Audiokit news

07-11-04 The idea to work with 2 separate ECC83 tubes in parallel gave me the opportunity to build two completely separated channels. A modular setup was the next step. The advatages of a modular setup are: compact, easy to change (look at the grey PIO coupling condensator), easy seperation of voltage and signal wires, modules can be build in series and exchanged easy. The name audiokit indicates that I eventualy want to make an amplifier in kit-form. Specially for the less handy audio-lovers these modules should be a step closer to a diy kit. 

The first picture shows a finished EL95 part. The print is attached to the tube-base with a distance bus. Later they will be mounted to the inside of the chassis. This can only be done when the holes in the chassis are perfectly machined so that you don't need the rings to cover the holes. The 2 pictures on the right show one finished channel where the ECC83 and the EL95 find a place. Only the power supply, input, output and attenuator should be soldered to the print and the amplifier is ready. 

20-08-04 I used the holiday period to inprove the prototype. Not that I was not happy with the sound of the prototype but I had to make more space in the chassis to build an improved version with an extra ECC83 tube as I mentioned before. Therefor the electrolyte should move to the bottom side but in the prototype this was impossible due to lack of space. The picture below shows the extra partition between the power supply and the actual amplifier. Apart from a modular way of building it improves shielding and gives more space. On the partition, the electroytic condensator, the choke and a soldering strip can be mounted. The soldering strip is used to connect all the 6,3 V and earth wiring. On the picture you can see that I start with soldering the twisted heating wires for the tubes.

05-08-04 I finaly made the decision to have the chassis build by a specialized company. I spent a lot of time in punching and drilling of the holes with a chance of mistakes and scratches. It will be a brushed stainless steel chassis and the first prototype is in production now. This new chassis is slightly wider and higher then the Hammond chassis. This gives the advantage that bigger output transformers can be used now (if the client wishes). More information (and pictures) will follow when the prototype is finished.

04-07-04 I started building the different modules so that I later can install them in the different amplifiers. For instance the stepped attenuator can be build on forehand, it is a time consuming job if you want to do it in a neat way. This one is a 12 position switch. The advantage of a stepped attenuator is that the 1% tolerance resistors give an equal attenuation to both channels, also in the low volumes. A lot of sites can be found on the internet to calculate the resistors. (just fill out stepped attenuator in a search engine). I noticed that you have to finetune the resitors afterwards to get the preferred soundlevels.

Myself busy producing 5 attenuators, right the result. The 3 lugs that represent the 3 potentiometer connections are not yet soldered.

19-06-04  A scan of 2 different sized boxes.The measurement is there to be sure that the drawing is at scale if you print it. Otherwise you can magnify (or shrink) it on the computer or with the copier. If this does not work, please let me know.

17-06-04 I will scan some drawings that allow you to make your own carton boxes to safely put your tubes in. An empty box from cookies will do, make a scratch with a blund iron on the inner side of each fold and you get a very nice angle. Of course there is a piece of carton from corner to corner to prevent the tube from breaking too easy.

You don't have to use the inner collor (grey) of the box, some have very nice prints on the outside (see the picture of spounge bob)

17-06-04 Regularely I read that using the two halves of a ECC83 for 2 different channels will give a negative effect on deviding of the channels. In my next amplifier I will use 2 ECC83 tubes of which both halves are connected parallel, this will lower the resistance and I can compare both amplifiers. The amplifier which uses only one ECC83 has a very good sound, voices and instruments can be placed at the scene and to my opinion it sounds better then the original AG9016 which allready sounds very good. Tastes differ and the best way to find out is to build it and listen. I have not much time at the moment so it will not be for the very near future. Any comment on this subject is welcome, I will write down the comments that can help us further.