JMLab/Focal Spectral 913 Crossover Upgrade

[BeyondTheGravestone]

Greetings everyone,
I'm currently working on a pair of JMLab/Focal Spectral 913, rebuilding and re-finishing the cabinet and making some improvements in terms of acoustical issues (mostly dealing with sound diffraction on some rough edges), I'm a cabinet maker.

And I removed the crossovers, realized that some inductors are broken, so I'd love to re-make a crossover from scratch (but keeping original values), with better quality parts, but I have a lot of questions (photos will be linked straight after) :

- I'm a newbie so I can't draw the schematic from this PCB, if anyone can help me drawing it (in order to make a different placement for better quality - and most probably bigger sized parts they will handle)

- On the resistors, there are no values written, so how do I know original values ? (I mean I could mesure them after removing I guess, but how I'd know if those values are originally correct ?)

- Same problem on Iron Core Inductors (which will be replaced by Air Core inductors)

- Could you recommend me some great sounding elements (I've heard Jantzen Silver Caps are seen a lot on high quality projects for example), but I don't know much on Resistors and Inductors' brands, I'm ready to spend quite a big amount of money if they improve a lot the clarity compared to original crossover.

Many thanks !

PS : I can take much more photos to show what's written on some elements (resistors mostly)

Regards.

 

[Galu]

I'll give your thread a bump by saying that I'd be content simply to replace the NP electrolytics with Mundorf E Cap AC Series Electrolytics:

https://partsconnexion.com/collections/mundorf-e-cap-ac-series-electrolytic-capacitors

This would be enough to restore the original sound balance as intended by the manufacturer - provided the broken inductors are dealt with.

Inductor wires can break where they connect to the circuit board, but this should be repairable.

The trouble with using an air core inductor as a replacement for an iron/ferrite cored one is that it could add unwanted resistance.

As well as measuring the inductance of any iron/ferrite cored coil requiring to be replaced, measure it's DC resistance - which will be low.

 

[AllenB]

The legwork has been done if someone would like to take a shot at the schematic..

 

[Galu]

Nice work, AllenB!

 

[BeyondTheGravestone]

Many thanks for your answers guys,

@Galu I'd love to upgrade even Capacitors and prevent using Electrolytic (as I've heard they're not the best), am I right ?

 

[Galu]

The loudpeaker will have been 'voiced' with electrolytics in mind. This type of capacitor has a higher ESR (equivalent series resistance) than an equivalent film type, which affects the filter action.

Substituting with film types may make the sound different, but not necessarily better.

Expert AllenB may tell you that, without measurement, the outcome is uncertain. He'll soon correct me if I'm wrong!

 

[BeyondTheGravestone]

Oh ok, perfect, I didn't knew all this !

Many thanks !

 

[AllenB]

Galu's advice has been sound. First, attend to the broken inductors.

If these speakers have had 30 years of unknown use, changing the electrolytic capacitors for like types may or may not offer an improvement, but it would make sense since you have them open at this stage.

 

[BeyondTheGravestone]

Solder them back will be the solution then ?

Yeah I think you're right, I'm replacing all the caps by the ones he showed me then !
And I'll glue everything on the board to prevent from unwanted vibration as well.

Many thanks to everyone !

 

[Galu]

Solder them back will be the solution then ?

Yes, make sure the inductors are soldered in securely and add mechanical support using plastic ties where appropriate (and glue where necessary).

Hopefully, your efforts at rejuvenation will arouse sonic satisfaction. At least you will be able to rest assured that the new electrolytics will extend the life of the crossovers for another 30 years or more.

Do let us know how it goes.

 

[BeyondTheGravestone]

Greetings guys,

Little update, I could get the full schematic of the crossover thanks to Focal who kindly sent it to me. So I can rebuild it from scratch.

I had several asks considering the components and quality of them :

- Inductors, on the Low circuit : I have to get 3mH Inductors, and sould I get Jantzen Audio C-Coil 12AWG or Mundorf BS140 Wire Coil, or even that one : https://www.lamaisonduhautparleur.com/en/self/686-self-ad-30-mh.html (I think this last one is AirCore bur not sure, if so as you guys told me, better choose between the two others right ?) They're around the same price Range so I was wondering !

