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Model: SLA-1 Category: Amplifier (SS) Suggested Retail Price: $300 USD Description: 100 Watt Amp: unbalanced TRS/balanced XLR inputs, bridgeable, ground lift,,variable sensitivity Manufacturer URL: Applied Research and Technology Model Picture: View
Review by PeAK (A) on June 18, 2003 at 07:16:38
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for the SLA-1
I've been thinking about the amp end of things for a while. I looked at the AKSA kit amplifier and had my ear to the ground hearing about the Samson Servo 170. The 55W/Ch AKSA kit does not include chassis or a transformer costing about $385 Canadian verus the SLA-1 at $300 even. The immense success of the DI/O in my playback system persuaded me to become a repeat customer.
The guys/gals designing at ART are turning out some pretty decent stuff (DI/O for one) these days with great price/performance ratio. Hinting stronly to my wife, I recieved a belated BD gift in the form of a SLA-1 over the weekend. I was tuned into the Audiogon SLA-1 infomercial thread prior to it being deleted and am aware of some of the underhandeness going on with regard to false pseudonyms posting about their own companies. Regardless, I sensed something very real underlying all of this. I have the original post that mentions the SLA-1 in the same breath as Mark Levinson and Pass amplifiers.
The specifications on ART's home page show the ART SLA-1 to have high power and low distortion.
The one indpendent review found was one of the SLA-1 and partnering SLM-1 speaker. Being down under, the price premium for shipping this product there is quite steep. There is a PDF available. The manual is currently not available.
Any component evaluated needs to be taken within the context of the system it is evaluated in. This section covers short term and longer term impressions of the SLA-1. The latter section will be updated over time and as the SLA-1 is evaluated in different systems.My long term reference has been the integrated amplifier that I have used for the last two decades. It is not perfect. Its imperfections to me are known and I can to some degree filter them out when comparing components ahead and behind it...to some degree. To a large degree, the changes that I have wrought on the 3020 are very similar to how the SLA-1 comes in stock form: No tone controls, simple gain path from line level to to amplifier input circuitry. The NAD has the benefit of the following: Seperately regulated predriver for the amplifier output stage, Boutique caps (Wondercap), Updated internal wiring with Kimber 8TC, DC coupled preamp output, ALPS potentiometer and most impotantly a host of subtle mods/cap types to tune it to my system over time...most of which I have forgotten. Out of the box, the SLA-1 has some of the NAD "sound/imperfections" removed and this has encourage me to listen to some CDs which I have not listened to in a while. The balances are close but I'll have to wait until I compare it to my friends 50W reference Tube Soundtech amplifier based system to sort out
the signature of the SLA-1. From what I have heard to date, the designers at ART have done their homework. I could live with it for quite a while.
I presently run a highly modified NAD 3020 that is the equal of more costly amps in terms of the first Watt (probably more) of amplification. It has served very well in the role of a microscope to sort out deficiencies in upstream cables and sources. Out of the SLA-1 box, last night, I still find the 3020 to win in terms of information retrieval and overall balance. The SLA-1 sounds surprisingly close, though. From turn-on, the 3020 normally takes about an hour or two to warm up to its sonic splendor.Within 1/2 hour, I opened up the top, disabled the fan and gave it more of a listen. Updating the power cord to an Belden 83802 based unit gave a bit more resolution. The next morning it sounded somewhat better after having been left on all night. I'm not sure if it sounds better with or without the ground "lifted". It sounds promising. I do not know if it beats 95% of the amps out of the box (as claimed by Don) but it sure has potential at this early stage. Perhaps my little 3020 beats 96% of the amps
The amp is stable driving 2/3 Chris Venhaus CAT5 loudspeaker design.As these cables are fairly capacitive, the fear of the output stage blowing up and frying my speakers was in the back of my mind. I tested this first on my "cheaper" Radio Shack LX5 speakers before moving onto my Axiom M22ti.
The urge to unplug it has not hit...which is a good initial sign. I am beginning to listen to CDs from start to finish (always a good sign) at this early stage.Using a wider variety of music over the last few days shows me that it is getting better as I leave it plugged in. I did not expect my jaw to drop on the first day but good systems have a way of proving themselves worthy over time.
