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Old 26th November 2009, 10:11 AM   #11
webby is offline webby  United Kingdom
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Tubelab rocks!
Thanks very much you guys for the help. Added the jumper pin 02, bingo.
Now pumping out the tunes with plenty of volume.
Love this project, and amazing assistance from the forums.
Cheers
Ian
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Old 4th December 2009, 12:10 PM   #12
webby is offline webby  United Kingdom
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Hi All,
I am getting on very well with the tubelab SSE, Love the clarity & sound staging. Real improvement on my little ASL Wave 8's.
I wanted to know where to take a feed for a 6.3V, .15A bulb, Can i connect it to T1-GRN 6.3v or will that inject noise into the circuit?
I also have some 6P3S valves kicking about, but am unsure if i can just drop them in place of the 6L6GC's. When using 5AR4, i am getting 458V. With a 5U4G, 434V. I just have the 560Ohm R17&R27. Will this be too much for the 6P3S, the data sheet i have is unclear about the maximum ratings?
Many Thanks
Ian
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Old 4th December 2009, 12:32 PM   #13
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Quote:
Originally Posted by webby View Post
I also have some 6P3S valves kicking about, but am unsure if i can just drop them in place of the 6L6GC's. When using 5AR4, i am getting 458V.

Click the image to open in full size. Click the image to open in full size.

http://s69.photobucket.com/albums/i4...E/P1110492.jpg
http://s69.photobucket.com/albums/i4...E/P1110495.jpg

Are they 6P3S, or 6P3S-E? I've been told the 6P3S are not particularly impressive, and they may not hold up well under your voltage and current conditions. On the other hand, the 6P3S-E is a very nice tube. I often prefer it myself in my own Simple SE. I would recommend increasing your cathode resistance a bit. I started out with 560 ohms, which was good for KT88 but a bit much for the other tubes. I have since increased it to 810 ohms and all is well.
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Old 4th December 2009, 01:09 PM   #14
webby is offline webby  United Kingdom
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Hi TY,
They are not the -E version, just 6P3S. Maybe i should just leave them and buy the -E version. Are there any other low cost valves i could play with. Cant afford KT88's for now.
Any thoughts on the power bulb?
Many thanks
Ian
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Old 4th December 2009, 01:40 PM   #15
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If you want more options for playing with other types of tubes, maybe this idea will help:
Choke modification for Simple SE

Click the image to open in full size.
http://i69.photobucket.com/albums/i4...E/chokemod.gif

On the back side of the board, cut the trace between C1 and R2. Ignore my note about the jumper. Add a big (6H ~ 10H) choke between the SW1-O1 terminal and the L1-O2 terminal, as suggested by George. Now you should get just slightly more than 300 volts B+ and you can play with 6V6 type tubes. Your 6P3S should be happy as well, and the very pretty 6L6GA could be tried too.

As far as the rectifier is concerned, I would recommend just staying with a quality old stock 5AR4.
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Old 7th December 2009, 06:19 PM   #16
webby is offline webby  United Kingdom
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Hi TY,
Thanks for the link, interesting mods. I might even by another PCB, really impressed with the quality and just using a baking tray for a chassis. Will be really nice when finished. I had to use .47 coupling caps as i ordered the wrong size, will this effect the sound much?
I think i will keep the voltage as it is now and buy some more tubes. Do you know if it possible to run an 807 SE by modding the circuit and changing the valve socket? They look so cool with the blue glow and top cap!
I bought some fender style jewel power lights,and wanted to know where to take a feed for a 6.3V, .15A bulb, Can i connect it to T1-GRN 6.3v or will that inject noise into the circuit?
Many Thanks
Ian
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Old 7th December 2009, 07:37 PM   #17
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I'm glad you enjoyed. I forgot to point out that with the lowered B+, you will likely need to jumper around R14 and R24 (the 10K, 3 watt parts) or else the CCS might not get enough voltage to work at its full potential.

The use of larger coupling caps shouldn't make much of a difference at all. You'll get a lower Fo cutoff point, but it's already pretty low with the stock values. The formula is 1/(2piRC), if I recall, which should put it at ~3 Hz with the stock parts. Doubling the coupling cap will lower the F0 by half to ~1.5 Hz. Pretty much inaudible in any case. There was a discussion around here about using the smallest cap that got the job done, as the grotesquely large caps seemed to rob detail or something. In any case, I'm sure your amp will be fine either way.

Tubes that don't have the standard 6L6 or EL34 pinout are awkward. With the PCB type design, it's impractical to substitute different sockets, add plate caps, etc. Some have done it but I would seek a different platform for such experiments.

I can't comment on your power lamp. Try it and see - it shouldn't hurt anything, assuming you've got sufficient reserve on the 6.3 volt winding.
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Old 11th December 2009, 09:59 AM   #18
webby is offline webby  United Kingdom
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Hi TY,
I have ordered four nos 6P3S-E's and a couple of nos 5u4g's for the amp. They are really cheap to buy from Europe. I will drop in the 810 ohms resistor, should be a little kinder to the tubes.
I was hoping there might be another SE project that SimpleSE builders could try out using the same hardware, just swap the PCB over. Now that would be awesome, have a PCB that drops into the same chassis, just a different type of output tubes like UX5 type.
I make is sound easy, shows how little I know.
I am very grateful to Tubelab & this forum, i have fumbled together a great amp and learnt a lot on the way.
Next up, a phono stage. I will start a new thread for this one.
Cheers
Ian
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Old 24th December 2009, 08:38 AM   #19
webby is offline webby  United Kingdom
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HI all,
Ok, the NOS 6P3S-E & 5u4g's have arrived. I am going to install 810Ohm resistors on the PCB, but what value do i add to the switch to get 560Ohm at the PCB?
Many Thanks
Ian
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Old 24th December 2009, 01:22 PM   #20
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Quote:
Originally Posted by webby View Post
I am going to install 810Ohm resistors on the PCB, but what value do i add to the switch to get 560Ohm at the PCB?
Click the image to open in full size.
http://i69.photobucket.com/albums/i4...E/P1100584.jpg

I just left the 560 on the board, and added another 250 in series with it. If you want to go back to 560, just add a switch that jumpers around the 250.
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