Which tubes for Art MPA Gold upgrade?

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dickiefunk

dickiefunk

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Which tubes would you recommend I get for my ART MPA Gold?

I would like something that would give me a fuller and warmer sound with a smoother top end.

I've read that the Mullard 12AT7 is quite popular. Is there any other tubes that would be more appropiate for what I'm after?

Thanks
 
Just about anything will be an improvement over what ships in the unit. I notice you're in the UK - does that mean you live close to an electronics shop run by some close-to-retirement guy who doesn't post on the internet and has whole bunch of new-old-stock Mullard "valves" on hand? If so, or something close, then get a bunch and try them out (and send me some! :D).

I currently have old GE 12AT7s in mine, and I think it sounds pretty good in the manner you describe.
 
I hope I'm not hijacking but I have the a similar question. I heard mullard is the king but I got some Mesa engineering pre amp tubes since that's only thing my local Guitar Center had. Should I return them and stick with the Chinese tubes and use my money to by Mullards or are they a good enough upgrade to keep until getting Mullards down the line.
 
Lazaro said:
I hope I'm not hijacking but I have the a similar question. I heard mullard is the king but I got some Mesa engineering pre amp tubes since that's only thing my local Guitar Center had. Should I return them and stick with the Chinese tubes and use my money to by Mullards or are they a good enough upgrade to keep until getting Mullards down the line.
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chances are that the mesa ones are either chinese or russian, just that they are tested to be within mesas specs for their guitar amps.

i have the Jan 5751s from www.kcanostubes.com in my MPA Gold and i like them very much
 
Thanks for the replies so far!

Any other suggestions?

Also, how much difference would upgrading the tube make?
 
The MPA Gold and Digital MPA do include one or more solid state gain stages (two per channel, I think), no doubt about it -- the opamps they use are good, which is nice. The tube stage is a real gain stage, and can be run at about 300V plate voltage, which is in anybody's range for actually using the tubes in the proper way.

... the ART, which is far removed from any conventional tube preamp.
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- certainly true

It would not be accurate to even call this a "tube amp". It's a solid-state amplifier
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- misleading, I think, certainly it does have solid state amplification, and so you could accurately call it a solid state amplifier, and it's certainly not a "tube amp" in the conventional sense, but strictly, I'd argue that it is a tube amp because it uses a tube for amplification purposes.

with a tube-based harmonic distortion circuit.
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Here's where I lose him -- ART and other companies do make "starved plate design" preamps, like the ART Tube MP family, and those certainly fit that description -- they are disdainfully called "toob" preamps by many. I've got a couple of them, and I don't use them for much. But as I mentioned, the MPA Gold / Digital MPA actually use the tube at high voltage for gain, so I think this is off the mark. I'm not dissing this guy by any means, and I'm sure he knows a lot more in this area than I do, but I've seen plenty of knowledgeable folks conflate these two designs prior to hands-on investigation. I bet this drives ART crazy -- they're sort of responsible for it, by becoming the de facto standard "toob" vendor. Anyway, search this board here, and you'll find defenses of the MPA made by folks who have plenty-strong technical backgrounds in this area.

BTW, to be complete, I should have noted that I use 12AT7 not because I think that's the best tube model for the job, but rather because the NOS ones are in plentiful supply for me. I'd definitely be trying other models (like 6072a or 12AY7 or 12AX7) if I had two NOS ones that were about the same -- it's important to me to have both channels sounding similar -- but I don't. Among the old 12AT7s that I have, some are noisy and not suitable, I should add.
 
dickiefunk said:
I though the ART MPA Gold was a proper tube preamp!?

According to this it is a starved plate design :eek::confused:

http://forum.cakewalk.com/tm.asp?m=1543560
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only if you have the voltage switch in the low position. also keep in mind that a lot of people speed read forums or just don't read anything but the subject and end up posting things about the MPA Gold thinking that you are talking about the Tube MP. most of these types don't even seem to know that the MPA Gold exists
 
Monkey Allen said:
Check out this discussion about the Gold:

http://forum.cakewalk.com/tm.asp?m=1543560

Seems there is some debate over the legitimacy of the ART MPA Gold's tube claims...

(You have to read about half to three quarters down)
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Well, I think they are kinda confused about tubes, honestly. The engineering analysis is fine, but let's step back a minute. They seem to say the goal of a tube is to increase even-order harmonic distortion. Then they criticize the circuit for running at +150V (I have measured higher, however, so the schemo might not be 100% accurate). Then they criticize the circuit for using feedback. Hmmm.

