$100-150 or less amplification for K701/K702? Cheap tube amp if I have my own tubes? Perhaps even DIY?
Apr 25, 2011 at 11:14 PM Thread Starter Post #1 of 14

Napilopez

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Hey guys. Yes, I know that a gazillion people have asked about amplifying the K70X before, but I thought that with the apparent recent influx of new amps and my own unique situation it was worth starting a new thread for. I apologize in advance for sounding so noobish.

So, I'm looking for something to amp the K70X I'm likely to buy at 150 or less. I know I won't be getting the best possible sound from them, but I'm not expecting to. I just want it to bebetter than what I have now and to be able to scale nicely as I upgrade my components, which it should.

I also have a bit of a special situation I've recently realized. I might be able to build my own amplifier for almost no money as I do work-study in the physics department of my university, and they seem to have almost all the parts I need for building an amp.. Tons of gear old and new, which I discovered after finding a drawer full of vacuum tubes. Since my boss was okay with me using their stock(and he said he'd help me out), it sounds like something I'll end up doing eventually. I just don't think I can invest the time at the moment, but perhaps I can towards the end of summer.

My options for DIY:

I've heard good things about the Millet Starving Student. The name REALLY appeals to me XD. The Mini^3 also seems like an enticing project. Any ideas as to what's the best relatively simple DIY project? If anyone can give me a recommendation for the best cheap DIY projects synergistic with the K701s(I'd probably want more warmth/bass out of them) that isn't too complicated, it would be much appreciated!

Although it seems to me that I'll get the best sound if I build my own stuff(assuming I build it right XD), in the meantime and in case I find that project too daunting, I'd like to find something... preassembled.

Preassembled options:

Unlikely to power decently, but cheap:
-Fiio
-Cmoy

Possibly powering decently?:
-Total Airhead/ Bithead

Cheap tubes I might be able to replace with my own tubes?:
-Qinpu Q2 or A1
-Hifiman EF2A

The one $200 product I've considered is the Maverick TubeMagic D1, because it seems to be such a nice all-in-one device, and I eventually need a 24bit/96khz source.

I keep hearing about the Matrix Mstage, but I'd really rather not stretch my budget that far. I'll see how it's doing on the FS forum when the time comes though.

Thoughts much appreciated!
 
Apr 25, 2011 at 11:39 PM Post #2 of 14

zest

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What about Indeed amps, especially the MK2 and G2 models, MK2 have more power capacity. These amps are good for tube rolling and modding.
 
Indeed MK2
 
Indeed G2
 
 
 
Apr 26, 2011 at 12:46 AM Post #3 of 14

Napilopez

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Wow those look very cute and very affordable. Does anybody have any info on those compared with other amps, and especially paired with the K70Xs?? They are so cheap that they might at least make a good starting point... I do need an amp fo my other headphones anyway.

EDIT: Oh and can someone elaborate on the differences between a hybrid and vacuum amp? Thanks!
 
Apr 26, 2011 at 3:15 AM Post #4 of 14

brendon

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The Indeed *might* power your K701. However the E9 *will* power your K701 decently as it is designed to offer loads of current for low impedance headphones like the K701 and its well within your budget to boot. :)
 
While I dunno the technical differences, basically tube amps come in many variants - push pull, single ended triode/pent-ode, Output transformer coupled etc.
 
A tube amp is driven by well tubes and while some contain PCBs (like most Little Dot amps) the majority of tube amps have point to point wiring without any PCB or circuits inside. A tube amp requires a huge power transformer to work.
 
Tube hybrids are driven mostly by transistors or mosfets rather than tubes and the tubes act as a preamp or a power amp in harmony with the transistor amps working as a pre or power amp to give a bit of tube coloration to the sound.
 
Most tube hybrids can provide plenty of current that low impedance cans need.
 
Pure tube amps generally cannot provide massive amount of current that hybrids can but they make up by providing a rather massive voltage swing which is great for high impedance cans like the Sennheiser HD650/Beyer DT 880 etc.
 
Apr 26, 2011 at 3:58 AM Post #5 of 14

Napilopez

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Thank you for that! Now that I've been looking into the amp world, I'm honestly astounded by the sheer variety of amplifiers that exist. I had heard of some of the more popular ones, but being as budget conscious as I am, I've been on the lookout for some cheap performer. While the e9 seems like a solid option, It seems like it isn't as warm as I'd like to match the K70X, FWIR, and the Indeeds seem to pair well with the K70X from the few posts I've read pairing the two. Still, I need to research more. I'm trying to find the best balance between price and sound without skimping too much on audio quality. I know the indeeds are likely not gonna bring them anywhere near potential, but someday I'll have equipment that will.
 
Apr 26, 2011 at 4:27 AM Post #6 of 14

Snag1e

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I was just looking for a cheep amp that would sound halfway decent with my 702s myself (I sold my little dot, cause I'm a poor college student and I've been reading about otls not being Ideal for low z phones), and I came across this.. http://www.rwaudio.com/products.htm#ecwid:category=151187&mode=product&product=313548 .they have a diy kit for $100, and it looks interesting. Does anybody know anything about these??
 
