The headphone amplifiers are mystery for me. Form one perspective it should be simple but from another perspective I never heard any interestingly performing headphones amplifiers. Well, I have to take it back probably as wherever I even heard different headphone amplifiers I always listen them with whatever headphones they were demonstrated. This last condition always was difficult for me as I also am conditional to the headphones. The problem is that for many years I am very much habituated to use Japanese made Audio-Technica headphones but they for whatever reasons are not widely used by hi-fi people. With my headphones, and having over the years a half-dozen different headphone amps in my room I always found that they all sounded not as good as full scale amp driving headphones through an  impedance converting adapter. Actually, the cheap phone amplifiers built into the ¼” jack at consumer radio sound way better then those “dedicated high-end phone amplifiers”.

I do not know what the reasons but I decided probably try to get a headphone amp. I asked myself that if I so like the Melquiades and if the Milq’s sound live in the driver’s stage then could the driver stage to drive the headphones. I called Dima and he confirmed that he use to bult the headphone amps around a single 6E5P.

Well, I figured that it would not be difficult to do. The Milq’s plate resistor will be replaced with amorphous Lundahl1627 with enormous for 6E5P gap and all the rest will be identical to the Milq, with exception of the magnetic currents. I ordered the transformers and for a time being, during the Black Friday, put together the amplifier section. It took a little over 4 hours.

The gain stage sits in magnetically sealed enclosure and should be operational now, thought I did not tested it. I will get the transformers in ~10 days and the will put it all together.

I wonder if anyone heard any deserving attention headphone amplifiers? Any further advise to a person who never imploded any dedicated headphone amps?

Rgs,
Romy the Cat

This weekend I found some transformers in my storage and I put together the Baby Melquiades headphone amplifier. It turns out to be very cure little amp. It is 9'x9' but has all Milq’s incidents including the choke intuit supply for plates and the Milq’s biasing idea. The fine part that this 6E5P tube is so obnoxious that it can drive speakers directly. I was contemplating to put in the secondary the headphone jacks or the binding post and to drive my tweeters… but the headphones won. :-)

Well, the most important how this versatile and “dynamically viscose” 6E5P will be sounding driving the load directly. The question still without answer as the "Baby Melquiades" so far sounds despicable horrible. I kind of screw up and mistakably used a wrong output transformer, the only on that I had and that looked OK. I would need another one with 10 times more inductance in primary (60mA, 60H, 10K/40R), then I would be able to see how it sounds. After I find a good transformer then it will be very interesting to listen this thing…

To be continue…
Romy the Cat

Romy the Cat wrote:

I wonder if anyone heard any deserving attention headphone amplifiers? Any further advise to a person who never imploded any dedicated headphone amps?

Michael,

I never head Single Power gears, or ever herd this company. I kind of have very specific type of sound that am wiling to get out the headphones. It is hard to describe but it should be very-very soft and moist but still with upper bass horn very slightly flooding it region with yellowish colored dominating second harmonic + superb speed (but not sharp) and the response all the way down. Something kind of sound of my Mono SPU. The SPU is too yellow, so I would need a very minor injection of blue and magenta into its tone. In addition I need “slower” bass, as slow as possible but with all preservation of the “reasonable” articulation…

I contacted the Lundahl people with my requirements for the new transformers. I am little afraid that for the headphones this trans might be too “fast” but perhaps they would be able to come up with excessive inductance of primary and by means of it they would slightly male it less “HF changed”… I generally had very success with thier transformers in past and I would eagerly aware what they would come up with this time.

Rgs,
Romy The cat

I did today some interesting listening. I took my SL-CT470 walkman and plugged it directly into the Baby Milq amp. It was fan. The Baby Milq has no bass now and all together sound kind of screwed but the dynamic capacity of that entire set really impressed me, partially at the lower level. I wonder if, considering that I can glue this walkman right to this Baby Milq via a few inch of cable then can I take the feed out of this CD player filer bypassing it’s out stage? The size and flexibility of this littlie amp is really comfy for all possible interesting experiments and despite the Baby Milq is sick not but there is something very interning in it’s sound. Perhaps Dima is correct and the Baby Melquiades will inherent what a fill scale Melquiades does. It would be great! Meanwhile, I would need to attach the handles to the Baby Milq and bring it to my client’s site?  :-)

The Cat

Chirag wrote:

It seems the 6e5p is driving the transformer directly. I've used various versions of even simple mosfet followers to good effect at the headphone level, but never considered using a speaker level transformer.  Did you and Dmitry consider scaling down the SS version of the Milq you showed us in a different thread?  I'm trying to understand the thinking behind the approach and how it correlates to your desired end result.

