Couple questions before I order

[vinylb]

I am about to put in an order for the Stereomour || and possibly one the upgrades but wanted to know if

 a) the minor errors in the manuals have been updated (after scouring all the threads here I came across some mentioning couple typos)
 b) if funds were limited what would be the biggest upgrade ? is it the shunt regulator ?
 c) can you implement the upgrade(s) during build of the Stereomour || or is it best to get that build working first then the upgrades?

Thx
Neville

[Deke609]

b) if funds were limited what would be the biggest upgrade ? is it the shunt regulator ?

This depends in part on your setup. If you have very high efficiency speakers (I "think" 97 dB sensitivity or greater is the usually quoted figure, but check the DCF product description to be sure), then you might get some hum and might want the DC filament upgrade. I use my Stereomours with headphones (see signature line) and the DCF upgrade made the amps completely silent.

But if hum isn't an issue or a concern, for me and my ears, the Shunt Reg is an incredible upgrade. So much so that if I had to choose between hum and giving up the SR upgrade, I might decide to live with the hum.

c) can you implement the upgrade(s) during build of the Stereomour || or is it best to get that build working first then the upgrades?

There's almost no benefit to integrating an upgrade while you're building the stock unit, and a lot of downside. It might save you about 5 ot 10 minutes in build time (literally). But it will make troubleshooting a lot more difficult.

cheers, Derek

[Paul Birkeland]

It will take more time to build the amp with the upgrades all at once.  If anything goes wrong, you'll need to pull the upgrades  out and go back to stock in order to properly debug the amp.  The instructions are written assuming that you are starting with a completed amp, so it gets complicated to figure out what does and doesn't need to be built in from the get go. 

The current manual was revised on 9/21/18, so anything you've seen in the forum posted after that hasn't been incorporated.

As Derek mentioned, if you have very sensitive speakers, I would go for the DC filament upgrade.  If you're using the Stereomour as an integrated amp (using the level control), then I would go with the attenuator.  If you're going to turn the volume controls all the way up and just use a preamp, I would go with the shunt regulated driver upgrade.

[Raymond P.]

I received and built a Stereomour II (with DC Filament and Shunt Regulator) amp a few months ago. I did not notice any errors in the manuals.

If I could only get one upgrade, it would be the DC Filament. I have 90db and 99db sensitive speakers and could detect hum from them. The hum bugs me a lot. I cannot get myself to ignore it. So if you're like that, the DC Filament upgrade is a must, and it works.

The one upgrade I personally would not get is the stepped attenuator because it doesn't have balance control, which for me is very useful.

[vinylb]

I have Zu Audio 97db speakers and I am sensitive to hum so guess it’s the dc filament upgrade for now. Yes it will be used as an integrated so down the road I can purchase the attenuator.

I have never heard 2A3 tubes and I know it’s comparing apples to oranges because of tubes and circuits can anybody describe the sound of 2A3 to an el34 or even kt88?

Thx
Neville

[Paul Birkeland]

That's a tough comparison because the performance of an EL34 or KT-88 will depend greatly on whether it is wired as a triode, a pentode, or setup with an ultra-linear output transformer.

The 2A3 itself is far more linear than a triode strapped EL34 or KT-88, so at least on that basis it will be a far cleaner presentation on the side of the 2A3 compared to a KT-88 or EL34, though the KT-88 and EL-34 can make a bit more power.

Oddly enough, the Stereomour II (not the gen 1) could very much be modified to run KT-88s triode strapped, that might be a fun thing to mess around with if someone happened to have an extra laying around.

[Jamier]

Hey PB,

     Is that going to be a “factory supported” mod, or are we on our own?

Jamie

[Paul Birkeland]

I'll point fingers and make suggestions, we aren't going to make a manual for something like that!

[oguinn]

If you warn him that there’s, at best, negligible gain in performance possible I bet Derek will do it

[Paul Birkeland]

If you warn him that there’s, at best, negligible gain in performance possible I bet Derek will do it

I think it would go the other way.

[Deke609]

If you warn him that there’s, at best, negligible gain in performance possible I bet Derek will do it

I did think about it.    It might be interesting to look at the curves of the 2A3 and a triode-strapped KT88 or EL34 and then rejig an SII to use one of the latter just to hear what a loss in linearity sounds like. And it would be a good learning opportunity re tweaking operating points. Still considering it. But i think I'll learn more by designing/building my own triode-strapped EL 34 amp using the SEX/SII iron.

cheers, Derek

[dth31]

I have Zu Audio 97db speakers and I am sensitive to hum so guess it’s the dc filament upgrade for now. Yes it will be used as an integrated so down the road I can purchase the attenuator.

I have never heard 2A3 tubes and I know it’s comparing apples to oranges because of tubes and circuits can anybody describe the sound of 2A3 to an el34 or even kt88?

Thx
Neville

It's almost impossible to describe the sound of a tube in isolation.  EVERYTHING affects the sound, to some extent: circuit, resistors, capacitors, output transformers, wire, etc.

I own PP EL84, EL34 and KT88 amps. Several 300B SETs (all series feed) and a Bottlehead 2A3 Paramount (of course, parafeed).  The 2A3 Paramount with EML 2A3 meshplates is my favorite amp on AN/E speakers.  Natural, clear, liquid, transparent, plenty of bass and above all MUSICAL!  With JJ 2A3's, I lose some of the transparency and clarity, but there's a bit more warmth and body.  I pretty much don't use the JJ 2A3's, but it's definitely a matter of taste.  I'd still take the Paramount 2A3 with JJ 2A3's over the other amps.  YMMV.