MPX3 and MPX3 Slam.

[Len]

Hmmm. I've found 12SN7 to possess more inherent self-noise. Interesting

But it's really a marginal difference, and 12SN7 is definitely the better value. They're just harder to source, that's all. If ever 12SN7 got popular in commercial designs, their prices will go nutty much faster then 6SN7

Load up on them now.

5687 is not a good 6SN7/12SN7 alternative to my ears. I still use this tube in one application (as a driver in my Audio Note amp), but it's not my preferred signal tube. 7N7 is a nice, cheap tube too, but loctals are yucky

 

[sacd lover]

Quote:

Originally Posted by Len Hmmm. I've found 12SN7 to possess more inherent self-noise. Interesting But it's really a marginal difference, and 12SN7 is definitely the better value. They're just harder to source, that's all. If ever 12SN7 got popular in commercial designs, their prices will go nutty much faster then 6SN7 Load up on them now. 5687 is not a good 6SN7/12SN7 alternative to my ears. I still use this tube in one application (as a driver in my Audio Note amp), but it's not my preferred signal tube. 7N7 is a nice, cheap tube too, but loctals are yucky

Theoretically, the identical tube run at higher voltage/ lower current, used with DC heaters, will have lower noise. It sure sounds that way to me.

Len, you need to hear a 5687 as the cathode followers in one of the Singlepowers. Combined with a good 6sn7 (or one of those yucky loctal 7n7's)

for the gain tube (in the mpx3 circuit) the sound is very 6sn7 like, but faster and more dynamic. You may give up a little sense of space, and the sound moves forward ever so slightly, but the clarity, speed and dynamics are improved. As I said earlier... I wouldnt say the 5687 is a better tube than the 6sn7. But I wouldnt say the 5687 is inferior either. I am sure both tubes will have their share of supporters. I am very pleased with both.


With the ppx3 circuit I definitely like the 5687 better. The 5687 adds back a good deal of the upper treble air and openess missing from using the 3x 6cg7 tube configuration. Furthermore, the ppx3 circuit sounds even more weighty and powerful using the 5687's. I absolutely love this amp for rock and electric blues.

 

[adhoc]

true or false?

as long as i can procure the necessary sockets, i can use 7n7s to replace 6sn7s in any application.

and i'm curious as to why loctal tubes = yucky.

 

[woodcans]

Quote:

Originally Posted by sacd lover I heard this amp at the Ohio Mini-meet..... Oh My!!! He forgot the silver wire upgrade too. I think the silver wire works best with the paper-in-oil caps myself. For an all out version the above mentioned upgrades package is what I would get.

Yes, I forgot to mention the silver wiring, sorry! I think SACD is right on about the differences b/n the mpx3 SLAM & regular mpx3. I think it boils down to personal preference - I find that my amp has enough detail and bass oomph such that I actually prefer the greater sense of 'airiness' / openess of the 6sn7 tubes.

 

[sacd lover]

Quote:

Originally Posted by adhoc true or false? as long as i can procure the necessary sockets, i can use 7n7s to replace 6sn7s in any application. and i'm curious as to why loctal tubes = yucky.

True.. the 7n7 is essentially a loctal base 6sn7. The 7n7 has even lower capacitance and some claim they sound even better than 6sn7's. There isnt, however, much variety in 7n7's with just Sylvania and National Union manufacturing the tube. You have to be careful to get the older and better sounding tubes that are made like the 6sn7gt too. 7n7 tubes made after around 1955-56 went with a 6sn7gtb like plate structure. You will see tung sol, philco, RCA 7n7's... but they were all made by Sylvania from what I can find from my research.

Sometimes loctals get build up on the pins and you need to clean the pins before you can use them. The loctal base is metal and can also rust if they were not stored properly. Mine are all very nice though. I have read some comments these tubes can go noisy too. But I have about 200-300 hours on a pair I am testing out and they have been fine so far. The Sylvania 7n7 is a great sounding tube IMO. This tube in my old chassis mpx3 sounds like the Sylvania vt-231 but has more bass. I am using a Sylvania loctal 7n7 in the gain position of my old mpx3 with two RCA clear glass 6sn7gt's on the outputs right now..... yummy.

 

[sacd lover]

Quote:

Originally Posted by woodcans Yes, I forgot to mention the silver wiring, sorry! I think SACD is right on about the differences b/n the mpx3 SLAM & regular mpx3. I think it boils down to personal preference - I find that my amp has enough detail and bass oomph such that I actually prefer the greater sense of 'airiness' / openess of the 6sn7 tubes.

Your amp was awesome and one of the very best I have ever heard. I am jealous.

Actually what will make me more jealous is the first person that figures out you can wire the 5687 for 6 or 12 volt operation (but not both) and does a 12sn7/5687 x2 combination. That was my original idea. But I didnt want to wait any longer for him to order a 12 volt transformer and do a custom chassis etc. etc... so I did the ppx3 version instead. But then again, I love the ppx3 SLAM so maybe I'm not jealous; just greedy.

