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POSITIVE FEEDBACK ONLINE - ISSUE 14
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Our readers respond…we respond right back!

Send your comments to either drobinson@positive-feedback.com or dclark@positive-feedback.com

 

To the Editor,
In David Robinson's review of Walker Vivid CD treatment, Audience Auric Illuminator (AI) is not mentioned as one of the CD playback enhancement products that David has found useful. I suspect many will interpret this silence as implying that David has not found AI to be useful. An alternative explanation might be that David has no experience with AI. I would appreciate clarification on this question.

I ask about AI because this is a product I am familiar with. One could very well ask the same question with regard to Optrix, or any other popular product which Vivid is competing with. Other than being a satisfied customer, I have no relationship whatsoever with Audience.

Thank you,

Henry
St. Paul, MN

Hello Henry...
No, my silence on the subject of alternatives was not disapproval (arguments from silence are always tricky!); I listed my other current references (JENA Labs Esoteric Mist and Record Research Labs Shine-OLA) in my article.

I have no personal experience with Audience's Auric Illuminator, though Dave Clark has, mentioning it in PFO Issue One (see http://www.positive-feedback.com/Issue1/auric.htm). Nor am I familiar with Optrix.

I can therefore offer no comparisons to the products you mention, Henry. I can say that I was extremely pleased to find a treatment that finally allowed me to bid farewell to my old friend, Esoteric Mist.

Hope this clarifies the context of the review for you.

All the best,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com

Hi David
 "... a number of sprays, goos, compounds, polishes, and compounds have been touted by a number of audio manufacturers..."

"Long-time readers know that I have tried a number of digital treatments and enhancements over many years now."

"But there is good news. I've finally found a replacement for my much-lamented, departing Esoteric Mist: Walker Audio's ViViD SACD/DVD/CD Enhancer."

I believe that any reader would take away form the above that: you are very familiar with the products out there, and that none other than Vivid has proven to be a suitable alternative to the no longer available Esoteric Mist. This does a disservice to widely used, and reputable, products such as Optrix and Auric Illuminator (both of which, by the way have, been endorsed elsewhere by Bob Neill). This damning by innuendo of other products may well have been unintentional, but it does, I am sorry to say,
cast doubt on your commitment to fairness and full disclosure.

"You really owe it to yourself to give Vivid a try; with a 30 day money-back guarantee and no evidence of problems with any SACDs that I applied Vivid to, I'd say that you have nothing to lose."

Well... one may well have something to lose.  One may miss out on a product which is as (or more) effective, less costly, and easier to apply than Vivid. Please notice that I said "may."

With best wishes,
Henry

We'll have to agree to disagree on this, Henry.

My review did not claim to be "exhaustive"; it merely gave a double-thumbs up to a product that compared very favorably with what I did have recent experience with... and think very highly of... and clearly identified in my review.

That your particular favorites weren't covered in my review... though they have been covered favorably by both Dave Clark and, as you point out, by Bob Neill... is neither here nor there. What you took away from the review ("...none other than Vivid", etc.) is neither logical nor legitimate, I think, since no attempt was made to do an exhaustive profile of "all" digital enhancement treatments, nor did I represent it as such.

Was I enthusiastic? You bet!

Do I have to try "everything" before I become enthusiastic? Nope!

Else, no one would be able to enthuse about anything without experiencing everything, an untenable position in my view.

One "may" (as you note) have something to lose... but only if you were displeased by the results and didn't get a refund. This allows you to try it against your favorites products, and see what "you" think, eh?

All the best,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com


David,
I have jus received a Xindak SACD2 player. I purchased it in part due to your reviewers favorable comments.

I can reiterate Bob's comments.

1. The SACD2 refuses to play 5.1 SACDs such as Norah Jones' Come Away with me.  You get a message saying "UNDISK".

2. In addition The SACD2 does not play Copy controlled CDs such as Norah Jones' Feels Like Home or Alicia Keys The diary of Alicia Keys.

What is really annoying is that whilst it will not play the originals of these it will play my neighbors computer CD-R copies and even worse my neighbor copied my copy of Alicia Keys' album and the Xindak will play his copy of my original but not my original!!!!!  It would appear that the copy controllers are encouraging us to go out and copy their copy-controlled disks!!

I have written to Xindak to ask whether they have a firmware/software fix for this.

Other that that, the player sounds excellent.

