Stereomour II (in progress)

Jamier said:
Have you had this amp up and running in completely stock form?
Click to expand...

Not yet. I attached the wires already. We'll see how it sounds. If I have any troubles it will be easy enough to disconnect the four extra wires from the selector switch.
 
I think I see where you're going with this. Maybe you would be better off including a purpose built preamp in you're system. The way you're going now might degrade the performance of both the
S-II and the headphone amp.But how will you know if you haven't previewed the stock StereomourII?
 
Jamier said:
I think I see where you're going with this. Maybe you would be better off including a purpose built preamp in you're system. The way you're going now might degrade the performance of both the
S-II and the headphone amp.But how will you know if you haven't previewed the stock StereomourII?
Click to expand...

PB said this was the easiest way to go. I'm basically following his instructions. But he never explicitly said how to wire the new RCAs to the selector switch. I think I've got it, though.

As soon as I get my replacement caps I should be ready to go!
 
OK, I got some ClarityCaps to hold me over till the replacement Solens come. Build is complete. Here are the only resistance inconsistencies:

terminals 21/40  0.5 

Note that I swopped out the good Solen cap with one of the CalrityCaps to make sure the caps weren't somehow throwing off resistance, but I get the same reading.

Any clue why these would be off?
 
Here are some. I've wired for 4ohms speakers.

fc740y.jpg


2f07m1l.jpg


ouvea0.jpg
 
You have mixed up the primary and secondary wiring on your output transformers.

Refer back to pp 57-59 and pay close attention to the terminal numbers on transformers.
 
Thanks, fixed!

Voltages check out perfectly, except that terminal 7 read 239 (still easily within 10%) and terminal 14 read 200. Does this have something to do with the balance control? I also noticed that I got two different brands of 12AT7 tubes, so maybe that has something to do with it?

I'll send some music through it now to see how it sounds.
 
I'm a total idiot! I had to move the amp from one side of my credenza to the other to have the RCAs in reach, and when I moved it I forgot to re-plug it in!  ::)

So it's going... I'm using the mono Pet Sounds to set the balance. It's sounds glorious! FAR, FAR more bass. Richer sound, wider soundstage, more detail. Etc.
 
By the way, I've got the hum down to completely inaudible, even with my ear up to the speaker. Should I cancel my DC filaments order, or are there other benefits to that upgrade, too?

212tyeb.png
 
Listening to Kitajenko conducting Shostakovich's first symphony on SACD now and it's jaw dropping!!

All due respect to the S.E.X. 2.0, even with MQ all-nickel iron upgrade, but this leaves that wonderful amp in the dust. Glad to have it as a headphone amp--that's for sure!
 
All this excitement about the sound of this amp made me forget that I had wired it for 4ohm, and still need to try 8ohm to see what difference I hear. Could it sound better?
 
Paul Joppa said:
It's the damping factor. Most speakers are designed to operate best with an amp that has a very high damping factor; SETs usually have a DF between 2 and 4. This makes the response sensitive to variations in speaker impedance. Peaks when the impedance is high are limited, but notches when the impedance is low are unbounded.

In the Forte II graph, the biggest dropout would be in the bass where it drops below half of the nominal 8 ohms. There will be a smaller peak in the upper midrange where the impedance is high. Room acoustics are significant, especially in the bass, so sometimes just moving the speaker around will adequately compensate. That's why I suggested trying both options and listening.
Click to expand...

Paul, if I understand you correctly, I am more likely to get better bass at 4ohm, but may lose something in the upper middle, whereas with 8ohm I may lose some bass?

I've got it at 4ohm right now and it sounds pretty nice all around. I'll be away for a week, but when I return I'll re-wire to 8ohm and listen.
 
OK, I've re-wired for 8ohms. The difference is subtle, but so far it seems like there's less rich bass. Whatever strengths this brings me might not be worth the trade-off. Honestly, I'm still so floored by the sound that I have a hard time focusing in on whatever slight drawbacks there might be in the different ohm wiring.
 
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