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Old 31st July 2015, 03:18 AM   #1
jdrouin is offline jdrouin  United States
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Default Tubelab SE 300b Build Thread

Finally started my TSE build tonight and thought I would document it and ask questions here. I soldered in R1-R7.

When soldering R7, some of the solder might have flowed onto the adjacent pad for R6, but I can't really tell. It could just be some flux in there (or it could be nothing). If I read the schematic right, R6 and R7 are actually connected at this point.

Anything to worry about? Should I try to clean it out?

Here's a closeup image.

Click the image to open in full size.r6-r7-cropped by jeffdrouin, on Flickr

Not my cleanest work.
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Old 5th August 2015, 03:31 AM   #2
BillEpstein is online now BillEpstein  United States
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Look at the schematic, they're connected.
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Old 6th August 2015, 03:41 AM   #3
jdrouin is offline jdrouin  United States
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Thanks for confirming, Bill.

I finished soldering the resistors and have begun on the tube sockets, starting with the octal. Some of the gaps in the pads were so large that it was difficult to fill the entire hole with solder, else I'd have to use an excessive amount and it would start running toward the socket. So, I soldered at the side with the smallest gap. It feels like a *very* secure joint and I don't think I need to fill them.

Is that OK, or should I try to fill the entire hole?

Here's what they look like:

Click the image to open in full size.socket-solder by jeffdrouin, on Flickr
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Old 7th August 2015, 04:31 AM   #4
jdrouin is offline jdrouin  United States
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My *very* large Electra-Print OPTs arrived today with their lemony scent like Pledge on steroids, so I'm planning the layout for the chassis and could use some advice on component orientation.

Here's what's going in it:

* Tubelab SE board w/300Bs
* Weber 2022798 laydown PT
* Electra-Print OPTs (5k:8ohm, 100mA, 15w)
* Triad C-14X choke (6 Henries, 200mA, 150 ohm)
* Motor run cap for C5

I've been sizing based on the availability of Hammond chassis/covers at Angela because I have small kids and want to make sure everything is well protected. I might have to go with different dimensions and make a cage, though.

(A) 16 x 8 x 3 aluminum chassis -- PT, choke, and future motor run cap on the left, board in the middle, OPTs on the right

Click the image to open in full size.layout-a-02 by jeffdrouin, on Flickr

Click the image to open in full size.image by jeffdrouin, on Flickr

(B) (more spacious) 17 x 12 x 3 aluminum chassis (no cage for this size, would have to fabricate), with the OPTs behind the board, PT back left corner, choke, and cap on the left. Length and width can be smaller here.

Click the image to open in full size.layout-b by jeffdrouin, on Flickr

Option A is the easiest, but I'm a little concerned about sandwiching the board between the magnetics, which are pretty close. Also not sure how the laydown PT might interact with board components, tubes, or choke.

And also, I've seen a lot of TSE builds in which Electra-Print OPTs are right next to each other with their laminations parallel, as in (A). I assume there is little to no magnetic interference between them with that arrangement?

Let me know what you think, and if there are other layouts I should consider.

Thanks!

Jeff
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Old 7th August 2015, 06:17 AM   #5
zman01 is online now zman01  Bangladesh
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Tubelab SE 300b Build Thread
Jeff,

As far as I know, placing OPTs side by side with laminations in parallel will be ok - you should have the power transformer at 90 degrees to the OPTs and that looks fine in the layout.

Is the Hammond chassis cover tall enough to accommodate 300B tubes? If I am not wrong, the chassis cover height is 5.2", while a 300B tube (JJ datasheet linked) is taller:

http://www.hammondmfg.com/pdf/1451-30.pdf

http://www.thetubestore.com/lib/thet...re/JJ-300B.pdf
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Old 7th August 2015, 05:41 PM   #6
Evenharmonics is offline Evenharmonics  United States
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Personally, (A) layout with OPTs turned so that bell housing face each other.
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Old 7th August 2015, 08:05 PM   #7
w5jag is offline w5jag  United States
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Quote:
Originally Posted by jdrouin View Post
.... Also not sure how the laydown PT might interact with board components, tubes, or choke.
Flat mount PT's are all I've used on my Tubelab amps, SSE and TSE, and I have observed no interaction with board components.

If you look at my TSE in the picture thread, that was later rebuilt to an SSE in the child resistant thread, you can see how compact both amps were built and how close the boards are to the magnetics. A lot closer spaced than on your 16 x 8 chassis.

Win W5JAG

EDIT : If you are going to use a Hammond cage, be advised that the perf sides have a "lip" that goes inwards about 1/8 or 3/16" of an inch ( don't recall off the top of my head. ) Doesn't sound like much, but when I rebuilt the TSE into the SSE and started fitting it for the cage, this was enough to necessitate a mandatory change of OPT's from Transcendars to the smaller Edcor's, with attendant filling of extra uneeded holes and drilling of new holes. Not a royal PITA, but an unexpected PITA that I did not anticpate.

That 16 x 8 chassis might be problematic with a cage and those huge OPT's. Just an FYI FWIW.

SECOND EDIT: as ZMan correctly notes, there is a height limit under the cage. I think 45's and 5930's would be OK. 300B's, I'm not so sure. Also, as you trap more heat under and close to the sides of the cage, touching the cage, while not a shock hazard, may be too warm to the touch.

Some of my thoughts and experience on this can be found here, and may or may not be useful to you:

A Simple Child Resistant SSE

Last edited by w5jag; 7th August 2015 at 08:25 PM.
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Old 7th August 2015, 08:27 PM   #8
w5jag is offline w5jag  United States
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Quote:
Originally Posted by jdrouin View Post
....

Is that OK, or should I try to fill the entire hole?
I think you should fill the entire hole. The solder tends to disappear over time.

Win W5JAG
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Old 7th August 2015, 09:21 PM   #9
jdrouin is offline jdrouin  United States
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Great, thanks for all these responses. This is very helpful, and I'll try to move the socket pins to the middle of the holes in order to make the solder adhere and fill better.

I found less expensive Bud Industries aluminum chassis on Amazon, and in dimensions like 17 x 12 x 3 that I think will work better to allow more space and cooling for these large components.

About the cage height: I'm planning to mount the PCB on common hardware screws with nuts and washers so as to make the height adjustable. That means I could lower the PCB to allow the 300Bs to fit under the cage. It would also be possible to shim the cage up a bit to make more room.

However, if I want something a little less nice than the circular-hole perforated metal, for $20 I can buy enough 22 ga sheet and expanded metal at Home Depot to make a 6-inch tall (or taller) cover, allowing more room between the cage and transformers. Would be very easy to cut with aviation snips and bend on my worktable edge.

2 more nuts & bolts questions:

* Will this thing get hot enough that I should use high temp primer and paint on the chassis & cage?

* Any recommendations for gauge and brand of solid copper hook up wire to use?

Thanks,

Jeff
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Old 7th August 2015, 10:28 PM   #10
BillEpstein is online now BillEpstein  United States
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FYI.

I bought a Hammond cage for my 10x17 SSE chassis. With 5AR4 and a pair of KT-88s, it became shockingly hot and now gathering dust.
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