Crack tube adapters and high-end OTL question

[Paul Joppa]

Love it - my first electronic project was in the third grade. A headphone beeper; my dad thought I would be eager to learn Morse code. He was wrong, I never did, but it started the soldering bug.

I usually recommend getting a text from a community college electronic technician course. They tend to be much more hands-on and practical. There are some online resources too, I expect others will post some links.

[earwaxxer]

Hey Jim, thanks for reminding us that you are blind - I sometimes forget about the 'quotes' for folks like you.

Cheers - Eric

[adamct]

Paul,

I've thought about it some more, and I would actually be interested in pursuing the idea of using a modified BeePre as a headphone amp, but I would need help figuring out what mods would be necessary. Is that something you would be willing to do? Or is this a stupid idea that should be laid to rest?

I think there is a real market for a super high-end headphone amp. People regularly spend over $1,000 for headphones (Sennheiser HD700 and HD800, HiFiMAN HE-6, LCD-2 and LCD-3, Ultrasone Signature Pros, Ultrasone Edition 8 and 10, Stax 007 and 009, etc.), and regularly spend over $1,000 for headphone amps (Beta 22, SPL Phonitor, Burson amps, Woo Audio WA22 and WA5, Eddie Current amps, etc.). Why shouldn't BottleHead get a piece of this pie, especially if it can be had by "merely" tweaking an existing product?

Even if you're not interested in creating this as a regular product, I would still be interested in this as a one-off...

Any interest? Or would the necessary modifications be impractical and too complicated? Is the end result unlikely to be a real improvement?

Best regards,
Adam

[adamct]

Also, can I use these adapters to run 6SN7s in my Crack?

http://www.tubemalls.com/plated-Gold-pin-tube-socket-adapter-6SN7-to-12AU72PCS-a-lot-52.htm

Note that it says "filament must be 6.3V". Is this a problem?

Best regards,
Adam

[Paul Birkeland]

Those adapters will work well.

IMO, the Paramount is highly adaptable to headphone use, so much more so than a BeePre.

-PB

[Paul Joppa]

Paul,

I've thought about it some more, and I would actually be interested in pursuing the idea of using a modified BeePre as a headphone amp, but I would need help figuring out what mods would be necessary. Is that something you would be willing to do? Or is this a stupid idea that should be laid to rest?...

The BeePre can't get below 600 ohms on its own, so damping factor of 1.0 for 600 ohm phones, worse for any others. So I mentioned the possibility but can't say if it will actually work out.

Doc B has several Senns, so does PB I think - let's let them do some critical listening before we get carried away. The only mod I was proposing would be to install a headphone jack.

If it can't be done without a transformer, we have a few different approaches using transformers. I expect there will be a higher end something, eventually.

[adamct]

Those adapters will work well.

IMO, the Paramount is highly adaptable to headphone use, so much more so than a BeePre.

-PB

There is also a 12V version of those adapters available. Which version is preferable with the Crack?

Would I need 2 Paramounts for use with headphones? If so, I'm afraid that is out of my league...

Best,
Adam

[Paul Birkeland]

You'll want the 6.3V version for use with the Crack.

Yes, you'd want a pair of the Paramounts for headphone use.  While they are expensive, my AKG K-1000's on 300B Paramounts is a combination that has not been topped by any other headphone systems I have heard.

-PB

[adamct]

Paul,

I see now that the Paramount price is for a pair. I originally thought it was a per mono block price. That makes the price entirely manageable, although the physical size of two Paramounts would likely be an issue for my intended purpose. I'll have to measure it out...

Best regards,
Adam

[Paul Birkeland]

Yeah, they are just a bit on the large side, but man are they fantastic!

To cut down on the size, I believe the bases can be trimmed down a little bit (for height).

You could also build them on one chassis plate to save a bit of footprint. 

The Paramount will offer the most step-down of the signal on the plate of the 300B, giving an outstanding damping factor into headphones of any impedance, and offering some serious power! 

I'm hoping to cobble together a second set of Paramounts for myself that will become a dedicated headphone rig with balanced outputs.

-PB

[adamct]

Do you use them with any other cans, or just your K1000s? I have a pair of HE-6s which might be a good match, but would the Paramounts also pair well with my HD800s or, say, high sensitivity, low-impedance cans like my D7000s or Ultrasone Signature Pros? Not a problem if they wouldn't be a good match for the Denons or Ultrasones, but I would like to be able to use them with my HD800s...

[Jim R.]

Hi Adam,

I've heard this rig that PB is talking about, but only with the K1000s, and not under the best listening conditions for them (open canjam room at RMAF 2011).  I think they'd be wonderful with the HE-6s, and probably finewith all the other cans you mention as well, but you might also want to have a look at the s.e.x. 2.1 which a number of people really liked with the K1000s as well as the LCD2/3s.  I heard this amp with my Shure SE-425 IEMs and it was very nice as well -- especially considering that they are the polar opposite in terms of sensitivity from these big guys I mention.  I know Doc has also said that it's nice with his HD-800s as well.  Don't want to throw a monkey wrench in the works, but it shouldn't be discounted out of hand either.  And the s.e.x. can be wired for balanced outputs, as well as have the impedance switching board installed, which will give you a range of impedances and balanced/unbalanced options at the flip of a switch.

You probably can't go wrong with any of these but the paramounts may still be the top of the heap.

-- Jim

[adamct]

Thanks, Jim.  I'm sure the S.E.X. is wonderful, but my goal here was to find the best OTL amp I could. The S.E.X. is transformer coupled, isn't it? (While we're on the subject, are the Paramounts OTL?)

I already have several transformer coupled amps, and I find the Crack to be a miniature revelation...I'd like to pursue that OTL sound. Then again, maybe this is a fool's errand, and I should just be happy with the Crack. I just bought a Tung-Sol 5998, and I will try rolling in 6SN7s. Plus the cap upgrades...we shall see!

[Paul Birkeland]

Yes, the SEX and the Paramounts are transformer coupled.

I'll keep you posted on the high end OTL developments. 

[adamct]

Thanks, Paul.