[ThanatosVI]

Running two EL34 tubes (1x per channel) runs the tubes at around 90-95% dissipation - still possible, but pretty hard on the tubes and relatively short tube life. Running 2x tubes per channel drops the dissipation per tube down to 50% or less dissipation per tube for long tube life



That's correct, it can run the KT120/KT150 (max of 2x per channel) as well using the same EL34 -> 6080 adapters The KT170 is a bit too wide to fit without scorching some paint off the transformer covers behind them, and I've also heard about reliability issues with the KT170 on launch (though they may have solved those by now).

Nah KT170 quality didn't improve, still unreliable

 

[Xcalibur255]

The supply situation for KT150 is also quite bad and not likely to improve anytime soon. They're also getting pretty expensive for what they are. For a while it seemed like a couple of the Chinese tube makers would jump into this game but now nothing seems to be happening on that front.

 

[raindownthunda]

Lots of creativity on display here. Enjoy the results!

I have a feeling that this LED implementation is going to be seen and copied at some point and will show up in some commercial offering down the road for massive $$$. If that happens you can smile and know that you did it first.

Thanks @Xcalibur255! I've been building LED setups around the house for the past few years and was disappointed with the lack of color VU meter backlights or any kind of user control... Originally I just wanted to be able to dim the lights myself. So I went down the path of trying to figure out how to make that work without knowing how it would turn out.

I need to clarify and emphasize the VU meters and power switch with colors/effects are totally custom and not included in the BH+ VU meter add-on. There was a lot of DIY modding/experimentation on my part to come up with the setup myself i.e. I went through 3 pairs of VU meter prototypes before I had a "production ready" set. Getting the power switch to change colors as part of the circuit was a huge challenge in and of itself. I configured and tested everything on my end and mailed the fully assembled setup to @A2029. I paid additional labor fees for the install as well as troubleshooting unforeseen issues that came up during testing. Unfortunately there isn't (yet) a streamlined process to re-produce these type of meters. I don't think @A2029 is offering this as an option due for the aforementioned reasons.

Here are some process/fail pics:

 

[Xcalibur255]

Very cool. I'm sure the amp will be a ton of fun in the coming months.

 

[raindownthunda]

So after ~24 hours, initial impressions of the Blue Halo+ are very, very good. Here's a quick brain dump (all while using my Verite Closed):

• This amp brings the alluring boldness/detail/slam with inexpensive power tubes that can only be attained with top-tier $$ tubes in my Bottlehead Crack.
• Improvement over the BHC in almost every way from a technical standpoint. Especially notable is improvement in treble detail, treble presence, and speed/immediacy.
• The imaging & staging is leaps and bounds above the BHC I'm used to. Clearly defined layering while still sounding cohesive and full. Super immersive and spacious. With inexpensive tubes the 3d staging is already better than the best I've ever heard on the BHC with S-tier tubes.
• BH mode is blackhole silent. Extreme clarity while still sounding full and powerful. Electronic music absolutely rips in BH mode. Bass is out of this world addictive.
• BH+ mode brings a bit more pleasing distortion with slightly less pinpoint detail. Based on the few tube rolls I've tried, you can get a slightly more relaxed/cozy listen. The excellent technicalities are still clearly the foundation. The incisive speed, slam, stage, and layering are still noticeably present, but now the sonic paintbrush has more tube texture and ever so slightly larger brush strokes. At least with the rolls I've tried, this is very far away from a lush/bloomy tube sound (a la RCA 6AS7G in a Bottlehead Crack). BH+ mode is for those who want exemplary technicalities but still having a healthy dose of euphonic tube tone.
• Having both BH/BH+ mode is exactly what I was hoping for. Option to change the tone slightly depending on mood to keep that spice alive. I don't think I can say one mode is objectively "better" than the other.
• 4x 6080 tubes sounds tighter, faster, more slam than 2x 6080 tubes.
• Low-ohm mode, with electrolytic output caps in parallel to film caps, sounds surprisingly similar to High-ohm mode. That's to say it sounds very, very good and not audibly worse (to me) than just running the film caps by themselves. This seems to go against the "electrolytics sound bad" mantra. @A2029 noticed this too and theorized it's possibly some combination of 1) higher capacity film caps in parallel handling a good portion of the frequency spectrum 2) Miflex bypass caps handling the high frequencies, and 3) extremely high quality electrolytics used that may actually sounding pretty good in their own right. Given cap burn in takes 100's of hours, it will be interesting to see if this observation holds up in the long-run. I'm very interested to know how low-ohm headphones / planars sound on this OTL.
• The amp can get HOT in BH+ mode without active cooling. There are 2x fans on the bottom that need to be running at ~50% speed to keep the sides of the amp from being too hot to touch. The amp runs much much cooler in BH mode which won't need active cooling. @A2029 did some thorough stress testing and component optimization and assures me the amp components will handle the heat.
• The amp form factor and size is perfect. It’s very compact for the amount of tubes and components packed inside. This is a desktop friendly TOTL tube amp.
• The 58x I’m using to test new tube rolls sounds like $1000 headphones on this amp. Whoever says 58x doesn’t scale?

