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MP-3 DIY tweaking - possibility, resources? (long)

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Posted on May 2, 2006 at 03:20:09
gordan
Audiophile

Posts: 434
Location: Belgrade Serbia
Joined: July 9, 2005
Hi, being new to this forum I was wondering if I could get some help from you avid users of Atma-sphere devices.

I have an offer for an early spec MP-3 with phono for around 1.300$. I am seriously considering purchasing it as I can't live anymore with Krell KAV 250p. The speakers are active (studio version) ATC 20A. They are great, extremely neutral, with amazing dynamic possibilites for such a small box (20liters) but can be very dry and lean if not correctly matched. They need a neutral, relaxed but slighly fuller partner. So the most common recommendation is either Ayre models or some better tube preamps.

The problem with MP-3 offerred to me is that it is an early model without any of the later upgrades that helped it gain such a good reputation. On the top I am based in Europe so the whole action with sending the preamp to the factory and back would set me a fortune and in that case I would definitely look for something else.

What I am wondering is if there are known resources on the net related to MP-3 tweaking, as precise as possible. Among local audiophiles here, there are several very good tube tweakers and technicians and I am pretty confident they would be able to implement anything that is not a rocket science. But it would be much easier to follow the known and proved steps.

I am also wondering what are the most essential upgrades that are by any means obligatory to perform immediatelly? I guess it must be power regulations, also hows about teflon caps, do they really work?

Also are there schematics for MP-3 available?

The next issue is tube lufe - as it has 11 of them, it makes it rather expensive to change them so i am wondering how often it is needed. In my home music playes 24/7. I can't remember when did I switched off my current system for the last time.

Last but not least, the common rave about MP-3 is its phono section. On contrary I seldomly use phono and I am wondering if its line sections is of similar quality (as you may hear different thoughts here)...

I know this is long, I apologize, but you can see that these are all pretty serious issues for someone who lives pretty far from the States, without much possibilities of using a good customer support.

Kind regards

Gordan

 

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Re: MP-3 DIY tweaking - possibility, resources? (long), posted on May 2, 2006 at 06:42:17
Legendre
Audiophile

Posts: 503
Location: Saint Paul
Joined: October 22, 2004
Of all of our products, the MP-3 has probably changed the least over its production life. Most of the update/upgrade work is fairly straightforward, and should not be a problem for someone with general electronics experience. Depending on when it was built, there may be a number of fairly subtle changes to be made.

The only exception here is the addition of the HV regulators - this job is non-trivial, and requires a lot of cut & rework on the board. I've seen supposedly 'expert' individuals screw this job up.

If you can get back to me with the MP-3's serial number, or even better, a nice hi-res color photo of the internals, I can tell you the current state of the unit. $1300 is a very good price, and I'd think twice about letting it slip.

About the linestage / phono stage thing.. think of it this way: If the linestage didn't work very well, you'd probably never hear anything good about the phono, either.. difficult to have the latter without the former.

 

Re: MP-3 DIY tweaking - possibility, resources? (long), posted on May 2, 2006 at 07:05:21
gordan
Audiophile

Posts: 434
Location: Belgrade Serbia
Joined: July 9, 2005
Thanks a lot, Legendre.

I will let you know the serial no as soon as I get it, the same goes for pics. I'll send you a private e-mail.

I am wondering about benefits of the regulators you mentioned. If this can't be done otherwise than by an Atma-sphere qualified person (and I can't send the preamp over to the States) does a lack of them really spoils the fun?

What is an average tube life?

 

Re: MP-3 tube life, posted on May 2, 2006 at 08:30:44
Ralph
Manufacturer

Posts: 3209
Location: Minnesota
Joined: April 24, 2002
Contributor
  Since:
April 1, 2002
The line section tubes last a very long time- if you run the preamp 24/7 they will go over a year with ease.

The phono tubes do not last as long- as they fade they become noisy. 24/7 operation will kill them in about 5 months. But if you are not using the phono, I would remove the rear 4 12AT7s (you need some of them in place, even though you are not using them).

If you do decide to use the phono the good news is that the 12AT7 is inexpensive.

Since you have been used to a transistor preamp, you have also been used to running the preamp all the time. You don't need to do this with the MP-3 or MP-1. Especially if equipped with Teflon caps and the regulators, the MP-3 will 'warm up' in a surprisingly short time 30-45 minutes.

 

Re: MP-3 tube life, posted on May 2, 2006 at 13:37:17
gordan
Audiophile

Posts: 434
Location: Belgrade Serbia
Joined: July 9, 2005
OK this will force me to learn to switch off the preamp. I think my poor Marantz hasn't been switched off for last 10 years, except when I renovated my flat. Krell is still pretty fresh but it hasn't been off ever since it is here.

What are the usual prices for new tubes that do a good job in MP-3? Am I wrong that I read somewhere it doesn't like NOS tubes as they can't stand its heavy load?

 

Re: MP-3 tube life, posted on May 2, 2006 at 14:13:22
Ralph
Manufacturer

Posts: 3209
Location: Minnesota
Joined: April 24, 2002
Contributor
  Since:
April 1, 2002
NOS tubes work fine, except that we've not seen any quiet enough for the phono section in 10 years at least, so we don't recommend NOS 12AT7s as a result. The stock 12AT7s in good shape are much quieter and they are inexpensive.

There are all kinds of NOS tubes that can be used in the line section and the prices are all over the map! I prefer to use the stock tubes and spend the extra cash on more LPs...

 

Re: MP-3 tube life, posted on February 11, 2017 at 06:34:13
MP
Audiophile

Posts: 10
Joined: July 2, 2001
Ralph,

I am taking a short break from vinyl. Which four 12at7 in MP-3 phono stage should I remove, of I only use line stage? Thanks. Ming

 

Re: MP-3 tube life, posted on February 11, 2017 at 06:47:36
MP
Audiophile

Posts: 10
Joined: July 2, 2001
Figure out with trial and error. Thanks.

 

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