Hello, this is my first post and I’d like to thank in advance to all who might comment or help.
I have pair of M-Audio BX8 D2 powered speakers and one speaker’s tweeter line is busted. Tweeter is OK, but either dedicated amp on that line or crossover is busted. It is all on the circuit board and I am not in position to fix it. Authorized service is asking $75 in advance just for diagnostic so cost of repair can easily exceed $100 and I can buy a working, used speaker from Guitar Center for $135.
However, I’ve been wondering if I can go the other way… gutting all the electronics, adding passive crossover and binds and use those speakers with and amp like Onkyo A9010?
One option is obviously to make my own crossovers and the second one is to buy pre-made. How about Dayton Audio XO2W-2K 2-Way Speaker Crossover 2,000 Hz (Dayton Audio XO2W-2K 2-Way Speaker Crossover 2,000 Hz) or (https://www.amazon.com/Aoshike-Frequency-Divider-Speaker-Crossover/dp/B01NAKQS8V)?
Finally, is this a silly idea to begin with?
Below is a table with technical specs for your info.
Technical Specifications
Type - 2-way near-field studio reference monitors
LF Driver - 8-inch (203 mm) Kevlar curved cone with high temperature voice coil and damped rubber surround, magnetically shielded
HF Driver - 1-inch (25 mm) magnetically shielded natural silk dome
Frequency Response - 38 Hz – 22 KHz
Crossover Frequency - 2.2 KHz
LF Amplifier Power - 70 W
HF Amplifier Power - 60 W
Signal-to-Noise Ratio - > 100 dB typical A-weighted
Input Connectors - 1 x XLR balanced input connector and 1 x TRS balanced/unbalanced input connector
Polarity - Positive signal at + input produce outward LF cone displacement
Input Impedance - 20 KΩ balanced, 10 KΩ unbalanced
Input Sensitivity - 85 mV pink noise input produces 90 dBA output SPL at 1 meter with volume control at maximum
Protection - RF interference, output current limiting, over temperature, turn-on/off transient, subsonic filter, external mains fuse. [/TABLE]
Thank you!
I have pair of M-Audio BX8 D2 powered speakers and one speaker’s tweeter line is busted. Tweeter is OK, but either dedicated amp on that line or crossover is busted. It is all on the circuit board and I am not in position to fix it. Authorized service is asking $75 in advance just for diagnostic so cost of repair can easily exceed $100 and I can buy a working, used speaker from Guitar Center for $135.
However, I’ve been wondering if I can go the other way… gutting all the electronics, adding passive crossover and binds and use those speakers with and amp like Onkyo A9010?
One option is obviously to make my own crossovers and the second one is to buy pre-made. How about Dayton Audio XO2W-2K 2-Way Speaker Crossover 2,000 Hz (Dayton Audio XO2W-2K 2-Way Speaker Crossover 2,000 Hz) or (https://www.amazon.com/Aoshike-Frequency-Divider-Speaker-Crossover/dp/B01NAKQS8V)?
Finally, is this a silly idea to begin with?
Below is a table with technical specs for your info.
Technical Specifications
Type - 2-way near-field studio reference monitors
LF Driver - 8-inch (203 mm) Kevlar curved cone with high temperature voice coil and damped rubber surround, magnetically shielded
HF Driver - 1-inch (25 mm) magnetically shielded natural silk dome
Frequency Response - 38 Hz – 22 KHz
Crossover Frequency - 2.2 KHz
LF Amplifier Power - 70 W
HF Amplifier Power - 60 W
Signal-to-Noise Ratio - > 100 dB typical A-weighted
Input Connectors - 1 x XLR balanced input connector and 1 x TRS balanced/unbalanced input connector
Polarity - Positive signal at + input produce outward LF cone displacement
Input Impedance - 20 KΩ balanced, 10 KΩ unbalanced
Input Sensitivity - 85 mV pink noise input produces 90 dBA output SPL at 1 meter with volume control at maximum
Protection - RF interference, output current limiting, over temperature, turn-on/off transient, subsonic filter, external mains fuse. [/TABLE]
Thank you!
Welcome to the forum,
Converting active to passive would most likely be a downgrade in sound quality.
