Have you tried the ART SLA-1 amp yet?

d911,
I just visited your website, and would like to ask a question about your reference upgrade. As I understand it, it includes your standard mods, plus dual mono attenuators to replace the stock detented potentiometers. Are these Shallco based attenuators a ladder design or series design?

Thanks in advance,

Sean,

I believe we simply has a difference over nomenclature. By ladder I'm referring to an attenuatior which switches both a single series resistor and a single shunt resistor for each attenuation level. This has a number of benefits in that it minimizes the total number of contacts through which the audio signal passes. It also requires a doubling of the poles/decks used in each attenuator. It also has the benefit of of choosing either a constant input or output impedance, but not both. The ultimate attenuator would be a T configuation which offer both constant input and output impedance.
If I understand you correctly, the shunt configuration you are referring to is a single series resistor and and a variable series shunt configuration, with either a switched series of resistor via a switch or a potentiometer. This offers neither this the constant input impedance of a classic series attenuation. Regardless, I would not dispute that the shunt configuration you suggest is not the 'best' configuration for a given price, and that the the L(adder) or T configuration offers insuffient benefit considering their inherent incremental costs. The SLA purchaser also has the option (given the assumption that the input to the existing pots are driven by an opamp of sufficient drive capabilities), of adding/changing a series resistor and configuring the pots that are there as a variable shunt element. For others who aren't familiar with this, please look at the following thread on diyaudio.com -
http://www.diyaudio.com/forums/showthread.php?s=cc0a06ce413d87f170148c94b6919c22&threadid=2608

If indeed, Mr. Nance is offering a shunt or ladder attenuator, is he providing those same 42 levels of attenuation? Given the cost of Shallco switches, he is either compromising on the type and/or the granularity of the attenuators. I personally, find a attenuator with less than 40 positionss unusable, but many others are content with 12-24 positions.

This would all be moot, if d911 hadn't posted on his site -
"These attenuators are the very best I know how to design and make use of Roderstein MKII resistors".

Notice he did not add - "within the constraints of cost/profit."

If the attenuators are not L or T configuration, I can only conclude that Mr. Nance is not a particularly competent engineer, specifically with regards to what is "...the very best I know how to design...", or that he continues his diengenuous ways....

From d911's website -

"This is the mod that has to be heard to be believed. It is quite extensive and employs new sheet metal, computer grade capacitors huge chokes, 20 amp breakers, Cardas binding posts and RCA's and many more additions."
http://www.dn-audio.com/id11.html

20 amp breaker? This as a replacement for the <=10amp fuse?
Its a truly wonderful idea iff'n you want your insurance company to tell you to take a leap (or look to those deep pockets of DNA Audio) when your house burns down.

Admittedly, a 20amp rocker breaker will replace the switch and existing fuse and offer substantially lower resitance under heavy current draw. But, in any and all countries electrical codes, this is the equivalent of putting a penny in as a replacement for a fuse. So, you put in a 20amp breaker on a device that would typically plugged into 15amp house circut. What exactly is the point?, other than a continuing display of engineering 'expertise', from someone who claims and Electrical Engineering degree?

No doubt, Mr. Nance will now change his website, but I've saved this page on my computer, so I will always have this 'gem'. Truly amazing......

Satfrat,

Indeed, I am Occam over on AudioCircles. But unlike Dandy Don, I only post under one name on each forum. No pudpuppets for me! Please don't misunderstand me, I don't doubt that the SLA, as is, or with a few $hundreds max, at retail from a competent, honest modder (or DIY), is a fine value. But as Sean has so cogently pointed out, the volumetric and transformer constraints would put this product, if one were to spend $500 on modifications, in the realm of 'polishing a turd'.

From d911's website -

"Because the whole is greater than the sum.

ART SLA-1 modification is priced at an INTRODUCTORY USD$500 the normal price for the mod is USD$1,000 due to the cost and level of the material used in the modification process. The introductory pricing is extended through the month of June.
This is the mod that has to be heard to be believed. It is quite extensive and employs new sheet metal, computer grade capacitors huge chokes, 20 amp breakers, Cardas binding posts and RCA's and many more additions."

Golly, we should all act now, lest this $500 bargain slip away. And while we're talking bargains, I live in Brooklyn, and have this bridge to sell, and I'll be raising the price as of July 1st....

