The Build
Our Beta22 build is a four boards with two Sigma22 and two separate toroidals providing power for each stereo channel. Also, the wiring is totally dedicated for fully balanced operation, and so unbalanced headphones are not supported. You may notice the presence of an RCA input at the back and the use of Neutrik combo-jacks, because initially we wanted to build the Beta22 to have support for unbalanced headphones and sources, but the plan was changed to support only balanced connections, mainly for simplicity reasons. The 1/4″ TRS jacks at the back panel was installed for a ground return connection. Zobel networks were also installed, following AMB’s recommendation, as a safety measure.
This particular build was done by Psychaudio. Parts were obtained from AMB Labs Shop, Glassjar Audio, and HeadAmp, according to the recommended parts list from AMB Labs. The particular wire used in the amplifier section is a high quality Japanese copper wire which is one of the best copper wires we have ever tested. We choose copper instead of silver primarily because we wanted a more musical amplifier and not a “technical” sounding one.
The attenuator is a DACT CT-2 4-gang attenuator. Installed in the back section of the amplifier, with the aid of an extension shaft to minimize the signal path. For the DC umbilicals that connect the PSU unit to the Amplifier unit, we used a super thick Kimber PK10 cable. (probably an overkill) The connectors for the umbilicals are Neutrik Speakon connectors, primarily due to availability reasons.
buz
How far away from the BCL would you place it? (Going by the description, I think I’ll made a good call in getting my M-Stage, because this sounds a little dull to me 🙂
Mike
Hi Buz, the BCL wins in speed, but overall the Beta22 is still superior.
xnor
The "lack in bass" your friend heard was most likely just due to the (very) low output impedance (= good) of the b22. And the layered bass you've mention is the logical side-effect. This has nothing to do with the amp itself. Add two 100Ω resistors in series, or just connect your bass heavy headphones to a receiver and you'll get a "punchy" bump in the FR (depending on the headphone).
xnor
About soundstage: moving the headphones even millimeters on your head will cause more drastic changes than what you'll ever be able to hear between most, if not all, amps that are well designed.
(Check out headphone measurements from HeadRoom expert Tyll posted at headfi, if you don't believe me.)
So this is a moot point for me as well.
As for "treble that sparkles", "less neutral", "more PRaT and impact" … why not use the E7 with bass boost plus some equalization instead. t_t
Note: I'm not defending the b22 or amb here, I don't even (want to) own one.
Mike
Thanks for the comments, xnor.
As an experiment, I have tried adding a resistor on the headphone out on another amplifier, and the higher the resistance at the output, the bassier the sound is. I don't remember it adding bass punch though. Perhaps you can share the particular amplifier and headphone combination you've used for your experiment.
I know that Tyll is a measurement expert (we talked about headphone measurements before), but I never realized if he has made such remarks about headphone positioning being able to replace soundstage characteristics inherent in an amplifier design.
Lastly, I don't understand how using an E7 can alter PRaT and impact, besides the fact that it's a very inadequate source for something like the Beta22.
xnor
Punch is a matter of accentuating frequencies around 100 to 200 Hz, where many headphones have an impedance peak. Combine that with high Zsource and you're likely to see more punch (again: it depends on the headphones). It doesn't have much to do with the amp itself, except that some amps might roll-off sub-bass which could result in the punch sticking more out of the music.
Maybe the resistor value was too high/low.
Slightly different positioning will result in big differences – peaks and nulls especially at higher frequencies. That's what he measured.
Now think of playing a mono signal, you should hear the same on both ears but you don't because of positioning differences. It might not be so easily noticeable with a mono signal, but has an effect on stereo imaging nevertheless.
I'm sorry about the e7+bass boost+eq joke, but that last paragraph was just too much.
Mike
Hi Xnor,
I understand what you're trying to say, and I'll try to experiment with what you just shared.
Cheers,
Mike.
glac1er
Thanks for the review Mike. This B22 makes all headphones sound good, even the ibuds.
xnor
An amp does NOT improve the signal.
Yours seems to be quite broken if even ibuds (!) sound good.
Mike
Thanks for the information, xnor.
Brian
Nah, I think Glacier brought up a very important point in a sense that all these cool devices only serve as a bridge between your ears to sweet, delicious music.