 

[Len]

Singlepowers aren't very sensitive to hum or microphony (a good thing

). However, in other applications, 12SN7s are more prone to hum IME.

Ya, I'd love to hear a 5687 in the Slam. I've never found this tube very fast sounding but rather comparitively sluggish and thick when put against the better 6SN7s. It's certainly got more weight and impact, but I like the tonality, air, soundstaging (in speaker systems), and speed of 6SN7s better. Funny thing is as I type this, I have a dozen Tung Sol 5687s in front of me

It's all application-dependent and I'm talking out of context (re: Singlepower amps). I should shut up now

 

[sacd lover]

Quote:

Originally Posted by Len Singlepowers aren't very sensitive to hum or microphony (a good thing ). However, in other applications, 12SN7s are more prone to hum IME. Ya, I'd love to hear a 5687 in the Slam. I've never found this tube very fast sounding but rather comparitively sluggish and thick when put against the better 6SN7s. It's certainly got more weight and impact, but I like the tonality, air, soundstaging (in speaker systems), and speed of 6SN7s better. Funny thing is as I type this, I have a dozen Tung Sol 5687s in front of me It's all application-dependent and I'm talking out of context (re: Singlepower amps). I should shut up now

The 5687 is clean and clear and starts and stops on a dime with a 6cg7 driver; atleast the RCA clear top 6cg7. The tube slows down and becomes more refined and open with a 6sn7 driver, regardless if its the ppx or mpx circuit. I really like the 5687.

I have over 100

so I will be using them more in the future too.

Dont like the 7n7? I really like Sylvania and the National Union gray glass round plate 7n7 is very good too. I need a few more adapters and I will try a NU/ Sylvania 7n7 x2 trio to see how close that gets to my 6/12sn7's.

 

[Len]

I think the 7N7 is a fine tube. I just don't like loctals

Long story ....

You've got enough 5687 to last you three lifetimes!

 

[sacd lover]

Quote:

Originally Posted by Len I think the 7N7 is a fine tube. I just don't like loctals Long story .... You've got enough 5687 to last you three lifetimes!

I like long stories. PM me if you want to.

 

[Len]

Long story short, a 7N7 was the first tube ever to start smoking on me

To this day, I have no idea what happened, but I guess I'm traumatized

It's a yucky, evil tube I tell ya!

 

[sacd lover]

Quote:

Originally Posted by Len Long story short, a 7N7 was the first tube ever to start smoking on me To this day, I have no idea what happened, but I guess I'm traumatized It's a yucky, evil tube I tell ya!

Thats the way I feel about the 12ax7/12au7 and 6dj8/6922. I always have trouble with them

and I just dont like to use them.

 

[BrainFood]

Quote:

Originally Posted by sacd lover The 5687 tubes when combined with a 6sn7 for gain in the mpx3 circuit give you a faster, bouncier more dynamic sound vs an all 6sn7 tube mpx3. Some will like the more laid back and airy all 6sn7 presentation while some will prefer the faster harder hitting 6sn7/5687 combo.

S.L the only trouble is, as clearly as you've explained the differences between the mpx3 in its standard and Slam guises (for which I'm grateful), there's no way to know which I'd prefer before buying, as I live in the UK. Both sound appealing- the bouncy slam 6sn7/5687 combo and the airy 6sn7. That's my only concern.

 

[e_dawg]

Don't forget the MPX3-6CG7 version as another alternative. The tubes are pretty cheap and they generally sound very good. The 6CG7, after all, is electrically the same as the 6SN7. The gold standard 6CG7 tubes, the RCA Cleartops, can be found everywhere and are only ~$10 per tube. If you want a little more speed and detail, you can put an RCA black plate as the gain tube and have Cleartops as the outputs. If you want more bass and weight, put a GE as the gain tube.

 

[woodcans]

Quote:

Originally Posted by BrainFood S.L the only trouble is, as clearly as you've explained the differences between the mpx3 in its standard and Slam guises (for which I'm grateful), there's no way to know which I'd prefer before buying, as I live in the UK. Both sound appealing- the bouncy slam 6sn7/5687 combo and the airy 6sn7. That's my only concern.

The bad news is, you're right, you won't be able to know for sure unless you listen to both. The good news is, they both sound fantastic and you'll more than likely be thrilled with either version.

A couple of things to consider. What are the characteristics of your other components? I'm using a DAC1 which is a quick and detailed dac and I think the qualities of my amp balance it out very nicely. If you use a source on the warm side of things, maybe the slam would balance out your source? Just a thought.

Also, how much do you have budgeted for tubes? I find that a great deal of enjoyment comes from tuberolling and if you can go for a few sets of 6sn7s, great! But if you only have a little left to spend on tubes, the slam would also be a consideration. But then this brings up the dilemma of the 12 volt regular mpx3.....

Overall, either way, you'll be getting a great amp and you really can't go wrong.