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EHHA Rev A - Interest Thread - Page 98

post #1456 of 1671

Balanced EHHA or Balanced Millet Hybrid Max?

 

Whats the pros and cons to both?

post #1457 of 1671

@preproman: Can't help you on that question, sorry.

 

But I have another question (already asked a while ago here...)

 

 

How much power does the EHHA consume?

post #1458 of 1671
Quote:
Originally Posted by Sathimas View Post

How much power does the EHHA consume?

Typically, for the MOSFET version, each of the output devices are biased to 100mA.

Since they are run class A, be sure to budget accordingly.
post #1459 of 1671

I got all the right parts (incl. transformers) with a kit from glassjaraudio.

 

 

Just to clarify my question:

 

How many Watt does it (2 channel, standard mosfet build) consume when running? 15W? 30W? 50W?

 

 

I'm just curious and since it won't be able to finish mine before the end of this year I thought let's ask here.

post #1460 of 1671
Quote:
Originally Posted by Sathimas View Post

I got all the right parts (incl. transformers) with a kit from glassjaraudio.


Just to clarify my question:

How many Watt does it (2 channel, standard mosfet build) consume when running? 15W? 30W? 50W?


I'm just curious and since it won't be able to finish mine before the end of this year I thought let's ask here.

That will depend upon what you pump through it.

You could calculate at the class A bias as a sustained load and then assume no more than a 2X increase over the class A bias and get a rough idea. So, assume 100mA per output device (MOSFETs biased at 100mA) and then again at 200mA. Don't forget to add in about 500mA for each of the heaters and that should give you a rough idea.
post #1461 of 1671

Since this thread has pretty much come to a screeching halt I might as well add something new.

Over the holidays I was finally able to breadboard my EHHA RevA and fire it up.

 

All went really smooth, rails of the Salas shunts are sitting at 30V, Mosfets are biased to the

recommended 100mA and DC offset is hovering around 0.8mV in both channels.

 

It only has a few hours on it so far (with my hacked off heatsinks reaching about 55°C, but I will

add additional heatsinking once it gets cased up) so am not able to say alot about the sound...

other than that it does the job really good. At first listening it sounds lightfooted, balanced and clean,

highs are well integrated and bass is really deep and well controlled.

 

More in a little while... wink.gif

 

 

post #1462 of 1671
Looking good Stixx!

What brand of tubes are you using? Did you go with the standard gain implementation?
post #1463 of 1671

Thanks!

 

For testing I put in a pair of Philips Miniwatt ECC86, but I also have Amperex 6GM8, 6N27P and some Valvo.

I built it using the standard gain configuration but have the respective resistors socketed to play around later. wink.gif

post #1464 of 1671

How high is the standard gain by the way?

 

I'm also building one at the moment (takes way too long, but I don't have enough time ...)

 

 

I fear the standard gain is quite high?

Since I only have quite efficient cans at the moment, a gain of 2 would absolutely sufficient.

 

 

And another question - do you have any chance to measure the power uptake of your amp?

(See my question some posts before - I'm just curious bigsmile_face.gif  )

post #1465 of 1671

I seem to recall that the standard gain was around 9, but you can read up on it in that part of the thread --> http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1065...

I will probably exchange my pre with a unity gain buffer (DCB1) as one of my next projects because all modern sources put out 2V.

 

As for your other question I don't really understand it... do you mean the power consumption of the amplifier? This has been explained on the Cavalli site (which seems to

be down at the moment (?), but as jdkJake already mentioned: when I'm right you need about 200mA per channel for the Mosfets and a little extra for the rest, so make that

250mA at 30V for the amplifier and about 500mA for the heaters (per channel). I specced my toroids at 2x27V/0.6mA and 7V/0.5mA per channel. I had them custom wound

at RONDO Müller, and they are of excellent quality at a good price wink.gif
 

post #1466 of 1671
Quote:
Originally Posted by stixx View Post

Thanks!

For testing I put in a pair of Philips Miniwatt ECC86, but I also have Amperex 6GM8, 6N27P and some Valvo.
I built it using the standard gain configuration but have the respective resistors socketed to play around later. wink.gif

You will have to let me know what you think of the 6N27P. Both myself and bk_856er really enjoyed their sound.

Sounds like you have a very flexible build with lot's of nice tube options. smily_headphones1.gif
post #1467 of 1671
Quote:
Originally Posted by Sathimas View Post

How high is the standard gain by the way?

...

Since I only have quite efficient cans at the moment, a gain of 2 would absolutely sufficient.

As stixx stated, the standard gain is around 9. I have taken it down to around 5, but, not any lower. If you shoot for 2 be aware you may need to play around with the compensation caps to keep it stable. Perhaps Alex will chime in on the potential to take the gain down that low.
post #1468 of 1671

Glad this thread started again.  Started soldering mine yesterday.  Unfortunately, this will be a lower priority until I finish my AMB M3.  For the most part, my build will be done using parts supplied in the Glass Jar kit though I am open to some minor mods.  One that I am considering right off the bat is using SumR transformers, but have not decided yet.

Another is using a 10,000 uF cap. for C1H in the heater supply.  I already have a few and they fit in the holes perfectly.  Any pros or cons considering this change?

I would be interested to hear of any changes made by you guys before I solder in the parts  esp. in the caps department.   Tubes and opamps can come latter.

 

Stixx, I see that you had a M3.  I would be interested in your thoughts comparing the EHHA and the M3.  BTW, yhe casing you did on the M3 was first rate!

 

Thanks

post #1469 of 1671

Thanks for the advice, stixx.

 

I didn't say I wanted to cut down the gain to two, just that it would suffice.

I'll try the standard gain, my alpha20 preamp has a gain of eight, what works o.k. too.

 

 

Power consumption should be arround 21watts then?

(I studied medicine, doctors are really bad in calculating ;-)    )

post #1470 of 1671
Quote:
Stixx, I see that you had a M3.  I would be interested in your thoughts comparing the EHHA and the M3.

 

OK, one reason I sold the M3 is that I am running out of space with currently 5 (6) headphone amplifiers in my possession wink.gif.

The other is that even it sounded very neutral it always seemed to lack something... I just didn't get the same close feeling as

with tube amplifiers. Maybe it always sounded a tad technical, sterile. Don't get this wrong... it is still a world class amp and the

new owner (driving K1000's with it) is very happy!

The EHHA on the other side has a better balance, even though it doesn't have a lot of mileage on it. And it has the advantage of

tube rolling etc. So my vote between the two goes to the EHHA RevA wink.gif

 

And btw. when those big caps fit nicely put them in... filtering heaters can never be enough.

 

 

Quote:
Power consumption should be arround 21watts then?

 

Yes, but you want to double that just to be sure. Where will you get your transformer(s)?  A 2x30W toroid is not that easily available

in Germany, so that's why I am asking. A 30-0-30 40-50VA should be fine, but then you need a second one for the heaters. Thats why

I had mine custom wound...


Edited by stixx - 1/14/13 at 11:17am
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