefully, I can BARELY make a noise floor.
* Switching to low-gain, I am not sure if I can hear it anymore or not.
* 1-stage mode and high-gain - I cannot hear it anymore! Totally silent.

On a semi-related note: switching between 1-stage and 2-stage modes requires power-off and waiting for 30-seconds (for caps to discharge).

Being a tube amp, it is important to note that different tubes may have more or less noise. I will report back after testing with different tubes.
Also important to note that 2-stage / high-gain mode that had the "most" noise floor - was still VERY low. This is one of the quietest tube amps that I ever tested!
Usually, noise floor is a problem for me - but here it was definitely NOT a problem at all. That is just me nitpicking

I’m late to the party but congrats on the amp! I had Tomas at Ultrasonic Studios build an amp for me that put an emphasis on tube rolling as well. I can roll plenty but yours has even more possibilities! I remember wondering why more amp builders don’t make such flexible amps and then it occurred to me, who is crazy enough to put that many ways to blow up an amp into consumers’ hands? Lol. I know I’m going to screw something up at some point and blow things up, I might have already done it actually…


I have rolled 8-9 different output tubes and probably 12-13 input tubes. Add my tube preamp into the mix and there’s about a zillion different combos to be had. I have found that several tube combos will give me similar-ish sounds and so now I tend to think in terms of families of different kinds of sounds. And now that I know that I have an almost endless number of tube possibilities with the tubes I already own I have mostly been able to kick the tube buying habit which feels good too.

You’ve already found the Fivre 12j7gt, one of my go-to input tubes, mind if I make a few recommendations for other off the beaten path tubes? Oh good! Lol. For output tubes I’m in love with the vt60a, 5b/254m, RCA 6bg6ga, Sylvania *av5 (I have 12av5 but there are also 6av5 and 17av5), and the mighty gu50. Since you have a form of auto bias you might also want to check out the n34 if you’re willing to get an adapter with the funky British 7 pin base.

There are plenty of great input tubes but some non 6v ones that I really like are Raytheon 12j5wgt, Raytheon branded 2c50, GEC KTZ41 (with a weird and rare base through), 11n7g, and the 14n7. 7n7 tubes mirror the same Sylvania 6sn7 tubes with the exception of the original metal base 6sn7w. I am convinced that the 14n7 is the same tube as the 6sn7w metal base complete with copper support rod.

Have fun with the amp and hope you can take advantage of the good deals that alternative voltage tubes offer!

 

[Zachik]

Have fun with the amp and hope you can take advantage of the good deals that alternative voltage tubes offer!

Thanks

Surprisingly enough, I have not tried ANY tubes that required adapters on my Solar Flare. Used 6922 and 12AU7 and 6J5 - for drivers, and for output tubes: 71A, 45, 2A3 and 300B tubes.
Honestly, those tubes already offer MANY combinations. Add to that topology options (SET vs. Parafeed) and load options (Resistor vs. CCS) - and that keeps one very busy...

 

[Isaacc7]

Thanks

Surprisingly enough, I have not tried ANY tubes that required adapters on my Solar Flare. Used 6922 and 12AU7 and 6J5 - for drivers, and for output tubes: 71A, 45, 2A3 and 300B tubes.
Honestly, those tubes already offer MANY combinations. Add to that topology options (SET vs. Parafeed) and load options (Resistor vs. CCS) - and that keeps one very busy...

Oh whoops! I might have gotten your amp confused with some of the other amps here. Yours are directly heated triodes right? Well, forget the output tubes I mentioned then lol. Sounds like others here could use them though

 

[kamui]

I know this is a long shot, but has anybody tried Mod House Tungsten with Blue Halo?

I suspect Tungsten will be a tougher test for an OTL, requiring around 20v at 150 ohms (not the ideal impedance for an OTL).

I have, albeit briefly. Was a Double Sided Tungsten, and running 6528 power tubes, and 6J5 drivers. Ran Tungsten with ease. Used low gain, and using a Holo May L2 as a DAC, and had no problem driving it. I haven't heard Tungsten on anything else, but it sounded amazing on the BH+.

 

[whirlwind]

Thanks

Surprisingly enough, I have not tried ANY tubes that required adapters on my Solar Flare. Used 6922 and 12AU7 and 6J5 - for drivers, and for output tubes: 71A, 45, 2A3 and 300B tubes.
Honestly, those tubes already offer MANY combinations. Add to that topology options (SET vs. Parafeed) and load options (Resistor vs. CCS) - and that keeps one very busy...

Ha! Yeah, no kidding that amp will keep one very busy.

You will never need any adapters

That is a killer amp.

 

[ScornDefeat]

I have, albeit briefly. Was a Double Sided Tungsten, and running 6528 power tubes, and 6J5 drivers. Ran Tungsten with ease. Used low gain, and using a Holo May L2 as a DAC, and had no problem driving it. I haven't heard Tungsten on anything else, but it sounded amazing on the BH+.

Awesome, thank you! I suspected BH+ could work, sounds like that's the case. Tungsten + an OTL sounds like it can be an amazing combo. Sucks I missed the last Tungsten drop, which lasted about 1 minute total.

Holo May L2 is a pretty hot DAC, though, right? I've heard that it can put out quite a bit more line level voltage than the usual 2v/4v.

 

[kamui]

Awesome, thank you! I suspected BH+ could work, sounds like that's the case. Tungsten + an OTL sounds like it can be an amazing combo. Sucks I missed the last Tungsten drop, which lasted about 1 minute total.

Holo May L2 is a pretty hot DAC, though, right? I've heard that it can put out quite a bit more line level voltage than the usual 2v/4v.

Yeah, it's a bit hot (2.9v/5.8v), and I was using the Cinemag transformers so getting more voltage coming in, but I had a ton of headroom, so it might still be fine with a more standard 2v/4v input signal. Might still need the Cinemag's to get higher than 2v input though.