How much power does an OTL headphone amplifier need? If we are to make 600mW, but we double the wasted heat and the size of the power transformer in the process, is that a worthwhile trade?cddc said:
Tube Rolling w/Crack
- Thread starter Dr. Toobz
- Start date
Deke609 said:
Thanks, you are correct, I missed the max power dissipation figure from the 2A3 datasheet. I read it again and indeed 2A3 has 15W max plate dissipation and 3.5W max power output. But for 6080/6AS7 tubes datasheets only show 13W max plate dissipation, nowhere can I find their max power output figure.
But as you said max power output is a fraction of max plate dissipation, so I think the max power output of 6080/6AS7 should come close to 3-ish Watt, which means 6080/6AS7 could possibly output as much power as the 2A3's ?
Paul Birkeland said:
Thanks, PB! You are correct 0.3W should be enough to drive 300 ohms headphones in an OTL design. I'm just interested in the potentials from 6080/6AS7 tubes, considering the huge power demand from planars, but of course not in an OTL design as their low impedances are not appropriate for OTL's.
For planar headphones to do OTL, you would want to look more at a speaker type amplifier with multiple output tubes and some feedback to straighten things out. We of course would suggest the SEX amp...
Thanks PB, my knowledge on electronics is very limited, impossible to design an amp :-[
I always think it would be a great idea for BH to add a headphone jack to the 300B/2A3 speaker amps (with some modification to the circuit of course). Amps like WA5 or WA33 that can power both speakers and headphones are quite popular. There should be a niche market there
I always think it would be a great idea for BH to add a headphone jack to the 300B/2A3 speaker amps (with some modification to the circuit of course). Amps like WA5 or WA33 that can power both speakers and headphones are quite popular. There should be a niche market there
D
Deke609
Guest
Paul Birkeland said:
But if you're going all out, I would recommend the combination of BeePre and Kaiju, or BP and Stereomour. I haven't heard the S.E.X., but in my experience BeePre+Kaiju > BeePre+Stereomour > Stereomour.
cddc said:I always think it would be a great idea for BH to add a headphone jack to the 300B/2A3 speaker amps (with some modification to the circuit of course). Amps like WA5 or WA33 that can power both speakers and headphones are quite popular. There should be a niche market there
You can just use a speaker taps to headphone adapter cable -- I still use one with my Stereomours. But from a business perspective, you might have point -- I've often thought something similar. Folks who are willing to pay $2K to $6K for planar headphones are probably willing to pay at least that much for amps to drive them. But how many of those folks are interested in soldering the amps together themselves? Dunno, but I suspect not many. But I agree that there is a niche, spendy market there waiting to be tapped.
cheers, Derek
Paul Joppa
Moderator
The 6080 was not designed for audio and is not very linear. In Crack, it operates at a small fraction of its power capability, and with negative feedback (as a cathode follower). Both substantially reduce distortion.
As a power amp, running (for example) 130v at 100mA without feedback into a 600-ohm load, it will deliver about 1.5 watts - at about 15% distortion! At 5% distortion, it is only capable of 0.15 watts.
That's why there is no audio power output specification.
As a power amp, running (for example) 130v at 100mA without feedback into a 600-ohm load, it will deliver about 1.5 watts - at about 15% distortion! At 5% distortion, it is only capable of 0.15 watts.
That's why there is no audio power output specification.
Paul Joppa
Moderator
There was a brief period in the early 50s where push-pull designs were popular with the 6AS7 / 6080. Push-pull cancels the even order harmonics, which improves the situation even without feedback. I think it was overtaken by the greater power available from pentodes and beam tetrodes.
raymondp1138
Member
Off topic, but I just got a pair of 25ohm planars, and I can attest to to the SEX amp driving them well, as well as my SS amp. I also briefly tried them on the Mainline, which also seem to drive the planars well.Paul Birkeland said:
ChetJettison
New member
I've seen the sticky about compatible tubes, and at just under 150 pages, it's a tome of valuable information. I'm new to tube rolling, and it does sound fun. But with all the options and information, it's hard to make an informed decision. So I seek specific recommendations: Which alternate tubes should I try first? Are there any tried-and-true choices out there? A consensus on particularly nice tubes that don't cost a fortune? I'm open to suggestions.
Buy a smattering of what's cheap on eBay. I would suggest not buying any new production tubes.
ChetJettison
New member
Paul Birkeland said:
I meant to post my question as it's own topic. Oops. But since we're on the subject- any particular tubes you'd recommend?
ChetJettison said:
It's a spendy way to go, but the Western Electric 421A is always good (if you can find one) and I've been enjoying that with my Tung Sol tall bottle halo 6SN7 with the Garage1217 adapter (http://garage1217.com/garage1217_diy_tube_headphone_amplifiers_012.htm#e80)
ChetJettison
New member
tim273 said:
At $230+, that Western Electric is a bit out of my price range just now. But I'll add it to my wish list for the future, when I become inexplicably wealthy! That Tung Sol on the other hand is much more attainable. Thanks for the suggestions!
Yes, you did post it as its own topic, then I merged it into this thread where it belongs.ChetJettison said:
ChetJettison
New member
Paul Birkeland said:
Haha, whoops! Thanks for keeping me in line!
