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Amp/Preamp Asylum: REVIEW: Antique Sound Laboratory Limited MG Head DT OTL III Amplifier (Tube) by nurxhunter

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REVIEW: Antique Sound Laboratory Limited MG Head DT OTL III Amplifier (Tube)

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Model: MG Head DT OTL III
Category: Amplifier (Tube)
Suggested Retail Price: $395
Description: Tube Headphone Amplifier
Manufacturer URL: Antique Sound Laboratory Limited
Manufacturer URL: Antique Sound Laboratory Limited

Review by nurxhunter ( A ) on May 14, 2006 at 12:33:59
IP Address: 71.224.254.102
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for the MG Head DT OTL III


Tube headphone amplifier using 2 x EL84 and 1 x 12AX7/5751. Separate power supply powers amp via umbilical cord. Removable IEC PC. Weighs about 10 lb for amp, maybe another 5 lb for PS.

Source: Slim Devices Squeezebox II

DAC: Cal Audio Alpha 18 with NOS GE 3 Mica Black Plate 5751

Phones: Sennheiser HD580 and Grado SR-125

Cables: Zu Oxy Fuel

Other HA: Sansui 1000A with high-end tubes all around

Review:

I was pleasantly surprised with the sound of the amp with the HD580. No problem driving them to blasting levels--at or below 12 o'clock in normal listening. Sounded a bit dark, but with excellent bass--maybe even a bit much. Not much difference to my ear between OTL and normal output, maybe OTL muddied the bass a bit. My Sansui outperformed the ASL, however, with 2 x Westinghouse 7591 and 2 x Mullard EL84 (with THD Yellow Jacket Converters, [review to come for this odd approach??], 2 x Sylvania GB5751 3M BP and Westinghouse 6AN8A--all nosty.

Surprisingly, the Grado SR-125 with 32 ohm impedance (?) sounded better than the HD580! It took a bit of rolling (not done yet) to refine the sound. So far, Sylvania round black plate EL84 from '60 together with RCA 12AX7 with black plates and square getter from '50s gave the best sound--I'm pretty sure.

Normally, the Syl EL84 are a bit bright and the RCA 12AX7 a bit too warm. Together this combo beat out Amperex, Mullard and Telefunken EL84 and Sylvania GB, TS 5751 ('50s with bent square getter) TS 12AX7 (same vintage) Raytheon 5751-3M, GE 5751 3M BP from '50s and Raytheon 12AX7A from 1960. Not all done rolling yet, but it goes to show:

***The best tubes in a system depend on its mates and the entire circuit from source to ear. I never would have thought that any 12AX7 would sound better than the Syl GB 5751--but here it did, TME.***

With the tube complement described and the Grado SR-125 (which sounded overly bright and not so refined in the Sansui 1000A), the ASL really rocks. Excellent, tight, detailed bass that is not overpowering and not light but just right, superb mids and vocals, excellent, airy highs with perhaps just a tad lack of ultimate detail. With the Grados, I prefer the OTL mode as the overall balance and musicality seems a bit more refined than normal mode.

I bought the ASL for a great price to validate whether the Sansui HP output is as good as I imagined--it is, esp. with the HD580. The impact and scale of the Sansui HD580 combo is better than the ASL Grado combo, as is the depth of bass. In all other areas, the ASL/Grado combo more than holds it's own and may even be more refined. I was surprised.

BTW, I compared the SBII (with a linear 5V, 2A power supply from a Zip Drive!) as a transport to my Cal Delta and ICON II HDCD in several of my nice systems extensively (tricked out CJ-MV52/Monitor 9is and Alpha 24/96), Ayre 3(X)/VSA-VR3.5 and EAD Encore and ASL KI-15 Fox and Kestrels with Alpha 18)--I sold my transports on Agon within the week. I listen to hi-bit (320 KBS) well-ripped MP3s only. Not distinguishable to my ear from the originals on any systems of mine, or to my golden eared, 17YO bass player with an absolutely remarkable photographic memory for audio. In double blinded trials, neither of us could tell the SBII from the transports under any conditions, even with Meridian 518, Monarchy 24/96, Jasco and decent cables in the mix with my well-optimized systems, which are pretty revealing--not the final word in price--but in value.

Summary: The ASL MG Head OTL III is a respectable tube headphone amp that is quite sensitive to the source (different DACS) and especially to tube rolling, which is quite fun for those of us with not much of a life beyond work, and an anal perspective on perfection. Worth $395, YES!—if-- you are well stocked with exotic EL84 and 12AX7 varieties and have a good source. Otherwise, just OK with current glass. If you can get it used for under $300, it’s a true value, as for all of ASL's line of tube gear (I love my FOX with NU 6113 or TS 6SL7; and Sylvania staggered plate 6SN7 (1952)or NU 6sn7). The ASL is a good match with the HD580, and a surprisingly stellar match with the Grado SR-125 with the right tubes to refine the otherwise somewhat lean sound of the Grado phones. Too bad they are not as comforting and soothing on the noggin as the HD580, but not bad as they are (kinda cheap in comparison.

I am on the lookout for Singlepower to see just how good my Sansui and ASL are in comparison to that benchmark. My HD580 have sat in a draw for 5 years, and now, I enjoy HP listening ALMOST as much as my tubes amps and speakers--ALMOST. I even bought the SR-125 and am eyeing the AKG 701. Sure is nice to listen horizontally in a waterbed.

Best regards to all.


Product Weakness: A high levels, can sound a bit confused. Stage and impact may not be the ultimate, but very enjoyable nonetheless.
Product Strengths: With tube rolling to optimize, can yield a surprisingly refined sound with the benefit of hot glass but not sound slow or 'tubey'. Reasonably compact and good looking in a retro way.


Associated Equipment for this Review:
Amplifier: Cal Alpha DAC
Preamplifier (or None if Integrated): None
Sources (CDP/Turntable): Squeezebox II
Speakers: NA
Cables/Interconnects: Zu Oxy Fuel
Music Used (Genre/Selections): Classic rock, Classic Jazz, RAP/RnB
Type of Audition/Review: Product Owner




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Topic - REVIEW: Antique Sound Laboratory Limited MG Head DT OTL III Amplifier (Tube) - nurxhunter 12:33:59 05/14/06 ( 1)