SDA 2B crossover build considerations

hauxon

I'm trying to put together a shopping list for my 2B crossover build. I would be thankful if some of you would read over my list and let me know if there is something missing or wrong.

Prices are in british pounds and from www.hificollective.co.uk

Gimpod boards and connectors
Polyswitch - jump it (or 0.5 resitor haven't decided)
TL mod - 2x 12uF 250V Claritycap CSA - £16.17 (ESA 0 since I alreade have em)
2.7 Ohm resistor. 2x 2R7 Duelund CAST Resistors - £50 (£29 standard)
750pf Silver Mica bypass Capacitor. - Not needed??
12uf Polyester Film Capacitor. 2x 12uF 250V Claritycap CSA - £26.96 (£18.88 ESA)
20uf Electrolytic Capacitor. - 12x 10uF 250V ClarityCap CSA - £150.48 (105.36 ESA)
0.4mh Inductor. - 2x 000-1489 0.4mH Jantzen Air Core Wire Coil AWG22 - £3.22
1.25mh Inductor. - 2x 000-1137 1.25mH Jantzen Air Core Wire Coil AWG20 - £6.58
2.50mh Inductor. - 2x 000-1695 2.5mH Jantzen Air Core Wire coil AWG20 - £9.8
16mh Inductor. - 2x 000-6577 16mH Jantzen C-Coil, 14AWG - £110.94 (£51.22 000-0873 air coil)

---

Total CSA: £374.15 / $499 (not including gimpods)
Total ESA/Standard Duelund/16mH air/ reuse 5.6 uF caps: £224.06 / $299

18uF+22uf on dimensional array + 4x 10uF (instead of 12x 10uF)
CSA £349.03 / $465
ESA: £206.46 / $275

And now some questions.

1. The dimensional array originally has two 20uF caps making a total of 40uF. Am I right assuming I can use a 18+22 rather than 4x10F?

2. The 750pf Silver Mica bypass Capacitor is not needed?

3. The original plan was to use ClarityCap ESA but I've started thinking that I should maybe use the new CSA. Any thoughts on this? Any sense in mixing 'em? Where would it be the most beneficial to add higher quality caps?

4. Does anyone have opinion on Duelund standard resistor vs Duelund Cast?

5. In general would it be worth spending the extra $150 for the better components?

Hope I'm not annoying ppl with too many threads!


Hrannar

hauxon

TL Mod should bhave been 2x 5.6uF ...just a typo.

westmassguy

The CSAs are essentially ESAs with an improved connection between the electrodes and the leads. http://www.claritycap.co.uk/products/csa.php
Clarity makes a 39uf which is well within tolerance for the 40uf, but the 18 + 22 will also work.

hauxon

Thanks for the reply westmassguy. I might just go with the 39uF cap then. I already have ESA 5.6uF caps at hand that I bought for the TL mod. Do you think I should buy the CSA version of the 5.6uF if I go the CSA route or are they sonically close enough so I could use my ESA caps with the CSA?

I actually started doing the TL mod tonight on the original crossover. Left speaker almost done.

westmassguy

Save your money, and use the ESAs

hauxon

Just listened to the speakers after doing the TL mod. I used the ClarityCap ESA 5.6uF I had and cut off and jumped the polyswitch. I left the 750pF in place since I kept the old caps (for now).

The difference is quite obvious, I thought it would be more subtle. I can hear great difference right away with cymbals, a ride cymbal is less bright and more subtle/soft. Stereo imaging also seems improved. All listening was done at moderate/low levels since the family is asleep. Will have to listen more in the over the weekend. First impression is positive.

I might post some pictures tomorrow.

hauxon

I might just use the original crossover boards and keep the original inductors too. Since Claritycap has a 39uF resistor it might not be that hard to fit the caps. HifiCollecti e don't carry Mills so 29 pouns for Duelunds is lrobably less than ordering Mills from the US with shipping.

hauxon

My SDA 2B Studio's ready for surgery.


Here's the unmodded crossover. The crossover board is mounted to the inductor with those white pins/clips. It's easier to loosen them on the inductor side.


I has some trouble with loosening the inductor since the not on the inside did turn with the bolt. Ended up removing the XO board from the inside to be able to hold the nut while turning the bolt. Probably the most time consuming part of the TL job.


Here are the RD0-198 and the SL2000. I find the older one looks nicer and has better quality plastics in the frame. ..but who cares!! You can connect the black wire to the smaller plug on the tweeter (+) and the white (-) needs to be connected to the larger plug.


The 5.6uF cap in it's place. I read somewhere here one the forum that the cap should be soldered into the top cap hole and hole labelled H. Hole H was however covered with glue from the inductor so I found another hole that seemed right.


The solder points seen from the back.


I snipped the top off thepolyswitch and folded the legs together and soldered to make a jumper.


The TL mod finished. Next up recapping!

xschop

Curious if the DCR on those new 198s is 5.5 ohm?

hauxon

xschop wrote: »

Curious if the DCR on those new 198s is 5.5 ohm?

I read 5.6 ohms somewhere.

Here: http://forum.polkaudio.com/discussion/73470/change-in-resistance-with-polyswitch-removal

MrBuhl

Looking good - I love my 2bTL's!

VSAT88

I only have 2b's...Booo Hooooo.

VSAT88

OH, and nice work !

headrott

Didn't read the whole thread, but I highly recommend buying the Duelund Cast resistors instead of the "regular" Duelunds. They are absolutely worth the little extra money they cost. Nevermind, if you already purchased the "regular" Duelunds.

Edit: I just now noticed your number 4 point in your OP. YES, my opinion is you buy the cast. The clarity and detail difference is very apparent between the brown colored Duelunds and the Cast (black) colored ones.