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Time for some impressions of this rare beast. The Icelandic distributor has a set on loan and they carved an entire afternoon out of the schedule for me to try it and do some comparisons. I showed up with the HE90 I built from spare parts, Aristaeus, Carbon amp and a port modded SR-007Mk2. Since they were using the built in dac on the HE-1, I just plugged both amps into as well to equalize the comparison. Over all, I like the build quality of the headphones. Imagine a HD800 built properly and you are pretty much there. The leather earpads are super nice and the headband has nice extension to even fit my large melon. I don't think they are super comfy though as they are fucking heavy (550gr) and all of the pressure is on the top of the head. The Stax 4070 is just about as heavy but far more comfy due to the suspended headband design. The earcups get a bit warm due to the internal amps but only about 5-7°C above ambient. The cable is also pretty nice and not microphonic at all but more on the amps etc. later. Amp itself...well it is just fucked up. I get that they were trying to cater to some nouveau-riche people who just want something expensive but the wank factor is off the charts. I also have serious doubts about what's hiding in that nice marble shell... As for the headphones them selves... well the drivers look pretty much identical to the HE90 units and the few pictures of them that exist, point to that. I wanted to rip off the earpads to check further but people get antsy with something this expensive... One worrying thing I noticed though is that both sides of the drivers have porous dust covers. They look identical to the woven nylon found on the HE90 and well...I would expect solid covers. Now for some actual impressions. As I said above the HE-1 dac was the source for all the amps. To that you have to turn off the headphones so no direct comparisons were possible but I know how both systems should sound so not a big problem there. The source feeding the HE-1 was a Macbook Pro running itunes but I bypassed that with my own FLAC files and player. There are some major changes compared to the older system, this one can do bass and isn't as horribly colored either but over all...I was not impressed and the system never made me really interested in the music. It doesn't engage like a good 007 system can, where I sometimes just sit in awe even after owning a set for all these years. Here, it just doesn't pull me in. This is clearly a midrange issue as there just isn't enough presence there. First off the major issues are the bass, treble and the soundstage. Let's start with the bass, it has this annoying hump to it sort of like the old Lambdas. I'm not sure if this is the mosfet driver (could be, the Cavalli crap boxes have similar issues) or the headphones but it is a clear coloration and once you notice it, just annoys the fuck out of me. Now on some tracks it wasn't as noticeable but always lurking in the background none the less. Next up is the treble...which is both subdued and bright at the same time. I know plenty of people complain the 007's lack sparkle and with the Mk1 this was mostly true but they could be bright if the source called for it. The HE-1 manages something different, the treble is just flat and boring but then it suddenly bites hard. Now I was listening at higher levels but still nothing super loud, only about 12 o'clock on the dial. This also wasn't like the upper midrange bite of the 009's, more lower treble fizz but the source material didn't call for this. I'm so used to listening to SR-X Mk3 Pro drivers now (which are pretty much the gold standard for treble) as they are in my DIY headphones and nope, nothing like this. I suspect the amp is a huge influence here too but no way to verify that... Last major issue, the soundstage. Many will know my stance on the old HE90 where it sounds like you are listening to some people playing in dense fog and you can't quite make out where they are. This time around it is much improved but the lack of pin point accuracy is still apparent. The soundstage is also a bit too far away for my liking and it just doesn't throw the same huge headspace the 007's can. This also affects the midrange and the whole "disconnected" feeling I got from the whole system. I once reached for my phone as I was just a bit bored listening to it. Over all I like that Sennheiser built this but they really should have spent more time on the electronics. I don't think there are any improvements to moving the amps to the cups over something like the Carbon where I can burn 50+W as heat and overcome the small capacitance in the cable. Next post will discuss the tech specs of the system but I'll end with another picture of it all... It was really dark in there and I suck at taking pictures... Now for some technical discussion. I found the specs in the back of the manual and it turns out the bias is 650VDC and the amps run at +780VDC. This makes this more than compatible with Stax so I see no issue with removing the internal amps and rewiring one of these for Stax use. I have been asked to that before but I'm really hesitant to mess with something this expensive. That said, moving to proper amps which are not just the HEV70 rehashed can only be an improvement. I've never found any mosfet device with sufficiently low Cob to work in this role so I truly don't get what Senn were thinking. Some other info, the entire amp only consumes 40W per the user manual which doesn't leave a lot for the actual amps. So we have 8 tubes running with heaters plus all the motors in there. HV supply for the tubes, another for the output stage and well...not a whole lot of power to spare here. Compare that to the BHSE, Carbon or even the T2. All of them use far more power and it is just for one goal, to power the headphones. I also played around with the amp and I could swear that the volume control feels like a RK27. No way to know but how it felt when moving to the extremes...it was just like a RK27. Now as a proper volume control aficionado... ... they all feel a bit different. TKD feels nothing like a P+G or a RK50... Until somebody opens one of these up, take it how you will. It is also clearly a volume pot and not a chip or some other setup.

Being stuck at home while sick does have it's benefits since i recently acquired some RPG modffractal diffusers. I have dragged the tv into the living room and connected it to the media-pc for a day dedicated to trying out different room correction and target settings. Different cycle length on True time domain settings sure do change the sound a lot. just a single cycle in the midrange can change the sound from being forward and aggressive to smooth and laid back. serious room correction sure is fun here is target example:

Hey hey, come on now, the main constraint of this exercise was OTL give the man what he wants, even if it is worse.

