Post by Owen Y on Nov 24, 2017 13:15:55 GMT 12
Not sure if anyone here has participated in any of the Massdrop group buys & specifically their Sennheiser HD 6XX version of the HD 650? A family member here has just received these HD 6XXs & here's some quick pics of the unboxing... Price, I believe was US$200 (+ $15 internat. shipping).   
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Post by Owen Y on Nov 24, 2017 13:16:47 GMT 12
Maybe it's about time I added a headphone output to my system? 
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Post by Owen Y on Nov 28, 2017 14:20:56 GMT 12
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Post by Citroen on Nov 28, 2017 17:05:04 GMT 12
Maybe it's about time I added a headphone output to my system? YES! And a very good way to start (and possibly end) are the 650's aka 6xx They do tend to the dark side, and perform best when well driven, but if your system can cope with those parameters...go for it! For not much more than NZ$300 you get a hell of a lot of headphone. The other alternative is Massdrop's AKG 7xx drop, which sounds quite different to the Senns (esp in the lower registers) but its a sound signature I really like.
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Post by Owen Y on Jun 2, 2019 16:46:32 GMT 12
Steve Guttenberg " loved the sound " of the Massdrop Sennheiser 6XX. Also, " it's so darn comfortable ". I have to agree, in my limited recent experience with headphones, these are beguiling, non-forward, comfortable (open back) 'phones, but not lacking resolution. I can appreciate why the HD 650 are regarded as a classic. At US$220, there can't be many better audiophile bargains out there, if any.
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Post by Owen Y on Oct 2, 2019 20:48:01 GMT 12
I am again 'babysitting' Jeremy's Massdrop Sennheiser HD 6XXs & although I have still to spend a decent amount of time with them, but driven by the wee JDS O2 headphone amp (which has yet to grow on me), they haven't lost their beguiling appeal, to me. Still excellent sounding to my ear - I like open-back phones. In the ' Why Vinyl' vid that Citroen posted, I see that Joshua Valour's channel has his Jul 2018 review of the Massdrop Senn HD 6XX - which is obviously more in-depth than my own experience with these to date. I can only echo his sound value assessment... " I'd be really curious to see if there is anything in this price range that can get the detail, the tonality, the texture, the depth of vocals that this headphone can offer. " " The mids are absolutely magnificent, especially for $200. " " Lows seem to depend heavily on on your amplification. " These h'phones are " famous for taking super, super well to a tube amplifier." We have a DIY tube headphone amp project 'in the works' here - a future DIY posting coming up.
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Post by colinf on Oct 2, 2019 22:33:22 GMT 12
DIY tube headphone amp...What sort of cost etc? Big tubes or small? Who’s design? etc. Sounds fun, can’t wait! 😀
AMR-iFi R&D
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Post by Owen Y on Oct 3, 2019 9:45:41 GMT 12
The other alternative is Massdrop's AKG 7xx drop, which sounds quite different to the Senns (esp in the lower registers) but its a sound signature I really like. - do you have the Massdrop AKG K7XX? Or regular K702s?
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Post by Citroen on Oct 3, 2019 10:01:18 GMT 12
Regular K702.
Great wide soundstage, puts you further back from the mix. Bass seems light but it goes deep and fast. I liked using it with headamps with bass bloom.
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Post by Owen Y on Oct 3, 2019 10:27:08 GMT 12
DIY tube headphone amp...What sort of cost etc? Big tubes or small? Who’s design? etc. Sounds fun, can’t wait! 😀 Thinking along the lines of something inspired by the Bottlehead Crack, which is known to work well with the Senns. It is a 6080 OTL with a direct=coupled 12AU7 in front. The Sennheiser, with its 300 ohm impedance, allows the highish output imped of a tube amp to be workable. The 6080 (cath follower) OTL output connection of course requires a big ugly electro output coupling cap - which I can do, or employ a huge met film cap. OTOH, I have these vintage Partridge OPTs, 8kPP:0/4/8/16/600, 12W (EL84PP possibly)- which I should find a use for. Ideas?
