ARC LS15: did they ever use Mundorf MCaps on it ?

the topic is all in the question.
I saw a used LS15 and it has M-Caps instead of REL or InfiniCaps; it is for sale by a dealer who says he's sure that his client bought it new and that this man told him he made no repairs or so apart from changing the tubes.

do you know of LS15 with stock M-Caps ??
Yet another one of those "minty" condition units.
Tell the seller to take a breath mint.
I eat a lot of mints but I have never misrepresented a product willingly, perhaps unwitingly, but not knowingly. I also refrain from words like new and mint, which are truly BS in most cases. BUT..... I guess it really depends on how you define mint and the rest. etc. etc.
Send it in to ARC for a check up. ARC will never send anything back out with mods. So when you get it back you will know.. If the caps stay, they were stock. If changed then mods.
Your freight and $ for the checkup easily exceeds the used price of the pre
Mundorf Mcap supreme may not be better than Infinicap type S.
silver gold oil is a different story. Most important is to get rid of the cheap bandaid .01uf bypass cap at the output if ever there's a mod attempt and you are using a premium cap there.
There were two versions of the LS15. The second version had different caps, an improved power supply, and a replaceable power cord. I had my original LS15 upgraded by ARC to the later version, except for the power cord. Don't remember the name of the caps though.
If you go to the ARC Database. The LS15 pictured has Infinicaps.
If you are truly interested in buying this preamp your best solution is to have the seller send it to Audio Research to be checked out. Once Audio Research has given it their approval they can forward the preamp to you after you have paid the seller. I have done this several times with great success. It relieves the seller of liability and the buyer knows he is getting a unit that is working properly.
ARC usually will replace ANY modifications back to stock.
I do not think they will work on a unit which is modified unless the owner wants it returned to total stock.
Just so you know.
And they certainy charge for the service.
so, the answer is: no, ARC never used Mundorfs on LS15, as I thought.
I am in Europe, and as some said I'd better buy an LS25 or some Ref than send the LS15 to USA and back, paying ARC's intervention in the middle... ;)
"ARC will never send anything back out with mods."

Some years ago they repaired my PH-2 containing numerous DIY cap substitutions. My caps were left in place.

Personally I wouldn't worry about the Mundorf Supreme substitution. IOW of today there are better caps available than either of these.

ClarityCap OEM Sales
OP says M-caps not M Supreme if I recall correctly.
As we can see there are several members here who belong to the school of die hard "keep it stock". I respect that but I personally am a "respect the mods as long as its done right (get close up pics), as long as you research the sonic character as the components replaced."
the key words are "as long as it's done right".
I cannot check in any way if it's done right at some thounsands km from the seller; and if the seller says he did not modifiy anything and I just 'caught' him, he may lie on many other things, maybe not so easy to see...

Moreover, I'd like to know how the original ARC design sounds; then I may even want to improve or change something in time, but firse I need to know the starting point.

Last, I don't have the chance of listening to the LS15 (neither stock nor modded) before buying, so I may not like it: I don't know how it works in USA, but in that case in Italy it would be very, very, very difficult to resell a modded object. I should almost give it away for free (well, ok, it's an hyperbole, but I guess you got it).

That's why I'm looking for an original preamp. :)
Close up photos will reveal workmanship of the mods.
If lack of reference point (you dont have friends who have a stock/similar unit) and resale value is an issue where you are then stick with a verifiably stock unit.
The LS15 is not that expensive. By the time you send it to Audio Research for check and retube and stuff you might as well pay a premium and buy a stock unit.
To my knowledge Audio Research never used Mundorf caps in production. They used Rel,Infini and MIT in older units. Hope that helps.
I would always choose a Mundorf Cap'd unit compared to a stock one.
yes, but for me not before listening to the stock one (that's a personal opinion, obviously); and then again, I would neet to be sure about who and how worked on the preamp.
moreover, as I already said, if a seller lies on one self evident fact, he may lie on anything...
anyway, in the end I decided to let the LS15 go... now I saw a pair of LS16 (one mkI and one mkII); see related thread :-D

but most people tell me that neither an LS15 nor an LS16 (regardless of mk) would be a significant upgrade for me.
most people tell me to go for an LS22 or LS25 or, at least, LS17.
they may be sure right, but that takes 1000 euros more...
I think I have to think it over for a while.
"the key words are "as long as it's done right"."

