my first post

[lorrain]

Hello everybody, I have been looking at BOTTLEHEAD for a very long time, and about
a year ago, registered in the forum.
Now being retired, I finally have time .
so far I have put together a passive pre from parts from BENT audio
also a pair of HAWTHORNE audio duet,and  all my cables.
I am using a mac mini, all my music is lossless going to a magic dac
Just received a STEREOMOUR that I want to build as amplifier only,
do I just bypass the selector switch and volume or is there something else
I should do?

This is a great forum, a great company,  thank you all,     Francois

[howardnair]

yes -here is the answer  from jrebman
http://www.bottlehead.com/smf/index.php/topic,1707.0.html

[Grainger49]

Welcome!  

With the volume all the way up the pot is pretty much out of the circuit.  You could omit the volume and selector switch.  You will need a fixed 100k ohm resistor to replace the resistance of the volume control.  You can put these from the center conductor to shield (outer conductor) of the input RCA jacks.

Then bring the hots of the inputs to the 220 resistors at the input grid of the respective driver tube (12AT7).  The outer conductors go to ground/signal common.

[howardnair]

grainger--watt!!! [couldn't -resist- the punnage]--would be  the power rating for this resistor-

[lorrain]

Thank you all

100kom   , watt?
as you can see, I am new at this.
also I have two pair of 2a3,  shuguang 2a3c  small pins front,  jj 2a3  40  big  pins
front if you call the logo the front .
looking at instructions for stereomour front is  small I think
emailed eurotube, they say they have yet to see a reverse 2a3 .
What is right ?

Thank you all     Francois

[Grainger49]

grainger--watt!!! [couldn't -resist- the punnage]--would be  the power rating for this resistor-

The input is a volt or two.  The power rating can be as low as 0.1W, lower if you can find them.  Of course higher is fine.  It is easier to find 1/4 and 1/2 watt resistors.

[Lee Hankins]

Francois, the label has no bearing or orientation with relation to the pins, there are 4 pins on the 2A3, two large (the filaments) and two smaller.  The tube can usually only be installed one way, but I have seen some extremely inexpensive sockets that would allow the tube to be installed incorrectly.

[Grainger49]

There have been a few Bottleheads who have managed to rotate the 2A3s.  I have tried and found it possible but difficult.  You would have thought they might have staggered the pins so it couldn't be done.  Too late now by quite a few decades, almost a century.

I'm installing better tube sockets on my (not stock) Paramours.  The 5 pin socket for my 76 driver is junk!  It gets loose way too easy.  

[Lee Hankins]

I always end up installing QQQ, teflon composite, or regular teflon sockets.  Learned long ago that the cheap ceramic sockets will cause problems in the long run, besides I do not like their looks or their lack of grip on the pins.  I am always rolling tubes so a better and tighter socket is just cheap insurance, it is a real pain to have to replace one after it goes bad, usually destroying a nice and neat build.

[ebag4]

Hi Lorrain,
I built my Stereomour as a straight power amp.  I used a couple of 100K Caddock resistors and located them at the terminal strips.  Jim Rebman recommended locating them there as a deterrent to picking up additional noise.  The terminal strips are a very convenient location to mount them as well.


Here is a pic of the resistors (the two square units), they appear to be mounted to the board but in reality they are mounted to the terminal strip beneath the board.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hawthorneaudio.com%2Fphotos%2Falbums%2Fuserpics%2F10060%2Fmundorfs.JPG&hash=25b7132529085290d253262f61d481ce3506265a)

Good Luck!
Ed

[Paul Joppa]

If you are using a passive preamp, then the following may not be necessary, but I'll include it in case others find this thread through a search.

You might want to include the level controls initially. That will allow you to adjust the gain for the best signal/noise performance in your system. See my article on signals and noise, linked form the Bottlehead "Community" page. Once the best gain setting is found, then the potentiometer resistances can be measured and fixed resistors substituted to get the best possible performance.

[InfernoSTi]

Francois,

Welcome and as you can see, the Bottlehead crowd is very knowledgable, helpful, and friendly!  It's nice to see a fellow Hawthorne guy get a Stereomour...I believe you will really enjoy it as it is a perfect match for a Duet!  I, too, use the JJ 2A3-40 and am very happy with that tube.  Enjoy your build and your Stereomour.

John