Balanced EHHA or Balanced Millet Hybrid Max?
Whats the pros and cons to both?
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.
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...
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.
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 )
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
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 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 ;-) )
OK, one reason I sold the M3 is that I am running out of space with currently 5 (6) headphone amplifiers in my possession .
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
And btw. when those big caps fit nicely put them in... filtering heaters can never be enough.
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...