Forgive my complete amaturity on this topic, I'm learning (and it's exciting!).
I have picked up a Libratone Lounge "speaker system" that originally only has DLNA and AirPlay. The unit doesn't function and, of course, there is something with the brain-board. It just blinks yellow so I got it basically for free. It seems this unit is actually quite nicely built and the drivers seem good in my inexperienced eyes and I feel like this speaker is worth salvaging so I want to put in a new amplifier.
There are 5 drivers and I think that libratone just rebranded existing stuff:
The mids and tweeters are directly wired to the amplifier, no crossover.
I'd like to get decent sound out of this but to be honest, I'm on a budget and I'd like to spend around $50-70 and I'm not sure what the best solution is here. Do I need to buy a 2.1 amplifier and buy seperate cross-overs? Or can I buy a 4.1 amplifier?
I have picked up a Libratone Lounge "speaker system" that originally only has DLNA and AirPlay. The unit doesn't function and, of course, there is something with the brain-board. It just blinks yellow so I got it basically for free. It seems this unit is actually quite nicely built and the drivers seem good in my inexperienced eyes and I feel like this speaker is worth salvaging so I want to put in a new amplifier.
There are 5 drivers and I think that libratone just rebranded existing stuff:
- 1x sub, 8" 50W according to libratones own spec
It says libratone 8" LBR-C001-04 not sure what brand this actually is.
- 2x mid, 4" 25W according to libratones own spec
It says libratone SB12PAC25-3-LBR, I think this is actually SB Acoustics, example.
- 2x tweeters, ribbon, 25 according to libratones own spec
It says the model number is RT-40011, but I think this is actually an Airborne RT-4001
The mids and tweeters are directly wired to the amplifier, no crossover.
I'd like to get decent sound out of this but to be honest, I'm on a budget and I'd like to spend around $50-70 and I'm not sure what the best solution is here. Do I need to buy a 2.1 amplifier and buy seperate cross-overs? Or can I buy a 4.1 amplifier?
Last edited:
Welcome to the forum!
I've looked at the drivers to which you've linked, and if disconnected from the current electronics they could be powered by a 2.1 amplifier.
This one, for example, has handy adjustments that just may make your drivers work together in relative harmony: https://www.amazon.co.uk/FamilyMall-Bluetooth-Subwoofer-Amplifier-Regulation/dp/B0B53R2ZPB/ref=sr_1_1_sspa?crid=3I4TFP67Q6FRW&keywords=2.1+amplifier+board&qid=1692483062&sprefix=2.1+mplifier,aps,111&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
Connect the 8" to the sub output and a mid to each of the L and R outputs - there should be no need for an external crossover.
Piggy back a tweeter on each mid, but add a 4 uF NP film capacitor in series with the tweeter so that only the high frequencies pass to the tweeter.
Add a power supply that suits your output power requirements as described in the 2.1 amp link above.
You should be able to squeeze all that into your budget and, you never know, it might even sound passable. I give no guarantees though!
I'm sure the experts will come up with more sophisticated suggestions, but there's mine to start the ball rolling.
I've looked at the drivers to which you've linked, and if disconnected from the current electronics they could be powered by a 2.1 amplifier.
This one, for example, has handy adjustments that just may make your drivers work together in relative harmony: https://www.amazon.co.uk/FamilyMall-Bluetooth-Subwoofer-Amplifier-Regulation/dp/B0B53R2ZPB/ref=sr_1_1_sspa?crid=3I4TFP67Q6FRW&keywords=2.1+amplifier+board&qid=1692483062&sprefix=2.1+mplifier,aps,111&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
Connect the 8" to the sub output and a mid to each of the L and R outputs - there should be no need for an external crossover.
Piggy back a tweeter on each mid, but add a 4 uF NP film capacitor in series with the tweeter so that only the high frequencies pass to the tweeter.
Add a power supply that suits your output power requirements as described in the 2.1 amp link above.
You should be able to squeeze all that into your budget and, you never know, it might even sound passable. I give no guarantees though!
I'm sure the experts will come up with more sophisticated suggestions, but there's mine to start the ball rolling.
