Woofer replacement in old Marantz boxes

I

IvoCRO

Active Member
Hello all,

I have Marantz speakers HD-44 and foam arround woofer is almost completely gone. I know that the best option would be to put new foam suspension, but this is not the option right now (I don't know where to get foam suspension and glue, and I have never change suspension before). I have found in my local shop woofer which fits in box, and has correct impedance, but I have one doubt. Looking at speaker crossover, ther is no any kind of filter before woofer, so all audio frequency range is fed to woofer.

My question is: is Marantz original woofer somewhat different from 'regular' woofer, and can hanle mid and high frequencies? Can I put new woofer which is declared as woofer, (not whole range) speaker?

This is crossover schematic from service manual for HD-44 speakers:

HD-44.JPG

I have asked same question in Marantz forum few days ago, so I apologize for asking for help twice.

Regards,
Ivo
 
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Replacing the foam isn't that difficult, there are plenty of videos online that will show you how to do it. If you can't find someone in Croatia that can provide the foam, there are many Chinese sellers of replacement foam on eBay and Ali Express that will ship to pretty much anywhere in the world, if you can wait a few weeks. Just make sure to take accurate measurements to ensure you get foam that fits properly.

Now, I'm not familiar with this particular speaker, but it does appear to be a relatively entry-level model. It wasn't uncommon on less expensive speakers to have just a capacitor for the midrange and tweeter crossover, with no inductors to limit the high frequency output of the midrange and woofer. Those drivers will naturally roll off at some point. If the drivers are designed specifically for this application, or the crossover frequencies are properly chosen, the woofer will naturally roll off starting at the crossover frequency. This is one of many reasons why simply dropping a replacement woofer into an existing system may not give the desired results, since the replacement is unlikely to have the same rolloff characteristics.
 
Thank you very much for your answer. Finding foam is not easy job here, but I will try to find one as you suggest. I have seen few videos, and in that case buying new speaker would be second choice.
If I manage to find foam, what type of glue is recommended?

Thanks,
Ivo
 
OP is in Croatia, Aleene's is probably not available there. Naming generic types of glue would probably be more helpful to him.
 
Thank you for your answer, but indeed Aleene products are not available in my country. Do you know what type of glue is it?
 
PVA glues – like Tacky Glues – are commonly known as white glues and are water based, using resin as a main ingredient.

Try these places. I bet they have it.

Perlica, art and hobby
Website
Craft store in Zagreb, Croatia
Address: Maksimirska cesta 31, 10000, Zagreb, Croatia
Hours:
Open ⋅ Closes 7PM

Phone: +385 1 4618 023

Rajcic & Ribičić Ltd. Materials
Website
  • In-store shopping·
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Address: Ul. grada Vukovara, 10000, Zagreb, Croatia
Hours:
Open ⋅ Closes 8PM

Phone: +385 99 527 1360
 
Thank you for detailed answer! I have wisited site in Netherlands, and they have foam for this speaker.

Here is the picture of speaker:

IMG_20201104_092909.jpg

Cone looks like it is not centered, but it is, it is just angle of picture taken.

Both speakers plays music on lower listening levels fine. I didn't try them on louder levels.
 
I have started to work on one speaker. This is the speaker removed from box:

IMG_20201209_174723.jpg

And after foam removal with just finger:

IMG_20201209_175214.jpg

I have used wood chisel and started to remove old foam from basket:

IMG_20201209_175422.jpg

Heere is result after foam is completely removed from basket and basket edge cleaned with alcohol:

IMG_20201209_181552.jpg

Here is closer view:

sp1.jpg

Basket edge is clean and without old foam residue. Then I started to remove foam from paper cone. All foam is removed, but what is left is sticky ring of old foam glue, marked with red arrow on picture:

IMG_20201209_185711.jpg


How to remove this sticky leftover from cone? If I try to scrap it, I might damage cone. It is in form of glue. Do you have any suggestion for removing this?
 
Take a sharp knife blade and hold at an angle and slightly scrape the old glue off. Or you could try some rubbing alcohol and wipe it off. I just usually use a knife blade and scrape off what i can. I have no problems with new glue onto old glue. Pozdrav iz Kanade!
 
IvoCRO said:
I have started to work on one speaker. This is the speaker removed from box:





Basket edge is clean and without old foam residue. Then I started to remove foam from paper cone. All foam is removed, but what is left is sticky ring of old foam glue, marked with red arrow on picture:

View attachment 2060144


How to remove this sticky leftover from cone? If I try to scrap it, I might damage cone. It is in form of glue. Do you have any suggestion for removing this?
Click to expand...

Just wipe it down well with some rubbing alcohol and leave what won't come off. It won't separate from the cone, and as long as you don't overdo it with the glue it will be just fine.
 
Thanks for advices, I will try to scrape some more of it or use rubbing alcohol.

@bcbud3 Pozdrav i tebi iz Zagreba:) Da li je 'rubbing alcohol' apotekarski alkohol, ili je to nešto drugo? Pretraživanje kaže da je to 70% alkohol.
 
IvoCRO said:
Thanks for advices, I will try to scrape some more of it or use rubbing alcohol.

@bcbud3 Pozdrav i tebi iz Zagreba:) Da li je 'rubbing alcohol' apotekarski alkohol, ili je to nešto drugo? Pretraživanje kaže da je to 70% alkohol.
Click to expand...
Neznam. Ja bi mislio da su "close enough".
 
Some foam sellers suggest that the last little bits of foam/glue left over may actually improve the holding ability of the new glue - a rough surface gives more surface area.
 
Nat said:
Some foam sellers suggest that the last little bits of foam/glue left over may actually improve the holding ability of the new glue - a rough surface gives more surface area.
Click to expand...

That is definitely true, with plastic cones. Leaving the original glue is definitely the way to go, in many cases. It can be difficult to get glue to re-adhere to plastic, if it's completely cleaned to where it's shiny. No porosity, in effect, without the glue layer.

I don't think it really makes a significant difference with fiber (paper, kevlar etc) cones , as they are inherently porous, anyway.

Regards,
Gordon.
 
To help center the new surround on the cone I take a small depth gage and make little tic marks with a fine point silver sharpie to the cone edges. Keep going around applying slight pressure to the new surround and adjusting as the as the glue dries. Afterword's you can touch up the tic marks with a sharpie close to the cone color. If you shim the voice coil the cone can be lifted up above the basket edge. If you go the 30hz tone route you can put folded paper towels under the cone to raise it up.
pNCC5km.jpg
 
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