R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

News:


Recent Posts

Pages: [1] 2 3 ... 10
1
Klaus Heyne's Mic Lab / Re: KM84 Low output suddenly
« Last post by boz6906 on June 17, 2018, 01:14:36 pm »
High static charges can puncture the gate insulation on some FETs, but usually not JFETs like the 2N3819.

With a close strike (little delay between flash and bang) and 100meV discharge anything is possible.
2
Klaus Heyne's Mic Lab / Re: KM84 Low output suddenly
« Last post by BluegrassDan on June 13, 2018, 10:50:24 pm »
Thanks guy! I really appreciate the help.
3
Klaus Heyne's Mic Lab / Re: KM84 Low output suddenly
« Last post by klaus on June 13, 2018, 06:22:29 pm »
Nichicon, Panasonic, Elna... all fine and, at 63V rating, will fit.
4
Klaus Heyne's Mic Lab / Re: KM84 Low output suddenly
« Last post by BluegrassDan on June 13, 2018, 04:42:08 pm »
One more question. Is there a preferred type of capacitor to replace the tantalums? Would be hard to find any film capacitors small enough to fit. Would small Nichicon or similar electrolytic be okay?
5
Klaus Heyne's Mic Lab / Re: KM84 Low output suddenly
« Last post by klaus on June 13, 2018, 01:42:28 pm »
You can obtain the original 2N3819, now made by Fairchild, from Neumann or any well-stocked parts house.
But you must properly bias it, otherwise the mic will have low or no output, will distort or be noisy.
6
Klaus Heyne's Mic Lab / Re: U67: Add More Top End?
« Last post by klaus on June 13, 2018, 01:38:21 pm »
A clerical mistake, not a design change: the second value on the schematic, a bit closer to the tube filament, shows the correct negative voltage.
8
Klaus Heyne's Mic Lab / Re: KM84 Low output suddenly
« Last post by BluegrassDan on June 13, 2018, 01:34:10 pm »
If the FET is bad (hopefully not), is there a preferred replacement that retains the excellent sonic character of the KM84?
9
Thanks mate... appreciate you sharing the articles... etc.   ;D
10
Klaus Heyne's Mic Lab / Re: U67: Add More Top End?
« Last post by Brian Campbell on June 13, 2018, 11:05:05 am »
For example the initial U67u 00-00-00S. (Considering that 17 is the highest number for a capacitor in this model, the designation  as C17 may be an indication that is may have been an afterthought...):

Interesting to note in that schematic that the heater supply is +6.3V on pin 4 not -6.3V.


(Pardon me for bringing this thread up again but I find this mic fascinating)
Pages: [1] 2 3 ... 10