Looking for feedback on any members who did do the upgrades on this preamp. Looking to improve the Phono stage and linestage, whether an upgrade on resistors would be the best for this preamp.
I think you should PM Audiogon member Pstores. He has a lot of firsthand info on Atma's. Of course, calling Ralph(-Atmasphere) directly would provide the most accurate info.
When I had Ralph build my MP-1, I had them install V Caps (as per Pstores advice). Bob
I have Both Pre-amps, Plus the UV1. I have owned a number of many other Pre-amps. VAC, VTL, Accuphase, Audio Research, MC, Jardis,Etc etc.
The MP-1 by far is the best I have had, mine is fully optioned with all possibly upgrade. Once you have dialled the pre-amp in with the quiet Tubes (Stay away from NOS) you will never bother looking at another pre-amp regardless of cost or technology used.
The MP-3 Fully optioned is not far behind but obviously no match either.
@zipost , My MP-1 doesn't have the Caddock resistors. Though I have to say is holds it's own against an Ayre KX-R. So, when moneys become available, I will upgrade the KX-R to Twenty status and the MP-1 to include the Caddock resistors-and any other upgrades Ralph might recommend. Bob
according to the manufacture they stated JJ for the preamp section (6sn7) and for the phono section they recommend the Shugan from China. Anyone with accurate info. let me know?
It's not too steep when you consider those resistors are not your run of the mill Caddock. They are manufactured to Ralph's specifications for optimal performance in the preamplifier. Fiven what people pay for an MP-1 to begin with what's another $2400.
Thank you, I know Ralph doesn't recommend NOS for the 12AT7 phono sections and he uses Shuguang as the stock tube which BTW is excellent.Fort the preamp he supplies Shuguang brown base which are good, I have NOS Sylvanias 6SN7GTBs on mine and found it to be an apparent improvement. I mixed the stock tubes with 2x CV181-Z, Shuguang Black Treasures and did not like the results, on my previous MP-3 these same tubes were very good but the MP-3 needs only 2 and the MP-1 6 of these.
according to the manufacture they stated JJ for the preamp section
(6sn7) and for the phono section they recommend the Shugan from China.
Anyone with accurate info.
This is correct. With any high performance product using tubes, the tubes have to be hand-picked. NOS 12AT7s that are quiet enough to work in a phono section capable of working with LOMC cartridges disappeared long ago. I'm not saying you can't find some, but they are very hard to find these days. So new tubes have to be used and the Chinese 12AT7 has the lowest rejection rate.
Spoke with Ralph, he wants $2400 for both the preamp section and phono
with caddock upgrades. I think that just too steep for Caddock
resistors!
@zipost , @clio09 is correct, the Caddock resistors we use are not stocked by Caddock and have to be built per custom order. They are pricey! But they are also the best we've heard, and one of the best performing resistors you can buy. Vishay now owns Caddock, but has wisely chosen not to mess with them in any way, since Vishay has never made anything with their name on it that performs as well.
NOS 12AT7s that are quiet enough to work in a phono section capable of
working with LOMC cartridges disappeared long ago. I'm not saying you
can't find some, but they are very hard to find these days
For the record, on the 12AT7's comment Ralph, I have Raytheons and Westinghouse NOS, Shuguang's the Z version new production. After measuring these tubes on my B&K 707 tube tester the "readings" are not comparable to your stock Shuguang's, the ones you supplied with your amp are 120 on the tester scale, the NOS I have are usually at 40-50 and the Shuguang's Z version (new production) are on the 90's So yeah I second your comment that finding a good 12AT7 older production would be challenging and even the new production chinese tubes won't measure "as well" as your stock ones.Someone people needs to understand, when China (Shuguang, PSVane) produces tubes their QC separates these tubes and distribute and prices these accordingly so even new the same tube you will find it for a very wide price range, "on average basis" the more expensive tubes will be better, my point is I am positive your source for your stock tubes must not be "cheap" (hence the high readings) and the product is better than purchasing directly from China from other sources. And this comment applies also I think to the Caddock resistors you use, like you mentioned special order.
