Hi all,

This is my long awaited project. After months of researching what to do, selecting the best parts (IMHO), and finally apportioning the time required to do the job, it's done. WOW!

I remember when I was at university in 1977, I walked into the local B&O dealers in Johannesburg (Recordia - for those who may remember), and stood open-eared and closed-mouthed listening to the latest B&O systems (Beomaster 6000 Quad, Beomaster 4000, Beogram 6000, with S-60's), on an Enoch Light Quad demo LP.

That sound was just out-of-this world!

I just knew that THAT was the stereo I wanted. Of course, I had no financial wherewithal or means then, to accomplish my goal.

However, fate was kind, and scouring the second-hand stereo stores over the next couple of years, I picked up 2 pairs of S-45's relatively inexpensively, which was the impetus of my B&O collection.

Fast forward about 30 years later to 2006. For many years now, my stereo has been sounding jaded. Just not enjoyable anymore. I had already upgraded the power and audio capacitors on my Beocenter 9300, and done the CD-transport mod. On my Beomaster 3400 Quad, I'd done a major rebuild, and additional mods, and also mods on my Beogram 4500 RIAA amplifier.

But there was still something missing, when I sat down to listen to music - like listening behind a heavy curtain.

I thought that my age (clocking 50) was starting to affect my ears, but my flight physical still puts my hearing in the exceptional top 0.5%, even though my vision is slowly starting to go! But it's my ears which I need for appreciating good music, not my eyes!

I even started to consider buying new speakers (but in my heart, I knew that was NOT what I really wanted).

Following the forums here, I started to get interested in redoing the speakers' crossovers. I thought that just maybe, that would help, but I wasn't holding out for any miracles. Ha Ha!

Before starting any work, I like to familiarize myself with all the technical detaiIs, and understand thoroughly what I am planning to do.

That encourages me to start with a clean table in my workshop!

I'll be writing up the project, as time permits!

Menahem Yachad

Good luck, Menahem.
I am really looking forward to following this thread.
How kind of you to share it with us.

Andy T.

As I said before, I am looking to do this on a pair of S45-2s and a pair of S30s as soon as my capacitor kits arrive from Martin, so this is a very timely thread.

Thank you for sharing your progress with us,  

That's the nice part about this site - there are many good things from one another's experience to enjoy!

Here is the circuit diagram, which I wanted to compare to the actual wiring onboard.

This is the XOver still mounted in the cabinet - it has 2 screws to remove it.

The board is made from paper fibre, with wiring slots on one side - really cheap stuff, but it's held out for 30 years.

Here's a close-up of an "alert area", which jumped right out as very obvious.

2 of the 3 capacitors are showing that they are joined together. Nowhere in the circuit diagram, are 2 capacitors shown joined together.

After examining the actual board wiring, I deduced that the positions of R5 and C3 were reversed.

I have seen many instances of discrepancies between the orignal Printed Diagrams in the B&O Service Manuals, and the actual wiring, so once again, I stopped to consider.

The first thing I did, was think "outside the box" (the one on which I'm presently working).

I opened up the other 3 S45 boxes to see if they had the same issue. All 4 had the same wiring, so it was not a case of a sleepy assembler.

I concluded that it was probably not an issue to reverse the position of a capacitor and a resistor, and it was easier this way on the assembly-line.

On the subject of new capacitors.....

I just replaced the capacitors on my S55's. 3 caps on each crossover, unfortunately haven't found a replacement for the 3rd cap, 6.8 mfd 63v (might have to ask Martin) but just changing the others.....Wow!! Almost burst into tears (seriously & I never cry!) Before my speakers were far to tingy, bit screamy and I had not much bass. Now its just wonderful and I can turn them up nicely without my hears hurting from too much midrange!! Imagine what they will sound like with the 3rd cap replaced!!

I'll be reading this post for sure to see how the S45s turn out!

When doing a lengthy thread like this, Menahem, there is a tendency to think no-one is watching!
I can assure you that we are following with interest.
Keep up the good work!

