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Is my RKV Mark II a dud?

post #1 of 30
Thread Starter 
Ok, I need some serious advice here...when I first got my RKV and ran it, it would work fine on the first song or first part of a song, and then start seriously warping the sound. I assumed maybe the tubes were dying, no prob, since it is a used RKV, thse things do happen, so I went all out to locate and find some new PCL 805 tubes. Slapped the new tubes in, and tried the RKV again...it seemed to be working, got in a good 3 songs or so. But then the warped sound came back again...so apparently the problem is NOT the tubes. So here I am freaking out...does anybody else know what is wrong with my RKV? Maybe the tube contacts need cleaning? Strangely, if I simply turn the RKV off, and then on again immediately, the problem goes away, but only temporarily. And from the blissful sound that is produced in the first couple of moments of startup, I KNOW that my RKV *SHOULD* work just fine. And this is trying with the Sony MDR-R10s and the Sennheiser HD-600s. What's going on?
post #2 of 30
From a newbie point of view (in the DIY world) I would quickly assume it is some type of connection problem with the power supply or something with the psu... can you open it to see any flaws in the wiring?

But man, that has got to suck, having such blissful sound for only a few moments... I would go insane...
post #3 of 30
What do you mean by "warping" the sound? I can't really offer any advice other than I know that when certain tubes blow in a guitar amp, they can take out some other components with them.

Sounds like a trip to the service center is in order.
post #4 of 30
Thread Starter 
Hmm...I have been using my Sennheiser HD-600s now for the last 15 minutes on the RKV, and it seems to be working fine...and this was after the last on/off powerup that I did. I wonder...maybe my R10s really are clipping the amp??? ARG...I pratically bought this amp strictly for the R10s!!! Nooooo...

Of course, the amp sounds wonderful with the Sennheiser HD-600s...but that's not the point, the point being, when the RKV works with the R10s, the combo blows the snot out of all my other headphones! More testing is in order to be sure here...but the RKV's impedance range is 100-2000 ohms. The R10's 40 ohms is probably pushing its luck.
post #5 of 30
Thread Starter 
Ok, now I'm dead certain that my R10s were clipping the poor thing. I've been on the Sennheiser HD-600s for about half an hour now, and the problem hasn't showed up again. Hmm...anybody know how to DIY an adaptor for low impedance headphones for this thing?
post #6 of 30
Have you tried a pair of grados with them yet?

The review that I posted by Ken Kessler a while back, had the grados (RS-2) teamed up with them with no problems.


Maybe the sonys do dip much lower than 40 ohms at certain frequencies.

post #7 of 30
Damn, that means I can't use this amp with my Grados. Too bad because this was an amp I was looking at getting next.
post #8 of 30

I found this:

The Audio Valve RKV MARK III
OTL Headphone amplifier

Click here for lots of info on Audio Valve products

3 W/Ch of Pure class A
Two PCL 805 (18GV8) output tubes per channel
Self-biasing (done individually for each tube)
Power Bandwide -- 15 to 100,000 Hz
Distortion -- 0.002%
Output Impedance -- 100 - 2000 ohms
Damping -- 3600 !
Dimensions (w-d-h) -- 140 * 320 * 100 mm
Dimensions (w-d-h) -- 5.5 * 12.6 * 4 inches
Weight Net -- 6 kg ( 13 pounds)
For low impedance headphones there is an
optional Impedance Matching Box -- $290 <-------Maybe the impedance matching box might solve your dilemma!

Here is the link:


Good luck!
post #9 of 30
at that $290 price tag..

there is just no end

post #10 of 30
Thread Starter 
Bootman, thanks a lot for that link! I'll give em a whirl...but good jeez, as Tides said...$290 for that dinky adaptor??? When does the madness end...
post #11 of 30
With us audio junkies it only gets worse!

If you want to rationize it you can look at it this way:

The R10 are $4000
The MII are $1200

Total is $5200

$290 is only about 5.5% of the total cost!

Peanuts, in audiophile money!!!

But seriously, can someone out there make one?
post #12 of 30
Thread Starter 
That is what I'm seriously hoping, that somebody could DIY one for me or something. I mean, $290 for an impedance adaptor is a little ridiculous...I might as well ditch the R10s and use the HD-600s instead at that rate.
post #13 of 30
Well here is my wild DIY guess... I'm sure Vertigo will pay $100 to someone to do it for him... wait a sec, hello Vertigo

So here is my really crazy guess... note, this is like the opposite of what I am doing to my Beyer 831s, still making an impedance adapter for my mg head... Dr. Meier said it would work (he also said that he thinks that the MG Head impedance isn't really a load impeadance switcher), simply hooking two resistors to the leads of the outputs of the amp (what I am doing is getting a plug and wiring resistors to them and then connecting them to another headphone jack). Just need to wait for my parts...

So, logic would tell me, to decrease load impedance, you would use transistors instead of resistors, and do what I described. Though, how to do this, I have no idea...

Update: I was thinking about this further... Then I remembered that issue about the Etymotic ER4p->ER4s, an increase of impedance... well, why don't we increase the impedance of the R10s? Now how is an impedance cable created?
post #14 of 30
So, logic would tell me, to decrease load impedance, you would use transistors instead of resistors, and do what I
described. Though, how to do this, I have no idea...
not sure about this, but i'm no electronics wizard. i think you should try to put the resistors in paralell instead of in series. IOW "short" the headphone output with a resistor. e-mail Jan Meier and please don't take my word for it.
post #15 of 30
Man oh man, now you know why the JudeMan is solid state.

-- Mr. Roboto --
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