On the construction side, I noticed internal construction details to ease/lower cost of construction related to the snap on connections between the power tranformer outputs and the full wave rectifier and the connections between the Attenuator controls and the main amplifying stage (read mod potential).
I will adding further comments to this section from within mostly the context of my system with specific references to how it fairs with different types of music.
Stay tuned. I'll might organize subsections to reflect this chronological updating of the evaluation. This might be week to week, month to month and include discussion from the various other parties who are also evaluating the unit. I will also try this amp in another system and report back but the basic rule of thumb for this evaluation is to use the unit "as is" with few to no mods. Section 2.2 will address the long term finessing/modding of the unit and resultant gains from doing so.
- Day 1 (Tuesday June 3,2003): See above.
- Day 2 (Wednesday June 4,2003): Tried 83802 cable with polarity reversed via cheater plug resulting in more air but more diffused bass. Tried alternate Belden SJT cable (normal polarity) resulting in better integration. Ground lift position preferred. Compared to NAD 3020, sound is now more CD/recording dependent.
- Day 3 (Thursday June 5, 2003): Busy night and no audition possible. Some measurements of various system DC voltages made. Notice slight transformer hum audible from about 8 inches from unit.
- Audiogon Review #1 dlshifi, June 4, 2003
"This speed and transparency really surprised me and continued to surprise me over the next few days- everything I played, from gigantic Mahler to intimate Patricia Barber, seemed to have acquired a snap and drive that floated it out of the grunge and actually opened for me a new sense of musical priority""...when I put my other amps into the picture the focus softened, things slowed a bit, voices and instruments thickened and somehow seemed “hotter” in an unnatural way: less revealing of time and space... For now, the kid stays in the picture."
"...it can sound a bit lean and at times even threadbare"
"...I find the SLA-1 a worthy, special little amp that can enliven the listening experience with its speed and transparency. But it's tonally thin, upwardly balanced, and can sound harsh unless carefully matched both up and downstream."
- Audiogon Review #2 Walter Salas, June 2, 2003
"To these ears, the ART is a very clean sounding and powerful little devil. Whether it is as good as D911 claims remains to be seen, but it appears to be holding its own in my system"
"I want to give the ART more time to break in and experiment with some different power cords and tweaks before commenting further on the sound, but I think it is safe to say that the amp is pretty damn good, perhaps even remarkable at its price point."
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June 13, Update: Walter Salas
"The amp is dynamic and clean, with precise placement of instruments in the soundtage, but can sound hard or lean at times and does not quite have the extension/dimension or musicality of reference quality amps costing thousands of dollars more""It is a credible performer even in audiophile systems... but I also know that I would choose the Plinius (SA-102) 10 times out of 10."
- Day 4/Morning (Friday June 6, 2003): Quick listen this morning with Belden SJT power cord attached and powering the SLA-1 unit overnight. Slight upper frequency emphasis/harhness eliminated when the "ground lift" is diabled.
Upper air and decay of piano is now fuller. Cello notes are sounding fuller with more of the "rosin" quality evident. I may be hearing the limitation of my DI/O DAC at this point. Will try to borrow friend's LT1362 modded DI/O as a point of comparison with SLA-1. The unit is now sitting on the styroforam packaging that came with the unit. Attaching rubber feet that came with amp and trying it out directly on the stand will be the next order of business. I will try to comment on how important the feet/isolation are to this unit. Reattaching the top and seeing how hot the unit gets with the fan off will tried and again re-evaluating it sonically. Test CDs are Norah Jones, Mary Chapin Carpenter, Neil Young, Rebecca Pidgeon and Rosanne Cash.
- Day 4/Night (Friday June 6, 2003 7:00pm-12pm): I'm writing this on Saturday morning with a smile on my face...the SLA-1 is for real. It staddles and combines the fine line of solid state's virtues (dynamics, bass) and tube's naturalness in the voice region. As someone said earlier "it is a remarkable amplifier at its price point"....I would add "period" to the end of that quote. With that said I think I'll run it stock for a while and thank Don for pointing out this unit to the audio community at large and get back to what I heard last night.