Andy T.

Hi Francois,

I've had a lot of luck with Solen Audio Metallized Propylene Audio Capacitors (made in France) - quite inexpensive, and high quality - try www.solen.ca

The PB680 6.8uF 400V is $3.35 FOB Montreal.

I decided to use AuriCaps on my own speakers - much more expensive (retail - about $48 each for the 16uF model), but through contacts, I got them at less than 1/2 price.

I'm sure that some of you would feel that that's excessive - after all, we are looking at 3 of these - around $80 (delivered) for EACH of the 4 speakers (Total 12 Capacitors), not including labour!!!!

Why not just buy a new speaker, and be done with it?

Well IMHO, that's exactly what this forum (and many of our personal motivations) is NOT about.

My personal motivation is to keep these old, magnificent units alive, and sometimes a little bit of extra care and effort (and/or money) makes a big difference, in performance or longevity. 

In this upside-down world of buy-today, throw-away-next-week junk, I derive much pleasure from enjoying extraordinarily high-quality sound from a 30, 40, or 50 year-old piece of equipment, which has been lovingly restored by my own hands.

Anyway, I am fortunate that the S45's do not have a foam surround (which deteriorates, as Andy found out), but instead rubber. Over the years, I've regularly sprayed ArmorAll on the rubber surrounds, just to keep it pliable, and prevent any unlikely deterioration.

I also got fed-up with the difficulty of removing the grill-covers, where they stick with the friction of the mounting ball-nipples. I solved that problem by spraying the nipples with Silicone Spray, which makes removal and replacement a piece of cake! 

Hi Andy,

Thanks for the comments - kind of feels like "Big brother's watching you!"

Back to the project:

Auricap sent me 12 x 16uF 400V, even though I had ordered 15uF. Not a big deal, as they measured out at between 15.7uF to 15.9uF each, and they are spec'd at 10% tolerance, so that's just fine by me.

The 400V spec is super - it can handle well over what any of my amplifiers can throw at it. The minimum which one should consider when replacing speaker caps is 100V rating.

Note that they have a red lead and a black lead, even though they are bi-polar. This is quoted directly from Auricap's web-site

http://www.audience-av.com/capacitors/a_applications.php 

Auricaps are standard bipolar film cap construction.

The black lead identifies outside foil so low noise performance can be optimized.

The black lead always connects to the lowest impedance point.

In signal path applications the black lead is "in" and the red lead is "out."

In power supplies the black lead should be connected to ground and the red lead to the + or – voltage.

In loudspeaker crossovers the red lead should be connected toward the + terminal on the drive unit.

So paying close attention to the above sentence, I set about deciding how I would arrange the layout on the fibre-board.

Referring to the previously posted Circuit Diagram - on C1, the Red lead is on the right; on C2 and C3, the Red lead is down.

Because the new caps are so large, I decided to reverse the positions of the 1.0 Ohm and 3.3 Ohm resistors (3W), so that the 3 new caps would lay end-to-end, making the most use of the board's real-estate.

Thanks for update.

I agree about wanting to keep older kit alive, even if it means spending more than the equipment would cost to replace. 

Apologies if I am missing the obvious here, but are the components soldered on the reverse of the circuit board or are they being pulled in and out of the slots in some way?

 Simon

Great reading, I should have a go at doing those in my Beovox 1000's.

Craig

Hi Simon,

The slots are a crude attempt at a cheap through-the-hole bread-board.

Holding the board vertically in one hand, the insulated part of a wire in the other hand, and the exposed portion in your teeth, you pull the exposed portion downwards through the slot!

Right! You get the idea!

Then you twist together the exposed portions of the other wires passing through the slot, and solder them all together.

Simple enough - but the fun starts when you want to SEPARATE the wires to move the component's position to another slot. Ha Ha!

The practicalist would say - just cut the inaccessible wire lead, and be done with it.

Oh, but that's not the done thing for a nitpicking perfectionist like me!!!!!!!!!!!