- Resistors, Should I get Mundorf MResist Classic or Mundorf MR10 range ?

- Capacitors, you told me all of them were Electrolytic right ? (Except the MKP one in the Medium range as far as I can see) So, should I get Mundorf E-CAP or Jantzen ELECAP (Jantzen's is about 3.4€ and Mundorf 2.9€ )?

Many thanks !

 

[Galu]

(I think this last one is AirCore bur not sure, if so as you guys told me, better choose between the two others right ?)

It is an air core inductor. I don't know the differences between the other two as you haven't supplied links.

If choosing an inductor, you should aim for a similar DC resistance to the original, as I mentioned earlier.

Resistors, Should I get Mundorf MResist Classic or Mundorf MR10 range ?

To me, a resistor is a resistor in a loudspeaker crossover application, so fill your boots!

Capacitors, you told me all of them were Electrolytic right ?

They are not all electrolytics, just the ones in metal cans. I've already mentioned the suitability of E-CAPS.

 

[BeyondTheGravestone]

The other two inductors can be found here :

https://www.audiophonics.fr/en/bobi...-copper-wire-ferron-core-coil-3mh-p-6117.html

https://www.audiophonics.fr/en/c-co...idal-coil-12awg-o2mm-3mh-004-ohm-p-14752.html

Fine fore Resistors, thanks !

Ok, I see ! Sure, but do you know if the Jantzen (which is more expensive) has better "sound characteristics" to it, like more clarity or anything considering it's more expensive, or one or the other would be the same ?

Links here :

https://www.audiophonics.fr/en/elec...ectrolytic-capacitor-100v-150f-5-p-15482.html

https://www.audiophonics.fr/en/elec...ectrolytic-capacitor-100v-150f-5-p-15482.html

Many thanks !

 

[Galu]

Inductors:
The Mundorf has a resistance of 0.18 ohm which is 4.5x greater than the Jantzen's very low resistance of 0.04 ohm.
The former will no doubt be the closest resistance match to your existing 3 mH inductors, which will help preserve the intended crossover action.
If you have a multimeter, you can measure the resistance of your present inductors (remember to subtract the resistance of the meter leads) and choose appropriately.

Capacitors:
I don't believe that the two makes of capacitor you are comparing will have different "sound characteristics".
They both have etched or "raw" foil, so are of similar construction. Consequently, they will have similar electrical characteristics.
Both makes have the same voltage rating (100 VDC) and tolerance in their value (+/- 5%). Just choose the ones you best like the look of!

 

[BeyondTheGravestone]

Many thanks for your shared knowledge 🙏🙏🙏

Will keep you in touch about the following work on them, might post the woodwork aspect as well !

 

[MZY]

Hi @BeyondTheGravestone !

Hope your restoration gone well

Actually, I bought a pair of 913 and I would like to change capacitors of the filters (I've done that on 2 others 30 yo pairs of the same manufacturer, the result is remarkable). Although I'm happy with it now, I know ther is some improvments to find in here.

I reached Focal SAV and they told me they haven't filters plan for the 913 (with black painted speakers) anymore, only the 913.1 (with yellow speakers).

Could you share with me the plan they sent you (if it's 913) please ?

Thanks in advance for your help

 

[BeyondTheGravestone]

Sooooo, end of story now.
I'd like to thank everyone for their answers. I'm a pro cabinet maker, so I could reach Focal, who had the kindness to provide me the PDF plans. Though they strickly forbid me to share them... And also, I had the help of "La Maison du Haut Parleur" (which translates by "The House of Speaker Drivers"), whom one of the owners (In the Toulouse region), actually knows the person who used to design crossovers for Focal, back in that era.
But, there you have the finished restoration process, I did heavily modernized them, and upgraded them with much better materials.
@MZY I did sent you A private message, Je t'ai envoyé un message privé.