Just rolled in 6x 6BX7 tubes that I've had for over 3 years that I bought from @L0rdGwyn. Feels good to finally get to put them to good use!

 

[JazzVinyl]

So after ~24 hours, initial impressions of the Blue Halo+ are very, very good. Here's a quick brain dump (all while using my Verite Closed):

• This amp brings the alluring boldness/detail/slam with inexpensive power tubes that can only be attained with top-tier $$ tubes in my Bottlehead Crack.
• Improvement over the BHC in almost every way from a technical standpoint. Especially notable is improvement in treble detail, treble presence, and speed/immediacy.
• The imaging & staging is leaps and bounds above the BHC I'm used to. Clearly defined layering while still sounding cohesive and full. Super immersive and spacious. With inexpensive tubes the 3d staging is already better than the best I've ever heard on the BHC with S-tier tubes.
• BH mode is blackhole silent. Extreme clarity while still sounding full and powerful. Electronic music absolutely rips in BH mode. Bass is out of this world addictive.
• BH+ mode brings a bit more pleasing distortion while losing out the smallest microdetails. Based on the few tube rolls I've tried, you can get a more relaxed/cozy listen without sacrificing too much technicalities.
• Having both BH/BH+ mode is exactly what I was hoping for. Option to change the tone slightly depending on mood to keep that spice alive. I don't think I can say one mode is objectively "better" than the other.
• 4x 6080 tubes sounds tighter, faster, more slam than 2x 6080 tubes.
• Low-ohm mode, with electrolytic output caps in parallel to film caps, sounds surprisingly similar to High-ohm mode. That's to say it sounds very, very good and not audibly worse (to me) than just running the film caps by themselves. This seems to go against the "electrolytics sound bad" mantra. @A2029 noticed this too and theorized it's possibly some combination of 1) higher capacity film caps in parallel handling a good portion of the frequency spectrum 2) Miflex bypass caps handling the high frequencies, and 3) extremely high quality electrolytics used that may actually sounding pretty good in their own right. Given cap burn in takes 100's of hours, it will be interesting to see if this observation holds up in the long-run. I'm very interested to know how low-ohm headphones / planars sound on this OTL.
• The amp can get HOT in BH+ mode without active cooling. There are 2x fans on the bottom that need to be running at ~50% speed to keep the sides of the amp from being too hot to touch. The amp runs much much cooler in BH mode which won't need active cooling. @A2029 did some thorough stress testing and component optimization and assures me the amp components will handle the heat.
• The amp form factor and size is perfect. It’s very compact for the amount of tubes and components packed inside. This is a desktop friendly TOTL tube amp.
• The 58x I’m using to test new tube rolls sounds like $1000 headphones on this amp. Whoever says 58x doesn’t scale?

Just rolled in 6x 6BX7 tubes that I've had for over 3 years that I bought from @L0rdGwyn. Feels good to finally get to put them to good use!

Very nice description! Well done! Thank you!

 

[mordy]

So after ~24 hours, initial impressions of the Blue Halo+ are very, very good. Here's a quick brain dump (all while using my Verite Closed):