So I curse healthily, and separate the wires slowly.

Right - On with the project.............

So I am now ready to mount my newly designed fibreboard back onto the 2 standoffs inside the speaker.

I had a niggling thought at the back of my mind - what about the clearance between the woofer's magnet, and the new fat capacitors?

As fate sometimes does smile on me, it turns out that I was fortunate in not trimming the original generous lengths of wire on the new capacitors. I had considered mounting the capacitors flush on the fibre-board, and securing them with hot-glue.

Glad I didn't!  If I had mounted the caps flush on the board, the woofer would not have been able to mount flush on the speaker cabinet.

So now they are distanced laterally from the board, with plenty of clearance from the magnet, and I ensured that they would not flop around by padding them generously with baffle material.

And now to close up the cabinet, and connect them to the BC9300 receiver.

The BC9300 specifies 2 x 80W into 6 Ohms.

The S45's are 45W, 4 Ohms each.

So I've got the wiring hooked up with each amplifier channel feeding 2 S45's in series, total 8 Ohms (nominal) impedance per channel. That's AOK in my book.

Over to my favorite music LP's - one of my Enoch Light's Project 3 CD-4 Instrumentals.

Put it on my BG4500, with modified RIAA, and SMMC2.

So I retire to my favorite chair in the middle of the living room - BTW, here's a picture of one wall, showing the corner wall unit, I built from 3 solid trunks of Bubinga (African Rosewood). Not a single piece of chip-board or sandwich-board in there.

Took me 9 months of working most afternoons!  

One S45 is on the top shelf, another S45 on the shelf on the right side, and 2 S45's behind me wall mounted in the corners.

Press PHONO on the BEO4, and..... Pure Heaven......

Sounds I don't remember hearing before - clear, distortion-free highs, bass more pure and powerful (even though this is not a really Bassy woofer) than I ever remember.  YES!!! This is what I've been waiting for. This is the cream on the cake, which confirms the worthwhileness of all my previous mods on the Receivers and Turntables.

These are great speakers - period!

Anybody who has the old passive Beovox's - do your ears a great favor - replace those old capacitors!!!! 

Let's hear it for Menahem

Well done mate! Doesn't it give you a sense of pride?
Love the photo' of your dining room too. It's obvious you are a perfectionist.
Trying to work out what is covered in a transparent dust sheet under the shelf unit. Is it a sewing machine?

My next project is going to be a Beomaster.
Over the last month I have bought....
One Beomaster 4000 plus a spare that Craig gave me for nowt
Two Beomaster 1000s
One Beomaster 1700 with Beocord 1700.
Now I need a crash course in soldering, guess this £5 soldering iron from B&Q will need replacing.

Andy T.

Andy, you are too kind!

Yes, it is a great feeling of satisfaction. I love doing these electronic things myself - ever since my fantastic dad bought me a Radionic set (I still have it) for my 10th birthday!!!

When you get to your Beocord 1700, give me a call - I've got some left-over bits for that. Actually Martin Dillen gave me a lot of help in the rebuild of my BeoCord 2200 (the Dolby version of the 1700) - kudos to him!

As far as soldering equipment goes, I never stinted on that right from my earliest days - I highly recommend the Hakko 936 (Japanese) with an additional round 0.8mm tip. I had the Weller solder station for many years (and many repairs), but this Hakko unit is like the Rolls Royce quality. Always use solder paste, even when others tell you that you don't need it. I find that good (patient) soldering technique is great therapy at the end of a long rushed workday, and I always look forward to it.

You're right, it is my wife's sewing machine - my mother (I'm blessed with great parents) taught her to sew, and now she earns a bit extra pocket-money doing neighborhood seamstressing. It sits on a solid Stinkwood folding table made by my great-uncle in the early 1900's.

Here's a close up of my BC9300 and BG4500 in the wall unit - I never took off the BG4500's original plastic covering . Let's see who can identify the 1980's era accessories!