DarkVoice 336SE OTL Headphone Amp Discussions | Drop

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DarkVoice 336SE OTL Headphone Amp

Nov 6, 2018

Just bought one, and I really really don't want to start digging for the best tube for the DV.. Can someone do me a solid and recommend the best VFM power and pre tubes for it? Not looking to spend a lot of money on tubes, so I want the best value tubes available for a reasonable cost that would be a clear upgrade from the stock tubes. Thanks..

Nov 6, 2018

pukkita

Nov 7, 2018

LIBY555I would wait for the tubes to get some use, and your brain to get used to them first. I have a plethora of tubes, from new production ones, to NOS, to NOS russian tubes manufactured in the 70's-90's, will test and report once I get the amp, which seems it will reach me by 2019... Depending on your headphones I wouldn't agonize over 6N5PJ tube rolling, i.e. for high impedance cans like 6XX the sound characteristic will be mostly dominated by the preamp tube, 6SN7. If your headphones are low impedance, then it can make a difference, if you go for 6AS7A/6H13C types, better suited for OTL, with the other area of improvement being output caps.

Nov 7, 2018

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ecline77

Dec 10, 2018

LIBY5556AS7's are plentiful and cheap. There is very little difference between them. I saw a person asking about a Mullard 6AS7. There is no such tube .... that is a rebrand of a USA tube. Europe did not make 6AS7's. They would be paying a fortune for an unknown USA tube. If I were getting a 6AS7 I like the black plate RCA's or the tung sols also sometimes branded chatham. The straight bottle 6080's are also the same but not as pretty/ cool looking. Input tubes are a different story. There are many excellent 6SN7's ..... Tung sol black glass, Sylvania bad boys, RCA gray glass, Ken Rad black glass etc.... But, they cost almost as much as your amp. I avoid the cost by buying a tube socket adapter off ebay to use a 7N7 loctal base tube. The NOS 7N7 tall bottle tubes are the exact same electrically as a NOS Sylvania 6SN7GT and sound great. You can get them at Radio Electric Supply in Florida. With the same adapter you can use the 7AF7 loctal; a 6SN7 variant and another great sounding tube. You can also buy an adapter to use 6CG7/ 6GU7 tubes for the input. These tubes have a brighter cleaner sound and are electrically nearly the same as a 6SN7. 6GU7's cost $5. I had a DV 336 years ago and I liked the brighter sound of the 6CG7 with my Senn 600/650's.

Dec 10, 2018

pukkita

Dec 12, 2018

LIBY555I took off the 6AS7 and left the 6SN7 burning in for almost a week, listened to the amp yesterday for the first time. I'm really surprised by the stock DV336/6XX combo! Dead silent, zero hum. The stock 6SN7 sounds pretty good, considering its innards are crooked... The volume pot as expected on a cheap one, has bad tracking on the lower 1/4 turn, but fine from that onwards... first mod I'll be doing is shunting it with proper resistors for the 6XX. I used it with my "baseline" reference "system": a 2006 macbook built in audio out, which to my ears sounds really, really good, organic, mid-level detailed sound, not ultra-resolving, but always balanced and engaging, (whose character I know from heart after 12 years listening to it) before I start DAC rolling. First and most simple "tuning" you can do: find a sweet spot for your audio source output, i.e. while the player (itunes in this example) should be at 100% volume, you'll find that if laptop general volume is at 100%, and DV pot is at 1/4 turn, the sound starts to feel "compressed" and you'll also be on the bad tracking, suboptimal portion of the amp volume pot. To tune, start first by lowering source volume to say 40%. Raise DV volume pot to 12:00 (6XX), then try output volume at 80-95%, listen to a song you know well, you'll feel music "opens up" at a certain point; use the DV volume pot to adjust final volume and your ears to judge. Really noticeable with stock chinese tube, if you "drive it hard" compression will be very noticeable (congested sound, lack of separation, etc). When you get it right, stock tube though definitely being bass shy, is not bass dry. Pretty decent sounding, though not really "tubey" in character, (more of a hi-fi type and somehow lacking in "glitter" etc) imparts that relaxed, efortless tube character noticeable in things like ambience and decay. I need a little more listening before start rolling tubes... first one will be russians (6H8C) for sure. As ecline said, there are really, really nice NOS USA 6SN7 too... look for an old radio repair/antique tube shop, most honest ones will have them used but tested and will provide you % of emission and gm, I can source used, good condition (testing in high 80%-90%) NOS RCA's and Raytheons localy (in Spain!) for around 30€.

(Edited)

Dec 12, 2018

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LIBY555

192

Dec 15, 2018

ecline77I'm a bit confused as there's so many 6AS7 tubes out there.. You know what would be amazing and a huge help for many of us? If you'll give us some specific links on ebay for the best tube setup you had with good VFM ratio. Or the best you can currently see that are available at the moment. Also with the socket you talked about. I'd really appreciate it! Thanks in advance.

