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21
Black Market / Re: WTB summing box
« Last post by TwentyTrees on Today at 01:50:44 PM »
Hi Matt,

I'm selling a combination summing mixer / dual preamp based around a Neumann V472-2, London-based. It's fully working and all buttoned up though, so if you're looking for a project this ain't it, but hit me up if you're interested and I'll happily tell you more.

Cheers,
Andy
22
The Lab / Re: anyone know where to get these kind of knobs?
« Last post by PRR on Today at 01:48:37 PM »
> approximate 'close enough'.

Thanks and argh. I ass-umed 6-inch deck boards, calipered my deck, fotoshoped your image, and got numbers. When I went to post I saw your post and I am clearly very wrong. But maybe the ratios are valid and some help.

> measure the diameter of the base

The boards may be '6 inch' nominal decking, which ships wet and oversize, to give at least 5.5" when dry. Here in a damp autumn my by-6 deckboards caliper as 5.6", his look dryer. Taking 5.5" nominal we can scale-out the along-board skirt dimension as 2.94" which is probably a neat 3". Knowing the skirt is round, we can get transverse sizes. We can't get a height without knowing the angle of photography, but I took a guess based on the shadows of the board gaps.

skirt: 3"
stalk: 1.4-1.5"
top: 2.45"
height: roughly 1.9"
skirt height: rough 0.19"
pointer height above skirt: rough 0.29"
pointer width: 0.28"
width of groove on top: 0.15"
knurling: 18 per inch
bevel on top edge: 0.065"
23
The Lab / Re: anyone know where to get these kind of knobs?
« Last post by EmRR on Today at 01:38:09 PM »
I like the RCA knob that was right before their introduction of the classic John Vassos 'mushroom' knob.   Brass pointer.   I believe it pre-dates the Western Electric knob, with the WE being a design response to the RCA:

24
Drawing Board / Re: Fader + trafo buffer
« Last post by abbey road d enfer on Today at 01:36:13 PM »
So, the circuit is correct.
I just wanted to make sure it is ok. :)
It is correct in the sense that it will make some sound, but you don't need the inductor, the 330pF cap is largely enough to ensure stability.
I guess this LR network was intende to decouple capacitive loads, which is not necessary anymore since you have a xfmr.
I would ditch the inductor and the 47r, increase the output cap, since it sees very small offset voltage, you could use a 6V rated cap and increase it to 1000uF.
I would also implement two paths for negative feedback, one as it is but increasing R146 to 10k and adding a 10k from the other side of C74; that would be in order to tame the VLF hump due to the resonance of the output cap with the primary of the xfmr.
25
The Lab / Re: anyone know where to get these kind of knobs?
« Last post by EmRR on Today at 01:29:13 PM »
No calipers here, so approximate 'close enough'.

Note differences in the skirt slope and pointer interaction with.

Western Electric
2 screws hold the skirt and pointer to the brass insert.  This one has a metal insert for the indicator line, there are also those with a standard paint infill.
skirt diameter 2-1/8"
shaft diameter 1"
top diameter 1-5/8"
height 1-1/4"

Langevin
the brass insert is crimped to hold the skirt
skirt diameter 2-1/16"
shaft diameter 1"
top diameter 1-9/16"
height 1-7/16"





26
Drawing Board / Re: Guitar amp switching
« Last post by abbey road d enfer on Today at 01:24:00 PM »

The trick is to not play while changing the speaker hook up.  Having a mute input with millisecond delay before the speaker switch, can force that issue.
Even without signal, a tube amp can blow up when disconnected from the load, contrary to solid-state amps.
In most cases, it would withstand a momentary disconnection, such as the time it takes a switch or relay to changeover.
27
Drawing Board / Re: Guitar amp switching
« Last post by fazer on Today at 12:20:15 PM »
Quote
Flash bang wallop


The trick is to not play while changing the speaker hook up.  Having a mute input with millisecond delay before the speaker switch, can force that issue.   If your the one controlling the switch then you train yourself to not play when switching speakers.   If this is for some bonehead guitar player,  than all bets are off.   BTW all guitar players are boneheads at one time or another.  As a guitar player I can vouch for that.     
28
Drawing Board / Re: Guitar amp switching
« Last post by Tubetec on Today at 11:48:42 AM »
Switching speakers while the amps are cranked and delivering signal   ;D    Flash bang wallop:-[ 
 a re-think or re-jig of what your trying to  achieve  might be the best approach. 

Thanks for clarifying those points Abbey,   
29
Brewery / Rein Narma obit in AES
« Last post by PRR on Today at 11:13:29 AM »
AES magazine has an obituary for Rein Narma in this month's issue.
30
The Lab / Re: anyone know where to get these kind of knobs?
« Last post by rackmonkey on Today at 10:40:55 AM »
Hmmm....now I'll have to find them.....took those pictures years ago......

Okay no worries. I know how that is.
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