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Brief Review: Apheared's CMoy variant #42

post #1 of 7
Thread Starter 
Apheared was kind enough to let me test out his new creation: The Apheared CMoy Variant #42. If you haven't already seen his thread about it, click here (you'll also find pictures there). Here's a brief review:

Apheared designed this amp with the Sennheiser HD-600's in mind. Now here's something you have to know about Apheared in case you didn't know already -- he is extremely fond of Grado headphones and the signature Grado sound. HD-600's aren't really his cup of tea. So why did he make this amp?

Quote:
"I decided to make an HD600 portable amp. Not that I really like HD600s or plan on walking around with them, but hey it's a project."
As most folks here know, the HD-600's have a well-earned reputation for being a bit laid back. The Grados have a reputation for being anything but laid back. Keep this in mind because....

....my HD-600's freaked me out when I plugged them into this amp! Why? Because they were instantly Grado-ized! Don't get me wrong -- this wasn't a bad thing. Especially not for Grado lovers, or folks who love the ability of the Senns to reproduce micro-details but find the overall tonal balance of the Senns too polite. Variant #42 takes the kid from a fancy boarding school and slaps a few tattoos on him.

Over the last six months, I have gone from being a Gradophile to more of a Sennheiserphile, but I still adore the Grado character at times. Through Variant #42, my Sennheisers at times actually sounded like Grado SR-325's that went to etiquette class -- more overall slam than I think even Sennheiser engineers ever knew their HD-600's could produce, yet still providing more bass tautness and treble refinement than I ever heard from the Grado SR-325's. It was a pretty wild experience to hear the HD-600's like that, and it took a true Grado lover with mad amp-building skills to design and voice an amp to do that.

So did I prefer the Grado-ized HD-600's or the more standard, laid-back HD-600's? Well, my tastes have gone to the more laid-back side, so for the HD-600's I'll probably stick with my HeadRoom Max for a while (and I thought my Max brought a forwardness to my HD-600's!).

Where the Variant #42 totally stunned me was (surprisingly) with my Sony MDR-7506/V6's. With Grado SR-80's the Variant #42 was a bit too aggressive to my ears, but it still sounded good. Since the 7506/V6's are also lower impedance (compared to the HD-600's), I figured #42 would have also been too agressive for the 7506/V6's. Not so! In fact, they were magic with them. I thought it might make them overly bright, and that wasn't the case at all. In fact, compared to my Max with the 7506/V6's, the #42 did very well, with the Max edging out the #42 in terms of treble refinement and a bit more reach down low. But the #42 had one very key advantage over every other amp (including the Max) with the 7506/V6's -- soundstage. The normally closed-sounding 7506/V6's opened up significantly with this new amp by Apheared -- impressively enough that I may actually consider paying someone (if not Apheared himself) to build one for me exclusively for use with my 7506/V6's. Simply put, I was floored by the #42's overall performance with the 7506/V6's.

The parts for #42 aren't cheap. Apheared wasn't messin' around with this one, putting a fancy Noble pot on it, among other things. But if you're looking for more attitude from your HD-600's without foregoing the Sennheiser capabilities for catching even the finest details, then this may be the one for you to build next (if you can get your hands on the parts). If you do build it, and you don't already have a pair of 7506/V6's, make sure to pick some up, as you will almost certainly be impressed by this pairing too.

Thanks for two weeks of fun and experimentation, Apheared!
post #2 of 7
Great Report Jude I think that the EL2001's are a great Buffer and Although I like to use (4) of them In Parralell for the V6's and i also Like The AD-825 for an opamp finding the 823 lacking the Slam i am used to. Yes the 825 IMHO is a Great Sonic match for this Buffer. As far as soundstage is concerned The 825 is alot Better than the AD-823. While i do use the 2001/823 in my Pocket Amp operating on (2) 9 volts. For the V6's and SR-60's the bass is just to Light For my Taste and most of that Lightness comes from the 823 with only one 2001 per ch is indeed for High impedance Phones. Although i haven't tried the HD-600's I have tried this with My Pro4AA that is a 220 ohm Phone and One EL-2001 drives them as good as more Buffers in Parralell. I must add that My idea of a portable amp is a Kerll operating on batteries and since we are using Headphones a lot less power. Nontheless i still like the Bass to Knock the fillings out of your teeth and do this while still controling the Driver. With low impedance Cans This takes lot's of Current. However you did accuartly discribe the sound of the 2001/823 on the V6's quite well. and since i am always looking for the Best in Headphone Amps I value the views of people like yourself on what somthing sounds like.
post #3 of 7
I definitely agree with Jude's review of the Apheared #42. With my HD580's, there was just more bass oomph and a characteristic treble detail that isn't quite there with my Szekeres amp (which I've been using for the past few days since blowing my #42's chips ).

