Introducing the Stereomour II

[Doc B]

Here's link to the newly revised Stereomour 2A3 amp kit. The first five customers to order one will receive a free Quicksand battery powered amp kit - a $99 value.

http://bottlehead.com/product/stereomour-ii-stereo-single-ended-integrated-2a3-amp/

 

[marantzfan]

Nice.  The stereomour was my first Bottlehead kit and I enjoyed it thoroughly for years.  Glad to see that it has been reborn and will continue on for more folks to build and enjoy.  Also, it looks like its already setup for a BeeQuiet upgrade kit... 

 

[Natural Sound]

Looks awesome but I sure would like to know a few more details. Like what the three pots do and more details about the future upgrades. A photo of the goodies under the hood would be nice too.

 

[chard]

Here's an educated guess. The pot on the right is a 3 option selector switch. The middle pot is a volume control for the left channel. The pot on the left is a volume control for the right channel. The middle and right pots could also be used as a coarse and fine variable series and variable shunt stereo volume control.

 

[chard]

I meant to say the holes and spaces taken up by the middle and right side pots could be used for two selector switches to construct a variable series and variable shunt attenuator.

 

[Doc B]

It's our new standard setup - source selector, volume, balance. There will be an upgrade kit, to our coarse/fine stepped attenuator, which will replace the volume and balance pots. We are not showing a photo of the underside yet because the production prototype is not yet built for the assembly manual, and we show a photo of exactly that chassis. The current working prototype is laid out slightly differently than the production model will be. Upgrades will include the stepped attenuator, and also shunt regulation and a DC filament supply. These upgrades are not ready yet and will be released later in the year.

 

[denti alligator]

I forget, are there three inputs and one output, or three inputs and two outputs?

 

[Doc B]

Uh, this is an amp.

 

[denti alligator]

Uh, this is an amp.

Duh, never mind...

 

[Grainger49]

Uh, this is an amp.

So, one output but not on RCA jacks.

 

[chard]

It's our new standard setup - source selector, volume, balance. There will be an upgrade kit, to our coarse/fine stepped attenuator, which will replace the volume and balance pots. We are not showing a photo of the underside yet because the production prototype is not yet built for the assembly manual, and we show a photo of exactly that chassis. The current working prototype is laid out slightly differently than the production model will be. Upgrades will include the stepped attenuator, and also shunt regulation and a DC filament supply. These upgrades are not ready yet and will be released later in the year.

With the dc filament supply will the Stereomour II be suited for headphones? Will their be a second pair of outputs so a choice can be made between headphones or speakers without manually disconnecting from one and connecting to the other? Will the dc filament supply, stepped attenuator, or headphone use be available to retro fit into a standard stereomour?

 

[Paul Birkeland]

With the dc filament supply will the Stereomour II be suited for headphones?

No, this is more intended for sensitive speakers.

Will their be a second pair of outputs so a choice can be made between headphones or speakers without manually disconnecting from one and connecting to the other?

No, this is a speaker amp, not a headphone amp.  If you're interested in this functionality, we recommend the SEX amp.

Will the dc filament supply, stepped attenuator, or headphone use be available to retro fit into a standard Stereomour?

No.  The new Stereomour has a very different power transformer to allow all of this to work, and many extra holes in the chassis plate to accommodate the upgrades. You could, however, use a Submissive in front of your existing Stereomour to similar effect.

-PB

 

[chard]

My speakers have a sensitivity rating of 99 db. I have an old stereomour with ac filaments but hum is not an issue. I have to put my ear up next to the speakers to hear hum. I never hear any hum while the music is playing even during parts of the music when there is complete silence. Other than hum what other advantages are there in dc filaments? 

 

[Paul Joppa]

My speakers have a sensitivity rating of 99 db. I have an old stereomour with ac filaments but hum is not an issue. I have to put my ear up next to the speakers to hear hum. I never hear any hum while the music is playing even during parts of the music when there is complete silence. Other than hum what other advantages are there in dc filaments?

That's pretty much it. It's not important to everybody, so it's not in the basic kit; the upgrade will be available for those who really want or need it - some of our customers have 110dB speakers! This way the price of the basic kit stays low. One other application: subwoofers can be more easily taken from the speaker outputs, which almost always gives better integration with the main speakers. Hence there are no second preamp outputs (another cost saving).

The original Stereomour does not have enough filament power available to make DC heaters (I tried); the new power transformer fixes that. (It's also the power transformer for the Seductor.)

We already make two dedicated headphone amps (Crack and Mainline) and a combination amp (SEX) so we neither considered headphone performance nor added the cost of additional wiring and jacks to Stereomour II.

The Stereomour II uses two 12AT7 tubes as drivers, using half of each tube. This makes it possible to have an upgrade kit that uses the other half as a hybrid shunt regulator for that stage, bringing it closer to the Paramount sonics.

Going to separate volume and balance controls allow for the possibility of the BeeQuiet type stepped attenuator, the best sounding option we've found - without adding much cost to the basic amp.

It retains the OT-2 output transformer, which has been quite successful. That means the impedance switch upgrade kit will also be available.

Hope that clarifies a few questions.

 

[chard]

Thanks Paul J. and Paul B. for the information. The Stereomour II sounds like a nice upgrade.

 

[cspirou]

Will you be able to use a 45 tube like the original Stereomour?

 

[Paul Birkeland]

Will you be able to use a 45 tube like the original Stereomour?

Yes.

 

[jrebman]

Will this amp retain the 10" x 12" top plate dimensions?

Thanks,

Jim

 

[fullheadofnothing]

Yes.

 

[jrebman]

Thanks, Josh.

-- Jim