[WyldRage]

Added the EHHA vs Crack and updated the conclusion.
 
Also, I've finally found a 12AU7 I like for the Crack: the Gold Lion reissue from New Sensor. Haven't done extensive rolling yet, but it beats my NOS on my phono stage.

 

[stringgz301]

Neat comparison.  What tubes are you using in the EHHA?

 

[WyldRage]

Quote:

Neat comparison.  What tubes are you using in the EHHA?

The boxes say amperex 6GM8, but there are no markings on the tubes themselves.

 

[sachu]

The EHHA was the first amp that i fell in love with and actually drew me into headphones and to this day remains a personal favorite. Fantastically capable amp. Congrats on the build..as for your next build, i'll only say The CTH will probably turn out to be more than just a transportable amp ..
 
Is your EHHA using MOSFETs or BJTs?
 
If MOSfets, give the BJT with toshiba 968/2238 a try ..just tryin to be helpful

 

[WyldRage]

MOSFETs.
 
Thanks for the part recommendation, but my EHHA matches so magnificently with my HE-5LE that I have absolutely no intention of ever modifying it.

 
As for the transportable amp, my line of work (mineral exploration) causes me to be away from home for periods of 30-40 days. It would actually see more use than my home amps.

 

[WyldRage]

Third in three days: added tube rolling with crack, modified castanet vs crack and conclusions.
 
I'm done for now.

 

[WyldRage]

Oh, and if it interests anyone, here are my favorite combos.
 
AMB Gamma 2 DAC -> Hagerman Castanet -> Grado HF-2
AMB Gamma 2 DAC -> Cavalli Audio EHHA Rev. A -> HifiMAN HE-5LE
AMB Gamma 2 DAC -> Bottlehead Speedball Crack -> Sennheiser HD 600
AKG k601 -> Box
 
 

 

[WyldRage]

I've added measures made with Rightmark Audio Analysis. I don't have much to comment on, except THD > 11%

 
If anyone has suggestions for further analysis, I'm all ears.

 

[WyldRage]

Should have included this: the Inspire 1394 at 24/96. I'm posting it in the article.
 
It seems the roll-off in the highs is due to it.
 
Anyone know a good USB or firewire Audio Interface?

 

[holland]

Quote:

I've added measures made with Rightmark Audio Analysis. I don't have much to comment on, except THD > 11%

 
If anyone has suggestions for further analysis, I'm all ears.

That looks right.  OTL amps don't have the guts to drive higher current demands, so it's exceeding it's comfort zone for power output.  It's probably clipping, but you'd need an oscilloscope.  Also note the nonlinearities of OTL amps.  I don't know what else to say, other than it's expected.  The Crack is not meant for low sensitivity low impedance headphones.  It's a mismatch of equipment.

 

[WyldRage]

Yeah, I never expected the Crack to run my orthos, but I wanted to check just how good/bad the combo was. At the very least, I'll know what to answer when someone asks if he can drive his HifiMAN or Audez'e with the Bottehead Crack.
 
Also, I find the results for the Sennheiser very interesting: it seems that just about any kind of amp will be able to give good results for high impedance headphones. It just makes me wish for a 600 ohm Grado more than ever.

 

[holland]

Quote:

Also, I find the results for the Sennheiser very interesting: it seems that just about any kind of amp will be able to give good results for high impedance headphones. It just makes me wish for a 600 ohm Grado more than ever.

More or less, unless you hit the need for voltage swing.  Power is overrated in these parts, especially folks that say the Sennheisers *need* power...if it did, it would clip the amp output and distortion would spike.  I've had some fun with OTL, but have been thinking transformer coupled is the way to go for tubes, even cheap transformers like that castanet.

 

[burgunder]

This thread is a great read good job WyldRage.

 

[WyldRage]

First off, I've added the k601 and Beyer DT-770/600, as well as exporting the results by amplifier. It's in the main article.
 
@burgunder: Thanks for the kind words.
 
Quote:

Quote:

Also, I find the results for the Sennheiser very interesting: it seems that just about any kind of amp will be able to give good results for high impedance headphones. It just makes me wish for a 600 ohm Grado more than ever.

More or less, unless you hit the need for voltage swing.  Power is overrated in these parts, especially folks that say the Sennheisers *need* power...if it did, it would clip the amp output and distortion would spike.  I've had some fun with OTL, but have been thinking transformer coupled is the way to go for tubes, even cheap transformers like that castanet.

Remember that most nowadays play their headphones straight out of battery powered iPod and other mp3 players. That's the where the "need more power" comment is targeted. Any amplifier should be able to drive any dynamic headphones, with rare exceptions (AKG k1000).
 
I've heard that the Hammond PT-119DA output transformers were pretty good for the price asked, but I've often wondered how it would sound with better transformers. Do you have any suggestions?
 
From the amps I have heard, I prefer transformer-coupled. I try to keep an open mind though: I'll probably try the Bijou sometime this year... and the L'espressivo Torpedo... and any other pure tube design coming out... Yeah, building amps becomes quite the hobby/obsession.

 

[WyldRage]

Added a few lines in EHHA vs Castanet for the Grado HF-2. Basically, I prefer the Castanet's warmer and more emotional tone, unless the music if fast and complex, where the detailed presentation of the EHHA shines (as in most metal genres).