By the way, whilst we are on the subject of Chinese built hi-fi, how about you guys asking Daniel at DK Design Group for a review sample of their DK-VS1 that I am a proud owner of and I think that at the $3000 retail price (I got mine for a third of this price!) is a bargain, rivaling my neighbor's Krell integrated and even the Mark Levinson integrated.

Regards
Raymon Moonilall

Hello Raymon...
Thanks for sending in this report from the field. I have the Norah Jones SACD, and have never had problems with it in either the EMM Labs/Philips SACD 1000, the Linn Unidisk 1.1, or my modded Sony SCD-1.

"Copy-control" schemes are a real headache: they don't stop the determined, sophisticated hacker, but they gum up the works for legitimate users in a world filled with shifting standards and new platforms. The phrase "pain in the ass" comes to mind.

My suspicion is that this problem should be fixable via firmware upgrade. Let us know what Xindak has to say on the subject, and we'll publish the results for the good of our readers, Raymon.

I don't know that we have any contacts with the DK Design Group. If they get in touch with us, I'm sure we would be able to arrange a review.

Thanks for the useful report.

All the best,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com


Hi Dave!
One question: It seems that I have seen along your pages an ultrasonic record cleaner but I cannot retrace the page. If  am right could you tell me who the manufacturer is and all the available information regarding this tool.

Thank you for your answer.

Cheers!
Patrick

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Bent Audio's site is http://www.bentaudio.com. According to their product page, the NYL Ultrasonic is still not in production. We were promised a review sample, but haven't heard a peep from anyone since VSAC.

Perhaps you can email them, and roust them out, eh? It's certainly an interesting concept....

All the best,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com


Mr. Robinson
I was just wondering if you have any early opinions on Richard's fully modified player? I know you have a review upcoming but i am curious as to any early thoughts.

Thanks
Dave Smith

Hello Dave...
I do have a review in the works on Richard Kern's mods to the Sony SCD-777ES, though it isn't for one that is "fully modified." There's a list of what was done to this player that will accompany the review; you'll see that many things were done, but Richard could have done more.

In a nutshell, Richard's work on the review 777ES has completely transformed it from the stock sound of that unit, a sound that I know pretty well. From the darker presentation of the stock model, the modded player is now well-extended, more spacious, and more cleanly detailed, with very good image depth.

Details will be forthcoming....

Best wishes to you on your audio journey,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com


Dear Positive Feedback Online,
I turn to you with great confidence with the following question. What cartridge upgrade do you advise? 

Currently I'm using a Benz MC Gold in my Rega P25 with Orbit PSU on a wall mount shelf. The phono pre-amp is a Electrocompaniet ECP-1; the pre-amp is an Electrocompaniet 4.6; the power-amp an Electrocompaniet AW 100 DMB. My speakers are Magnepan MG12QRSE; the cable is Nordost Solarwind.

Although I'm rather happy with the MC Gold, some female voices produce a harsh sound when pushed hard. For example Kari Bremnes' Norwegian Mood sounds terrific. But when the lady delivers some volume, things go wrong. Due to the fact that Rega has no adjustable VTA, and I'm not willing to use their spacers, I need to know what cartridges fit splendidly in the RB600 and will allow me to forget my MC Gold easily?

Many thanks in advance for your kind reply. 

Best regards,
Roy Jennen 

Roy's question was sent to two of PFO's very experienced turntable users Jennifer Crock and Mike Lavigne. Their responses follow…

[Jennifer Crock]

I am at a loss as to what to suggest, Roy, other than any cartridge with an elliptical stylus, and NEVER one with a Shibata (TM) or other straight-line-edge stylus geometry.

