SBL cross-over

[say it as it is]

how much you reckon it will cost to do this?

have a set of SBLs so watch with interest

 

[onlyconnect]

how much you reckon it will cost to do this?

have a set of SBLs so watch with interest

me too!

Tim

 

[James]

1. Am I correct to think that the 2x 1.5uF bypass caps (C3 & C6) are less critical and something basic like Jantzen Cross Cap will do just fine (instead of ClarityCap CSA/Miflex MKP-14) that I plan to use elsewhere?

C3 is in series and used on the HF filter, so more critical than C6, which is parallel with woofer.

2. Is it worth spending more (ClarityCap CSA) on the 22uF, 4.7uF, and slightly less (Miflex MKP-14) on 12uF, 16uF, and 1.5uF (C4)?

In a similar vein to my first point, the HF section of the filter will benefit more from better caps. All of them.

All the inductors will be replaced with Jantzen Air Core.

3. As 135uH is not a standard value, I plan to ask the dealer to send photos of 130uH and 140uH side by side, work out the additional coils on the 140uH and unwind half to achieve 135uH. Would this work or am I being silly...?

Do you know what the DCR values of the original ferrite cored coils? The replacement air-cores will need to have the same value. There won't be much difference between 130uH, 135uH and 140uH. That's less than 4% difference. Go with the 140uH. Pictures won't tell you how much to unwind. An LCR meter will.

4. I intend to replace the resistors (changing 1R to 2R and 27R to 20R respectively) with Mills MRA-10W, or will Ohmite Audio Gold be equally good?

Don't forget R3. Mills are fine.

 

[poorcow]

Thank you, James.

So good caps for LF section, better caps for HF section.

The 135uH (and each inductor's DCR) value is based on John's findings. I'll find a way to borrow a LCR to measure.

Will replace all 4 resistors with Mills.

Much appreciated!

 

[Mosquito]

Hi Poorcow. Have I missed something in the thread? Changing the resistors from 1R to 2R and the 27R to 20R in the HF
I think somewhere someone changed these to something else 10R?
Looks like TimH has fitted a 12R mills resist and a Powertron resistor Value not given in his writeup. How has that setup gone?

 

[timH]

Hi Poorcow. Have I missed something in the thread? Changing the resistors from 1R to 2R and the 27R to 20R in the HF
I think somewhere someone changed these to something else 10R?
Looks like TimH has fitted a 12R mills resist and a Powertron resistor Value not given in his writeup. How has that setup gone?

Its 2r. New crossovers were definitely worth doing and cost around £250 for parts. I’ve used four hackernaps so each driver has its own monobloc amp

 

[poorcow]

Have I missed something in the thread? Changing the resistors from 1R to 2R and the 27R to 20R in the HF

It was a typo. I've opted for 1R to 2R and 27R to 12R.

Apologies for not following up sooner as was busy making a new board for the crossover as I prefer to keep the stock one untouched.

 

[poorcow]

Hello All,

I’ve got the components for the crossover now and have prepared artwork for a new PCB.

I’ve not deviated much from the original as the initial plan is to use it on the back of the cabinet, therefore I’ve just stretched/shortened the tracks based on the physical dimensions of the components. It's a tight fit!

Would you kindly have a look and proof it for me as I worry that being so close to the action and might have made a terrible schoolboy mistake or two...

Once I have confirmation that there’s no issue with the artwork, I will proceed to get the PCB made and get the parts on and let it sing...

As always, thank you in advance for your time and input.

Cheers.

https://flic.kr/p/2kVmxYX

 

[2_dive]

How about getting a group buy for the boards. I would have a pair and I know of two others who would as well.

 

[chrisn]

I would be interested too. Yours will be better than my home made effort. I populated it with components which came from clive's crossovers. Sounded good but not really any better than the Naim original. Ended up blowing the 8.2r 10w and a main driver at party volume.
https://www.dropbox.com/s/t504wlsqbegk060/Crossover FINAL ETCH.jpg?dl=0

 

[say it as it is]

group buy sounds like a plan id be up for that plus someone to hold my hand with a how to guide haha

if a group buy was possible id be up for a couple of pairs

 

[say it as it is]

Looks good is a group by possible then?

 

[jagdesign]

I'm sure my dad would be keen to give these a go, so count me in too please!

 

[say it as it is]

Is a group buy possible then?

 

[Mosquito]

Looks very interesting . Can you list exactly which components you are fitting into the board so I understand how its all going to combine . I got as far as designing a x over board with CSA Clarity caps. air cored on the LF and and foil inductors on the HF. Similar to Avondale and ended up with a board which was 140 x 250mm. Should fit into the back of the rails on the SBL . Much bigger than yours and possibly overkill.

 

[Mosquito]

Because I am sad and have nothing else to do I have created a spreadsheet for the cost of making the crossovers. Might save you a bit of work. I looked a Humble Hifi's capacitor test ( humblehomemadehifi.com) and used the ratings from his site.(Thanks for the work put into this ) Avondale crossovers use Ansar Superior which achieve a 7.5 rating ,Clarity caps ESA range go up a bit to 8.5 and so on up till Jantzen Superior which get a 10+ However the cost goes up significantly to get there . Deeper pockets required !
Hope this is of assistance to you . You need to watch the size of components as some of these capacitors get big. In the post just above this I have shown a layout for Clarity caps CSA and ended up with a bigger board than std Naim The 22uf capacitor varies significantly in size Clarity cap ESA 40mm diam x 45mm Clarity cap CSA 40mm diam x 51 length Jantzen superior is 52mm diam x 70mm so significantly bigger


https://www.dropbox.com/scl/fi/5oz5...ver.xlsx?dl=0&rlkey=r80knvp3f23ldfbrfaoekzgpg
With a bit of luck this is a link to a spreadsheet which gives the price of making a crossover using different capacitors . I have priced up Ansar Superior , Clarity Cap CSA and ESA ranges , Jantzen Cross caps, Standard and Superior. Mills Resistors £5.04 and Jantzen are £2.54
Prices range from about £ 63 up to £244 per side
Hope this is of some use. My thoughts are that the SBL is probably worth spending a couple of hundred quid on the crossover but not £500+ so I am looking to the Clarity Cap CSA range .
Add to this Naim plugs x4, 2mts speaker Wire, PCB boards and some banana sockets and you are about ready to go.

 

[poorcow]

Ended up blowing the 8.2r 10w and a main driver at party volume.

Did you find out what was the cause?

I've not organised/participated in a group buy before, but if my proto-type does work, I'm happy to get more made.

However, before we get there, I'm still waiting for advice if my version is going to work, so for everyone's convenience, I've just learnt how to insert a photo here.

Many thanks.

 

[say it as it is]

well i got a reply from wilmslow to make a new set from scratch at £170 a pair plus vat

 

[Mosquito]

If that is with some half decent capacitors then Its not expensive I would suggest . What were they suggesting ?

 

[say it as it is]

They said built to the Avondale layout not as expensive parts clearly but what they spec on their own builds so imagine decent as they are well regarded