ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
As seen on Beoworlds "flash your B&O" thread there are so many beautiful B&O installations around your homes and offices around the world, it would be a shame to get rid of it because of missing spare parts. This thread is ment to be a source of some technical information especially for the older Beolab families (Beolab 4, 4000, 6000, 8000, 1 ...) to keep them alive in our homes as long as possible.As e.g. Beolab 4 and 4000 seem to become unrepairable due to spare parts fading away somebody here on Beoworld (I can't remember the thread) mentioned the idea to outsource the electronics of the speakers to keep using the chassis and case. Different solutions are possible: BEOCREATE, digital speaker controllers, crossovers etc. are widely available which can lead to an external box containing crossover, EQ (e.g. for limiting bass response on the small speakers) amplifier, powerlink connection (to a B&O source). Some kind of "Beoamp" but different settings for the different speakers. Or a simple analog crossover to be put into the small Beolab 4 case plus an external powerlink connected amp (beolink passive, Beoamp etc.)The information can look like this:Speaker type: Beolab 4Chassis: 2crossover frequency between Tweeter and Midrange/Woofer: xx kHzmax. Tweeter power: xx wattmax. Woofer power: XX watt lowest Woofer / casing bass frequency: xx Hzparticipating, ideas and enthusiasm is welcome :-)
I love this idea.
I’m an Electrical Engineer with lots of interest in designing electronics for audio, thigh admittedly no practical experience. (I have designed ultrasound and laser medical devices, stage lighting, consumer products, military tools, and test equipment.)
The BeoCreate platform looks quite interesting but seems to pull speakers away from the B&O environment. That is to say I don’t believe it supports he current NL / Beolink Multiroom environment. For me that support is very important, but for others may be less valuable. I would prefer to design circuits to keep speakers inside the B&O ecosystem, but perhaps can design to work inside out outside the BeoLlnk Multiroom world
Let me say I am happy to participate in this project. How can I help?
-Alex
Sources: 2x Beosound Moment • 4x Beosound Essence Mk II Speakers: 3x Beolab 8000 • 2x Beolab 6000 • 2x Beolab 3 • 3x Beolab 2 Integrated: 1x Beosound 2 • 1x Beosound Level • 4x BeoPlay M5 • 1x BeoPlay A6 Control: 16x* Essence Remote • 1x Beoremote Halo
* Yes, really! 🤦♂️
I would be very interested in converting my BeoLab 4s into a set of passive speakers. One of them died last year and it is too costly to repair. If I could remove the internal amps and transform them into a simple passive speaker (to be used with my Marantz AVR), they would at least still have some function. Now they just sit in storage, waiting for a single unit to pop up on the second hand market for a fair price.
I have no idea however on how to do this? I'm not afraid to get my hands dirty, so if anyone could guide me through the process, that would be highly appreciated!
Beolit 12 - Beolab 4 pc (dead now) - Beoplay H5 - Beolab 9 - BeoRemote One BT - Beoplay M3
crossbytje
According to this or this page the beolab 4 are small twoway speakers with a crossover frequency of 3'300 Hz, equipped with ICEpower amps of 30W. The bass chassis seems to be a 101 mm dia with 1.55l volume, in bass reflex type enclosure. It should be possible to bring a proposal for a passive crossover network. I would start with a simple 12 dB per octave design for reasons of simplicity. If you'd know the Thiele Small parameters of the bass chassis, and could provide some basic data on the tweeter and provide the cabniet geometry, I could give you a proposal for such a crossover. This requires the chassis to be OK. You can measure that with an ohm meter. According to the service and repair manual, page 4.1, bass unit should be at 2.7 Ohm, the teeter at 5.7. If that's the case, such a conversion from active is possible, else you'd need to replace the units. I doubt replacing the chassis makes sense (see below).
I should point out, equipped with a simple passive crossover, it will sound different. With iterations you could get closer to the original sound. But you will definitely loose the adaptive bass linearisation part. Thus, if at all, I'd rather propose a repair. You could start reading the service and repair manual. On page 1.1 it is indicated, the box does have 6 PCBs. I am no electronics engineer. Thus, I would start compairing visually the two sets you have at hand. Maybe you can pin a pcb as defective and hopefully order it.
Finally the author of this page states "Beoworld says: Compact speakers suited for a PC. These are not Hi-Fi ! Think CX50. Very expensive for what you get! A pair of second hand Beolab 4000s will blow them away! ". So why not putting both units on ebay, and getting some bl 4000?
greez
chris
Hi,
Thanks for your thorough reply.
I also found the same info on the crossover frequency and decided to buy 3300Hz crossover circuits on ebay. I removed the internals (and kept them in a box) and mounted the crossovers in the cabinet. They were just about small enough to fit.
For now, I use them just like this. The sealed cabinets are still open on the bottom, and I wonder if closing them off would lead to a serious improvement or not?
On their own, they sound pretty thin and not very good. I placed them on the ceiling and use them as back surround speakers in a 7.0 setup (with Beolab 9s as fronts) powered by a Marantz AVR. Calibration and room compensation through the audyssey setup have improved their sound significantly. They sound decent enough as rears now, also in multichannel stereo for music listening.
So I'm fairly happy with my "recycling" project.
As said above, I just wonder if a more sealed bottom plate would improve sound on these? There is a bass port which is open anyway.
Those timy speakers are vented cases. You absolutely need to close the box. The only opening shall be the bass refelx port. Else you will never get close to the original sound.I hope the "new" crossover does not consume too much volume. Should be about the same size/volume as the components removed and geometrically in a similar arrangement too.
By the way: a pic and circuit diagram of your crossover would be nice.
Greez
@TWG posted on 12-13-2020 9:04 AM
May I suggest to add - where possible - TThiele Small parameters?
Chris
@Seuchato: Of course, this is a free thread, I'm not a moderator. ;-) Happy so see more people thinking about that option to keep the beautiful Beolab housings...
seuchato: By the way: a pic and circuit diagram of your crossover would be nice.
I bought these from amazon: click Seems to be crossover at 3200Hz instead of 3300Hz, but that should be 'close enough' I figured.
I'd say the circuits are a little less bulky than the standard internals of the BL4. They were packed quite full originally.If I find the time, I'll bring them down from the ceiling and will close the chassis.
To be honest, I was ready to get rid of them anyway. I used them as computer speakers and had already replaced them with a couple of M3's. Replacing the PCB was too expensive and I'm pretty sure the other unit would die pretty soon too. Also, I don't have power nor power link connections in my ceiling, so I wouldn't really have any use for a repaired set of active BL4 speakers anyway.
As they are now, they sound decent enough. The originals didn't sound that exquisite either...