Hey, Chirag, long time no see. My thinking behind the approach was very simple. I feel that 6E5P has own very interesting “puss” as Tony Soprano would describe it. This “puss” has something to do with dynamic viscosity and with its ability to sound “dynamically inelegance”. There are some other interesting things about this tube but to enumerator then would be a different subject. Anyhow, the Melquiades’ Sound is primary determined by the sonic idiosyncrasy of the 6E5P. Some people see Melquiades as a 633C-base amp but I see the Melquiades as two stages SET with 6E5P driver and grid’s current comforter. Dima use to bult two stages amps with 6E5P driver using SS, GM70, 6L6GC, KT66 (if I am not mistaken about those PP) and he clamed that all of the amps, though sound differently still were able to express the 6E5P’s signature. Since he discovered this tube for sound I have no reasons to down in his hints. So, the idea was to see if the 6E5P, driving a headphones directly would preserve it’s contribution to Melquiades. And since the 6E5P has quite a lot of own power (8W plate dissipation) then it asked to try it….

Chirag wrote:

I do have a need for a headphone amplifier and quite a bit of my music has been heard through various and mostly unsatisfactory methods.  The current amp uses a very simple and fairly regulated triode driving a mosfet follower.  I was considering trying a few collected pentodes (7721, EF86 etc) to drive a headphone transformer for my beloved grado phones...this loudspeaker transformer method is making me rethink some of my output plans.

Well, I have ordered LL1623 amorphous transformer from Lanhale gaped for 50mA. This would give over 50H primary inductance and well below 10Hz low frequency roll off. I hope the trans arrive near the end of the year or in the worst case in January. I will let know how it would turn out to be. So far I have primary ~8H with roll of at 63H and it sound quite badly across the entire range. Still it has some “signs” that it preserver the 6E5P’s puss. I will be able to say anything defiantly when the magnetics will be here.

Still I do not know if I would be an objective judge in your case as I did not research the subject of headphone amplifies dearly and do not have a lot of experience with them. I have home a few of “class A” SS amps that were unshakable crap. I heard out there a few headphone OTL amps and a few “the best headphone amps ever were bult” - I meant those high-end many thousands dollars amps with shiny chassis and high attitude sales people behind them. The sound of those amps did not impress me. What whatever reasons people out there are trying to make the headphone amps to sound like electrostats and I find it very repulsive. From different perspective I used their headphones, thier crapy consumer front ends and this disgusting music. So, it would be from very difficult, to imposable to say anything objectively about those headphone amps. 

If the 6E5P amp would not "do" then I would try in some way the similar amp replacing the 6E5P with 6C19P...

Rgs,
The caT

Romy the Cat wrote:

Hey, Chirag, long time no see.

Romy the Cat wrote:

I feel that 6E5P has own very interesting “puss” as Tony Soprano would describe it. This “puss” has something to do with dynamic viscosity and with its ability to sound “dynamically inelegant”....Some people see Melquiades as a 633C-base amp but I see the Melquiades as two stages SET with 6E5P driver...(if I am not mistaken about those PP) and he clamed that all of the amps, though sound differently still were able to express the 6E5P’s signature....And since the 6E5P has quite a lot of own power (8W plate dissipation) then it asked to try it….

Romy the Cat wrote:

I hope the trans arrive near the end of the year or in the worst case in January. I will let know how it would turn out to be....Still it has some “signs” that it preserver the 6E5P’s puss.

Romy the Cat wrote:

Still I do not know if I would be an objective judge in your case as I did not research the subject of headphone amplifies dearly and do not have a lot of experience with them.