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Pundit
Post by beeman on Oct 3, 2019 10:35:36 GMT 12
My son bought a pair & absolutely loves them
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Post by Owen Y on Oct 3, 2019 10:44:06 GMT 12
My son bought a pair & absolutely loves them Sennheiser or AKG?
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Post by colinf on Oct 3, 2019 20:11:18 GMT 12
Owen, the Bottlehead Crack inverts phase. I’d use a more elaborate input stage to fix that. Otherwise the 6080 with a constant current source would be fine into a 300 ohm headphone. Don’t worry about the electrolytic on the output, just use Elna Silmics. A few smaller ones in parallel sound better than one big one. I made a headphone amp with EL84s and Sowter output transformer in the past, it sounded good in triode.
AMR-iFi R&D
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Post by Owen Y on Oct 3, 2019 20:43:24 GMT 12
Thanks colinf - good point about the phase, 1 inverting stage + CF. In the past, I have simply inverted the internal output wiring - there should be no problem with this I imagine? (It seemed to do the trick.) Thanks for reminding me about Silmics, the only low voltage electros I use now, beautiful tones.
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Post by colinf on Oct 3, 2019 23:48:03 GMT 12
Yes but then if others decide to build it they’ll be obliged to change the wiring on their headphones as well to invert phase. Although it might be ok if you use a stereo 4 pin XLR or dual 3 pin XLR balanced connection though, instead of the usual TRS phono socket. (And not an adapter from balanced to TRS plug! That won’t work, since the negative is common to both channels at the sleeve.) On a balanced connector just swap the hot and cold wires.
AMR-iFi R&D
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Post by Owen Y on Oct 4, 2019 8:02:52 GMT 12
Hi colinf - I simply build everything to be phase-correct at the output, if I can.
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Pundit
Post by beeman on Oct 4, 2019 11:48:50 GMT 12
My son bought a pair & absolutely loves them Sennheiser or AKG? Sennheiser of course 
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Post by michaelw on Oct 4, 2019 12:51:03 GMT 12
i've never heard phase inversion through headphones.
is it more pronounced due to the proximity of the drivers to your ears ?
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Post by colinf on Oct 4, 2019 18:37:37 GMT 12
It seems to be less of a problem through headphones as the soundstage is different than through speakers. But it does seem to affect the tone slightly. I prefer normal phase because it sounds more even harmonically. Owen, it might be better to have a phase correct input stage then. i have some AKG K601s here which I bought in 2007. I preferred them over the 701 when they came out as they just had a little softer top end. They have 65 ohms impedance. I’d love to hear some Senn HD 6xx phones just to see how the affordable headphones have progressed over the years. Apparently Grado have a great lower cost headphone too, but I believe it has low impedance, more tricky to drive with an OTL tube headphone amp. 😊
AMR-iFi R&D
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Post by Owen Y on Oct 5, 2019 14:27:28 GMT 12
The HAGERMAN Tuba headphone amp is interesting. It seems to use a triode-wired EL84 pentode, single-ended output, in 'parafeed' config (choke loaded), cap-coupled to ungapped output transformer. (As I recall, an old topology that became popular again in the late 90s via the VALVE magazine boys.) Not sure what is at the input & driving the EL84. PSU is in-built switch-mode I think. Interestingly, he uses a (subtle) 'crossfeed' cct to enhance stereo effect when using headphones. HEADPHONESTY's review of the HAGERMAN Tuba.  (We need to start that DIY Headphone Amp thread )
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Post by colinf on Oct 5, 2019 18:53:58 GMT 12
The schematic for it is in the user manual. It’s a single ended EL84 in triode. The EL84 has a gain of 20 in triode (with constant current source) so it doesn’t need an input stage. It has quite a few things in the circuit that I ended up taking out on mine as it sounded better without them. The 330 ohm resistor on the screen grid makes the sound less rich. The input includes a cap to increase ultrasonic top end where the output transformer starts to roll off...not really needed as it changes the distortion on the top end. The parafeed circuit works with a small, ungapped output transformer and has 2 taps for both high and low impedance headphones, a good idea for the two outputs. I used a Sowter transformer without parafeed on my previous one, which eliminates a (potentially expensive) coupling cap. Finally, I ran mine at 230v HT instead of 140v, it ends up lowering distortion by using a larger part of the EL84 curves and gives more drive. A bit like a V8 at low, comfortable revs instead of 4 cyl at medium revs. 😴😴😀
AMR-iFi R&D
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Post by Owen Y on Oct 6, 2019 13:36:42 GMT 12
Hahaha, a V8 just idling along You built this? - What was the prim imped of your (gapped?) OPT? - Your PSU? - I seem to recall a transistor or other SS device at the front end of this cct? - He comments somewhere that he gets ~6dB (2x) of gain.
