Hi
I would like to build a tube amp for headphone. Preferably that can drive 32r load. Main headphone is hd6xx
I have seen bottleneck crack. But shipping is too expensive to asia
Wondering if there is any other alternative and suggestion
Thx in advance
Erwin
I would like to build a tube amp for headphone. Preferably that can drive 32r load. Main headphone is hd6xx
I have seen bottleneck crack. But shipping is too expensive to asia
Wondering if there is any other alternative and suggestion
Thx in advance
Erwin
32R is quite a low impedance for tubes without some form of transformer or impedance multiplier design (ie mini ZOTL). This is because tubes are better at voltage rather than providing current that the 32R headphones will want.
The bottle head crack is an OTL tube amp. Without a transformer the output tube sees the impedance of the headphones so you are then limited to larger current capable tubes or paralleled tube sections (if the tube has two triodes for example). Those tubes such as the 6AS7 and 6080 were originally designed for higher current and so have lower internal resistance (which means lower output impedance). You could have ecc99s but they're still fairly high internal resistance so would need paralleling to reduce the impedance mismatch.
Take it from me (3 years and counting) for attempting to design a good low impedance headphone OTL, it's more expensive and probably easier just buying a pair of Lundhal headphone output transformers and run some proper tubes. Alternatively go hybrid (using solid state output) or ZOTL (expensive and complex).
OTL can work but you'll find bass rolling off if the output impedance isn't kept in check.
There's plenty of threads about tube headphone amps for example 6AS7: https://www.diyaudio.com/community/threads/6as7-otl-headphone.360671/
Just be wary that 32R is a pain for a tube to drive without a transformer..
The bottle head crack is an OTL tube amp. Without a transformer the output tube sees the impedance of the headphones so you are then limited to larger current capable tubes or paralleled tube sections (if the tube has two triodes for example). Those tubes such as the 6AS7 and 6080 were originally designed for higher current and so have lower internal resistance (which means lower output impedance). You could have ecc99s but they're still fairly high internal resistance so would need paralleling to reduce the impedance mismatch.
Take it from me (3 years and counting) for attempting to design a good low impedance headphone OTL, it's more expensive and probably easier just buying a pair of Lundhal headphone output transformers and run some proper tubes. Alternatively go hybrid (using solid state output) or ZOTL (expensive and complex).
OTL can work but you'll find bass rolling off if the output impedance isn't kept in check.
There's plenty of threads about tube headphone amps for example 6AS7: https://www.diyaudio.com/community/threads/6as7-otl-headphone.360671/
Just be wary that 32R is a pain for a tube to drive without a transformer..
I have built a few tube headphone amplifiers. The end result is headphones dependant, much more than a typical solid state amplifier. This is most noticeable when the circuit is zero/low feedback or a transformerless cathode follower. I currently like pairing Sundara headphones with a zero feedback triode-wired EL84 amplifier with output transformers. No voltage gain stage is needed before the EL84 to get satisfactory volume on the Sundara; they have flat 38 ohms impedance over the full audio bandwith. The output transformers are inexpensive 5W 5k/8 ohm, so the EL84 is working with 4 times higher load than the datasheet optimal value. This does not seems to be a issue whith the right tube bias, but it does not work for high impedance headphones. With my 300 and 600 ohms headphones, I use cathode followers amplifiers.
I am pretty happy with my single-ended OTL headamp. It's based on a project by Aren van Waarde (6922 with 6AS7G).
Link:
https://headwizememorial.wordpress....e-ended-otl-amplifier-for-dynamic-headphones/.
It is driving my Sennheiser HD599 and Phillips SHP9600 with very good results. Both are low impedance pairs.
It is a simple, yet pleasant design.
I will post some pictures of my actual build to get an idea.
Link:
https://headwizememorial.wordpress....e-ended-otl-amplifier-for-dynamic-headphones/.
It is driving my Sennheiser HD599 and Phillips SHP9600 with very good results. Both are low impedance pairs.
It is a simple, yet pleasant design.
I will post some pictures of my actual build to get an idea.
Some pics of the build:
Overview
PSU with 2 x 6C4P (russian equivalent to chinese 6Z4)
Those 12W resistors could be 20W for better dissipation but I had limited room.
Overview from the back
Close of the elevated AC filament circuit. Those tombstone resistors are to lower AC to 6.2 volts.
Regarding how it sounds, I'd say it compares favorably to my other projects.
I like it better than another, somewhat similar OTL tube design that uses an SRPP for gain instead of the single 6922 in this one.
It has even less grain, better separation and wider soundstage.
It is dead-quiet if you do the AC filaments right. No need for DC in this one.
Going regulated DC (i have tried it) will get you in trouble with massive amounts of heat.
And sonically, DC lighting is inferior in my opinion.
Compared to the Tortello design, this one is fuller and more 'holographic', but that is to be excpected since Tortello is solid-state.
An excellent sounding solid-state though. At least for my ears.
