Art MPA v. EH 12AY7

[river]

So really, when someone says that the MPA has a fuller sound, really it's because of the tube used, not necessarily that it's a "better" pre than the EH.

That's part of it, but the design and component quality of the rest of the circuitry matters too. Since the EH is designed to use a 12AY7 (lower gain) it might be wise to ask EH tech support if a 12AX7 is useable, or would it cause distortion or damage downstream from the tube? Tube saturation is one thing, but you don't want to blow up any caps or cook any resistors with excess voltage. Since the MPA (and many other pres) are based on a 12AX7, it's safe to use lower gain tubes, not sure about the other way around.

Like your experience with the MPA's, different tubes in each for different applications, right?

Yup!

[LDT2]

The designer of the EH pre said it's fine to use any 12A_7 tube in the pre for what he called "tube rolling".

I appreciate all your input on this subject.

I just noticed that you're in Nashville, too. Small world.

Lucio

[kayagum]

The designer of the EH pre has posted on the site. Search on "analoghacker", and you'll get all of his posts. As far as tube rolling recipes and caveats, here they are:

one other thing you should all be aware of... you can also "tube roll" with this pre for an added dimension of sonic flavor. provided you have a high impedance input to plug into, you can replace the 12AU7 with any 12A_7 type tube for some interesting changes. you can also replace the 12AY7 with a 12AX7 for a little more gain, a 5751 for a darker color, a 12AT7 for a more "frontal" or direct sound... (punchier but less detailed). mix and match. if you need to drive 600 ohms, forget it... leave the 12AU7 right where it is. i personally like using 2 12AY7s... its more delicate and colorful for airy things. 12AZ7/5965 is also very nice. but don't take it from me... play around with it. you can even put 2 12AU7s in it and use it as a balanced line driver... (lo gain). just make sure the tube you plug in is a 12A_7 type or pin for pin compatible. if you are not sure, don't do it. you'll void your warranty.

http://messageboard.tapeop.com/viewtopi ... &&start=30

[8th_note]

Do you think that maybe the difference you're hearing between the MPA and EH has to do with the tubes used?

I'm sure that has something to do with it but I did an intensive tube swap last weekend and no matter which tubes I tried in the 12AY7 or the Pro Channel I never heard them sound the same, particularly on the bottom end.

If you put the 12AX7 tube into the EH wouldn't it sound more like the MPA?

I tried that and I can't say that that it made the 12AY7 sound more like the Pro Channel, just different from the 12AY7 with the stock tube - at least on acoustic guitar. I know that others here are reporting large sound differences between different tubes but I have to admit that to my ears the differences were pretty subtle. I'm going to try this some more to see if I can hear the degree of difference that others report.

So really, when someone says that the MPA has a fuller sound, really it's because of the tube used, not necessarily that it's a "better" pre than the EH.

This gets into the core of the issue, to me. I have never said that the ART is a "better" pre. It's a little fuller on the bottom end but that doesn't make it better, just different. It's been interesting to see the ART vs. EH discussion progress because I think both are excellent preamps. People may have lots of reasons to choose one over the other but in my experience both sound amazing for their cost.

I feel that this is a great advantage with tube pre's, being that one pre can sound like many, or am I way off here?

I totally agree. I love to tweak stuff so tube pres are right up my alley. You can get several kinds of tubes for under $40 or you can spend $700 on a diamond bottom Telefunken. Knock yourself out.

[LDT2]

8th,

Thanks for the reply info. I guess, like many, I made an assumption that when you said about the fuller bottom that it implied "better", but you're absolutely right, different means different, not better.

I really appreciate all the comparing that you've done. It really helps to have a refference to go by.

Thanks again,

Lucio

[;ivlunsdystf]

Does this MPA make my bottom look too full?

[river]

Yes, you'd better give it to me. I have no butt and need the padding.

[8th_note]

I guess I dig full bottoms, what can I say?

different means different, not better

Exactly. For example, an engineer might choose the 12AY7 precisely because it has a leaner mid bass than the MPA. Perhaps that engineer has been having problems with low frequency buildup (mud) in his or her tracks and wants a pre with a slightly leaner character.