CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS

Lobby => Head Amps, DACs, Sources, Portable Equipment Discussion => Topic started by: Tari on September 29, 2014, 02:22:30 PM

Title: Audio Guild EMAC 515SE
Post by: Tari on September 29, 2014, 02:22:30 PM
Looks like this finally may be ramping up for production so I figured I'd include some info on it here, all ripped from Steve's site/faceboook.


This looks to be a production quality shot of the new amp/power supply:


(http://i.imgur.com/mQVjnfA.jpg)


The transformers have octal bases and are removable, (presumably to have multiple options for different sound?  Could rolling transformers become the new nervosa?) and look beautifully custom:


(http://i.imgur.com/hiXtwW9.jpg)


Steve has seemed incredibly OCD about every aspect of this build, with posts about knobs, engraved serial plates, switches and lights... both the look of the amp and the anal attention to little cosmetic touches will remind some here of Joel Marshall of Moth fame. 


As for the innards, here's what Steve has to say about his design (a while ago, so maybe something has changed...)



"So, about that headphone amplifier...


When it comes to signal amplification, between tubes and transistors, I tend to prefer tubes. However some years ago (I guess it's been about a dozen or so by now), I found that I preferred something more than tubes. A technology that actually pre-dates tubes; transformers.


When most people think about transformers, they usually think power supplies or perhaps the outputs of tube amplifiers. But transformers are also capable of signal amplification. A well designed and well made step-up transformer can amplify a signal with vanishingly low noise and distortion as well as offering other benefits that active circuits simply cannot offer such as ground isolation between components.


Using transformers for signal amplification is hardly unknown. In audio they have been used for stepping up the voltage of low output moving coil phono cartridges, and in the studio are commonly found in some of the finest microphone preamplifiers.


The EMAC 515SE headphone amplifier utilizes a very high quality 1:5 step-up transformer to provide all of its signal amplification passively, eliminating power supply issues at the most critical stage of any amplifier.


And even though the 515SE uses RCA inputs, the transformer primaries are inherently balanced and provide outstanding common-mode noise rejection even when fed from unbalanced sources.


However being a passive device, a transformer cannot provide any more power out than is put into it. So in order for the amplifier to provide power amplification, active devices must be used.


In this case, the 515SE utilizes a single-ended, single-supply unity gain output stage made up of a pair of JFET and bipolar transistors configured as a Darlington pair (or FETlington if you will). After experimenting with numerous output stage configurations, we found the FETlington circuit to provide the best match for the transformers.


For signal attenuation, the 515SE uses a precision 40 step attenuator for unmatched balance at all levels (channel imbalance, particularly at lower levels, often plagues designs using continuous rotation potentiometers).


The 515SE also includes switched, transformer-coupled preamplifier outputs allowing it to be the heart of a high quality headphone/loudspeaker system. The switching is handled by the headphone jack itself using high quality welded crossbar palladium switch contacts.


Power is provided by a separate discrete, zero feedback series regulated power supply."


In the past, inevitable comparisons were made between the 515SE and Black Diamond due to the usage of transformage.  That would certainly be an interesting test, but from the looks of it this amp is so artistically unique in the current amplifier landscape that its merits really deserve to be judged on their own.  This really seems like a passion project, as with price estimates of $3500, many headphone junkies will be priced out off the bat.  It's still really cool that Steve and Co. want to dip their toes in these waters.  I believe Steve used to be involved with Coda and this seems like striking out in a totally different direction. 

Oh.  The kicker on this site, how does it sound?  No idea, hope they'll bring it to a meet sometime so someone here can get a lead on that.
Title: Re: Audio Guild EMAC 515SE
Post by: dsavitsk on September 29, 2014, 10:59:53 PM
Beautiful! Great to see Steve finally has these ready to go.  :-DD
Title: Re: Audio Guild EMAC 515SE
Post by: LFF on September 29, 2014, 11:25:54 PM
Definitely a fan of the looks.

Just hope it sounds great. I know it's been in development for a LONG time.
Title: Re: Audio Guild EMAC 515SE
Post by: Anaxilus on September 29, 2014, 11:49:25 PM
1-Love the looks!!  He did great with that.  I've been looking at special finishing touches for the Leviathan project and can see some of those in this amp.  That tells me these aesthetic options are actually as limited as I feared they might be.  I couldn't find a brass colored collar for that amber jewel light either.  ;)

2-Great implementation of rollable transformers.  Another idea we were talking about but much more elegant and streamlined that we had come up with.  However, that elegance and aesthetic refinement seems to come with a cost of potential transformer designs.

Do you have any information on what transformer options are available and their construction?  Because their size/shape and mounting suggests a potentially narrow range of possibilities in sound and performance.  I'm guessing the output power ranging from anywhere between 2-3 watts?

3-Have to say not a fan of top mounted jacks just like Decware.  Only TRS?
Title: Re: Audio Guild EMAC 515SE
Post by: OJneg on September 29, 2014, 11:58:00 PM
Wouldn't expect output power to be limited here as the transformer is followed by a buffer
Title: Re: Audio Guild EMAC 515SE
Post by: Anaxilus on September 30, 2014, 12:07:19 AM
Quote from: OJneg on September 29, 2014, 11:58:00 PM
Wouldn't expect output power to be limited here as the transformer is followed by a buffer

Gotcha.  Haven't followed the amp much since most of updates and progress were posted on Facebook.  So he really is just using these as tubes for selective coloration.  I misread the comment on input devices prior to the FETlington output stage.
Title: Re: Audio Guild EMAC 515SE
Post by: dsavitsk on September 30, 2014, 03:09:38 AM
Quote from: Anaxilus on September 29, 2014, 11:49:25 PM
2-Great implementation of rollable transformers.  Another idea we were talking about but much more elegant and streamlined that we had come up with.  However, that elegance and aesthetic refinement seems to come with a cost of potential transformer designs.