Lehmann BCL is pretty good but can't compare to the amps mentioned above.
All in all, I recommend this build since it's easy to implement and can be tweaked to you liking.
Overview
PSU with 2 x 6C4P (russian equivalent to chinese 6Z4)
Those 12W resistors could be 20W for better dissipation but I had limited room.
Overview from the back
Close of the elevated AC filament circuit. Those tombstone resistors are to lower AC to 6.2 volts.
Regarding how it sounds, I'd say it compares favorably to my other projects.
I like it better than another, somewhat similar OTL tube design that uses an SRPP for gain instead of the single 6922 in this one.
It has even less grain, better separation and wider soundstage.
It is dead-quiet if you do the AC filaments right. No need for DC in this one.
Going regulated DC (i have tried it) will get you in trouble with massive amounts of heat.
And sonically, DC lighting is inferior in my opinion.
Compared to the Tortello design, this one is fuller and more 'holographic', but that is to be excpected since Tortello is solid-state.
An excellent sounding solid-state though. At least for my ears.
Lehmann BCL is pretty good but can't compare to the amps mentioned above.
All in all, I recommend this build since it's easy to implement and can be tweaked to you liking.
This post is a reiterration of another one found in an identical topic launched a while ago...As nobody reads older topics today I don't feel like repeating myself either 🙂
I'll stard by shamelessly recommend two of my own designs just because I can...but...
although my best sounding headphones amplifier(more of a buffer than an amplifier...about 1.5x gain due to transformer ratio if I recall right) implied tubes and output transformers: https://www.diyaudio.com/community/threads/teardrop-headphones-amplifier.315827/#post-5463972
and the second most interesting to me implied the use of germanium transistors :
https://www.diyaudio.com/community/threads/germanium-foundation-chapter1.381869/#post-6910367
building about 15 different amps from the simplest to the most complex , I'd recommend 5 comercially valid designs in total for any beginner with limited resources and high hopes .They are on the surgical side, very precise but simple to build, except one.They are a better introduction to headphones amplifiers because they were tried, built by the thousands and found in pretty expensive and reveered "refference" or real refference audio equipment.
1.The first would be any variation of Studer A800, A810, A820, A827 reel to reel tape machine's hedphones amp, line amp without output transformer or monitor output.The basic design constitute the standard that you find more or less in almost any professional recording console or dac.
2.Second honorable mention would be the last version of Tandberg 3014 cassette deck headphones amp.Now that's discrete and complex...
3.Third amp(actually unity gain buffer but just a buffer is all you need with general 32 ohms headphones) that really deserves attention is a very odd one, but encompasses a secret revealed by D.Self 20 years later although he probably didn't know Nakamichi would dare using 100k ohm resistors for common mode canceling: Nakamichi CR 4 cassette deck headphones amp
4.Fourth amp is the one found in Yamaha kx 930 cassette deck .Being inverted design surprised me one day listening on the monitor line in while recording a cassette.
5.Fifth amp although unapealing to some and having the biggest bang for the buck as it allows the ordinary njm4556 to fight any modern op amp is the one found in Technics SP L990 cd player.
I'll stard by shamelessly recommend two of my own designs just because I can...but...
although my best sounding headphones amplifier(more of a buffer than an amplifier...about 1.5x gain due to transformer ratio if I recall right) implied tubes and output transformers: https://www.diyaudio.com/community/threads/teardrop-headphones-amplifier.315827/#post-5463972
and the second most interesting to me implied the use of germanium transistors :
https://www.diyaudio.com/community/threads/germanium-foundation-chapter1.381869/#post-6910367
building about 15 different amps from the simplest to the most complex , I'd recommend 5 comercially valid designs in total for any beginner with limited resources and high hopes .They are on the surgical side, very precise but simple to build, except one.They are a better introduction to headphones amplifiers because they were tried, built by the thousands and found in pretty expensive and reveered "refference" or real refference audio equipment.
1.The first would be any variation of Studer A800, A810, A820, A827 reel to reel tape machine's hedphones amp, line amp without output transformer or monitor output.The basic design constitute the standard that you find more or less in almost any professional recording console or dac.
2.Second honorable mention would be the last version of Tandberg 3014 cassette deck headphones amp.Now that's discrete and complex...
3.Third amp(actually unity gain buffer but just a buffer is all you need with general 32 ohms headphones) that really deserves attention is a very odd one, but encompasses a secret revealed by D.Self 20 years later although he probably didn't know Nakamichi would dare using 100k ohm resistors for common mode canceling: Nakamichi CR 4 cassette deck headphones amp
4.Fourth amp is the one found in Yamaha kx 930 cassette deck .Being inverted design surprised me one day listening on the monitor line in while recording a cassette.
5.Fifth amp although unapealing to some and having the biggest bang for the buck as it allows the ordinary njm4556 to fight any modern op amp is the one found in Technics SP L990 cd player.
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