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-   -   Starting a SSE build (http://www.diyaudio.com/forums/tubelab/216689-starting-sse-build.html)

neomat 24th July 2012 06:58 AM

Starting a SSE build
 
Hi !

Like I said in the thread "Board availability", I received my SSE PCB. It's from the new batch and I've some questions (I think George may/will be updating his website when less busy), so I made my thread...

a_ 2 diodes are added (D3 & D4) on PCB. Referring to http://www.diyaudio.com/forums/tubel...ml#post2978955, it seem to be 1N4007 diodes, like these 1N4007-T Diodes Inc | 1N4007DICT-ND | DigiKey . Am I right ?

b_ A place marked TR1 is also added, which semms to be a GE CL140. I don't see other components that could have be discussed in a thread...

c_ Two unused holes are under C22. What is their function ?

For the moment, I do not have any other component, but here is my purchase list :
- big CXSE25-8-5K Edcor OPT
- Edcor XPWR059 (750V (375-0-375) @ 175mA CT, 50V @ 50mA, 6.3V (3.15-0-3.15) @ 6A CT and 5V (2.5-0-2.5) @ 3A)
- Edcor choke
- Standard purchase list from Tubelab website
- KT88 tubes
- maybe no SS rectifier
- A cathode bias resistor switch (rotary or toggle, don't know yet)

I will take my time (I'm pretty busy (work, familly, ...). moreover, Edcor order is about 400$ :eek:, I'll wait few months to save money...
It's gonna be a really nice project !

Davec113 24th July 2012 03:47 PM

Great, good luck!

If you want to save money, maybe try EL34 tubes first, they are a bit cheaper and I preferred them (-C- EL34) over some new issue Tung Sol 6550s. If you implement your cathode resistor switch you can always buy the KT88s later.

tubelab.com 24th July 2012 11:01 PM

There are 3 new components on the new board. If you really want your board to be exactly like the old board all 3 can simply be replaced by a jumber wire made from a resistor lead.

D3 and D4 are indeed 1N4007. I suppose a purist will use an UF4007 but it shouldn't make any difference since the rectifier tubes characteristics dominate.

TR1 is a GE CL140.

All 3 or these components were added to make life easier on the rectifier tube under start up conditions. Many of the current production tubes aren't built like the old ones were.

You may find that 47uF 500V electrolytics are hard to find. 56uF's seem to be available, yet this is above the reccomended limit for a 5AR4. I am testing the 56 uF with several dozen 5AR4's and the 3 added parts before recommending this though.

The 2 unused holes near C22 are for connecting the circuit from one side of the board to the other. No components are placed in those holes. These "extra" holes have been in all SSE boards made.

These boards use plated through holes. This means that there are copper circuit traces in ALL of the holes. Many of the holes used for component leads are also used for top to bottom connection. Do NOT drill the holes out to fit a fatter component lead.

There has been exactly ONE SSE that didn't work and couldn't be fixed on this forum. I had the builder send it to me and found that he had drilled the coupling cap holes larger to fit some really big caps with really fat wires. This killed the connection, and broke the amp. The cure is to solder the component to the board on both sides so that the component lead completes the connection.

neomat 25th July 2012 06:42 AM

Thanks George for this detailed answer.
Quote:

Originally Posted by tubelab.com (Post 3103376)
You may find that 47uF 500V electrolytics are hard to find. 56uF's seem to be available, yet this is above the reccomended limit for a 5AR4. I am testing the 56 uF with several dozen 5AR4's and the 3 added parts before recommending this though.

Thread about C1 value mentions 33F, which logically seems better for the tube.
Quote:

Originally Posted by tubelab.com (Post 3103376)
These boards use plated through holes. This means that there are copper circuit traces in ALL of the holes. Many of the holes used for component leads are also used for top to bottom connection. Do NOT drill the holes out to fit a fatter component lead.

There has been exactly ONE SSE that didn't work and couldn't be fixed on this forum. I had the builder send it to me and found that he had drilled the coupling cap holes larger to fit some really big caps with really fat wires. This killed the connection, and broke the amp. The cure is to solder the component to the board on both sides so that the component lead completes the connection.

Yep, I saw that in 1 or 2 threads, for example : http://www.diyaudio.com/forums/tubel...ml#post2560571

Davec113 25th July 2012 06:54 AM

Quote:

Originally Posted by neomat (Post 3103715)
Thanks George for this detailed answer.

Thread about C1 value mentions 33F, which logically seems better for the tube.

I would go with less than 47 uF for c1 unless you plan on buying a NOS 5AR4, the new ones will eventually arc over and fail. When I first built my SSE I also had a preamp with a 5AR4, and I had a Sovtek and a JJ go out on me. After purchasing a few NOS tubes I went the next 4-5 years with no problems. The diodes added probably save the new 5AR4s, as they can't seem to perform up to spec. You can get a 47 uF 500V JJ cap from partsconnexion.

rknize 25th July 2012 04:30 PM

33uF should work fine in that position and won't affect the B+ is any meaningful way.

neomat 30th January 2013 06:25 AM

Hi all !

I'm updating this post !
I'm starting soldering, even if I'm lacking R14/ R24 (10K 3W) and R2 (150K 3W), and the GE CL-140.
In BOM, these resistors are metal film oxyde, is it ok if I order carbon film resistors ?

I just have another question : what is the approximative length of Edcor transformers wires?

Thanks !

rock12 30th January 2013 09:40 AM

these are not shown on the schematic? how can they be added to the old design?

neomat 30th January 2013 10:18 AM

You can find D3 and D4 in a post mentionned in my first post, and the CL-140 is added in main input, to be confirmed.

rknize 30th January 2013 02:46 PM

Quote:

Originally Posted by neomat (Post 3348247)
Hi all !

I'm updating this post !
I'm starting soldering, even if I'm lacking R14/ R24 (10K 3W) and R2 (150K 3W), and the GE CL-140.
In BOM, these resistors are metal film oxyde, is it ok if I order carbon film resistors ?!


As long as they have the right power rating, they will work fine.


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