Romy the Cat wrote:

If the 6E5P amp would not "do" then I would try in some way the similar amp replacing the 6E5P with 6C19P...

Chirag wrote:

The 6E5P is an interesting device (I did some research after you dropped the "tetrode" hint and bought a few :-)), but the bias scheme with the OA2's is still incomprehensible to me.

The cathodes must sit on ground, this it given. You can apply fix bias to the tube but it would require a transformer or a cup to decouple the DC from input. Defiantly you do not want to do it. Dima came up with an idea to milk voltage on a grid resistor, that works very nice but it require an opposite polarity voltage compensation at the input. So, the schema of the “resistor bias” was born. I built the amps I listened it. The problem is that the amp sounded too rough and too unbalanced. It was a very good enough to get the “Best sound at CES” of to thrill the idiots DIY-enthusiasts but my objectives were much more evolve and I found that this was not as musical enough as I would like to. Dima and I initially thought that the problem was due to the minute drift of the voltages across the bias. Dima, come up with a number of quite elegant automated ideas how to get the reference voltage from AC, not really the regulation but rather the active monitoring…. I implemted them but unfortunately they did not sound good.

We were thinning about a solution and the probable reasons and eventually we found it. I had a guy (Geoff Cook) who managed to make microphone amplifiers and phonocorrectors using input penthods that did not sound as the usual input penthods. The Input penthods all sound “hard” but his amps were “soft”. One of his secrets was a very specific type of screen supplies. So, we decided to apply the similar principle to our bias supply, feeding the 6E5P grid and to treat the 6E5P’s grid as the penthod screen. Dima, disagreed with this semantic substation but I personally, operating in the conceptual language rather then via the language of the mathematical approximation still call the 6E5P’s screen and grid interchangeably.

You see, it is very fascinating to feed screen of a penthod with different type of voltages and to see how the penthods sound changes.  The penthod screen, or in Milq’s case the grid, pick come currents/violates that travel to the source - the screen/grid voltage supply. The whole story is how the power supply would react to those “returned alien voltages”. The PS is basically a termination of a transition line from the grid. It should very gently absorb those “bounced voltages” and completely decuple the “bounced voltages” from the plate supply. I build two, negative and positive regulators, to do the job. They were ultra fast regulator unsung 7788 as an amplifier and 6C19P as at regulator. It still did not produce the sound that I needed. Then, and I do not remember who and how the ideas come to us, we decided to put as simple well sounding gas regulator tube in a negate supply of the bias. The rational was that a gas tube essentially should be beautiful buffer that should very softly react to the grid currents and would be perfect isolation from the plate supply

I remember as I very first time when I connected a separate gas regulator of my Fluke 409 tube power supply to the Milq’s bias. It was 10PM and it was like an instant bliss. It immediately reimbursed me with the exact sound that I was visualizing for quite along time. It slowed down the brutal and unreasonably fast dynamics, it harmonized and coordinated everything and set the correct relation and reasoning between the pitches, it created completely different phenomenal (!) bass and it basically made up the Milq sound in a way in which it is know today. After that to put a positive regulator juts to balance out the DC at the amps input was a simple mater.

I know electrically it completely has no meaning and it all was done juts get a correct sound out of the driver stage. All together it took a month and a half or so to discover all of this and to optimize the driver’s stage performance. This is why I fully inherited the Milq’s driver stage for the “Baby Melquiades” project- because it works. If you wish I might post the complete schematic of the “Baby Melquiades” in a way in which is currently assembled. However, looking at the compile Melquiades schema is very simple to figure out what the “Baby Melquiades” is. Juts replace the plate resistor with a transformer and drop the plate supple voltage. In my case I feed the 6E5P ‘s plate with 178V…

Talking about the headphones amplifiers: Sugden HeadMaster.

I do not subscribe audio publication and buy them only if I’m mood to bitch about something. Occasionally I buy the British Hi-Fi+, which is kind of mandatory to buy living in the New England. I buy it from time to time not because it is better magazine or because the writing in there less foolish then in another publication but juts because the Hi-Fi+ has better pictures, that do this magazine a wonderful bathroom reading…

Today I bought an issue #41 where somebody named Jason Hector writhe his doodles about the Sugden HeadMaster headphone amplifier. I have seen some quite positive media bout this amplifier before but this time I think I need to say something.