• This amp brings the alluring boldness/detail/slam with inexpensive power tubes that can only be attained with top-tier $$ tubes in my Bottlehead Crack.
• Improvement over the BHC in almost every way from a technical standpoint. Especially notable is improvement in treble detail, treble presence, and speed/immediacy.
• The imaging & staging is leaps and bounds above the BHC I'm used to. Clearly defined layering while still sounding cohesive and full. Super immersive and spacious. With inexpensive tubes the 3d staging is already better than the best I've ever heard on the BHC with S-tier tubes.
• BH mode is blackhole silent. Extreme clarity while still sounding full and powerful. Electronic music absolutely rips in BH mode. Bass is out of this world addictive.
• BH+ mode brings a bit more pleasing distortion while losing out the smallest microdetails. Based on the few tube rolls I've tried, you can get a more relaxed/cozy listen without sacrificing too much technicalities.
• Having both BH/BH+ mode is exactly what I was hoping for. Option to change the tone slightly depending on mood to keep that spice alive. I don't think I can say one mode is objectively "better" than the other.
• 4x 6080 tubes sounds tighter, faster, more slam than 2x 6080 tubes.
• Low-ohm mode, with electrolytic output caps in parallel to film caps, sounds surprisingly similar to High-ohm mode. That's to say it sounds very, very good and not audibly worse (to me) than just running the film caps by themselves. This seems to go against the "electrolytics sound bad" mantra. @A2029 noticed this too and theorized it's possibly some combination of 1) higher capacity film caps in parallel handling a good portion of the frequency spectrum 2) Miflex bypass caps handling the high frequencies, and 3) extremely high quality electrolytics used that may actually sounding pretty good in their own right. Given cap burn in takes 100's of hours, it will be interesting to see if this observation holds up in the long-run. I'm very interested to know how low-ohm headphones / planars sound on this OTL.
• The amp can get HOT in BH+ mode without active cooling. There are 2x fans on the bottom that need to be running at ~50% speed to keep the sides of the amp from being too hot to touch. The amp runs much much cooler in BH mode which won't need active cooling. @A2029 did some thorough stress testing and component optimization and assures me the amp components will handle the heat.
• The amp form factor and size is perfect. It’s very compact for the amount of tubes and components packed inside. This is a desktop friendly TOTL tube amp.
• The 58x I’m using to test new tube rolls sounds like $1000 headphones on this amp. Whoever says 58x doesn’t scale?

Just rolled in 6x 6BX7 tubes that I've had for over 3 years that I bought from @L0rdGwyn. Feels good to finally get to put them to good use!

Can the amp handle a pair of 6336/6528 tubes?
Although the current draw is double that of a 6080 the spec sheet introduction states that one of these tubes can take the place of two or three 6AS7/6080 tubes.

 

[raindownthunda]

Can the amp handle a pair of 6336/6528 tubes?
Although the current draw is double that of a 6080 the spec sheet introduction states that one of these tubes can take the place of two or three 6AS7/6080 tubes.

With upgraded power regulators, yes it can run a pair of 6336/6528 tubes. That will be my next roll It can technically run up to 6x 6080/6AS7G tubes but I believe it's not recommended for regular/long-term use as it would strain some components on the amp and shorten lifespan. @A2029 can chime in if there's any other guidance here

 

[A2029]

Can the amp handle a pair of 6336/6528 tubes?
Although the current draw is double that of a 6080 the spec sheet introduction states that one of these tubes can take the place of two or three 6AS7/6080 tubes.

With upgraded power regulators, yes it can run a pair of 6336/6528 tubes. That will be my next roll It can technically run up to 6x 6080/6AS7G tubes but I believe it's not recommended for regular/long-term use as it would strain some components on the amp and shorten lifespan. @A2029 can chime in if there's any other guidance here

As @raindownthunda said, the amp is able to comfortably handle 2x 6080/6AS7/5998 per channel, and can do 1x 6336/6528 per channel with the optional 6336/6528 handling upgrade. When you get into 3x 6080/6AS7/5998 per channel, the amp gets into inferno heat territory and the lifespan of internal parts starts to really suffer, so 2x 6080/6AS7/5998 per channel is the max I recommend for running long term.

EL34 tubes only take 60% of the heater current than 6080/6AS7/5998 though, so those can run 3x per channel in adapters.

6BX7/6BL7 on the other hand need to be run 3x per channel when running the amp in constant current sink (CCS) power tube bias mode, but it's possible to run as little as 1x 6BX7/6BL7 per channel when using the resistor (RES) power tube bias mode.


Edit: I'll give a more comprehensive technical background of what is happening with all the different modes of the amp in the next few days when I get some time off work. It's some neat technical elements that allows the amp to be kind of like three somewhat different kinds of amp all wrapped into one and swappable with flicking some switches on the back (with amp off).

 

[mordy]

As @raindownthunda said, the amp is able to comfortably handle 2x 6080/6AS7/5998 per channel, and can do 1x 6336/6528 per channel with the optional 6336/6528 handling upgrade. When you get into 3x 6080/6AS7/5998 per channel, the amp gets into inferno heat territory and the lifespan of internal parts starts to really suffer, so 2x 6080/6AS7/5998 per channel is the max I recommend for running long term.

EL34 tubes only take 60% of the heater current than 6080/6AS7/5998 though, so those can run 3x per channel in adapters.

6BX7/6BL7 on the other hand need to be run 3x per channel when running the amp in constant current sink (CCS) power tube bias mode, but it's possible to run as little as 1x 6BX7/6BL7 per channel when using the resistor (RES) power tube bias mode.


Edit: I'll give a more comprehensive technical background of what is happening with all the different modes of the amp in the next few days when I get some time off work. It's some neat technical elements that allows the amp to be kind of like three somewhat different kinds of amp all wrapped into one and swappable with flicking some switches on the back (with amp off).