Thank you for taking the time to reply Galu, I appreciate it!
That's good news, that I can put the mid and the tweeter on the same channel of the amp. You say a 4 uF capacitor, I guess this is to create a low pass filter. What frequency would that be by the way? From the graphs that I have looked at I guess that a 3 kHz crossover would be good.
That's good news, that I can put the mid and the tweeter on the same channel of the amp. You say a 4 uF capacitor, I guess this is to create a low pass filter. What frequency would that be by the way? From the graphs that I have looked at I guess that a 3 kHz crossover would be good.
The 4 uF capacitor would act as a high pass filter, blocking the lows while passing the highs to the tweeter..
The resonant frequency of the 4 ohm tweeter is 2000 Hz and, if we use simple capacitor filter, we would have to cross over at least two octaves above that frequency, i.e., at least 8000 Hz, so as not to damage the tweeter with lower frequencies. The reason for this is that the roll off produced by a single capacitor filter is very gradual, only 6 dB per octave.
4.0 uF would start rolling off a 4 ohm tweeter at around 10,000 Hz, giving a large safety margin.
5.0 uF would start rolling off at 8,000 Hz, so is viable.
I am suggesting letting the tweeter roll in gradually to augment the mid at the higher frequencies.
A 12 dB/octave, two component, capacitor/inductor crossover could be used to cross over lower, but it would have to be 4,000 Hz at least - as in the 12 dB case we only have to cross at least one octave above resonant frequency.
Since the mid will reach pretty high on its own anyway, a 12 dB crossover is probably not worth the extra effort in this application, but I could advise you on the components.
This is all pretty much seat of the pants stuff and the experts will be, tut-tutting, shaking their heads and telling you that you must take measurements and perform computer modeling. However, I am assuming that would represent a giant leap forward for you.
The resonant frequency of the 4 ohm tweeter is 2000 Hz and, if we use simple capacitor filter, we would have to cross over at least two octaves above that frequency, i.e., at least 8000 Hz, so as not to damage the tweeter with lower frequencies. The reason for this is that the roll off produced by a single capacitor filter is very gradual, only 6 dB per octave.
4.0 uF would start rolling off a 4 ohm tweeter at around 10,000 Hz, giving a large safety margin.
5.0 uF would start rolling off at 8,000 Hz, so is viable.
I am suggesting letting the tweeter roll in gradually to augment the mid at the higher frequencies.
A 12 dB/octave, two component, capacitor/inductor crossover could be used to cross over lower, but it would have to be 4,000 Hz at least - as in the 12 dB case we only have to cross at least one octave above resonant frequency.
Since the mid will reach pretty high on its own anyway, a 12 dB crossover is probably not worth the extra effort in this application, but I could advise you on the components.
This is all pretty much seat of the pants stuff and the experts will be, tut-tutting, shaking their heads and telling you that you must take measurements and perform computer modeling. However, I am assuming that would represent a giant leap forward for you.
High pass, of course. Now it is clear how little I know...
Thank you for the detailed explanation! It is a pleasure to get such good answers.
When I search for 4 uF capacitors to buy I get a plethora of choices. Is something like this OK?
Also, I've looked into increasing the budget and going for DSP. It looks like Sure electronics / Wondom JAB-series DSP boards. Is this worth looking in to?
Thank you for the detailed explanation! It is a pleasure to get such good answers.
When I search for 4 uF capacitors to buy I get a plethora of choices. Is something like this OK?
Also, I've looked into increasing the budget and going for DSP. It looks like Sure electronics / Wondom JAB-series DSP boards. Is this worth looking in to?
Yes, a non polar MKP film capacitor is just the type you need.
DSP is a great idea, but I'm afraid it's not my area of expertise.
You may have to make a new thread specifically on the application of DSP to your project.
DSP is a great idea, but I'm afraid it's not my area of expertise.
You may have to make a new thread specifically on the application of DSP to your project.
Before committing resources to this project, test the drivers by connecting them to any amplifier you may already have. A faulty electronic board may have damaged the drivers, or they may not have the quality you are seeking. You will also get a general picture about the frequency response. DSP may be required if the response needs equalization.