Apr 26, 2011 at 10:39 AM Post #7 of 14

zest

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Indeed G2 has the best design among other Indeed, Bravo or Miridy amps, better Mosfets (improved bandwith in the highs), has both RCA and Jack inputs. People at Rockgrotto forum think the best value of output resistor for universal use is 68 Ohms, output resistor and tube are the components that mainly change the sound signature.
There are threads on Headfi for Indeed and Bravo Audio amps, but the best source is at Rockgrotto, the manufacturer made some changes after reading people comments on this forum.
 
Apr 26, 2011 at 3:27 PM Post #8 of 14

Napilopez

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I indeed read almost every single post on rockgrotto on the three main threads about them, after you first linked to them XD, thanks. The g2 seems like a good cheap choice for now, especially since I have my own tubes lying around. I don't know what models they are exactly but I kow I have at least a couple of sylvannias which seem to be popular.
 
Apr 26, 2011 at 5:40 PM Post #9 of 14

zest

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Sylvania are good tubes, if you're lucky, some Sylvania JAN 7308 would be great. The best default tube for G2 is the russian 6N23 (link I posted above), vintage tubes are becoming rare and there's some hype around them, that's why they're overpriced. You can do some bargains on ebay, but some are selling fake tubes, be careful.
 
Apr 26, 2011 at 8:40 PM Post #10 of 14

Napilopez

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I'm pretty excited to go back to work tomorrow, since my boss is letting me take whatever equipment I need. As I said, I found drawer fulls of old tubes and such, which seem to be new. Lots of the equipment at the labs is really old, but we store it anyway just in case, hence how I came across the tubes. Perhaps I can even share some with headfi members if they are looking for specific tubes.

Do you by any chance know if that one you linked to brings the New Mosfet(FR510)? ONe of the other listings shows it in the image, but this one doesnt.
I guess i can just ask him =P
 
Apr 27, 2011 at 8:28 AM Post #11 of 14

zest

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I bought my G2 in August 2010 and it was equipped with IRF510 yet, I don't see why this new unit would not. I noticed a picture of the tube :

If this is real, it has the Voskhod print (a rocket logo), year is 1983, tubes build by the manufacturer in the 70's and early 80's are known for sounding pretty good, and in the specs it is mentioned OTK meaning it passed the military test. If not Voskhod's, Reflector 6n23-ev are not so bad, e means long life (~5000hrs) and v improved mechanics.
 
On my amp i keep using my RTC (La Radio Technique) E188CC from 1979 (new in box), but they're not easy to find in the US, I guess you should look for Amperex, Mullard or Philips first. This pages would be a good start :
 
http://www.audiotubes.com/6dj8.htm
 
https://www.tubeworld.com/7308.htm
 
Happy tube hunting !
wink_face.gif

 
Apr 27, 2011 at 9:42 AM Post #12 of 14

d1554573r

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Hi Napilopez,
 
I was facing the same problem about a half year ago, and I came to the conclusion that You can't drive 701's properly for that sort of cash, I bougth few amps and none of the sub 200$ made good impression on me. In the end my akgs spent some time unused, 2 mounths ago i bougth trends audio pa 10.2 - it's just 225$. I have to admit i spent another 50$ on tube rolling to get what i wanted but in the end it paired just nice with electro harmonix 12au7.
 
To sum things up, I know it kinda streches Your budget but better save some cash and buy something a bit better, I've been there and I tried it and I lost about 300$ and insteaqd of buying some searious amp i messed around with little ones. Frankly im mad as hell that I havnt bougth Schiit Valhalla in the first place!
 
DIY migth be risky to Your wallet but dang if You got free parts give it a shoot :p (and share Your conclusions after)
 
Good Luck
 
Apr 27, 2011 at 3:36 PM Post #13 of 14

Napilopez

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Thanks for the advice! It seems like I will end buying an amp and then building my own though so we'll see how it goes. I understand that you, like many others feel that the K702 can't be driven approppriately for that sort of cash, but there seem to be a good number of people that are happy with their relatively cheap ones. I'll see how it goes for me.

On another note, I'll inform you guys what tubes I find at my job later today. A lot of the equipment is truly vintage and has been there since the 70s or older, and I wouldn't be surprised if they have some old tubes that some head-fiers would want that are no longer in production.
 
Apr 28, 2011 at 6:16 AM Post #14 of 14

d1554573r

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If You'll have problems identifying them post their images.
 
About amp and sound quality, keep in mind that source is extremly important I tried various sources and from my expiriances asio driven DAC pwns everything :)
Also sub 200$ stuff are actually possible to get if You order them straight from China and bypass taxes and/or duty fees somehow (not that im encouriging You to break the law or something :p)
 
Check for Yulong, M-Stage or Trends.
 

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