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Post by colinf on Oct 6, 2019 19:20:33 GMT 12
I think I used a Sowter 9351 (can’t find the schematic, but from memory it was very simple), which has 5k primary and 4 secondaries that you can arrange to have an output impedance of 600, 300, 150 or 40 ohms. It’s designed for an EL84 in single ended. The power supply was a 6v toroidal on which I wound the HT winding myself. The HT was a SS rectifier with conventional C-R-C-R-C. I ran it at 20mA in triode. It could be used as a line stage as well, I remember the gain was 5. No transistor required for gain, all the transistors in the Hagerman are in the power supply. The input goes straight to the grid of the EL84 via the volume pot.
AMR-iFi R&D
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Pundit
Post by beeman on Oct 7, 2019 18:56:16 GMT 12
I'm a big fan of EL84 headamp power. Had this little MingDa running my HD650 for years 
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Post by colinf on Oct 7, 2019 19:31:28 GMT 12
It seems well sized for the job 😊
AMR-iFi R&D
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Post by cooksferry on Oct 8, 2019 8:19:29 GMT 12
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Post by foveaux on Oct 8, 2019 15:30:35 GMT 12
this amp always worked well for me. Mine was a little different being a limited edition with a magic eye tube. I believe Foveaux still uses his. Yes Cooks, Mapletree EAR + Purist HD still in action and sounding great. Mine is the 2005 version. (british racing) Green chassis, stained oak side panels. Enjoying the combo: Beyerdynamic T90s, especially with the 1963 NOS Sylvania 5751 triple mica grey plates driver tube (as pictured). Of course, I have you to thank for my introduction to tube headphone amps and decent 'phones - many years ago.    
"I see music as a lifetime affair." [Rory Gallagher]
"Free - I miss that band, but when I look back, we were very young" [Paul Rodgers]
862 posts
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Post by colinf on Oct 8, 2019 20:59:05 GMT 12
The 12B4 output valve would work well too. It’s an indirectly-heated triode, roughly half the power rating of an EL84. For efficient phones it would be fine. The 12ax7/5751 on the input stage could be made to work a little better.
AMR-iFi R&D
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Post by cooksferry on Oct 9, 2019 6:41:28 GMT 12
I believe the Mapletree Ear amp was designed nearly 20 years ago when the whole headphone scene was barely a glimmer. The top 'reasonably priced' audiophile quality headphones were the Senheiser HD650/600 and the Grado RS1. In the very early days of Headfi the Ear + was touted as being suited to the Senheiser pair . I know I threw everything at mine from HD650s to RS1, Audeze and Beyers to various high end Audio Technicas including the L3000 Leatherhead. Output never seemed to be a problem with any of the phones although to be fair most were of the low impedance design except for the Sens. My special edition also had the added advantage of high and low gain outputs.
Limited editions of special versions of the most popular Mapletree components are offered this fall in limited
editions of 5 units. The Ear+ Purist HD100 (S/N 0204100) is an open ended project so that customers can
specify the details they want. The first unit, built for my daughter, has an EM80 magic eye tube, two switched
line inputs, a passive line output, and high and low impedance headphone jacks.
Getting back on track I did get around to buying a 2nd hand HD650 from TM a few years back but despite several months of ownership just didn't really enjoy them. I was mainly using them with a Meier Audio amp which had plenty of power to drive them but they just didn't gel. I never found them very comfortable and in the end preferred the Philips X1 which had a some what similar sound but a bit more energetic. Both however now long gone.
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Post by Owen Y on Oct 9, 2019 8:20:52 GMT 12
What was the magic eye tube used to indicate?
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