Maybe you could shed some light on this question:

Raindownthunda mentioned that he is running a sextet of the 6BX7 tube. This tube has an amplification factor of 10. Common power tubes such as the 6AS7 and 6080 and variants have an amplification factor between 2-5 approximately. I guess that it depends on how the amp is designed, but the usual rule is that power tubes with a higher amplification factor introduce more noise into the system.

When you use power tubes with a higher amplification factor such as 6BX7 (mu10) and 6SN7 (mu20), what is the combined amplification factor that the amp sees? Is it the same as for one tube? Or is it related to the quantity of tubes are being used?

 

[Marutks]

• BH mode is blackhole silent.

Is it dead silent when no music is playing? Do you use Verite Closed cans?
I wonder what makes your amp dead silent. Is it 6080 tubes ?

My BlueHalo is dead silent only when I use 6N6P tubes ( or single 6080 ).

 

[raindownthunda]

Is it dead silent when no music is playing? Do you use Verite Closed cans?
I wonder what makes your amp dead silent. Is it 6080 tubes ?

My BlueHalo is dead silent only when I use 6N6P tubes ( or single 6080 ).

Yes it's silent with no music playing & VC headphones with the tubes I've tried. I'm actually finding BH+ to be pitch black silent w/o music with the right tubes as well. Right now I'm using 4x GEC 6080 power and 1x TS 12SN7 driver and it's also dead silent. Sounds basically the same as my Jotunheim 2 with no music playing. The 6x 6BX7 had a more noticable noise floor and one pair of TS 6080 were slightly microphonic (settled down after they warmed up). Both of the times I noticed any slight noise in BH+ mode due to the tubes, I tried switching to BH mode and it was dead silent again.

I seem to have pretty good power in my house with nominal voltage ratings in a residential area so that could have something to do with it? I have seen a bunch of threads on trying to isolate amp noise and wouldn't really know where to begin. What tubes do you have the most issues with? Later I'll try some tubes I know are noisy in my BHC and let you know how they sound with BH.

edit:
Just tried a pair of Fivre 6C5G that I know are noisy from using in my BHC. I definitely hear the same interference noise in BH mode. It's a little quieter than in my BHC but it's still noticeable when no music is playing. So doesn't seem like the amp will "erase" any inherently noisy tubes. With quiet tubes, the noise floor is much lower than my BHC, even in BH+ mode.

 

[A2029]

Maybe you could shed some light on this question:

Raindownthunda mentioned that he is running a sextet of the 6BX7 tube. This tube has an amplification factor of 10. Common power tubes such as the 6AS7 and 6080 and variants have an amplification factor between 2-5 approximately. I guess that it depends on how the amp is designed, but the usual rule is that power tubes with a higher amplification factor introduce more noise into the system.

When you use power tubes with a higher amplification factor such as 6BX7 (mu10) and 6SN7 (mu20), what is the combined amplification factor that the amp sees? Is it the same as for one tube? Or is it related to the quantity of tubes are being used?

The second stage of the amp where the amp is using the power tubes for the output, the BH+ mode, has an amplification factor (mu) of 1 or less for the power tubes as the power tubes are run in cathode follower configuration. The more power tubes that are run, the closer to a mu of 1 that second stage has. The first stage driver tubes do all of the amplification (e.g. mu of 20 for the 6SN7), so pairing a 6SN7 driver with quad of 6080 outputs would give total amp mu of 20 x ~1 = ~20.

 

[Marutks]

What tubes do you have the most issues with?

Almost all of my 6J5 and 6SN7 tubes. My BlueHalo is dead quiet only with 6N6P tubes ( or single 6080 ).
I have found some tubes (B36 and 6H8C) that reduce noise floor to almost non-audible level. Also burn-in helps for some tubes.

 

[mordy]

Almost all of my 6J5 and 6SN7 tubes. My BlueHalo is dead quiet only with 6N6P tubes ( or single 6080 ).
I have found some tubes (B36 and 6H8C) that reduce noise floor to almost non-audible level. Also burn-in helps for some tubes.

Can the Blue Halo be used as a preamp with speakers? Personally, using my amps with speakers, I have found that almost any combination of tubes sound noisy at very high volumes, but by judiciously using both the volume knobs on the headphone/preamp and the volume knob on the receiver for the power amplifier, I can eliminate the noise to the point of not being noticeable at all, even without music playing.
IMHO listening to tube amplifiers, even with the noise being masked by the music, is just fine. There are combinations that are really quiet, but that is not generally the rule.
Audiophile proverb: If they make it, it hums. JUST KIDDING!