The problem lies not with the 12AT7 tubes it lies with the Atma-sphere and its gain. When you have old stock 12AT7s that will work with 99 out of 100 preamps with the single odd guy being the Atma-sphere...guess what is to blame? I have nothing but the highest respect for Ralph and Atma-sphere but I think that blaming old stock tubes is nonsense and noise at least with the older MP-1s was a real problem.
Now it makes sense that when Ralph designed this piece he would use new production tubes not old stock and I think this is likely the case.
@audition__audio , Interesting comment. Can you provide an explanation to explain the reason why Atma amps are improperly designed? Are you a tube amp designer? B
too many tubes on the phono section (10 tubes total ), no way it can handle .20v low mc, even when the manufacture claims that it has a total of 78db gain, both chassis are the flimsiest designs, the power supply parts are from surplus ( not a single caps & resistors that are quality built in the power supply section). the silks screen letters would fade after many use. That in all equal to very noisy preamp!
Oh boy! I didnt say they were improperly designed I simply said that they have very high gain. Also I was addressing the preamp not the amps. I have a pair of MA-1 amps on order as I write this so obviously I dont have a problem with Ralph's products I just think he is taking the easy way out with this explanation. Of course if you dont own the MP1 or havent heard it you really should probably take the 5th.
too many tubes on the phono section (10 tubes total ), no way it can handle .20v low mc, even when the manufacture claims that it has a total of 78db gain, both chassis are the flimsiest designs, the power supply parts are from surplus ( not a single caps & resistors that are quality built in the power supply section). the silks screen letters would fade after many use. That in all equal to very noisy preamp!
We run cartridges of that output routinely at shows and of course with customers. The main reason the tube count is high in the phono is that there are three 12AT7s in the front end of each phono section that are in parallel for lower noise and greater ability to drive the cathodes of the 12AT7 with which they are in a differential cascode circuit. This give the input circuit quite a lot of gain with low noise. These days any high end preamp has to work with 0.2mV cartridges. The equalization is passive and executed differentially; the losses of that are made up by the following gain stage. So that’s 5 tubes per channel.
The MP-1 chassis is made of 1/8" aluminum. The side panels are 1/4" machined aluminum. They hold together quite well- we’ve been shipping nationally with either UPS or FedEx ground and internationally for over 35 years; you can have an alright shipping container but when shipping like that, the chassis design has to be robust, especially when going overseas. You can’t have it coming back because a chassis fell apart or got tweaked, and none of them have.
There are no screens on the boards; the text is etched. The boards have a mil-spec ’conformal coating’ to prevent damage from corrosion or moisture.
Most of the resistors used were made custom for us- if not by Caddock, then by Vishay (Draloric). We purchase the filter capacitors in the power supplies from a variety of vendors such as Mouser and DigiKey- to my knowledge none of them are selling surplus parts. The power transformers are all custom built to our spec; we were recently issued a patent for our use of the transformers. Because of their proprietary nature they certainly can’t be sourced surplus!
When you have old stock 12AT7s that will work with 99 out of 100 preamps with the single odd guy being the Atma-sphere...guess what is to blame? I have nothing but the highest respect for Ralph and Atma-sphere but I think that blaming old stock tubes is nonsense and noise at least with the older MP-1s was a real problem.
The problem we’re up against is that we’re using the preamp with really low output cartridges without the help of either an SUT or solid state input circuits- its all-tube. To do that you simply need low noise tubes. I agree that many of the NOS 12AT7s that we can’t use will work fine in other preamps but those preamps can’t take a LOMC cartridge in directly while being all-tube. However my insistence for low noise tubes really only applies to the input tubes- the 3 in the rear of each channel. The remaining two tubes in each channel can be NOS as they are less noise sensitive. Its also true that in the older preamps this was a more serious issue- to make them work the first two input tubes had to be low noise. We changed that up a bit when the Mk3.3 was introduced 5 years ago.
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