(Edited)

Dec 15, 2018

ecline77

Dec 16, 2018

LIBY5556SN7 Sylvania GT 1940-1953/ RCA 6AS7 6SN7 Tung Sol GT (round plate black glass way expensive)/ RCA 6AS7 Another very good Tung Sol is the black or gray plate clear glass .... much cheaper. I like the Ken Rad black glass 6SN7GT (way hard to find). The Hytron tall bottle 6SN7GT is a very clear,lean tube that works well. 7N7 tall bottle with adapter/ Tung Sol 6AS7 see 7N7 adapter .... https://www.ebay.com/itm/1-x-7N7-7F7-TO-6SN7-5692-6SL7-tube-socket-adaptor-converter-adapter/282939102462?hash=item41e07c14fe:g:vHIAAOSwQrJbUX-q:rk:1:pf:0 The 7N7 is a 6SN7 with a loctal base. All 7N7's were made by Sylvania but you will see them with brands like Raytheon, GE or RCA etc... ignore the brand. The 7N7 changed around 1954-1955 as did the 6SN7 GT. The 6SN7GT became the 6SN7GTA/ GTB. This tube can take higher voltages and is easier to find and less expensive. But, the sound quality is not as good. This tube still sounds better than any new production Russian or Chinese tube I have heard. The 7N7 remained the 7N7 but the internals became like the 6SN7GTB. Most , if not all 7N7's with short bottles are the GTB types. With the adapter you can also use a 7AF7 as well but that tube has a lower gain and the 6SN7 barely has enough gain. The secret with the 6SN7/ 7N7 is to use a brighter tube like a Tung Sol clear glass or Hytron or Sylvania for gain , The sound of the DV 336 is inherently richer and darker. Use a darker 6SN7 (RCA 6SN7GTB for example are awful/muddy) and you get a thick, slow sound to my ears. Add the Senn 650 and you just have to much thick and dark. In addition, the DV does not have a lot of gain with a 6AS7. 6AS7's are hard to drive. Personally, I liked to use another different tube socket adapter and use a 6CG7. The 6CG7 has been called a 6SN7 in a 9 pin bottle. Electrically they are very, very similar but the 6CG7 does not sound like a 6SN7. The 6CG7 is brighter and faster sounding. Most of the 6CG7's are brighter sounding tubes, again, except for the RCA . You will find Sylvania, GE, Raytheon and even the occasional Tung Sol gray plate 6CG7. Depending on your ears all of them may be good for you. The RCA 6CG7 later became 6FQ7 and either will work ok but the RCA is richer sounding than the other 6CG7's but still brighter than most 6SN7's. I liked the 6CG7's a lot better most of the time. The investment in a 6CG7 and adapter is much less than any good NOS 6SN7. see 6CG7 adapter ..... https://www.ebay.com/itm/1-6CG7-To-6SN7-6SL7-ECC33-Vacuum-Tube-Amplifier-Convert-Socket-Adapter/312212264304?hash=item48b14d1570:g:DZEAAOSwksBbYVRv:rk:23:pf:0 If I could pick a gain tube for the DV I would use a 12AV7/ 6414 like the old Singlepower Extreme used. But this tube is biased differently = not electrically the same. You can get tube socket adapters for the 12AU7 to 6SN7 (the 6414 has the same pin out as the 12AX types) but the tube will not be running in its optimal bias range and could clip or just sound off. The 12AV7 has lots of gain and good current drive and really wakes the 6AS7 up. RCA black plate 6414's and Raytheon 6414's were my favorites. I experimented with some in my DV336 and at the volume I listened to I liked the result. Trying the tube will not damage the amp you will just be out the cost if you do not like the result. But, that was a 2004 or so DV amp. Where to get tubes? Radio Electric Supply in Florida has the most tubes and best prices. Figure out what you want before hand and buy it. The seller does not have time to discuss tubes with you to make a ten dollar sale. Ask for a 6SN7GT. http://www.vacuumtubes.net

6SN7GT.000
6SN7GT GENERIC
20.00

6CG7.000
GENERIC 6CG7, 6FQ7
8.00

Dec 16, 2018

ecline77

Dec 16, 2018

LIBY555The 6AS7 is not the tube that will most influence the sound. You can put in any good 6AS7 and get good sound. Good 6AS7's are RCA black plates, Tung Sol black or gray plate 6AS7's, Tung Sol's branded Chatham. These two manufacturers made most to the 6AS7's. A 6080 is a straight bottle 6AS7. These were made later (60-70's) and you find them from GE, RCA, Raytheon and Sylvania. These are not as good as the coke bottle shaped 6AS7's. I would say go Sylvania for these unless you can get a Raytheon. Raytheon 6080's are the best if you can find them and sound nearly as good as the 6AS7's mentioned. The Raytheon's I have are very well made. The 5998 is a variant a lot of people like but I do not think they are worth the premium cost. If I am going to spend on tubes for the DV I am buying better input tubes.

