Teddy_fr:

Congratulations Rich to your M70 restoration (just a slight criticism about their new fabric  )!
I have used mine during many years and I was very pleased with their natural and linear sound.
Their efficiency is low, less than 90dB/W/m so they need a very powerful amplifier, I think a BM1900 is a little just enough.
I have hooked mine to a Beomaster 8000 with a good Monster M1 MKIII cable and golden banana plugs and in this setup the M70 have revealed all their qualities!
Don't be afraid by the 2x150W RMS of the Beomaster 8000, they hold the power during hours and hours without any problem. Fantastic speakers which have not usurped their qualification of Monitor!

Marc

Thanks.  The BM8000 has caught my eye in the past few months.

When I was in my early 20's, I always wanted a stacking 5000/5500 - or so I thought.  As noted above, I think it'll be a BM4x00 for these M70s.

Last night I got the spare RX 2 back out.  I took the dust cover off and had a close look at the tonearm/counterweight.  I took the counterweight off and the ~2 mm rod was indeed bent.  I estimate the rod was bent about 10 degrees down and 5 degrees toward the outside of the turntable.  By hand with just brute force, I tried my best to bend it back.  Seems to have worked OK.

I did a bit of cleaning with a damp sponge and reassembled.  I have no idea what could have caused the damage.

So, what we have in the dinette has been christened the Frankenbeosystem One twenty-five.  Because that's what you get when you take a pair of Beovox M70s you find locally on Craigslist for $50, a Beomaster 1900 you find locally on Craigslist for $50, and a Beogram RX 2 you find on Ebay for $25 that the seller doesn't think works because she doesn't know to lift the platter and loosen the shipping screws (50 + 50 + 25 = 125).

We interupt our regularly scheduled program to note the Beovox CX 50 restoration is complete.

The woofers were refoamed.

EASIEST.  REFOAM.  EVAR.

The old adhesive/foam peeled right off the paper cone.  I actually cheated a bit and mounted the new foam UNDER the paper cone.  Seemed the best thing to do.  I also decided not to cut into the dust cap to shim the voice coil.  I had shims and replacement dust caps ready to go, but it just seemed unnecessary when the time came.  The woofer is so small, I just made sure there was no rubbing of the voice coil by pushing the cone in a millimeter or two every so often.  Also, I don't know if you'll be able to pick it up in the picture, but I didn't bother trimming the excess foam of the outer diameter.  Also didn't seem necessary when the time came.

Start to finish, I think both woofers took about 50 minutes to refoam.  Then I left them for two days before continuing work.

I left everything inside as is except capacitor replacement.  Used a Solen.  And of course I performed the surgery:  Beovoxian Americanization picutred below.

Based on comments I've read here from people who I've come to respect a great deal, I really expected them to sound like ... well, less than stellar.  The CX 50s aren't so bad.  I'll leave them on all week playing the radio while at work and see how they sound after a proper break-in.

Now that the M70s are done, I'd like to get rid (free to good home(s)!) of the extra capacitors left over from the experimental stage.  See the Private Sales area.

Rich:

Also, I don't know if you'll be able to pick it up in the picture, but I didn't bother trimming the excess foam of the outer diameter.  Also didn't seem necessary when the time came.

Where did you buy these foam-rings? A serious seller would have sold you some that fits perfectly for the CX, so you don't have to trim the outer diameter

Steffen:

Rich:

Also, I don't know if you'll be able to pick it up in the picture, but I didn't bother trimming the excess foam of the outer diameter.  Also didn't seem necessary when the time came.

Where did you buy these foam-rings? A serious seller would have sold you some that fits perfectly for the CX, so you don't have to trim the outer diameter

Good point, I suppose.  I bought generics from the same cat I've bought from before.  Excellent product, excellent service.  Didn't inquire from anyone else for CX-specific parts.  Besides, if the CX-specific parts performed like the original rotted junk, I wouldn't want them anyway!

Well -I guess we'll have to wait another 15 to 20 years to see if those new foam rings rot like the originals...

Trim the rings Chris

And now back to M70 rescue and adoption!

I got the second pair of M70s out this evening and actually listened to them for the first time.

And...

...they sounded great!  Just had the BM 1900 tuner playing the local classic rock station.  One Rush and one Led Zeppelin song later and I was fetching my iPod to listen to a few very familiar tracks.

Bottom line:  even in the less-than-ideal setup shown above, this pair of M70s sound great as is.  I gotta tell you, it crossed my mind to just swap this pair as is out with the refurbed pair (i.e., put them on the new stands and stick the repaired/reclothed frets on them) and see how they sound.  But I resisted the temptation in the end, and instead opened one of the new pair up.

