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Bottlehead Amplifier Discussion / Comparison Thread: Crack, SEX & Mainline - Page 10

post #136 of 944

What impedance were the S.E.X. amps configured for?  And do any of you have the impedance selector switch installed? 

 

Also, I believe that there is an optional transformer that allows for a 128ohm impedence, which would make for a difference when driving high impedance headphones.  Does anybody have that option?

post #137 of 944

@Loquah  I just found that the buzzing was more apparent with the 3's and therefore more distracting.  also I felt like the soundstage could have been bigger and lastly a bit more base slam.  With the 2's though it was fantastic.  I can't wait to try the mainline with the 3's though.  I bet it sounds amazing.  

 

Quote:

Originally Posted by Compassionator View Post
 

What impedance were the S.E.X. amps configured for?  And do any of you have the impedance selector switch installed? 

 

Also, I believe that there is an optional transformer that allows for a 128ohm impedence, which would make for a difference when driving high impedance headphones.  Does anybody have that option?

 

Ya I have an impedance selector switch on mine.  If you don't have the switch than you can pick 4, 8, 16 or 32ohms. With the switch I can change the impedence any time I want.  I think that 32ohms will work just fine with higher impedence headphones to be honest.  

post #138 of 944
Thanks guys for the info. You're all very helpful.
post #139 of 944

I'm curious, does anybody run the S.E.X. with Grado cans?

 

For those DIY minded, is there any reason why you cant fit two headphone sockets wired for different impedance's?

post #140 of 944
Quote:
Originally Posted by Zashoomin View Post
 

@Loquah  I just found that the buzzing was more apparent with the 3's and therefore more distracting.  also I felt like the soundstage could have been bigger and lastly a bit more base slam.  With the 2's though it was fantastic.  I can't wait to try the mainline with the 3's though.  I bet it sounds amazing.  

 

Quote:

Originally Posted by Compassionator View Post
 

What impedance were the S.E.X. amps configured for?  And do any of you have the impedance selector switch installed? 

 

Also, I believe that there is an optional transformer that allows for a 128ohm impedence, which would make for a difference when driving high impedance headphones.  Does anybody have that option?

 

Ya I have an impedance selector switch on mine.  If you don't have the switch than you can pick 4, 8, 16 or 32ohms. With the switch I can change the impedence any time I want.  I think that 32ohms will work just fine with higher impedence headphones to be honest.  

If im not mistaken, tube amps are usually said to fair better with higher impedance headphones, right? So technically, it wouldnt be an ideal pairing with the LCD lineup---I assume this impedance upgrade addresses those areas?

post #141 of 944

That's true of OTL (output transformerless) tube amps such as the Bottlehead Crack. WOT (with output transformer) amps like the S.E.X. can work very well with low-impedance headphones. The S.E.X. output transformer can be hard-wired for 4, 8, 16 or 32 Ohms. There is also an impedance switch available that lets you switch between those four output impedance settings. The switch doesn't make the lower output impedance possible, it just lets you change between various settings. It is the output transformers that produces the lower output impedance.

 

Best regards,

Adam

post #142 of 944
Quote:
Originally Posted by amcananey View Post
 

That's true of OTL (output transformerless) tube amps such as the Bottlehead Crack. WOT (with output transformer) amps like the S.E.X. can work very well with low-impedance headphones. The S.E.X. output transformer can be hard-wired for 4, 8, 16 or 32 Ohms. There is also an impedance switch available that lets you switch between those four output impedance settings. The switch doesn't make the lower output impedance possible, it just lets you change between various settings. It is the output transformers that produces the lower output impedance.

 

Best regards,

Adam

Thank you kindly. That was exactly what I was looking for. 

post #143 of 944
Thread Starter 

Well the Quickie is built, but the kit and the build beat the chassis so I wanted to share my current improvised setup courtesy of the shipping carton the Quickie came in...

 

 

Definitely not a permanent solution, but I thought it was worthy of a giggle!

post #144 of 944
Quote:
Originally Posted by Steve Eddy View Post


What trannies have you tried? I've been using Jensen's JT-11P1s and CineMag's CMLI-15/15Bs for years and have found them to have excellent bass performance (the -3dB for both are well below 1Hz).
The beauty part about good input transformers is you don't need to feed them with a balanced cable or even a balanced source. They provide excellent common-mode rejection even from unbalanced sources. A rare case of where you can have your cake and eat (most of) it too. biggrin.gif

se


It's important to consider the limitations that input transformers can impose on potential source components.  Sure, the CMLI-15/15B's may be good to -3dB at 1Hz, but from what source impedance? 

 

On the balanced/differential Crack thought - I built one in 2008 http://www.audioasylum.com/forums/tubediy/messages/13/137057.html  While initially somewhat interesting, I didn't like it nearly as much as a standard Crack. 

post #145 of 944
Quote:
Originally Posted by audiowize View Post


It's important to consider the limitations that input transformers can impose on potential source components.  Sure, the CMLI-15/15B's may be good to -3dB at 1Hz, but from what source impedance?

They'll easily meet that spec with source impedances upwards of 1,200 ohms. But no, you wouldn't want to pair it with an asthmatic output stage based on say a 12AX7 or something.

se
post #146 of 944
Thread Starter 

I just added a new DAC (Matrix X-Sabre to my desktop rig and I'm noticing that it has lessened the gap between the S.E.X. and the Crack. I wonder if the Crack scales better than the S.E.X. somehow?

 

I'll try a few more tracks, but it seems like I still prefer the S.E.X. by just the slightest of margins now...

post #147 of 944
Quote:
Originally Posted by Loquah View Post
 

I just added a new DAC (Matrix X-Sabre to my desktop rig and I'm noticing that it has lessened the gap between the S.E.X. and the Crack. I wonder if the Crack scales better than the S.E.X. somehow?

 

I'll try a few more tracks, but it seems like I still prefer the S.E.X. by just the slightest of margins now...

VERY interesting. Please continue to keep us updated. Thank you much

post #148 of 944

Subscribing! I am about to start this build in a month or so:D

post #149 of 944
Quote:
Originally Posted by Makuta11 View Post
 

Subscribing! I am about to start this build in a month or so:D

Cheers! :beerchug:

post #150 of 944
Thread Starter 

I've spent about a week now with my new DAC paired with the Crack and S.E.X.

 

Here's the update I've just added to the first two review posts...

 

DAC Upgrade Update - 27th October 2013

A recent upgrade to my DAC has brought some very interesting changes.

 

The new DAC is a Matrix X-Sabre based on the very detailed ES9018 Sabre DAC chip. The extra separation and clarity offered by this DAC (compared to the previous Audio-gd NFB-5.2) has brought the Crack (with Speedball) very close to the S.E.X. in terms of overall sound performance. It's so close now that I could actually be completely happy with either amp when driving the Beyerdynamic T1s. For lower impedance cans, the S.E.X. is still the only choice due to the Crack's high output impedance, but with high impedance Beyerdynamic or Sennheiser cans I would probably choose the Crack simply because it is cheaper and still excellent.

 

I think the key to this change is the signature of the DACs. The NFB-5.2 was slightly warmer than the X-Sabre. The X-Sabre is still musical, but a little closer to neutral than the NFB-5.2. The result is a cleaner sound from the Crack - still warm and rich, but not smoothed over at all. The S.E.X. can sound a little dry at times in comparison which makes the Crack a bit more seductive - it soothes the ears with detailed, mellow tunes while the S.E.X. presents oodles of details and clarity, but isn't always soothing.

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