Dec 16, 2018

ecline77

Dec 16, 2018

Dec 16, 2018

ecline77

Dec 16, 2018

LIBY555http://s79.photobucket.com/user/6bx7gt/media/076.jpg.html A custom Cavalli hybrid headphone amp on the left. What a great headphone amp. I really like the Cavalli designs. I have the Cavalli Liquid Spark Monoprice sells for $99 a nd the amp is stupid good. Best $100 I ever spent. Superb with my new senn 58X and Monoprice M1060. http://s79.photobucket.com/user/6bx7gt/media/048.jpg.html My Millet Max and hybrid headphone amp phase. I have not really listened to headphones for the past 7-8 years and concentrated on speakers. i am amazed at all the new headphones .... and the prices are crazy!!!! The was no Focal, Audeze, HiFi Man, Audioquest, Meze etc...

Dec 16, 2018

LIBY555

192

Dec 16, 2018

ecline77Thank you so much for all of this detailed info! I really appreciate this.

Dec 16, 2018

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pukkita

Dec 18, 2018

ecline77Hey ecline77, did you lurk around headwize, diyaudio, head-fi back in the days? I teamed back then (betatesters) with Alex for the Bijou and SuperBijou, though have them dissasembled right now. You made me really curious regarding the 7N7. I have tested so far a regular Russian NOS 6H8C (bottom side getter):

I left it burning in for a day, to find it had hum on right triode, left it a couple days and still had some hum, but once started listening to it I completely forgot. It has been definitely an improvement over the chinese tube, lower distortion (compressed sound feeling) and really good lows, with good lower extension and control. If I were to point a flaw for its sound, it is a tad "too fast" for my liking. Less harsh/gritty highs than the stock chinese. Tested a Short Bottle Tungsol GTB but one of the triodes seems to be gone. A shame because the other halfsounded "dark" but engaging. Next in line I have TungSol GTA Tall bottle, and what I remember as the "holy grail" of 6SN7 I tested back in the day, a Metz 6H8C. Problem is these tubes have become really really expensive! In any case I see several areas where the amp can be enhanced without resorting to rare and expensive tubes: ccs/led/trimpot biasing (to make up for triodes imbalance and be able to use lower grade 6SN7), bypasscaps, output caps, etc. Only situation where I'd consider a different output tube: If you're into low ohm cans (701, 7XX, etc), one of the single (but expensive) most noticeable improvements with these designs is using a 5998 (lower output Z). Will test and report once I try them on the DV336. Again, a rather expensive upgrade... and the reason I moved from OTL to hybrids... Remember 6H13C were really really good too, though ate significantly more heater current and had higher optimal bias points vs a 6AS7G. Will test and report. Again only worth if your cans are <120 Ohm.

(Edited)

Dec 18, 2018

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ecline77

Dec 18, 2018

pukkitaYes to all of them. I lost interest in headphones for awhile and have been restoring/ rebuilding speakers. Now there are all these new headphones that did not exist back in 2009 and some great sounding SS headphone amps.

Dec 18, 2018

pukkita

Dec 29, 2018

LIBY555Your petition left me thinking... so instead of start tweaking the amp innards, thought on what could be the most easy non-modding addition that meant the most enhancement for people like you... So far, the best 6SN7 I've tried on this amp, that really made an incredible difference for the better, is a russian Melz Metal base 6H8C from '55. You can find them between $20-$40 each. Has about 20/30% more gain than "plastic base" ones. I mean the "regular" metal base 6H8C from Melz, not the anode-perforated version which has become ultraexpensive. Chinese 6H8C < Russian (plastic base) 6H8C < TungSol Tall bottle GTB < Melz 6H8C Waiting for the 7N7s to reach me.

(Edited)

Dec 29, 2018

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pukkita

Jan 22, 2019

ecline77 @ecline77 I tested the DarkVoice with a Sylvania JAN 7N7 yesterday, impressive! A Killer driver tube option for this amp w/o breaking the bank, absolutely agree! Need some back & forth comparison with the Melz metal base 6H8C, but so far:

Ultradetailed
Excellent, thundering, pulsing bass when material calls for it
Silky highs
More forward presentation vs the 6H8C

My first impression is the 7N7 had a more balanced presentation all across the frequency range vs the 6H8C.

(Edited)

Jan 22, 2019

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