Have you tried the ART SLA-1 amp yet?

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......

Pmkap, you wouldn`t be related in any way to Occam over on Audiocircle would you? You two seem to talk the same talk, makes one wonder if you walk the same walk? I`ll be really curious to hear D911`s answers to inquiring questions, like your ever going to have Dandy Don do any modding for you. LMAO Regards, Robin

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

Pmkap or Occam or whoever you post as on all the other boards (Why use different names on audio boards but that's really not sockpuppeting now is it??): Ever hear a version of Will Durant's "To speak Ill of others is a dishonest way of praising ourselves"? Probably not. 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 you are left to do is try and get people's attention by posting negative comments about him on audio boards and fascinate everyone at AC with your technical knowledge of the innards of the stock SLA1 are ya? Just curious.