Enough!

I do not even quote Mr. Hector, the reviewer extraordinare! I wonder how a person who recognizes yourself as somebody who find that the HeadMaster might be used for sound, would qualify to write for anything more then for a newsletter distributed among the pig’s farmers!

Many years ago, when Sugden juts introduced thier HeadMaster, I was stupidly solicited with the sexy look of this painted aluminum and with 44 inch phrase “class A” on it top panel. I bought the unit sand spent a few weeks in absolute headphone agony. It is not that the HeadMaster sounded more horrible then a headphone jack of a consumer Sony 7700 DVD player. The most horrible was what the HeadMaster did with sound. It was so solid state, so dry and so digitalized that the op-amp from that cheap Sonny lifted up the lid of this DVD transport and screamed “Holly Cow!”

In fact the HeadMaster was so horrible that seriously wonder why it even was made. The depth of conversion of any sound into a syntactic crap via the HeadMaster way exceed the worst component from Krell and Levisohn. It was so disgusting that the dealer who lend it to me, after listing my justification, even offered to pay the shipment back.

Anyhow, the point is that the HeadMaster is not juts a sum down amplifier. If I were not a Cat but a dinosaur then pointing my entire 40 feet tail down would not be sufficient enough indication to depict how bad the HeadMaster sounds.

Your say the Hi-Fi+… The toilet reading…

Rgs,
Romy the Cat

As I promised, I am informing about the fate of the Baby Melquiades project. The Baby Melquiades was armed for few days with new 60H transformer.  The result was not positive. It sounded OK but it was not even close to the Melquiades sound. I was looking for very specific Sound but instated I got a very high quality H-Fi. I really do not know what is the problem, perhaps the high plate impedance should not drive active load, or perhaps the headphones have own attitude that make the Melquiades approach is not applicable. Anyhow, the Baby Melquiades was disappointment….

I desisted to change the Baby Melquiades tube, keeping the basic typology the very same and replaceing the 6E5P with 6C19P, driving it at 140V. I got eventually almost correct bass (thanks to the low R) but still it is all to far from the sound that I was searching. Yes, it is probably Sound more interesting then to drive headphones from an output jack of a commercial stereo but it is still not where it should be.  Well, at least my “big” system sound way more sophisticated then the headphones… if it says anything….

I will be continuing for a very littlie my time to make headphones Melquiades it to sound OK but there was another revelation that I made: I juts hate my headphones. My favorite headphones are not good enough to compete with Macondo (?) and my “new reference” headphones are juts plain garbage. I should review my entire way to deal with my headphone system. So, far what is going on with my headphone is unacceptable.

Rgs,
The Cat

jamesrm618 wrote:

I wonder if this will resemble your final results

Actually….it does look like I am on something with this Baby Melquiades project.

First of all it is not Baby Melquiades anymore as it become too far deviation from Melquiades. Therefore I would not call it this way anymore.

I spent yesterday a good part of the day training got make this 6C19P based headphone amp to sound correct or at least interesting but it was fruitless.  It was very high quality punchy and dynamic sound but it was completely amusical. It sounded like the tube was practically idling, having no harmonics. In fact the 6C19P was loaded quite aggressively at 2.800 Ohm. Still I feels like the tube wanted to be loaded even more. Since I did not have the “room” in the transformer anymore (LL1623A in F configuration) and the 3Kohm against the plate’s 500R sounded like “good enough” I was wondering if I was operating at the sound that the 6C19P is capable to give up.

Close to the end of the day I called to Dima and was bitching about the headphone amp’s sound using all possible illustrations and associations and describing why I do not like it. There were many “other things” that we could try but I was very skeptical as the direction where we could go sonically was not something where I felt might be a correct direction. Suddenly an interesting idea came to the Dima’s head and he suggested that from what I was saying he feel that injecting a positive feedback into the amp might be very beneficial. We took voltage from 1/8 of the secondary and… O wonder!… it feedback moved sound to very interesting direction. Suddenly the full of space, lush and wonderfully-slow presentation that I was looking for had happened “by chance”… A direct hit!

