EHHA Rev A - Interest Thread - Page 95

I would check the main EHHA thread as I am sure it has been discussed.

http://www.head-fi.org/t/422429/cavalli-ehha-embedded-hybrid-headphone-amp

The revA, for all intents and purposes, performs identically to the original version. At least in terms of output power.

hey..i'm also interested in it.. i've searched both threads and couldn't find any info about the output power.. anyone has any info about this??

Quote:

Originally Posted by redwarrior191 

hey..i'm also interested in it.. i've searched both threads and couldn't find any info about the output power.. anyone has any info about this??

Quote:

Originally Posted by glenda 

 

Power is not a concern only need 200 mW,   but voltage swing is a challenge for most headphone amps with inefficient 600 ohm phones.  

 

The Betta 22 would definately get the job done (specs are well documented) and a 2 channel build from GJA isn't much more than the EHHA kit,  read thru this thread and there wasn't much technical info on the design capability).  How close can the output swing to the rails before clipping ?

Start here:

http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1155#post_7238319

There are other snippets buried in the thread. Search is your friend. 
 

Thanks,  I found in that thread the output can swing well over 12Vrms before clipping which is great for my needs.

Now one other issue that I didn't find info on is the noise floor.  It looks like he rev a has inegrated DC heat which took care of some of the earlier noise issues,   but the noise floor on the scope shots on the EHHA website  look relatively poor. 

With the EHHA and  Grados or similiar high efficient low ohm headphones is there a "black" background?   On ecpaudio's's website Satvisky says one of the most important measures of a headamp is to hear nothing,  no static, hum, buzz, etc with grados playing a silence wav.   Has anyone tried this with their Rev A?    

One other curiousity question is why wouldn't you paralell two of the CRD's at the cathode of the input tube,  I mean a simple glance at the tube's datasheet shows this would put one in a much more linear region of the curve,  or is it that the NFB makes this a non-issue?  I am surprised no one has tried this, so I must be missing something?
 

thanks for the help,  I hope there are still others building/tweaking this innovative design and I am not needlessly bumping an old thread.

I am sure there are plenty of folks building the design, not so sure about tweaking it. Regardless, this thread has been pretty quiet as of late. Looking back, the Rev A is a little over a year old, certainly not ancient, but, obviously not FOTM any more. 

As for the noise measure, I have not seen anyone post any measures of the rev A. Personally, I have not objectively measured it, but, subjectively, it seems quite black to me. As of late, that can be a dangerous statement, but, my measurement tools are fairly primitive and would probably mislead rather than inform. I may try to change that situation, just not high on the priority list as of late.

That said, I think the noise floor is going to be impacted by the build techniques (power supply locations) as well as the overall gain setting of the amp and the source being employed. The nice thing about the rev a is the power supplies can be detached for a two case build if so desired.

I have Grados, so, if you can provide a silent waveform (which I assume is created to be a binary zero representation of silence), I will be more than happy to give it a subjective listen. 

​

As for the cathode bias point, I am not sure why Alex picked what he picked, but, I am sure there was rationale behind the choice. I think it would be most cool if you experimented a bit in that area and shared your results.

What are the differences between the EHHA and BETA22 in terms of sound?

Depends what tubes you put in the B22 

That's sooooo... funny.

:-)

Hang on in guys...mine is still in the works.

Just got seriously sidetracked by other projects and had to wait to get matching

black boards from the BiB Group Buy over at Diyaudio for Salas LV shunts regs.

Next will be to put in on a breadboard and fire it up... just a matter of weeks.

Hallo guys,

I´m quite new here in this forum and this is my first post.

Is it possible to still get a set of boards for a EHHA Rev A?

Maybe someone has one spare? 

I have a lot of DIY experience, but mostly with non-headphone based systems.

Now I would like to replace my OPA627 basedCMO derivative which I use for the last 2 years or so.

So, if anyone could point me in the right direction?

Thank you,

Flo

EDIT: Ok, I just found kits on glassjar audio... sorry

I just wanted to let you know I started this build on Monday.  Its my second tube amp build, and my 7th build overall.

One question I had with the GlassJarAudio kit.  I was sent a bunch of identical diodes, where Cavalli calls for a few different diods, namely the 4004, and the 5313.  Any idea on this?  I forgot what # I got, I'll have to check.  I just know they're all identical.

Hmm that's not good.  I figured that was the case.  I do not have the 5313's as far as I can tell so I need to contact Jeff I guess.

Thanks for your help.

The 5313's have been discontinured for quite a while. The CRD Jeff uses looks like a two-legged TO-226.

It's called a J511. Here's the data sheet, posted on page 90 of this thread. http://www.linearsystems.com/datasheets/J500.pdf

Quote:

Originally Posted by funch 

The 5313's have been discontinured for quite a while. The CRD Jeff uses looks like a two-legged TO-226.

 

It's called a J511. Here's the data sheet, posted on page 90 of this thread. http://www.linearsystems.com/datasheets/J500.pdf

So it appears, my bad - time to update the BOM on the Cavalli DIY site, though the J511 is also listed as obsolete at Mouser. But it will work, if you can identify the part in Jeff's kit.

EDIT: See post http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1290#post_7422832