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Beolit 707 Bluetooth

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matador43
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matador43 posted on Sun, Dec 30 2018 9:22 AM

 

Good morning to you guys,

In my quest for a Beosystem 10, i came across this Beolit 707 for a good price. I was lucky because even though it was very dirty, it also was in general good shape which is, aerial quite straight and with tip, no important damage, all markings present and strong and even the electronic diagram and the tubing were there. Sadly, one of the two slider button is missing (if any of you have one spare!). In the picture, both are missing because I take out the one there to try to 3D print it as temporary (I hope…) fix!

The panels were hard to clean. After a lot of bath and rubbing, I managed to get them "acceptable". But they are still whit some white stains and i can say if it's dirt or any chemical plastic aging phenomenon. I dont want to be to aggressive on them or spray any product with unknown side effects like plastic cleaners for instance.

About the color, it's a deep military green which i've already seen in various pictures across the web. But in the catalog, it don't seems to be a color which was available (I remember red, blue, black, violet and yellow…). Can it be the black who turns green with time, like some watch dials do?

The sound is good. I've read about it in a couple of post here on Beoworld but it's true it's quite impressing when you first turn it on. Very funny too were the crushing, grating and static noises you here when running the station. Seems I didn't hear them for ages!

The pictures here are after complete dismantling and cleaning.

But to be honest, I had something in mind for it…

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matador43
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As ever, I hope not to scare any Beo enthusiast and assure I try to maintain everything as original as I can and make all mod's "reversible".

So this time the goal was to bluetooth the AUX-in of the Beolit. And that was not so difficult in the end. Here it is finished:

The idea was to use an USB bluetooth dongle connected to an USB power bank which will fit the battery compartment and connect them to the inside pins of the DIN socket with a jack cable. But because the pins were hard to reach I had to connect the L+R wires to the orange wire in the Beolit, obviously going to the related pin and the ground of the jack to any grounded part of the Beolit (the steel box nearby was conveniently placed.

The I tucked the Jack wire through the void close to the antenna to make the jack outing the battery compartiment. Connected it to the BT dongle and connected the dongle to the power bank. And Voilà!

Pad it a little and insert it in the cardboard tubing and close the Beolit as usual.
No fire so far! 

matador43
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It works as expected but to be honest, it not gonna compete with any Beoplay!

First, the sound is here, clear and even, but its also very medium and not as defined as radio listening would have been hope for.
Maybe it's because of some sort of input level or impedance or whatever, but thats very beyond my understanding.
My opinion is that the Beloit was designed to give the best sound at his time (FM, Analog, spoken content, etc…) and it's not as comfortable with modern music and new (quality?) standards. 

Second, when I push the volume in BT mode, i still can here the FM program behind. This used to be the case using the original DIN socket, so it must not be related to the mod. I dont know if it's a normal behavior or some electronics getting old.

Of course you have to regularly take out the powerbank to charge it (it's like changing the cells in 75!).
My initial idea was to connect a slim USB charger to the mains, from the inside and even try to tuck inside any li-Ion battery to make it totally portable.
But i though it would have increased the chances to damaged or blew it up. And after all, I like the analog feeling of the wire or the battery ceremonial!.

Of course, all the original functions are ok, including the use of the DIN socket in a traditional way.

I'm a little bit concerned about the speaker though. The foam around (not the suspension, the turned brown foam) as dried and get into dust. I can see some light cracking on the suspension and fear it the start of a worse process. Is there any care to prevent this, like some oil or silicone to soften the rubber or i dont know what? I planned to replace the foam with wisdom isolation foam but for now, i didn't did it to prevent any stupid error. Any thoughts about it?

Thank you to you all guys and hope you like it!

matador43
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Old vintage meets new vintage…

 


MrRoast
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Lovely job! I was considering something similar for my Beolit 600. 👍🏻
matador43
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Because the Beolit 600 doesn't have a PSU, you can't tuck the receiver into the battery bay.Sad
But because it doesn't have a power supply it has a lot of space behind the speaker.Smile
So the mod will be even better on a 600 than on 707!

Lucky you !  :-)

matador43
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Good afternoon guys,

Next step is to make that little thing mobile again!
So the goal is to replace the 5 LR20 batteries with AAA batteries. I'm aware that they won't last long but if they can't stand a couple of hours that should be enough for say a shower or a little barbecue! Just to remember: the battery bay is now half occupied by the power bank fueling the Bluetooth adapter.


So i buy those battery holder and theoretically it works, I managed to have sound by just touching the battery contacts with the wire running out of the batteries holder.

 

Now i'm in front of math problems and your advices are more than welcome. Here is the problem;
- Beolit 707 is rated for 5x1,5v=7,5v. 
- I want to use rechargeable batteries which are 1,2v, so I put 6x1,2=7,2v.
- When i mesure newly charged 6xAA output I get 8,4v!

So my question is: could that voltage variation damage the beolit or is the electronic kind of flexible?
The question I ask myself are:

- Maybe it's 8,4v at really full charge but voltage will soon drop to 7.something on use. And the peak would be acceptable for the electronics?
- Maybe Voltage is not that relevant into that range (from 7,2 to 8,4v).
- Maybe it should be 7,5 and no more no less, so its a bad idea to play with this? 

As ever it's absolutely exclude to do anything which would arm the Beolit or not be easily cancelable.

Any input welcome.

Thank you.


matador43
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Hi alls,

With the help of a friend more into electronics than me, I finally use 5 batteries outputting in total 5x1,2=6V theoretically and a little bit more when fully charged practically.

I'm happy to announce than since yesterday my Beolit 707 is running on batteries. The blue one in the picture is just a spacer to fill the 4x holder.
You can also see the 3D printed tone slider which should need a little more precision in printing but is perfectly functional so far.

I'm still dealing with a little issue though: The bluetooth dongle is interfering with FM reception leading to continuous aground noise.
Dont know if its just wire related or really about radio waves perturbations. Any input welcome.

 


matador43
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A quick update just to say that I'm able to run the Beolit for about one day (5-6 hours) with 5 AA 2450mAh batteries.

matador43
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