[Carlos3]

Is there anything is the 6SN7 family that can't be used in the MPX3?

 

[Habib]

I've been using all 3 Sylvania VT-231s in my MPX3 for the past couple days now. While the clarity and resolution improved, bass didn't. I would describe the overal sound characteristic as neutral, transparent, and musical. Problem right now is with the Sylvanias, the MPX3 is great for jazz and classical but not so great for hiphop and rock. I am wondering if TS as gain tube will take care of my problem. Just something to make it bring out more of the bass. Then agian the TS are rare and expensive...

 

[Carlos3]

Quote:

Originally posted by Habib I've been using all 3 Sylvania VT-231s in my MPX3 for the past couple days now. While the clarity and resolution improved, bass didn't. I would describe the overal sound characteristic as neutral, transparent, and musical. Problem right now is with the Sylvanias, the MPX3 is great for jazz and classical but not so great for hiphop and rock. I am wondering if TS as gain tube will take care of my problem. Just something to make it bring out more of the bass. Then agian the TS are rare and expensive...

Try one of the stock Electro-Harmonix tubes in the gain position, and leave the Sylvanias in the driver positions.

 

[tom hankins]

Or you can try One KenRad VT-231 in the right spot and the other two the sylvanias and get ready to boggie. This is a really nice combo. Also the Kenrads are fairly common and not that much money.

 

[Hirsch]

Quote:

Originally posted by tom hankins Or you can try One KenRad VT-231 in the right spot and the other two the sylvanias and get ready to boggie. This is a really nice combo. Also the Kenrads are fairly common and not that much money.

He's right. The Ken-Rad in front of Sylvania's is another great combo.

I suspect that part of my preference for Ken-Rads/Tung Sols in the gain position may have to do with the R10. Those tubes give the R10 the jolt in the low end it really needs.

 

[bobjew]

Don't know about the Ken Rads and TS's yet, but every tube I've tried has become less impactful in the Bass as they burn -in.

 

[bobjew]

Hi all:
Got my one Ken Rad yesterday and put it into the MPX3 with two Sylvanias in the output spots. It was nice, with a nice mid and good hf detail, but wasn't what I expected from this combination. The bass seemed weak and inarticulate. I thought maybe the tube was defective or bad in some way. Oh well, maybe try some other combinations. Next, I got the brilliant idea to try a trio of three different tube types, so I stuck the Ken Rad into the left output, left a Sylvania in the right output and a Hytron as the gain. The reasoning being that if two different types were mostly complimentary then three can have even more possibility of some amazing synergy between them. I guess tubes don't repond to reason, because even though whole thing didn't spark and blow up, there was nothing great there. There actually seemed to be a subtractive effect going on where much of the good stuff of the different types are being neutralized or taken away.
Well here it is, third time was a charm. Revisited the stock EH's. Yes, I have forgotten how good these are. In the MPX3, they are the most dynamic with very fine Bass. The upper mid and hf are on the harsh side. I wanted to try the Ken Rad again just to see if it was really broken. The KR came alive! It wasn't broken and everything sounds glorious. The best roll yet. The Bass is additive to the already very good Bass of the EH's. Very big, tight, dynamic and detailed Bass that gets into Blockhead territory. Really, no exaggeration. Tried it with the Mickey Hart "Dafos" CD. Now it seems all there and "right" because everything else seemed to fall into place as well. It's got the great soundstage, nice mids, nice detailed, smooth and extended highs, great air and transparency up and down the line.
Why didn't the two VT-231's and KR combo work for me? I think because it's a MPX3 and not the Supra– there are differences.

 

[Dusty Chalk]

Quote:

Originally posted by bobjew Next, I got the brilliant idea to try a trio of three different tube types...

I'm not sure, but I think this is a bad idea, because: I think the two "power tube" positions represent the left and right channels, and should be matched.

Could be wrong here, someone verify please.

 

[bobjew]

DC:
I totally agree!

 

[Carlos3]

Yeah, middle and left tubes are the separate right and left channels. Need to be matched tubes.

 

[bobjew]

Just another idea:
I'm done tube rolling for now, but I bet there is a combination of three different tubes that would synergize together. The reason is that like eyesight, our two ears probably aren't equal and don't hear alike. I bet it would be spectacular to tube roll for each ear. I don't know if there would be an electronic limitation.

 

[immtbiker]

I see Bobjew's point. I had Lazik done on my eyes, and being that I'm nearing the age to need glasses for reading, the doctor made one eye 20/15 (for distance), and the other 20/50 (for reading without magnification or longer arms). The brain takes the average of both eyes and uses which one it needs to domiminate the need, and it works.
I'm sure that most peoples ears to not have the same exact capacity for hearing, and even though the 2 left tubes aren't for gain, the musical tastes maybe adjusted through the use of different tubes. I'm not sure if this causes complications with any feedback circuitry, though.

 

[Dusty Chalk]

Quote:

Originally posted by bobjew Just another idea: I'm done tube rolling for now, but I bet there is a combination of three different tubes that would synergize together. The reason is that like eyesight, our two ears probably aren't equal and don't hear alike. I bet it would be spectacular to tube roll for each ear. I don't know if there would be an electronic limitation.

An interesting thought. Sort of the aural equivalent of astigmatism? I guess...

 

[Carlos3]

Quote:

Originally posted by Carlos3 Yeah, middle and left tubes are the separate right and left channels. Need to be matched tubes.

Actually I'm going to take this back.

I'm not sure that I understand the parallel single ended topology, but I have been looking into it more and I think that the two output tubes is something akin to bi-amping. Both are amplifying the same signal in unison and feeding it to the same output. Each tube would be handing both the right and left channels, just like the gain tube. This is why they need to be matched.

Well, this is my poorly educated guess.

We need that "white paper" from Mikhail.

added:

Someone please correct me if I'm wrong and you know the answer.

 

[Stoney]

I believe it is simply this: one output tube for each channel. Each output tube is internally constructed as two triodes, but to lower the output impedance, the two halves are wired in parallel. So, one tube per channel, not balanced (same as most op amps), connected directly to the headphone for that channel. SET, OTL.