I am not saying that this headphone amp sound how it should be but at this point it’s potency made very enthusiastic for me to work on this amp. There are some other aspects that I need to resolve (for instance plugging the STV 280/40 or any other high voltage regulator) but at this pint the “new” headphone amp begin to look promising.  I think I need to deal with a need to build the proper sounding headphones should be next… :-)

Rgs,
The Cat

As I was saying: who the hell need a headphone setup if it does not sound as good as the speakers setup? So it is the way in which I approach the headphone sound. The headphones intrinsically have problem with MF and “wrong bass”. There are ways to deal with it, more or less successfully. But I am a lucky pussy and I have “correct headphones”… so care about it less…

What I usually do is sitting in my “sweet spot” for my speaker installation and putting the headphone on and off I would like having the identical sound. Well, almost identical as headphone could not really even approach the space, the imaging and the whole presentation of the big system. However, here is where the trick begins. Putting the headphones on, playing them along with the big loudspeakers system and adjusting the volume of the “big system” (primary the LF channel) it is possible to take the imagine and the upperbass performance of the headphones way out there.  The most fascination discovery that make with my headphone amp that injecting the positive voltage feedback the amp, when it plays alone, begin to sound like it has the “support” of the big system on background. The positive feedback (in this amp) makes sound larger, beautifully slower in bass and the starch the presentation from being inside of the head to an aura around my head. Very interesting effect!

I would not say that it’s it but I can see something is very promising in the direction where this headphone amp goes….

The Cat

Romy the Cat wrote:

However, here is where the trick begins. Putting the headphones on, playing them along with the big loudspeakers system and adjusting the volume of the “big system” (primary the LF channel) it is possible to take the imagine and the upperbass performance of the headphones way out there.

Ok, the Headphone “Baby Melquiades” protect is over. Well, kind of over as there are some issues still are hanging in there.

A brief summary. The initial idea was to use the Melquiades’ input stage to drive headphones.  Unfortunately it did not sound as I intended, primary in bass region. The decision to use a tube with lower plate impedance was and I went for 6C19P. After the further experiments the more or less reasonable sounding configuration was found. What I end up is the 6C19P with 125V on plate and minus 33V in grid. The bias is applied in the same way as it is done in Melquiades. I do not think that in the case the 6C19P the “Melquiades-type bias” as effective as it was in case of 6E5P but I desisted to reuse it without experiments with alternative biasing schemas around the 6C19P.

So, as you can see the new Headphone Amplifier has very littlie to do with Melquiades and the heart of the Melq was the 6E5P stage. Therefore I officially remove from this headphone amp the name “Baby Melquiades” and grant to it a new official name: “The Little Amplifier”

The “Little Amplifier” has two transformers: separate filaments and bias and separate plate transformer. All powers supply is identical to the Melq; with exception of bias supply is CRC filter with following gas regulation. The plate supply is LCRC with the last capacitor 6.000uF. The 30mA 6C19P drive in it’s plate the Lundahl’s amorphous core transformer with 50mA core and 60H primary. A positive feedback (a brilliant Dima’s ideas!!!) is taken from the second section of the secondary applied to the cathode of the 6C19P. This gives the necessary “kink” of space that I was so desperately was looking in the headphones...

The  “Little Amplifier” has no gain. It has very good bass, in fact quite phenomenal. I use it with my beloved Audio-Technica ATH-40fs headphones and quite happy with result so far. I know, I know … many people out there would be laughing that I feel that $80 worth ATH-40fs headphones, very much not the “high-end” headphones, are good enough and might be an objective tool for assessment of a headphone amplifier.  I use 40fs for 15 years or even more (had 4-5 pairs of them and when I break one I get other pair) and I prefer them to all other expensive headphones that I owned or heard. As far as I concern all among those to which I was exposed   were too hi-fi and the only the cheap ATH-40fs “sounds right” for me. I was an idiot ounces and read the Six Moon’s “exposing” the Audio-Technica ATH-W1000

http://www.6moons.com/audioreviews/audiotechnica/winning_2.html

I got them and … this peace of crap is still sitting on my self and I’m looking forward to find a fool who would be able to listen this headphone’s torture.