VTA is such a basic adjustment that is necessary for all the higher end phono cartridges. This is a function of the geometry of the side of the actual tiny diamond that traces in the sharp-cut V-shaped side walls of the 'groove.' Most of the higher end cartridges use a diamond shaped and polished with straight sides, which more accurately resembles the V shape of the cutter used to make the master lacquer from which the records are eventually produced. By closely resembling the shape of the tool used to make the original groove, you can more accurately follow the true shape of the groove for improved reproduction of the recording. Unfortunately, if the straight edge of the reproducing cartridge tip is not PERFECTLY aligned with the undulations in the groove, a lot of distortion can result. This is why VTA adjustment is so darn important... and why, ideally, you need to be able to adjust VTA on each record! The less expensive cartridges often use an easier [cheaper] to make diamond profile that has an elliptical curve side shape. This shape is far more forgiving of VTA angle, although it is not as ultimately resolving as the Shibata (TM) style tips. I would suggest strongly that for any arm that has no VTA adjustment, difficult VTA adjustment, or for someone not wishing to be bothered with making VTA adjustments, that ONLY a cartridge with an elliptical stylus be considered. It will tend to produce a more pleasing reproduction with the widest range of records. Whether you go with MC (moving coil) or MM (moving magnet) will depend on the pre-amp gain available in your system. MM has higher output for less sensitive phono sections; MC generally produces superior sound, but at the cost of lower signal output and noticeably higher prices. Elliptical styli can be found in both types of cartridges.

In recent times my only experience has been with very expensive MC cartridges that are inappropriate for this application, so I can offer you no suggestion of specific brands or models with which I would have direct experience.

Regards,
Jennifer Crock 

[Mike Lavigne]

Hi Roy,
Congrats on a nice system... it should make some great music.

Before you consider another cartridge, I think you need to find out the true source of your problem. The Benz MC Gold should not sound harsh if it is working correctly and the rest of your vinyl playback gear is also set-up properly. In addition, the Benz cartridges are usually not dramatically affected by VTA...their 'sweet spot' for VTA is pretty wide. The Electrocompaniet gear is not inherently harsh, and not likely the cause.

Typically, VTA will not cause 'harsh sound' or cause 'things (to) go bad'.

Too high VTA ('too high' meaning the rear of the arm is a good deal higher than the front) can cause the highs to get 'splashy' or a little 'edgy'... but high VTA won't typically cause the distortion you are indicating. It is difficult to know the degree of harshness you are describing. If it is severe then VTA is not likely the cause... if it is slight you might be right. Your comment that things 'get bad' at high volume of female vocals indicate that your cartridge is 'jumping' in the groove at higher modulated spots. 

Roy, I don't know your level of turntable set-up experience, so forgive me if I get too basic here. There are a few different things to consider before determining that your cartridge is your problem. 

1. VTF (Vertical Tracking Force):  Tracking force is a much more likely cause of distortion than tracking angle; and tracking force influences tracking angle. Distortion like you describe would likely be the result of too little tracking force. Try adding a 10th of a gram at a time to see how that affects things. As you add more weight you will also be raising the back of the arm (as the cantilever is more compressed by more weight) so these issues are interactive. As you add more weigh the stylus will have less tendency to 'jump' in the groove, which is what is likely causing the distortion. 

2. Cartridge Resonance:  Sometimes a cartridge will have a resonance at a particular frequency that results in distortion. I don't think this is happening here. But to check this you might try to attach something to the headshell that would absorb resonance... such as 'Bluetac' or a putty of some sort. This will add mass to the arm and require VTF adjustment... but if you can't find another cure, it is easy to try. Also, make sure your cartridge and arm are securely attached and not loose. I have chased problems assuming some deep mysterious cause... when just tightening something simple fixed the problem. Consider the basics first! 

3. Cleaning/maintenance:  Is the stylus clean? Is the record 'reasonably' clean? Is the record too worn to hold together on the highs? I know these are likely all OK, but I just want you to be sure on these points. 

4. Turntable isolation and the rack system:  Normally, I would consider the rack that the turntable is on as a potential problem... but a wall rack will eliminate most feedback or footfall issues. 

5. Cartridge/phono amp compatibility:  There is a slight possibility of a cartridge/phono stage incompatibility that would contribute to your problem... but not likely to the degree you are describing. I am not specifically familiar with this Benz cartridge or the Electrocompaniet ECP-1 as far as set-up choices of phono loading and gain. 

6. Turntable mat:  If this distortion is minimal, it might make sense to try some sort of turntable mat. There are a few different brands that are of varying thicknesses. Adding a mat will easily raise the record and lower the VTA. Remember, using a mat will also likely change the tonal characteristics of the sound (which you may or may not like). You could even experiment with paper and use different amounts of paper to see how different thicknesses affect the distortion. 