With the above experiments from the morning in mind, I spent some more listening to the ART SLA-1 in the company of my goldened ear friend Danny with his LT1362 modded DI/O. This unit has the default output level set to almost 7V RMS (compared to my DI/O set to 2V RMS) plus some recent critical fine tuning changes by Danny. I'll refer to this unit as "Danny's DI/O". To cut to the chase, using the supplied rubber feet with the SLA-1 is key to realizing a fullness in the bass and freeing up the amp's dynamics ( The styrofoam packaging blocks make for poor substitutes for the supplied feet but ease the return/exchange of the amp should I have decided to return it...NOT!!!!). Using a SACD/CD recording by Marc Vallee playing an acoustic version of U2's “I Still Haven’t Found What I’m Looking For”. The 7V RMS of Danny's DI/O was ably accomodated...it also bought the sonic level of my overall system closer to level/nature/preferences of my friend's tube based system.
Low level reverb information, bass rhythm details, drive and transparency were now much improved. The limitations of my DAC were more clearly obvious while the advantages of Danny's DI/O (only hinted at earlier seesions with the NAD) was much more tangible, obvious and evident. The SLA-1 is a transparent and fast sounding device that will expose a good signal. Notes come and go in a way that allows the music to breathe. With cork and blutak in hand, Danny made a few more adjustments over the course of the evening. This resulted in a lack of sibilance,quieter background and larger soundstage. Songs seem to play twice as long as their marked times...as if in suspended animation. Notes just seem to float about the room.
With my speakers, Danny was not able to clip the amplifier playing an extremely dynamic recording of a large church choir from Chesky's demonstration disk while playing it at comparable levels to his setup. He estimate's that it was putting out over 50W. The green "signal" LED stayed on continuously. His kilobuck amplifier (with his ATC monitor speakers) will audibly clip. Although I do not normally play at this level, it was interesting to see the SLA-1 hold up to playing levels derserving of the evil eye from my neighbour.
So for me in my system, with the appropriate upstream sources, the SLA-1 can hit a very decent sonic level almost right out of the box (ie. Given a few days of burn-in and a borrowed previously broken-in power cord). Do not evaluate it without the supplied rubber feet attached and use a good source. I ended up turning off the amp around midnight (5 hours later) and thinking about how I needed to upgrade my frontend/DAC to the standard of Danny's unit. I have been well aware of the compromises in my NAD 3020...it is a as someone said a "rose coloured frosted piece of glass" that I have grown to know and like/love for all its warts. The SLA-1 is a revelation. I've had my NAD 3020 for over two decades. Anyone out there want a highly modified 3020...? For a slightly different perspective, Tim Moorman posted his thoughts on the SLA-1, below:
- Diomods Review #1 Tim Moorman, June 7, 2003
"...certain mid and upper mid range frequencies highlighted or projected slightly forward of the mix..."
"Tonal quality is poor. Lacks the rounded organic tones of good tube or excellent SS gear. Some congestion. Not close to my SS Plinius 8150 integrated, which, admittedly, is far more costly, and pales in comparison to single ended tube stuff. "
"The clarity and speed are good, but at the expense of reduced mid bass and bass involvement...Probably nothing close to it in this price range. I like the attenuation for each channel, compact size, and bang for buck. Good starter amp."
- Day 8 (Tuesday June 10, 2003):
I'll need to update the summary below but a tweak has totally transformed the opinion of my system (with the SLA-1) in it. I've taken the liberty of quoting someone else's impression of the improvement:
"The difference I hear is in resolving the finest of details. Things like hearing the hall's shell, the *sparkle* of triangle, the "sheen" of a cymbal, the natural harmonics of a violin, the continuity of attack and decay of a piano. "Air" between the instruments. Brass sounding "sweet" instead of "hard." The ease of hearing a harmonic line. "Splashy" dynamics morphing into "bass slam." A *huge* improvement in stage depth. "
As a experiment, I put the OEM Unicab cable in and gave it a listen. Although the tweak above improve the overall system playback even with the Unicab cable, putting back in the Belden power cable wrought more easily heard changes than without the tweak between the two cables.
Note: See the link above that describes a tweak...it turned my system on its ear and most of the criticism leveled at the SLA-1 has been lifted. The following summary pertains to it prior to Day 8's changes and listening).It is still early. Some of the early adopters/reviewers (3 so far) have the relevant experience and ears to make an assessement of the SLA-1 within the context of their systems and tastes.
The positive comments are:
- Speed and transparency
- Engaging snap and drive...this I take to mean dynamic
- clarity/clean sounding
- delineation of "space and time"...soundstage/separation
- Not cold and not sterile or embarass itself in much more expensive systems. Mostly the sins of omission.
