Cathode Bias for SimpleSE

[kvk]

Well I was looking at the pictures. I suppose you could buy four extra two pins and then break one of the pins off and they might fit in the place where the ends of the cathode resisters are. Good or bad idea?

The instructions say something about the R not being to far off the board. Don't know why, particular if you are going to reverse wire it and put the non-tube components on the back.

[tubelab.com]

I was wondering if they made those 2 and 3 pin terminal strips in one pin so you could just screw in different cathode Rs.

I have never seen one with only one pin.

Well I was looking at the pictures. I suppose you could buy four extra two pins and then break one of the pins off and they might fit in the place where the ends of the cathode resisters are. Good or bad idea?

It is a good enough idea that I am going to try it. I currently have a box full of resistors with aligator clips on the leads. I just clip one across the existing cathode resistor when I want to "turn up the boost".

The instructions say something about the R not being to far off the board. Don't know why, particular if you are going to reverse wire it and put the non-tube components on the back.

That statement was meant for the builder who puts the resistors on the top of the board and the other parts on the bottom. The requirement is so that the resistors are below the level of the tube sockets and don't touch the chassis. I wrote the instructions asking the builder to place the resistors on the top side of the board to lessen the possibility of putting the wrong parts in the wrong holes, since the board is silkscreened on the top side only. The SimpleSE is a popular project for first time builders, so I tried to make it as simple as possible. It is perfectly acceptable to put the resistors on the bottom of the PC board, but you need to be carefull about placement since the resistors go on first and all of the holes in the board are empty.

[chrish]

After seeing some of the uncharitable comments about the Simple SE on one of the other threads, I thought it was time to do a little experimenting with mine. With the Hammond 374BX I think I was getting around 480V B+ with a GZ34 rectifier. This was fine for my JJ E34L and JJ KT88 valves, but a bit too much for the Wing C EL34 and some Soviet 6P3S (6L6GT) valves I had. One of the Wing C EL34s would glow a dull red, as would the 6P3S. I have 560R cathode resistors, so just replaced them with 820R with switcheable parallel 1.0K and 2.2K, so I have 820R, 597R, and 450R. So far it looks OK. Using a 5U4G to drop a few volts and the selectable resistance looks like it may have stopped the glowing plates. Will have to wait till it is a bit darker to confirm. From brief listening, still like the EL34s and E34Ls. Will put the 6P3S valves back in to see if they settle down a bit. Not quite as detailed as the EL34s.

Still having fun with this amp! Thanks George! Don't let the (one) negative comment/person stop your enthusiasm. We do appreciate the time you spend on the projects and on this forum

Chris

[budmaestro]

This is my first post here. I have recently completed the tubelab Simple SE amp and wanted to give a big thumbs up to George. I have run 4 different tube types (KT-88, El-34, 6550C, and now the Russian 6n3c-E). I have tried 2 different output transformers (Edcor xse15-8-5k and Transcendar 5K SE). So far I have only been brave enough to hook up some cheap minipod speakers (that I tweaked the crossover capacitors on) for listening/testing.
This is a great little board to play with !!! The sound is very similar to my $2000 Cary amp and with these cheap Russian 6l6's I have a little over $200 invested in the current set-up. Tremendous.
I am running the 560 cathode resistor and a Russian k-40 as coupling cap. Also, am using the 6K7VG Allied power tranny, 90 uf of motor run supplemental power supply capacitance and the recommended Triad choke and tube rectification( Sovtek 5AR4). Oh yes, I am using triode mode with NFB after trying all the different combos.
I haven't had this much fun since the fourth grade.

[budmaestro]

I just wanted to clarify the Russian tube I am using. This is the -E version of the 6P3S tube that has cyrillic (sp?) lettering of 6n3cE. This is sold on ebay as being a 6L6GC replacement. I tested my wall voltage with my Fluke 179 multimeter at 124.5 volts. This really gave me pause to put in a tube I was "somewhat" unsure of the limits. Testing with the same meter at the points on the Simple SE board that should be the plate and B+ I get 450 and 475 volts , respectively. I had ordered 25 of these tubes and just picked 2 at random, untested and plugged them in.
I am now listening to Yo Yo Ma ( after Pat Metheny earlier) and these tubes appear to be happily making excellent sounding music. These 25 tubes cost me $120 delivered.
thanks to you again, George ; Keep up the good work!!!