I've put up some technical discussion, constrained by the lack of a schematic or actual product, over on audiocircles,here -
http://www.audiocircle.com./circles/viewtopic.php?t=2924&start=0&sid=410f49c91552664b235ff1dc8b000aa7

Regards,
Pmkap, aka Occam

Eric, I post as Occam on AudioCircles and Harmonic Discord, all other boards I post a pmkap. As you can see above, I freely acknowledged this prior to your enquiry here. Discord and Circles are the last boards I joined, and the moniker is a reference to his razor, something I endeavor to wield properly. I've never used any other names and have certainly never engaged in pudpuppeting, that orchestrated 'call and response' between different aliases or between cronies. If you consider my consistent use of two different names, unique/board as sockpuppeting, that is your prerogative. Although Mr. Nance's shenanigans on the offending thread have been exorcised by Audiogon, his exploits on AA are still there for anyone to judge for themselves.
http://db.audioasylum.com/scripts/t.pl?f=tweaks&m=83630

the 'ménage a trois' between d911, audiodilbert and Jack Seaton is truly a marvel to behold.

“Ever hear a version of Will Durant's "To speak Ill of others is a dishonest way of praising ourselves"? Probably not.”

‘ol Will’s of the ‘Story of Philosophy’ ??? You’re right, never heard of him. Why in heaven’s name do you ask a question you already know the answer to?

“You aren't maybe a little jealous of Don Nance at least taking a shot at modding and marketing his modded amps and being the first one out of the gate while all-“

No. I admire tremendously those vendors/modders/hobbyists who provide substantial cost/performance. Mr. Nance, IMO, most definitely does not fall in that category.

“you are left to do is try and get people's attention by posting negative comments about him on audio boards and-“

My intent was that the audiophile community could make their own judgments of both the integrity to which he shows in his exchanges with the public, and the technical expertise and value that he provides in his products. You are free to judge the technical 'exchanges' between Mr. Nance, and myself as you so choose. I would think that some within our community might be interested in both in forming their judgments

“ fascinate everyone at AC with your technical knowledge of the innards of the stock SLA1 are ya? “

As you found my innocuous and obvious comments on the innards of the stock SLA patronizing, I apologize. Perhaps it was a fool’s errand to post such on AudioCircles, and it might well have been more appropriate to pursue such on other, more appropriate, forums.

“Just curious.”

Curiosity is a wonderful trait. Keep it up!

D911, I had assumed in my comments about that ludicrous 20amp breaker, that you are familiar with the time/trip characteristics of circuit breakers. My mistake. In an effort to save both life and property of your unsuspecting potential market, you might consider a small 'refresher'.

http://www.altechcorp.com/HTML/TABLE.HTM

If you'd like to familiarize yourself with other commonly used standards, i.e. AS, BS, dc-34, etc., please do some research, and learn how to properly specify components for their safe, appropriate, and effective use.

You might even attempt to model your super duper enhanced PS. Given that 130w into 4ohms, you really should include the calculated equivalent source resistance of the transformers secondary. Feel free to assume 1milliohm total of esr (residual) for whatever capacitance (COMPUTER GRADE, no less) you choose to put on the rails. Those MASSIVE CHOKES certainly aren't going to increase the current surges. No matter how you slice and dice it, you will find that, indeed, your 20amp circutbreaker is superfluous, the equivalent of a penny for a fuse, serving only as a switch, and to endanger the lives and property of your hapless customers.

You are free to engage in your commerce as you choose (until exorcised), but selling a faulty, dangerous product is ?????.

How can one tell when Mr. Nance is being disingenuous, dishonest, and duplicitous?
His lips are moving or his fingers are typing.

“My unit uses an Airpax breaker switch which I have found to be far superior sonically to the breaker I was once going to use.”

I’m quite pleased that your mod page no longer specifies those ludicrous 20amp breakers, but simply breakers.
http://www.dn-audio.com/id11.html
Respected folks such as Bob Crump have long advocated the use of breakers to replace the switch and fuse. I hope that your new ‘discovery’ of that better sounding breaker is also properly specified so as to not only provide an improvement of subjective audio qualities in addition to preserving the safety function, which is there to protect life and property. Whether this enhancement was facilitated by my comments or is simply an example of the synchronicity of the universe is not germane.

“I think this character thinks he can bait me into telling him about my circuit. He even attempted on Audiocircle to get me to send him my schematic (so that, according to him he could help me). I didn't ask for your help, I don't need your help, I don't want your help.”

There you go again, misinterpreting what was said, and not giving a link to what was actually said. So I will provide the link –
http://www.audiocircle.com./circles/viewtopic.php?t=2982&sid=9dab4c4df79b07e07ed2bad5a854dea0

I had thought it was clear that my response to Donny’s testosterone fueled adolescent challenge to a mod-off, was that before considering such, I would need either a schematic of the stock SLA-1 or a stock unit from which I would derive the schematic. In addition to Mr. Nance’s fine qualities he so amply demonstrates, we can add poor reading comprehension. Mr. Nance’s proclivities are amply demonstrated in another thread –
http://www.audiocircle.com./circles/viewtopic.php?t=2984&sid=9dab4c4df79b07e07ed2bad5a854dea0

“This is the last I am going to comment concerning this character.”

Amen. I will do likewise, assuming you keep your word.