Because I listen to almost all rock music, I've considered buying some Grados just to see if I'd like the sound (I still haven't bought any yet for concern of the 3D positioning in games, since I'm not much of a multi-headphone user). Jude says the sound is "Grado-ized", and I have a feeling the Grado sound is what I'd like for rock (except for the high trebles maybe). The #42 amp with HD580's seems like it should be a good compromise to using Grados with my preferred music.
post #4 of 7

823 and 825 interchangeable?

PPL - is it possible to use an 825 as a drop-in replacement for the 823, or must wiring be reconfigured for the other op-amp? Having a choice in the sound would seem awesome.

Aside from less battery life, are there any disadvantages in paralleling 4 EL2001's as opposed to only two, or one per channel? Is there a decrease in sound quality, or does it just not matter with high-impendance phones?

if the latter is true, than having 4 EL2001's will just make the headamp more flexible..
post #5 of 7
The AD825 is only available in SMT... ie, really small and hard to solder
post #6 of 7
The AD823 is a Dual Opamp and the AD-825 is a Single. Also as Thomas points out the AD-825 is a SMT device so some Kind of SMT to DIP adaptor is needed to use the AD825 in a Dip socket. The AD823 is IMHO one of the Best Dual opamps around if an Articulate and Detailed Midrange and Top end is the type of sound your after. The AD823 is a Drop in replacement for other Duals like The OPA-2132, But sounds way better than the 2132. If a laied back sound similar to the OPA-627 is what your after I would sugest the AD746. The AD-746 is a Dual version of the AD-744. The AD-744 is an opamp i like alot, But it is soft sounding like the OPA627. so if your Board is allready layed out for a Dual like the AD-823 and AD746 Then you can still swap Opamps to Change The Sound from One extreem to the other. The AD-746 I think has more Bass Punch than the AD-823. Both the AD-746 and the AD823 Need a Buffer to drive any Headphone since Nether is all that Great alone in Driving loads less than 10K.

Parallelling EL-2001's is Good. The High's and Mids remain the same as just one. The Big difference is on My SR-60's and MDR-V6's/7506 (I have Both) where (4) EL2001's give me the Bass Punch and offer More Control over the Driver. One 2001 with the V6's make the Bass slightly Fat with some overhang. By using (4) 2001's The Bass gets Tighter and has more Dynamics than using just one Buffer. The Good thing is that the Mids and High's remain the same using one or a parallel set of (4) On my Koss Pro4AA the sound quality remains Virtualy unchanged using one or Four Buffers. The Koss have an Impedance of 250 ohms so for Cans with a similar Impedance i cant Hear no advantage in using more than one EL-2001. This may change with other High Impedance Phones I have not tried this with the Likes of the HD-600's. In eather case the EL-2001 flat Kicks But on the BUF-634. I have measured the Output Current of Both the BUF634 and the EL-2001 into a 0.5 ohm load and it takes (2) EL-2001's to get the 290 Ma I get out of just one BUF-634. In terms of sound if i were to judge output Current based just upon what i hear I would think the EL-2001 had More output Current. The EL-2001 Flat out Rocks where as the BUF-634 makes me want to turn the volume up to get the Dynamics of a 2001.
post #7 of 7
Quote:
Through Variant #42, my Sennheisers at times actually sounded like Grado SR-325's that went to etiquette class -- more overall slam than I think even Sennheiser engineers ever knew their HD-600's could produce, yet still providing more bass tautness and treble refinement than I ever heard from the Grado SR-325's. It was a pretty wild experience to hear the HD-600's like that, and it took a true Grado lover with mad amp-building skills to design and voice an amp to do that.

...

I may actually consider paying someone (if not Apheared himself) to build one for me
Humm.
I would like to hear "Grado-ized" Senns and would order an amp if there are any willing builders.
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