If you are looking for a good excuse to upgrade your cartridge to a better one (we've all been THERE), I am not your best source for 'next step' cartridges at the price point right above where you are. I do like the various versions of the Benz Ruby. I own a Koetsu RSP II. Both of these are great on female vocals and reduce the likelihood of ANY edginess... but... I strongly recommend that you optimize your current cartridge first, so that you will know where you are now and what the source of the problem is. Otherwise, you could go to the expense and bother of an upgrade and still have the problem that your old turntable system had. 

I hope this helps a little. Maybe others have some thoughts as far as good steps up from your Benz MC. 

Best regards,
Mike LaVigne


Editor,
A warm thank you to Jeff Parks for the fine informative review of the Audio Research VT100 MKIII amplifier. I do have a couple of questions for Jeff since I own the earlier MKII version of this amplifier:

In the sidebar listing of your system it states that you have both the Svetlana 6550s and the KT88 power tubes. Assuming that you have tried both of these tube types in your VT100, could you comment on any differences  in the sound of the MKIII attributed by either of these tubes? I found that substituting Russian Electro Harmonic KT88s for the stock Audio Research 6550s has improved the sound of my VT100 MKII in several key areas.

Also were you able to directly compare the older MKII version of the VT100 with your MKIII in your system? If so would you be kind enough to share your impressions between the two? I have hesitated to upgrade my MKII to the MKIII as some say the MKII is a sweeter sounding amplifier, despite the MKIII having better bass.

Thanks,
Bob Fosse

Bob,
Hi! Thanks for your kind comments. I did have a chance to listen to the VT-100MKII, but it was several years ago. So, to tell you the differences between the two amplifiers that would be hard to do bearing in mind the amount of time that has elapsed. But, in short the MKIII is more neutral sounding with a better more defined bass as compared to the MKII which can be a little lush sounding as compared to the MKIII.

As far as comparing the Genalex KT-88s v ARC stock Sevtlana 6550Cs, overall, I found the 6550 not having as much impact with the deep bass and were not as detailed in the high end as compared to the Genalex KT-88. But, on the other hand there were times where I found the stock 6550Cs very musical and a joy to listen to. So, as usual there are always trade offs. Yes, the Genalex KT-88s in my opinion do have more bass definition and a more detailed high end as compared to the stock ARC Sevtlana 6550Cs. But, at $2200 for two matched quads for the Genalexes not a lot of people are going to go for that. You can get 90% of the Genalex KT-88 sound from the less expensive JJ KT-88s. You can get these from http://www.tubesandmore.com. Just be very careful when biasing these tubes. Should be no problem when going from 6550 to KT-88.  But, if you are going to KT-88 to 6550 I would turn the bias down considerably or you may blow up you 6550s especially if they are near the end of their useful life and slowly bring them up to stock suggested specs. How do I know this? It happened to me. So, please be careful. You may even want to ask for help and advice from ARC if you are not so sure as to how to bias the VT-100MKII or MKIII using tubes other than stock. ARC has shared me many a story of people causing damage to their ARC amplifiers through using possible unstable or poorly matched 6550 or KT-88 tubes. Ask for Chris Osuna—he's a great guy and should be very helpful.

Hope that helps.

Take care,
Jeff


The following is in response to the article by Dan Baquer, Brickwall Digital Filters and Phase Deviations in Digital Audio

My view is both twofold and predictable:

1) Since amelioratives (OK, tweaks) such as vibration isolation, damping, CD cleaning and decoulombizing make significant sonic differences (OK, improvements), these must also be reflected in the measurements. If they're not, then the measurements are misbegotten and results become moot. It's a well-known fact of science that we only measure what we already know about.

2) Is phase shift audible? That would seem to be an operative consideration, but one does not see it in the referenced article. Moreover, with so many people insensitive to 180 degrees of phase shift, who cares about less? (OK, I'm being rhetorical.)

Clark Johnsen

In regards to Dan Banquer's article, it's pretty hard to argue with the scope images—and I don't. In fact I rather agree with everything he states. Witness some of the early uses of the Bessler filter, especially in the Muse 2+ DAC which still sounds pretty good to this day.

My experience with so called "filter-less" designs in CD players has been uniformly unpleasant. I find the sound to be flat, lifeless, and uninteresting. I would also contend the same is true of "non-over sampling" units which tend to display exactly the same traits. Even worse, CD players that combine a lack of brickwall filter and no oversampling are some of the worse sounding audio equipment I have encountered.