First off, it's incorrect to say that 12AX7 was not designed to run at +150V. That's just plain false, and reading the datasheet will illustrate that. In fact, the datasheet I have (Sylvania) specifies operation at +100V and +250V, with +300V the maximum.

You probably do get an increase in linearity as you increase plate voltage, but I don't know how much.

Next, let's consider the goal of a tube in a design. If the only goal is to increase even-order harmonic distortion, you should go straight to starved-plate at +45V, which ART uses in their other designs. The failing of those designs is not the tube--it generates pretty good sounding harmonic distortion just fine (well, after a tube swap)--but the surrounding solid state stages sound horrible when they are clipped.

OK, so if you use +300V, you likely have a little less THD than at +150V. But either way, you'd have a LOT less than at +45V. If anybody on that thread had measured THD of the ART, they would know that. I have done this often myself.

Now that we have set aside the primary goal of a tube design to be harmonic distortion, it seems straightforward to design a circuit that minimizes such distortion. Indeed, you will often hear that the goal of a "real" tube mic preamp is not to generate distortion, but to minimize it, with the goal of realizing very high headroom. This is usually a statement made to denigrate starved-plate designs.

Now the ART, as noted, will still be restricted by the headroom of its +/-15V supply to its following opamps. So there is definitely a small range between where the tube (on high plate) starts to generate THD, and where the opamps clip. But I would argue the preamp was not designed to operate in that range. In fact, the VU meter set on tube is supposed to be used to help avoid that.

This can actually be a somewhat clean preamp, and is best that way. There are tubes in it, they run at +150V (or higher), those are the extent of ART's tube claims. You are free to buy a Brick if you want a "real" tube pre. Mind its input noise though.
 
Personally, I would gravitate towards something like a GE, Sylvania or Telefunken in a preamp. Then again tastes do vary. Mullards are generally very colorful tubes that play nicely with thickening up many guitar amps. Telefunkens however are a little more "hifi" sounding and often play nicely in more accurate type equipment. GE's and Sylvania's often fall between them all.

On another note, feel free to PM when you figure out what you want. I have bunches of each of those tubes for sale:)
 
I've got a Mullard 4024 in one channel and a Jan Phillips 12AT7WC in the other. The Jan is a bit cleaner, but both make me happy.
 
xstatic said:
Personally, I would gravitate towards something like a GE, Sylvania or Telefunken in a preamp. Then again tastes do vary. Mullards are generally very colorful tubes that play nicely with thickening up many guitar amps. Telefunkens however are a little more "hifi" sounding and often play nicely in more accurate type equipment. GE's and Sylvania's often fall between them all.
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I've tried a variety of vintage tubes, not any of the sexy stuff, because I am a cheap, cheap man :o I agree that I've found GE to be the most reliably clean and consistent, and that's what I have in my DMPA.

I have on old Lafayette tube, dunno what that is a rebrand of, but that thing is righteous in a guitar amp :cool:
 
I'm interested in at least having some other tubes to try out in my Gold.

btw...I'm 'montezuma' over at the Cakewalk forum.

So...xstatic...I think I will pm you about what you can do for me.

I will mainly be recording acoustic guitar and vocals. I suppose a cleaner sounding tube is better for acoustic guitar, though I am just as likely to be incorrect about that.
 
Thanks for the info. Would I be right in saying that the MPA Gold isn't a starved plate design as these normally run at around 45volts?
 
MsHilarious.... That LaFayette could be a Mullard. It gets a little tricky identifying some of the older and/or off brand but I think I actually have a couple of Mullard made Lafayette tubes. Does it say what county the tube was made in? That is often one of the best indicators.

As for the MPA of topic here, this is what I have noticed about some of the different tubes. Keep in mind of course these are fairly broad generalizations, but generally fairly accurate. On the more affordable side, the GE tubes seem to be pretty even keeled. They are built well, and tend to not affect the overall sound too much. Kind of non flattering, but in a neutral and not bad way. When compared with current issue tubes I find the GE's still sound much better than anything on todays market. The Sylvania's tend to have a little more focused low end that is sometimes viewed as thinnner, but has more punch. The highs also seem to be pretty extended and exhibit a good harmonic structure, but when compared with other vintage tubes are sometimes considered harsh. The Amperex Bugle boy tubes have a very thick and classic sound. Highly sought after for guitar amps, but maybe not so useful in recording gear. Good thick low end, smooth glassy highs, and very rich mids. The Mullards are similar to the Amperex's in tonal quality but tend to have an even more pronounced mid and a bigger low. The RCA tubes seem to vary a little more through the different builds, but generally have a smooth unobtrusive high end, and a looser but rich sounding low and low mid. The Telefunkens in my opinion are the ones that really differ the most. The Telefunkens seem much cleaner and more dimensional to me. In guitar amps the Telefunkens can almost make it sound like the amp isn't there and you really hear more guitar itself. Some people love this in guitar amps, where many others don't like it at all. In recording gear though, this is where I think they really shine. As a preamp tube I feel like they offer more depthe and dimension, and it seems like they almost offer a wider frequency range. They can still be pushed like other tubes, but they just have a bigger wider sound to me which as a recording preamp almost almost seems better to me.
 