It was done right when it left the Audio Reseasrch factory. Have you ever seen the facility at Audio Research? If you did you would never trust some guy in his garage or little shop with no real knowledge and no equipment to speak of other than a soldering gun. As far as I am concerned these guys are shysters just looking for a way to make a buck by leading you to believe they are going to enhance the sound of your already excellent sounding equipment.
Rrog, Do you work for Audio Research or sell their gear? Please kindly reconsider your comment.
You may be stereotyping a whole lot of well respected boutique component manufacturers who work with honest and knowledgeable modders out there.
Johnsonwu.....Amen with last post.

To the OP, If it has a GNSC badge on it no worries. Steve Huntley's (and his team) workmanship was without fault. He used premium parts as well IE; Vcaps, Vishay, Caddock, and others. I had many units modded by him including (but not limited to): REF3 LE, REF2 Phono, Classic 120's, DAC7 with astonishing sonic results.
Actually, when you look inside a REF5 SE and REF2 Phono SE you can clearly see some of Steve's signature work that i have in my units particularly the power supply upgrade.

.......and to the modder detractors, the launch of ARC was orchestrated by one of the most renowned modder of its time pre 1970.... William Z. Johnson.

Yes, a modded unit's resale value would typically be less than stock although i have sold a few ARC GNSC modded units at premium prizes over the years. There is a niche market for modded units including ARC's.
No, unfortunately it was not modded by GNSC: that would have been a different matter, indeed.
I know people, even here in Italy, who are very able at modifying electronics and I would trust them; Huntley is world famous and he would sure be one of them (btw: is he out of business ? I think I've read something about it).
But that 15... no one knows who put his hands in it.
Anyway, now that's past. :-)

Thanks again to you all.
Good luck with the ls16 bid
GNSC is no longer in business.
HifiGeek, you have all my respect for your knowledge of Audio Research gear. If I recall correctly you are one of their official off-factory repair depots. I sincerely hope you dont view GNSC's cease of operations as a one less competitor. Huntleys mods are expensive. But for many of us it sure beats paying big $$ for trade arounds.
Thanks for your wishes, but meanwhile several people tell me that even the LS16 would not be that great improvement over my LS7 and suggest me to go straight for a 22 or a 25 without caring for the... numbers in between (14,15, 16, maybe even 17).
wow ! confusion !
anyway, I guess I'll take some time to think it over and make up my mind.
thank you all.
Best of luck to the OP.
If you like the Audio Research sound, not to mention their great support (we here are spoilt by the excellent support from Leonard in the past and now Kalvin), then perhaps saving some $$ and jumping up to the reference series will save a lot of $$ lost in incremental trade ups.
LS22 / LS25 are balanced design. Do you use balanced cables from source to power amp to take advantage of that?
Yes they will work with SE source and power amps connected with RCA but yo uwouldnt be taking advantage of the design.
They are very dynamic sounding but overall not my cup of tea.
Both versions of the LS15 sound different than the other, the LS25 and LS25ll are also different. They all have different sounds, not simply better or worse. None are worth buying without a listen.
Johnsonwu yes I am one of Steve's official repair depots. I've known Steve for a very long time. He is a friend. I also do mods but we never 'competed' for business. We all have our niches.
Most important is to get rid of the cheap bandaid .01uf bypass cap at the output if ever there's a mod attempt and you are using a premium cap there.

Do you recommend replacing the cheap .01uf bypass cap with a premium cap or just leave it out?
Just my own personal un/non-professional opinion but based on my experience with modding a few Audio Research units.
Take out the whole output cap/0.01uF bypass combo, replace with 2.2 or 2.7uF Mundorf Silver Gold Oil or VCap TFTF. No need for 0.01uF bypass. The bypass caps are a bandaid for a less than optimal main output cap.
@Ketchup check out arcdb for the schematics of your line stage. Very easy inexpensive mod. If you put a scope right at the input of the regulator to look at the raw B+ you will see why I recommended a choke.