Octal transformers are a common thing:

(http://avforum.no/forum/attachment.php?attachmentid=31537&d=1207341182)

I'd guess that Steve's have a 1:5 turn ratio and work into a < 40K load (meaning that the source impedance should be ~150 Ohms or lower). The Altec 15095 may be a drop in replacement, though I'd assume Steve's to be better.
Title: Re: Audio Guild EMAC 515SE
Post by: Anaxilus on September 30, 2014, 05:36:50 AM
I'm assuming by your pic Steve's will be the only new production ones available?  So is it like a toroid with a ring core?
Title: Re: Audio Guild EMAC 515SE
Post by: dsavitsk on September 30, 2014, 08:10:31 AM
Cinemag makes them (they made Steve's). Jensen does, too. I am sure others do as well. You generally just have to ask the manufacturer.

(http://cinemag.biz/line_input/images/CMOL_group.jpg)

Core is most likely a small 80% permalloy EI.
Title: Re: Audio Guild EMAC 515SE
Post by: Claritas on September 30, 2014, 01:22:51 PM
What a splendid-looking amp!

I heard the transformers aren't meant to be rolled, but don't know that it can't be done.
Title: Re: Audio Guild EMAC 515SE
Post by: Marvey on September 30, 2014, 03:43:40 PM
That's nuts. Absolutely beautiful.
Title: Re: Audio Guild EMAC 515SE
Post by: zerodeefex on September 30, 2014, 03:54:12 PM
that's incredible. One heck of a looker.
Title: Re: Audio Guild EMAC 515SE
Post by: xzobinx on September 30, 2014, 05:03:15 PM
I think I just fell in love. This amp got all the great design from moth xana. Now if only the wood is red  headbang
Title: Re: Audio Guild EMAC 515SE
Post by: Tari on September 30, 2014, 05:23:15 PM
They have different wood colour options, including Cherry:


(http://i.imgur.com/VSuM2Mv.jpg)
Title: Re: Audio Guild EMAC 515SE
Post by: CEE TEE on October 01, 2014, 04:46:07 AM
^That's obviously photoshopped.  Send me a loaner to prove it isn't or I will say bad things about the amp in every thread.  This will start in a fortnight.  I just made room and bought another Salamander rack.  For serious.
Title: Re: Audio Guild EMAC 515SE
Post by: xzobinx on October 01, 2014, 06:06:04 AM
Quote from: Tari on September 30, 2014, 05:23:15 PM
(click to show/hide)
now I'm dreaming of some urushi layer  :-00
Title: Re: Audio Guild EMAC 515SE
Post by: Tari on October 01, 2014, 01:40:25 PM
Quote from: CEE TEE on October 01, 2014, 04:46:07 AM
^That's obviously photoshopped.  Send me a loaner to prove it isn't or I will say bad things about the amp in every thread.  This will start in a fortnight.  I just made room and bought another Salamander rack.  For serious.

I will not send you a loaner just so that you can say you've heard it when you trash it.  I know you hate all things Audio Guild, but Steve Eddy having two first names is not enough of a reason to justify a vendetta. 

As for the picture, I do have to admit it was shopped for its inclusion in this month's Vogue, here is the original along with the shop:


(http://i.imgur.com/113R4Ur.jpg)
Title: Re: Audio Guild EMAC 515SE
Post by: Armaegis on October 01, 2014, 05:25:25 PM
Looks like a dead body in the bathtub there...
Title: Re: Audio Guild EMAC 515SE
Post by: CEE TEE on October 01, 2014, 07:37:16 PM
Quote from: Tari on October 01, 2014, 01:40:25 PM
Quote from: CEE TEE on October 01, 2014, 04:46:07 AM
^That's obviously photoshopped.  Send me a loaner to prove it isn't or I will say bad things about the amp in every thread.  This will start in a fortnight.  I just made room and bought another Salamander rack.  For serious.

I will not send you a loaner just so that you can say you've heard it when you trash it.  I know you hate all things Audio Guild, but Steve Eddy having two first names is not enough of a reason to justify a vendetta. 

As for the picture, I do have to admit it was shopped for its inclusion in this month's Vogue, here is the original along with the shop:

(http://i.imgur.com/113R4Ur.jpg)

Don't think I didn't notice your attempts to subliminally induce Gene Loves Jezebel feelings toward Steve Eddy's amp designs. 

First of all, I wasn't criticizing Steve Eddy in the post.  But, I admit, I take umbrage with his use of "se" after his posts.  I don't type "ct" after each of my posts...

Also: I have manipulated genuine, simulated wood grain before- and thought I noticed some "tell-tale" burnishing that was the result of a lazy Healing Tool in Photoshop.  I may be mistaken, but then the image must have been softened (or downsized or converted into a different lossy format, or some other subterfuge) so it is hard to be completely sure. YMMV.

Those are the only reasons that I (merely) suggested sending a unit to me for OBJECTIVE OBSERVATION and another data point...for the good of the community.  Okay, fine.  I'll wait for the Six Moons review.

(And if you're going to try to make up some cool name for yourself, do it like Peter O'Toole.  ;) )