Yep, looks like an M70 on the inside, too.  Almost the entire volume of the box is filled with damping material.  I think there might be 20% to 40% more damping material in this set as in the other set (original, that is - I put different material in during the refurb).  The refurbed pair definitely has less damping material in it than this pair, but the new damping material is also denser.

Side note:  one thing I haven't gotten around to yet is playing with the amount of damping material in the refurbed pair.  And the type.  Maybe I should try putting the original material in for a round of listening.

Anyway, I pulled a bit of damping material away to look at the crossover network.  Hey!  What's that white thing I'm pointing at?  A capacitor, yes?  But is that original?  Or a repair?  Martin mentioned way back (on page 1 probably) the crossover network changed during production.

In my BM 901 I have these white caps, EVOX, the 901 was made until 1977, the M 70 production started 1975, so it may be original.

Worked on the second pair of M70s today.  I put my usual terminal cap on the backs, cleaned up the screws a bit, tried to clean the wood venear as best I could, and put Martin's recommended bead of epoxy on the phase link drivers.

The one blemish I couldn't get off is pictured below in the corner of the speaker.  A spot about 1.5 cm in diameter.  This picture is of the top of a speaker.  Perhaps a previous owner experimented with some kind of wood finish but didn't proceed.  If that's the case, WHY IN THE WORLD EXPERIMENT ON THE TOP?!?!  Use the bottom for crying out loud.

I don't know.  Maybe it's a nail polish spill or something.

There was some streaks of gray latex paint on one of the sides.  Much wood cleaner and rubbing with a cloth later the paint is gone, but so is the finish.

My Beomaster 1900 had a problem prop up this week.  Tuner presets 3 and 4 started playing the same station.  IIRC, preset 3 is playing correctly, and it's preset 4 that is not playing the channel it's tuned to, but rather playing the channel preset 3 is tuned to.

Never having experienced this type of fault, as soon as I noticed it I shut off the unit and unplugged it.  Don't want to take the chance of initiating a cascade of failures.

I pulled an NAD 7140 out of the garage that was just sitting on the shelf and brought it into the dinette.  I hooked the second pair of reassembled M70s up and had a listen to a few songs on my iPod.

Man, the second pair of M70s sound good.  After listening for awhile, I took the <WARNING - HIDEOUS FRET CLOTH ALERT> frets off the first pair and put them on the second pair.  No change in treble response.  Then I thought I'd get some vinyl out.  But what?

Hadn't listened to any Queen in awhile, so I thought I'd fire The Game up.  I turned it up pretty high, since the kids were in the bathtub and Mrs. Rich was dying her hair (i.e., no one was watching television in the living room).

Oh.  My.  Goodness.  The third cut is Another One Bites The Dust.  If you're not familiar with the song, it's built on a famous electric bass riff.

It was like I'd never heard the song before.  This was the kind of bass response I'd expected from the other pair of M70s a month ago when I refurbished them.

Was I imagining better bass?  Only one way to find out.  I swapped back in the fully refurbished pair and had a listen to Another One Bites The Dust again.  And again.  And again.

Not only is the bass response not up to the same level as the second pair, there's even some distortion in the right channel.  Does the source of the distortion have to be electrical?  Could it be mechanical?  A resonance that can be eliminated with damping material changes?

I left the fully refurbished pair wired up and shut down the system for the night.  I'm going to do some work on the cabinets of the second pair and then reinstall them.  After that I'll try to figure out why the bass response of the first pair isn't up to snuff.

I love Queens and Freddy Mercury, I have the DVD of the  last concert at Wembley, play it again and again.

As for your Bass and distortion problems, it may be your dampening, I have one of my S45s in a corner and I have to move it away from corner some 60/70 Cm to get the same sound as the other speaker, that one standing some 30 Cm from a straight wall.

Interesting waiting for news

From serial number 1442001 the Beovox M70 received a new woofer and four or five changes
were introduced to the crossover.
The fastening of the front grill also changed to a pin/spring lock instead of glue.

Your crossover looks original and seems to be of the later type.

Martin

Dillen:

From serial number 1442001 the Beovox M70 received a new woofer and four or five changes
were introduced to the crossover.
The fastening of the front grill also changed to a pin/spring lock instead of glue.

Your crossover looks original and seems to be of the later type.

Martin

The backs of the two pairs are different as well, both inside and out.

The second pair are both marked serial number 1355005.

The first pair have mismatched serial numbers:  the distorted bass one is 174020 (note six digits, not seven), and the other is 1227022.

I wonder which crossover network is illustrated in the service manual? 

I built the refurbished pair's network per the service manual - hope that's not for the later sets.....[:'(]

Here's the worst of the cabinet where the finish literally came off as I rubbed the gray paint off with furniture cleaner.