I disagree with many that feel oversampling is bad. I have compared many CD players and DACs side by side and always choose the oversampling model as a better all around presentation. You can easily compare for yourself in units like Cary's 306 where you can turn the oversampling off and on through the remote.

All that being said I do believe there is some room for improvement in the brickwall designs currently used. I would like to see the cutoff extended out a bit more to maybe 25 or 26KHzcloser to the super tweeter range as I feel there may be some lost "psycho-audio" information there. Of course this is all my opinion based solely on anecdotal experience but I commend Dan for putting his “scope” where his mouth is.

Going further, I would even suggest that the real controversy may lay in the amount of distortion required in the playback medium. Is less distortion really good? Perhaps music having originated and been "born" in an analog environment of rooms, halls, and amphitheaters really consists of the sound of musical instruments AND noise as the total ingredients traveling through incredibly varying atmospheres of air and to reproduce this realistically has not yet been accomplished because we spend too much effort on getting just the instruments right.

Ed Morawski

Hi Dave;
I have interesting links that Ed Morawski might be interested in reading that may answer his comments about distortion in the playback medium. All of the links provided below can be found at the Audioholics.com web site. I would also recommend to all to visit Chris Tham's web site; she's doing some excellent work. http://users.bigpond.net.au/christie/

Dynamic Comparison of CD, DVD-A & SACD - Diana Krall's The Look of Love

http://www.audioholics.com/techtips/specsformats/DynamicComparisonp1.php

Dynamic Comparison of CD, DVD-A & SACD - Diana Krall's The Look of Love Part 2

http://www.audioholics.com/techtips/specsformats/DVD-ASACDCD-compareiip1.php  Dynamic Comparison of CD, DVD-A & SACD - Diana Krall's The Look of Love Part 3

http://www.audioholics.com/techtips/specsformats/DVD-A_vs_SACD_digitalaudio.php
Current Trends in the Recording Format Arena - Part I

http://www.audioholics.com/techtips/specsformats/CurrentFormatTrends.php

To Ed Morawski and all: I think if you take the time to read the above links, you will realize that a good part of the "distortion" produced on so many of the CD's out today was never part of the performance, it was a rather deliberate  addition by members of the "Louder is Better" crowd.

To all Positive Feedback Readers: Join us in the fight to make people aware of this and demand better

Dan Banquer
www.redesignsaudio.com


Hi David,
Are you using the switchman 3 as your preamp nowadays? I'd sure like to get your impression of it. I have one integrated into a mulitichannel music and HT system with a CTC Blowtorch, and my system has become unwieldy, to say the least. I'm considering how to simplify, and getting rid of the Blowtorch, getting rid of the Switchman and switching to a Cretron controllable system are all options.

Thanks,
David Shapiro

Hello David...
Yes, I've been using the EMM Labs Switchman-3 ever since completing the Linn Kontrol preamp review project. It will be the subject of a major review in the near future.

The short and sweet version: the Switchman-3 is one of the very finest preamps that I've ever heard. I'd put in in the top three, for sure.

  • Keyword: TRANSPARENCY.

  • Terrific gain... no pain!

  • Four inputs... great!

  • Balanced on two; balanced/unbalanced on one; unbalanced on one. Balanced or unbalanced on out; I've used both, and prefer the balanced...but either is very fine.

  • DEAD silent.

  • No bad habits, not one single operational failure.

  • Handles both 2 and 6 channel operation easily,

The wired remote is a dream to operate, assuming that you can live without wireless, and has some very fine, pro-grade features. (Unfortunately, phase inversion is NOT one of them.)

Details later when I publish the review, but I'm already at the point that I would recommend the Switchman-3 m/c preamp unequivocally as a world-beater. This is one stereo/multichannel preamp that you could retire with.

Best wishes to you on your audio journey,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com


David
Question on the wavac he-833. How hot do they run? .... do they significantly raise the temperature of your room? ... can you listen/bear the heat in summer? ..... is AC a must? ....by the way, I really love your reviews and dream about getting a Wavac-Kharma-EMM Labs system.

Robert

Hello Robert...

Sorry for the laggardly response, but I just got back from vacation. To answer your questions briefly, in order of appearance:

1. The HE-833's do run warm, but not unacceptably so in an air-conditioned environment with good ventilation and decent cubic capacity. (See our "Meet the Staff" page for my room dimensions.) Summer time will definitely be the test, but I never reached the point at which the WAVAC was not used due to ambient temperature. My room never got warmer than 75-80 degrees, but some people don't like those temperatures...and when I added more people, the temperature was probably more like 82-84 degrees. Your mileage may vary, of course.

