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monekh 30th November 2015 04:43 PM

3-pin DIN wiring in Klemt Echolette - replacing with 1/4" jacks
3 Attachment(s)

I have a Klemt Echolette, the inputs and outputs of which I'm hoping to switch for mono 1/4" jacks. Attached below (sorry couldn't work out how to display them inline) are some pictures of the 3-pin DIN connectors currently installed. The first two pictures show one of the inputs with volume and tone control (which has a bunch of resistors and capacitors right before the connection), the third the input without these controls (looks much simpler, just wires).

Now I know that DIN wiring can vary a great deal depending on the application, so wanted to ask if anyone would be able to advise how to switch these sockets for 1/4" ones - where each pin of the DIN should be soldered on the new 1/4". In the first 2 pictures, the pin on the left is labelled 3, the one on the right 1, and the one at the back 2.

any help much appreciated!

Jazzamp 12th December 2015 02:01 AM

Hi I think I can help you here. I have just converted a #Klemt Echolette M40 to jack inputs, and I have been checking out the schematics for the #NG51 because i've got a couple coming for repair.
First thing pin 1 is the signal pin. this is the connected to the capacitors in pic1&2 and the wires in pic3 and these should be connected to the tip lug of the jack socket.
Pin 2 is the ground pin and whatever connects to that goes to the ground lug on the jack socket; but NOT ground itself, you need insulated jack sockets, will explain in a moment.
Pin 3 is connected to a 1k resistor that is itself connected to ground in pics 1&2 and is just connected straight to the ground pin in pic 3. The 1k resistors can be disregarded and heat shrink't out of the way or simply removed.

Now the important bit. I cant see in the pictures, and i haven't seen one of these in the flesh yet but i would say the ground connection on the first two inputs is connected to the shielding on the input wire, also one end of the 10M resistor goes to this point. The other end of the shield is connected to ground inside the machine and if you connect it to ground at the input side, you will create a ground loop that will cause it to hum.

Also on the 3rd input its important that the signal (tip) connection of the jack socket does NOT short to ground when closed, this will probably reduce the volume of the whole unit as this input is a line input that mixes with the other two inputs after they have been through an amplification stage, and their respective vol and tone controls. It is directly coupled (no capacitor) through what looks like 200k resistor(my schem is poor quality) If this input is grounded it will load down the whole input stage; much effect it would have i'm not certain, it all depends on how the preset global "pegel" input vol is set.

Now back to those first two input. These are high impedance "10M" inputs, i suppose to suit old fashioned crystal microphones or other very high output impedance devices.
This is achieved by using grid leak bias ) and an input capacitor to isolate the grid voltage. These stages do not have a cathode resistor and use the very high grid leak impedance to "choke off" the current generated in the grid of the first stage triode, this produces a small negative voltage on the grid for bias.
Those old #Eroid capacitors are notorious for being leaky; They're not quite as bad as some people make out, the real bad ones are the wax #Ero caps, and in my opinion should be junked straight away...I've seen these leaking HUNDREDS of volts.

Nevertheless if these caps are leaking just a tiny bit, it will screw up the bias on the valve/tube and maybe cause it to run away and burn out, especially if you have your jack socket tips to ground when closed...I would replace them, just make sure you get the grid leak resistors wired up right- one end to the input shield the other to input wire on the valve/tube side of the capacitor NOT the input side...

Anyway, i think thats all correct, (will check what iv'e written in a sec) Hope it helps... Jazz.

Uprightbassman 5th February 2018 02:08 PM

Hi Jazzamp, jumping on this a few years late. Do you still do repairs? Would you convert my echolette to jack inputs for me??

aquestionoftime 5th February 2018 07:30 PM

I got someone to wire custom DIN -> 1/4" jacks for me for a decent price. They improved the sound quality of the unit drastically than the adapters that came with it

Humblewarrior 7th December 2020 11:28 PM

Can anyone tell me what kind of cables I need to plug my klemt into my mixer, which has jack inputs? Many thanks