Anyhow…

The idea was to make the “Little Amplifier” very small and I am very pleased how I packed everything inside.  The only problem that I have is that for whatever reasons the positive feedback screws is the ground in the “Little Amplifier”. The amp is build using the properly implemented star groaning, which was followed anal retentively, but the feedback to the cathode screws everything up. No mater how much I tried to shield the run from cathode to the secondary and no mater how I applied the grounds I always picked the 60Hz LF hum. Interesting that with cathodes siting on ground the “Little Amplifier” is dead-quiet with no signs of any noise. Is anything special about the positive feedback grounds that I do not know?

Thanks,
Romy the Cat

I took today the “Little Amp” at my client’s site and was listening it today during the operation time. I detected something very interesting behavior.

The 6C19P that I put into the “Little Amp” are well-selected, equal gain, no microphonics and well burned-in. However, when I was listened I did detect some very minor microphonics. I was very surprised but then I did detect what was the problem.

I use the tubes cooler on the 6C19P – completely unnecessary things but I had them and I put them into the use. The fan part was that the 6C19P with the cooler did behaved microphonicly but without the cooler they were absolutely quite. I did a bunch of experiments, trying to find the relationship between the position of the cooler and the microphonics but was not able to detect any pattern.

I wonder if a tube radiates any magnetic field that makes the fins to vibrate? Or perhaps the cooler fines react to some other magnetic field? Aren’t the cooler fines should be made from a material that should be immuned to this behavior?

Rgs,
The Cat

After spending more time with my new headphone amplifier I decided to put it aside for time being. I have learned today that there is something g deeply wrong with it. It sounds quite fine before but today I actually has a first time not juts to “listen the amp” but to spent a day with headphones and listen the amplifier in duration.

Despise of quite nice all together sound (in fact I do like it) I have detected that this headphone amplifies produce some ….pain. At my work I seldom have a luxury to listen for one-two hours without interruption. Today I did have this chance. Suddenly in the third act of the Rigoletto I detected that I have a physical pain in my ears and in upper part of my head.  The volume level was very low, I was not tiered or something like and I never had any pain effects from headphones. It was something very new.

In took the headphones off and the pain gone within ~5 minutes. It was not really only a pain but rather a pain combined with feeling of scuba diving submersion. When I “vented” myself or did the swallowing then the pain did not do away though.  I put the headphones back and the pain returned with 10 minutes. Interestingly then since then the appearance of the pain was very predicable. I was playing with it for a while, trying to detect musical marital or anything else that might be responsible for it and then I made an exciting experiment. When the pain did show up again I unplugged the headphone from my “Little Amplifier” and pluged them directly into my CD played from which I sourced the signal for the headphone amplifier. The effect was magical! The pains was rapidly evaporating from my head and was gone within 3-4 seconds. It was very-very remarkable, as I was able completely predictably inflict the pain by my “Little Amplifier” and then very distinctly to remove the pain by continuing play the music from my CD player, even at volume of 6db louder than the headphone amplifier did.

Defiantly I do something very wrong in my headphone amp. Until I find what it was I would consider the amp unusable.

Bad bad bad kitty!
Romy the caT

Romy the Cat wrote:

I have learned today that there is something g deeply wrong with it.

Thorsten wrote:

Not quite. What is wrong is not the Amplifier, but ....

Interesting, I was searching the reasons of the headphone’s headache (read above) and I it looks like there was no oscillations (they should be seen on the 100MHz scope). However, while I was “there” I decided to look at the frequency response of the Little Amp. It looks very nice (the possitive feedback was disconnected for now):

Each square is .45V. I was not able to drive the Little Amp into the clipping. I drove it with 10.5V input as my generator does not output more. The above is 1000Hz

Above is 100.000Hz

Above is 20Hz. Longer exposure to get the entire wave.

Above is 5Hz. Longer exposure to get the entire wave.