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21
Well from what little info I have to go on these I've found out the following

For an inch square core, using 0.35mm with approx 1800 turns and a crate paper gap in core it's meant to give 300ma, 3H and be 46ohms.

It's a starting point I suppose.
I'll experiment and see what I can get on this core with what I've got as I think I have some 0.35mm
22
Drawing Board / Re: 1KHz 0dBu pocket generator
« Last post by Rob Flinn on Today at 01:55:10 PM »
Hi Ian,

A quick question.   Is there any reason in particular that a TL072 is specified ?   Power consumption perhaps ?  I was thinking that if one used a 5532 then the box would have a bit more drive capabilty ?
23
The Lab / Re: Neumann PsvB schematic/infos request
« Last post by thekid777 on Today at 01:48:47 PM »
Understood!
I'm looking for schematic to repair my unit and pinout as well
+ some data if there's any about hook up in the console
24
Brewery / Re: I don’t think this guy is married...
« Last post by Tubetec on Today at 01:48:26 PM »
There was a few guys in my years of hifi sales returned with their tail between their legs , they either got their money back on the gear or their marriage was over , on the few ocassions it happened we did accept the return of the gear or sell them something more 'spouse friendly'  as we used say ourselves in the trade .

The Bose style sat/woofer set up was the usual road for guys who were downtrodden by the wife   :(

 
25
The Chamber / Re: Polycarbonate Film Caps
« Last post by rackmonkey on Today at 01:42:18 PM »
I got it off track by mentioning that I like PC in filters, I think. It just happens to be where the differences can be heard most clearly. But the intent was to inform of an opinion that the OP could take or leave where coupling caps are concerned.

Very nice summary above, Abby. The dumbed-down line on coupling caps has long been "there's no voltage across the cap, so its affect on audio will be negligible." But the part usually left off that line is, "...provided the cap is sufficiently large." As anyone who's ever replaced 100nF or 2.2uF coupling caps with a same-value cap of different dielectric material in, say, a tube preamp knows, the cap construction has an effect on audio. Those old metallized paper in oil caps have a sound of their own.

To John's response above, yes, DA, DF and tempco in polycarbonate caps is significantly worse than PP or PS. But it's considerably better than polyester. If lowest distortion is the goal, then obviously use the parts with better numbers there - no argument. But I think the OPs question is more along the lines of subjective qualities, which to my ears PC is pleasing. People love the 1073's EQ, but Neve often used Mullard mustard caps in those, which are just polyester film/foil. A no-no on paper (polyester caps are not recommended for filters by any manufacturers guidance that I've seen), but subjectively something attractive to a lot of people over the years.

So you can use traditionally specced smaller values for coupling caps and use the objectively best measuring caps for lowest distortion in that situation; you can use caps for their flaws and the audio effects they impart; or you can just use sufficiently large electrolytics for coupling and not worry about it. It's all about goals.
26
The Lab / Re: Neumann PsvB schematic/infos request
« Last post by Khron on Today at 01:30:49 PM »
If it's faulty or damaged, it can be reverse-engineered, and then troubleshot and repaired.

If it needs to be recreated, there's more than one way to skin this cat (ie. a power supply doesn't necessarily need to be 100000% identical to the original's topology or components, in order to provide the same level of performance, or better).
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The Lab / Re: Neumann PsvB schematic/infos request
« Last post by thekid777 on Today at 01:18:07 PM »
What is the purpose of your questions?
would you have some infos about it eventually?!
28
Black Market / Re: FS: Lundahl LL15402
« Last post by telefunk on Today at 01:08:21 PM »
PM sent.

BTW, is that a 1540 or 5402?
29
The vox choke I re-wound just used random wound turns , over the years the wire insulation had broken down almost completely,  to the point where I could only measure 100mH,  practically a dead short across the coil.  One of the more heavily insulated types of magnet wire is probably best for that job , the marshall style has paper interleave which helps insulation but makes winding a bit more complex a job .



30
Machine Shop / Re: "Y" or why? screws
« Last post by abbey road d enfer on Today at 01:07:25 PM »
I am still trying to get my sump pump back working properly after a nearby lightning strike last weekend.

First the lightning trashed the after market float controller but that replacement arrived yesterday. Now the pump itself is not pulling water reliably.

I tried to take it apart and discovered screwball "Y" screws.  I have some screw drivers on order but why on a sump pump?

JR
Probably because a lesser skilled person may ruin a gasket.
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