Thanks for the info, very helpful!

I was thinking of getting one channel of Mullard 12AT7 and the other Telefunken.

Which Telefunken tubes would you recommend?

I haven't opened the MPA up yet. Do I need two tubes per channel?
 
dickiefunk said:
I haven't opened the MPA up yet. Do I need two tubes per channel?
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One tube per channel -- just rotate and remove the aluminum sleeves to expose the tubes. First thing I did was grab a screwdriver, which was totally unnecessary (after removing the top of the unit, of course)
 
xstatic said:
As for the MPA of topic here, this is what I have noticed about some of the different tubes. Keep in mind of course these are fairly broad generalizations, but generally fairly accurate. On the more affordable side, the GE tubes seem to be pretty even keeled. They are built well, and tend to not affect the overall sound too much. Kind of non flattering, but in a neutral and not bad way. When compared with current issue tubes I find the GE's still sound much better than anything on todays market. The Sylvania's tend to have a little more focused low end that is sometimes viewed as thinnner, but has more punch. The highs also seem to be pretty extended and exhibit a good harmonic structure, but when compared with other vintage tubes are sometimes considered harsh. The Amperex Bugle boy tubes have a very thick and classic sound. Highly sought after for guitar amps, but maybe not so useful in recording gear. Good thick low end, smooth glassy highs, and very rich mids. The Mullards are similar to the Amperex's in tonal quality but tend to have an even more pronounced mid and a bigger low. The RCA tubes seem to vary a little more through the different builds, but generally have a smooth unobtrusive high end, and a looser but rich sounding low and low mid. The Telefunkens in my opinion are the ones that really differ the most. The Telefunkens seem much cleaner and more dimensional to me. In guitar amps the Telefunkens can almost make it sound like the amp isn't there and you really hear more guitar itself. Some people love this in guitar amps, where many others don't like it at all. In recording gear though, this is where I think they really shine. As a preamp tube I feel like they offer more depthe and dimension, and it seems like they almost offer a wider frequency range. They can still be pushed like other tubes, but they just have a bigger wider sound to me which as a recording preamp almost almost seems better to me.
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...WOW...if you can hear those differences in specific tube brands in an inexpensive tube pre like the ART, I want some of "what you're smokin'" (no disrespect intended)...especially when you consider that almost any of those NOS brands were manufactured by multiple plants here and in Europe (RCA and Sylvania tubes were manufactured in USA, Germany, Holland, England, etc.) and were subject to all variations of storage environments and handling over the years...
...you also left out Siemens, one of the highest regarded manufacturers of audio tubes, and a source manufacturer for many of the other "brands"...even Telefunkens were not all made by Telefunken...in my experience using tubes in mic pres and microphones, each tube (even of the same design and manufacturer) imparts it's own particular character, but outside of the crappiest of Chinese and Russian tubes, the variation is ever so slight...I've even purchased expensive "matched pairs" from reliable tube dealers and found the two tubes "sounded" somewhat slightly different...no doubt, purchasing good quality NOS tubes will improve the sound when compared to the stock Chinese/Russian tubes, but what exactly you'll hear beyond that is, IMHO, just that..."what YOU will hear"...highly subjective at best...
...other than that, I have found that tube "character" is more easily discernable when utilized in guitar amp circuits...there the sound is more easily described as you have posted, but in an inexpensive tube mic preamp or inexpensive tube microphone, I believe you'd be hard pressed to make such distinct differentiations...just my .02c...;)

...that said, I have found the GE 5-Star 6072 (high-grade 12AY7) to be the best of the "12 series" tubes for audio application...can be substituted in any of the 12AT7, 12AX7, 12AU7, 12AY7 applications...particularly good in tube mics of Chinese origin...when replacing 6DJ8 tubes (as in the Rode NTK and K2) the Siemens and Amperex gold-pinned ECC88/6922 seem to be some of the best (also found as RCA made in Germany/Holland gold-pinned 6DJ8)...
 
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