Happy Birthday! (is now a bad time to admit that I secretly refer to you as Yalanda?)

I worked withDan Gardner quite a bit on this around this time, doing edits for the build guide, etc. I've never seen board files or gerbers for these, and I am pretty sure that Kevin doesn't have them either. Dan hasn't been active on these forums for a long time. Either we could contact him or I could possibly do a layout. I may still have a couple of boards but would need to look. Sent from my iPhone using Tapatalk

6c33 output tube for the win

I didn't say anything about an output transformer If using a tube in the second position is a must, a higher gm tube instead of the 6080 would be my suggestion. The 6922 has about double the gm. 40 of them will get you close to the Z out of the IRF610 ... 4 of them will get you into the range where Senns seem to shine. It's a great way to learn. One interesting upside of the 6080 is that the mu is so low that if you use a small resistor plate load, the output impedance from the plate is effectively the same as from the cathode. That conceivably opens up some interesting circuit experimentation options unique to the tube.

Yes, I've always wanted to build an OTL amp for my dynamic headphones and that's what lead me to this Menace thread. The Menace's simplistic circuit is also very attractive to me. With that said, I do like the idea of the CCS and I have experienced what good CCS can do to with JimL's SRX Plus. My plan is to build a simple Menace OTL as close to Nate's published schematic as possible. Once that's working properly I will be able to experiment and add on more sophistications. That, to me, is a big part of the DIY fun!

In addition to a regulator for the PS, a CCS plate load for the first stage will decrease distortion, a CCS cathode load for the second stage will also decrease distortion, and using a MOSFET instead of the awful 6080 will decrease output impedance, lower noise, and decrease distortion. It will also allow you to eliminate the 6080 heater power supply which is the most likely source of noise, and the source of tons of heat that needs to be dealt with. A first stage biasing scheme that does not involve an RC filter will also do good things. While we're at it, a 6SN7 gives you too much gain for nearly every headphone out there. That means that you are attenuating and then amplifying, which is a source of both noise and distortion. There are a number of ways to lower gain - the easiest might be simply eliminating the cathode bypass cap (this also increases plate impedance, so whether it can drive HF into the next stage will be an issue, but it is probably fine, but it has the benefit of getting rid of that RC filter). You can also find a lower mu tube, or perhaps a pentode with a low impedance plate load to lower gain. Or you could use a step up transformer on the input. I've now replaced every part of your amp

250V refers to plate to cathode voltage. Because the tube is biased up by the preceding stage, the voltage across the tube is considerably lower than 250V. Even if Blackgates were better than other caps, and even if they are still good, a small regulator using about $4 in parts will sound better. On that note, there is a lot that can be done to improve the circuit with minimal effort/expense.

at bottom center of each side are two holes for a solder loop or I plan to use spade connectors that is where Kevin put them and I copied his work Another benefit for the different caps are that they are shorter. So the board assembly is smaller

Office upgrades from earlier today Andrew Jones makes some good speakers.

Yes I consider artistic ground planes "Fancy" This amp seems to have very good noise rejection as I can't hear anything. but why not have a ground plane...... This is what I will make next, when the parts come in Think this is better then my last, with ground plane, lower ESR and a bit smaller.

Happy Entrance Day, Peter! Have a wonderful, cat-filled day.

Happy Birthday! Sent from my iPhone using Tapatalk

Happy Birthday! Enjoy the day

Happy Birthday, Dusty!!! I wish you have a great one

Happy Birthday Dusty!!!

Have a great one Dusty! Cheers!

happy birthday dusty!

Happy Birthday!

Happy Birthday from me and Prog Rock Cat!

Correct, the output coupling capacitors were indeed motor-run caps (about the size of a can of coke) and were paralleled to address your first point, lowering the overall output impedance of the amp to give it some potential to play nicer with lower impedance headphones. I'll try to take a look at the schematic relative to the second question raised about C4 and C5 later.

Tube OTL amps are best used with high impedance cans as their output impedance is relatively high, in the case of the Menace I estimate around 50 ohms. If we use a Sennheiser HD600 300 ohm as an example, it is specified as 102 dB/volt, so 10 volts will give a deafening 122 dB. Looking at the pics, I think the output caps C6 and 7 are motor run caps, as is C5 (note that all of these are rated at 370VAC, whereas C4 is likely electrolytic as it is rated in DC volts).

Looks like significant price reductions on what is probably NOS. Nothing new from ray in a few years. also I really like this one, complete lie from day one. The amp is not differential. Its 4 x single ended amps same as liquid carbon. no common mode rejection... and one of the worst phase splitters ever

A work colleague from Amsterdam sent me a YT link to this young lady, have been enjoying several videos.....nice guitar work, fun with vocal beatbox and tape loops. A couple times her guitar loops and playing reminded me of Vini Reilly from Durutti Column.....

Kimiko Ishizaka's just-released recording of the Art of Fugue: http://music.kimiko-piano.com/album/j-s-bach-the-art-of-the-fugue-kunst-der-fuge-bwv-1080

Here is what I drew up, no fancy ground plane like yours.......yet and why did I double the caps? dumbo turbo?

Earlier: Pappardelle Tartufo

Poor Gordon Hayward. I saw it live and it looked horrific. You never, ever want to see that. Hopes for a full recovery.