Shahrose
Very informative reviews. Instead of merely gushing, you've provided a balanced view with pros and cons and great detail within each section. I also felt your comparisons to other amps in the price range (or even to lower-end amps) was helpful as it gave me reference points to gauge the Beta with.
If you ever get a chance Mike, do post a review of the Dynahi/Dynamite/GS-X/GS-1. I think some of the shortcomings you've found with the Beta might not be present in the Dynahi or Justin's well-designed Dynalos. (I know some who feel the bigger Gilmore amps are superior to the Beta).
Mike
Hi Shahrose,
I'm glad you find the review useful.
A review of the Gilmore designs would be really hard to pull off. They're not very common around here, and HeadAmp is not the type that gives out loaners.
I felt that even a first class design like the Beta22 has weaknesses, and so it's only logical that the GS-X/Dynamite would do better in some areas than the Beta22.
Frank
as an audio mastering engineer i deeply prefer the HPBA-2 by Qes Labs
here you can read my review:
http://www.head-fi.org/forum/thread/479300/review…
no sound coloration.Plenty of dynamic.
A true balanced reference monitoring system through headphones
highly recommended!!
Mike
Thanks, Frank. Doesn't hear much about the HPBA-2, but you're welcome to post some impressions on it. 🙂
Jehan
Hey mike, how much is the total cost of a 4 board Beta 22 inclusive of a case? thanks
Mike
Budget roughly $1200-$1500 depending on the case you use.
Jehan
$1200-$1500 for a 4 board? Where can I get the case custom made? Lastly, how much will assembly of 2 boards Sigma 22 be? Thank you very much.
Mike
$1200-$1500 should be enough for everything, including 2 S22s with two toroids, case, attenuator, knobs, wiring, jacks, etc. There is no standard case, and so you need to find your own enclosure, design the layout and holes and get a shop to get the holes made.
Please visit the amb.org/beta22 site, under their parts list page, they have a list of suppliers for the enclosure.
I personally got the case for this built @ Kaichin at Sim Lim Tower (top floor) for SGD ~$40 each. It works well enough. The front panel is black anodized aluminum, but everything else is plain sheet metal. The paintjob is a bit thin and scratches easily though.
The audio store in Taiwan (check the link under amb website's parts list) makes nice looking cases, but the cost is quite prohibitive for me.
Jehan
Thanks Mike. Keep up the good work.=D
CheetahDeals Blog
Is there a company that sells pre-made Beta22s?
Anonymous
Hi, try Rockhopper Audio:
http://www.rockhopperaudio.com/store/
Brian
So Mike,
Ferdiansendjaja
Hi mike
I just bought beta 22 2ch from the local forum and when i test it with NAD RP 18 ortho, i spoted a noise comming from the driver (like the rp18 drivers broken). Is these caused by damaged mosfet like you mention before? Or the gain (gain 5) is to high for rp18??
The setup : ipad – b22 – rp18 via lod2rca
Thanx mike 4 d input
Mike
Maybe grounding issue.
Ferdiansendjaja
Ooo the grounding issue eh, do you know where the place to fix this issue in jakarta??
Thanx again 4 the info
Mike
You have to find a builder. Talk to the guy who sold you the amp?
BTW welcome to the world of DIY.
Gibran
Hi Mike. A noob question. How much improvement will I get from CMOY to Beta22 if I am using HD650? Will amp upgrade improve my listening experience by a big margin? Thanks in advance :).
Mike
Gibran,
The difference will be HUGE!
Gibran
Hahaha, I’m decided ;).
Caio Henrique Gonçalves Marque
someone tried the b22 with the audez’e lcd 2 ?
Mike
Pretty good but not really worth the hassle IMO. I’d just go for a Burson. Similar price and you get much better build quality.
Caio Henrique Gonçalves Marque
thanks again mike, i am thinking which amp i will use with the lcd 2 ”closed”
Mike
Nice.
Benedict Yappy
Mike, I’m curious after I read that you’ve tried Etymotic ER4 balance with the Beta22. How is the result compare to standard setup, say, ER4 out of AK120?
I’m interested in building a Beta22, tp use with LCD-X after I buy it and ER4. How do you advice about pairing Beta22 with LCD X? Seems like it will result in amazing sound.