2. See above.

3. See above... but I had no problems in the summer, and my listening room faces south.

4. AC is ALWAYS a good idea in a listening room. Without it, any big tube amp will be more of a challenge than it needs to be, and summer-time listening may become iffy, depending on the neck of the woods that you live in.

Thanks for the compliment...glad to hear that you enjoy the reviews. The WAVAC/Kharma/EMM Labs combination is a real match made in heaven...that's for sure.

All the best to you on your audio journey,

All the best,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com 


Editor
I was interested in the piece by Jeff Priluck on vintage gear. I still have many 78s - mostly jazz from the 20s & 30s, a Thorens TD-124 with SME arm to play them, and I would love to locate a phono stage with complete equalization curves and filters, especially the Owl 1 Restoration Module, a mono phono stage which had it all. The only ones I have encountered that are new designs are too expensive to justify for the old 78s, or they are old units, such as the Mac C-8 mono preamp which is priced for Asian collectors. I look forward to more on this stuff.

Gardiner McCauley


Dear Sirs
I'm not sure what thrift stores Robert was doing his shopping (see
Foolproof Ways to Buy Excellent LPs), but apparently he has atrocious luck. I'll leave him to his sealed reissue LPs and sealed, newly recorded LPs and continue bottom feeding and scoring great LPs at rock-bottom prices. Yeah, occasionally I'll splurge for new vinyl or reissued vinyl, but more often than not, the records are warped, off center, or noisy. At least I can look at the condition of vinyl before I purchase the used stuff!

Derek van Veen
Seattle, WA


The following are in response to a post on AudioAsylum regarding the new column on vintage gear by Jeff Priluck, DMD (see Vintage Hi-Fi: Basking in the Glow of Vacuum Tubes)

Sir
A post on AA's Vintage Forum alerted me to the thread about vintage gear reviews. IMO, such a series would be badly incomplete if the H/K Citation II was omitted.

A Jim McShane refurbed Cit. 2 kicks SERIOUS BUTT. I have the good fortune to own 1. Bring on an ARC or CJ of equivalent power. I've got a strong hunch that the current stuff is in for a "whupping".

FWIW, my amp was a VSAC 2001. Ask the attendees what they thought.

Eli D.

Dave
I have long thought that amplifier sound and performance is little changed from the Golden Era. To me the real gains have come from parts quality rather than design or manufacturing advances. A case in point would be a rebuilt ST-70. With the parts available now, it is possible to make the amp sound better than when it was new.

With that in mind how about reviews of relatively common vintage amps such as:

Heath W-4 / 5; Pilot 232; Eico HF-22/35/50/60 HF-86-87-89; Fisher SA-100/300-55a-30a; 500c. 

You get the idea. 

In order to make the comparisons/reviews valid, I would propose that the amps should be restored to original operating condition-but with average rather than boutique parts.

If comparisons are to be made, please keep relative cost in mind. A restored pr of Heath W-5 would cost ~$500-600; no sense comparing it to a new CJ MV-55 for example. Comparing to a NAD or Rotel on the other hand would be more valid.

Whatever form the vintage reviews take, I for one will be an interested reader !

Best Regards,
Ross Lipman


Dear David,
Having read of your vast experience with SET amplifiers and your glowing  review of the Wavac HE-833, I wondered if you might be able to help me make an amplifier upgrade decision. Congratulations on a very informative and entertaining article, by the way.

I use new Sound Lab A-1 speakers and I would like to pair them with a high-powered SET amp. The speakers are 88dB efficient and the impedance swings from 2 ohms to 40ohms(?) at the lowest frequencies.

I am able to purchase a used pair of Wavac HE-833 for a decent price (that is still about twice my planned budget) or a used pair of Viva Aurora Ts  for about half the price of the Wavacs (or, just a little over my budget).

Ideally I would buy the Vivas now and then think of moving to the Wavacs after saving up some money. The problem with that is that I may never find used Wavacs for a reasonable price.

Have you had a chance to hear the Aurora's? Have you had a chance to hear either with full-range electrostatic speakers?

I appreciate the fact that you must be very busy and don't have time to answer these type of emails but I would be very thankful for any feedback/advice that you could give me.