The negative comments are:
- lack of "deep authorative bass" and "some congestion"
- mid to upper midrange forwardness with a tradeoff to overall integration
- Lack full round organic tone (also referred to as "poor tonal quality" compared to the best). This has been described as "tonal thin" and "upwardly balanced" leading to carefulness in system matching in both upstream and downstream paths.
- Some solid state "hash and grit". The "highs are nothing special".
The summary above is my attempt to group "common" observations into a succinct summary from each of the three reviews. There is a slight filtering upon my part which I will address below. .
Some of the statements above come from user's with very extended LF speakers and tastes. For me, #1 is not so much an issue providing everything above the last octave is tight, controlled and fast. The smallish filtering in the power supplies is sometimes eclipsed by competing 100W amps by as much as 7x (ie. 35,000uF versus 4,700uF). This might lead to some of the comments regarding congestion and deep bass at loud volumes. LS3/5a users need not worry or comment. Issues #2 and #3 were not so much an issue with Danny's dac but were noticeable using my DI/O with the attenuated gain. For me, on femalie voice, it amounts to a slight edge and un-natural sharpness to the pitch and lack of chest/warmth. Issue #4 was made by a tube lover and I can understand his perspective. The high's comment is something I need to ponder as I did not find it particularly hard, bright or spitty...again a case of erring on sin's of omission? I'll pay more attention to these points with more extended listening when my frontend is updated. The overall impression the SLA-1 and Danny's DI/O was that I just listened to one CD after another and took off my analytic hat.
As mentioned above, the strength of the amplifier is mostly that of the sins of omission. If the sonic signature of amplifier in due to the first input stage, then op-amp substitution may very well help SLA-1 on the road to getting a fuller and more round orgainic tone. At the same time it is desirable not to upset positive speed, transparency, and dynamic nature of the stock unit. It is entirely possible that a more a "better" opamp in the voltage gain stage might lead lead to less synergy with the bipolar output stage. The AN6554 and the present passives could have easily done a lot worse.
If the issue are in the second stage, hopefully it does not have to deal with supply regulation and that beefing up the supplies can help. In this case, passive swaps of critical caps and gain setting resistors may address some of the weaknesses. The modification section will capture this as a work in progress. ClaudeG...where are you when I need you.
Product Weakness: Unbalanced inputs are 1/4" phone jacks. Stock power cord. Sound may be a little lean. System matching required. Product Strengths: Transparency, speed, and soundstage. Price/Performance ratio
Associated Equipment for this Review: Amplifier: Art SLA-1 Preamplifier (or None if Integrated): None Sources (CDP/Turntable): Modified Art DI/O Speakers: Axiom M22ti Cables/Interconnects: Cardas twin-ax Music Used (Genre/Selections): Jazz, femail vocal Room Size (LxWxH): 15 feet x 20 feet x 10 feet Time Period/Length of Audition: 8 days Other (Power Conditioner etc.): JR unit Type of Audition/Review: Product Owner
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Topic - REVIEW: Applied Research and Technology SLA-1 Amplifier (SS) - PeAK 07:16:38 06/18/03 (11)
- Applied Research and Technology SLA-1 Amplifier (SS) - Jack Seaton 23:44:29 06/23/03 (4)
- Could you be more specific about "surprised" - PeAK 03:27:10 06/24/03 (3)
- Re: Could you be more specific about "surprised" - Jack Seaton 10:47:49 06/28/03 (2)
- Re: Could you be more specific about "surprised" - PeAK 14:13:01 06/29/03 (1)
- Re: Could you be more specific about "surprised" - Jack Seaton 21:59:26 06/29/03 (0)
- (Apologies to Dr. Floyd Toole) This is high-end boilerplate at it's finest >nt< - eric the red 21:55:35 06/22/03 (0)
- Thanks - Great Review :) - RogerJ 05:14:50 06/20/03 (1)
- Re: Thanks - Great Review :) - PeAK 18:53:10 06/23/03 (0)
- Holy.... - Jon L 08:56:43 06/18/03 (2)
- Re: Holy....more info - PeAK 18:03:49 06/18/03 (1)
- I agree - Greg T 06:17:11 06/20/03 (0)