Best Regards,
Dave Hagelaar

Hello Dave...
Well, I don't know that I would say that my SET experience is "vast," but it has been varied and I've gotten to hear a pretty fair amount of SET kit over the years. As I said, my experience with the WAVAC HE-833's certainly hefted the bar to a higher level... that's for sure.

It's been a few years since I've heard the A-1's; my old audiobud Pat Hickman had a pair that I heard from time to time over at his place. They are on the downslope side of the efficiency curve; 87dB/Watt/meter and below is where is put the zone for "inefficient." I haven't seen an impedance curve on these puppies in so many years that I couldn't what it was; 2 Ohms at the low end sounds about right. That 40 Ohms figure looks strange... don't think so on that one, but would have to see a curve.

As to the amp question: I haven't heard the Aurora T's, so can't comment on the sound of that device.

However, this is an area that specifications *can* help us with, especially when I'm familiar with the speakers in question.

The Viva web site (http://www.artigianinet.com/vivaaudio/vivaaudio2.html) claims the following for the Aurora T's:

AURORA T

Our finest amplifiers.
Difficult speaker loads and complex music materials tax the ability of common single ended amplifiers.
We overcome these obstacles by providing a very stiff, but fast power supply that responds effortlessly to the most demanding music, even if your speakers are not typically friendly to single ended amplifiers.

The Aurora power supply begins with our custom wound mains and filament transformers. Two directly heated triode tubes perform the rectification for the 845 power tube. This configuration allows the characteristics of musical purity (offered only by directly heated triodes) to be maintained throughout the amplification chain. Mil-spec paper-in-oil filter capacitors and precision wirewound resistors ensure reliability and correct balance.

We use a very high quality input transformer in the Aurora. This allows a pure single ended input as well as a true fully balanced input to match with most preamplifiers.
As with our other electronics, we offer the Aurora in many colors of the rainbow

Specs.

*Single Ended 30W Power Amplifier
*Directly Heated Triodes
*Zero Negative Feedback
*Pure Class A Operation

Based on the specs immediately above, I'm pretty confident about saying that an 845 SET with 30 Watts of output is going to be (sorely) taxed by the A-1s. I owned a pair of the excellent deHavilland Aries 845-G's, amps that I have reviewed as the best 845 amps I've ever had in my listening room. After their upgrade by deHavilland, they were pushing 36 Watts per channel. I had them paired with my Nova Rendition II's, also at 88dB/W/m (but better behaved on the impedance swing); I can tell you that they definitely preferred higher efficiency speakers, like, say the Kharma Grande Ceramiques at 93db/W/m. The Bel Canto SET-80's (paired 845's at about 75 Watts per channel) were a much better match with the Nova's with their preferred threshold of 100 Watts per channel. Enormously better on the Nova Rendition I's (the predecessor to the Rendition II's) was the 200 Watts per channel of the Graaf GM-200 OTLs.

Either the Manley Snappers (push-pull) or the Joule Electra Marquis Mk. III (OTL) at 100 WPC also do quite well at 88dB/W/m.

The WAVAC HE-833s' 100 WPC of SET were simply imperial.

So I guess that I'd say that the load and behavior of the A-1s...like most big full-range 'stat panels, trickier than their dynamic cousins...really require a lot more ooomph than you're going to find at 30 WPC, regardless of how well put together the amp might be. I don't think that you'll be happy with the performance... I know that I wouldn't be.

You'll need 100 WPC (or more) to get the best out of the A-1's. If you can stretch to afford the WAVACs, then I'd do so, unquestionably. Used copies of these amps must be rare; this is the first that I've heard of one.

If you simply can't afford the WAVACs, and are wed to the A-1s, then I'd look at some of the higher horsepower alternatives. Manley, Joule Electra (be careful on the OTLs here... the A-1's dip pretty low on impedance!), Audio Research, Cary Audio Design, Wavestream, VAC, Conrad-Johnson, Rogue Audio and others have more affordable, higher power models that would make the A-1's sit up and take notice without breaking the bank. I'd stay away from anything that didn't have 100 WPC, regardless...and more is better in that regard.

Your only other alternative is to consider changing to different speakers, I think.

I hope this helps you in your decision, Dave...for what it's worth, eh?

All the best,

david 
Editor-in-Chief, Positive Feedback Online
drobinson@positive-feedback.com 

 

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