Off the shelf crossovers are next to useless as they cannot possibly know the characteristics of your speakers drive units.
Sell the speakers, buy some 2nd hand.
Edit: You could potentially do an active biamp with an appropriate home theater receiver.
Converting active to passive would most likely be a downgrade in sound quality.
Off the shelf crossovers are next to useless as they cannot possibly know the characteristics of your speakers drive units.
Sell the speakers, buy some 2nd hand.
Edit: You could potentially do an active biamp with an appropriate home theater receiver.
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If you really liked the sound before they broke, I'd spend the money on the authorized factory repair - unless you really want to invest the time and treasure in the learning curve to replicate what could be a perfectly adequate (there's one for the retired ocsynmoron thread - 24th letter on keyboard is broken!) engineering /production job.
That said, add something like a more sophisticated purpose designed DSP such as minidsp, - they also make plate amps, you know - and you could be on to something special, in a silk purse sort of way.
That said, add something like a more sophisticated purpose designed DSP such as minidsp, - they also make plate amps, you know - and you could be on to something special, in a silk purse sort of way.
Hi Mvelimir,
Part of what is missing in this calculation is how much you want to learn, and how much that is worth it to you. A lot of DIY'ers get started with a difficult project like this, but the first project is NEVER financially cost effective.
Financially, I'd say there's no way to make it pay off. An experienced crossover designer probably (but not certainly) could put together an inexpensive crossover, but that's not you yet. For the total cost... you would be better off getting a pre-built speaker kit from Madisound, or Meniscus Audio
From a personal interest and learning perspective, you could learn a great deal, but it will require investment of time, measurement, learning about crossover design, etc. This is also among the least efficient ways of learning, but for some reason many are attracted to it. I don't know why.
Pre-made speaker crossovers are not going to do it.
There is also the possibility (slight) that in passive the speaker efficiency's won't work out. If the woofer is much more efficient than the tweeter, you'll waste a lot of heat and efficiency making it work.
Part of what is missing in this calculation is how much you want to learn, and how much that is worth it to you. A lot of DIY'ers get started with a difficult project like this, but the first project is NEVER financially cost effective.
Financially, I'd say there's no way to make it pay off. An experienced crossover designer probably (but not certainly) could put together an inexpensive crossover, but that's not you yet.
For the total cost... you would be better off getting a pre-built speaker kit from Madisound, or Meniscus AudioFrom a personal interest and learning perspective, you could learn a great deal, but it will require investment of time, measurement, learning about crossover design, etc. This is also among the least efficient ways of learning, but for some reason many are attracted to it. I don't know why.
Pre-made speaker crossovers are not going to do it.
There is also the possibility (slight) that in passive the speaker efficiency's won't work out. If the woofer is much more efficient than the tweeter, you'll waste a lot of heat and efficiency making it work.
I've wondered this myself, as I prefer to use tube amplifiers for gain. The thread so far has discussed having to design new crossovers in converting the active speakers to passive. My question is, why would a new crossover be necessary? The powered speakers have a built in amplifier.... does it not take the source input (signal from CD player or whatnot), feed it to the inboard amplifier, which routes the amplified signal to the crossovers, which in turn directs the high frequency signal to the tweeter and the low frequency signal to the woofer? Isn't this really just a matter of bypassing the internal amplifier and substituting an external amplifier for that purpose?
I've had pertty good success with THESE I use them as repair parts in older speakers.
The only catch is that you need to remove their wire locks and solder on the back of the board if you are using decent sized wire.
That comes down to an important distinction.
Powered speakers are much like you say, built-in amplifier but passive crossover. This is very common in the ca. sub-$100 realm - generally the electronics are built into one speaker, with one telltale twin lead connecting the second, all passive speaker. You may still see considerable EQ being applied (e.g. JBL 104).
Active speakers generally imply an electronic crossover and dedicated power amplifiers for each driver. The advantages of active crossovers include low incremental cost of high orders (4th order is not at all uncommon) and parts that are a pretty good approximation of their ideal selves... no coils to saturate here.
Strictly speaking, none of that stuff needs to be inside the speaker - doing things externally is the standard path of enthusiasts "activating" passive speakers, and even a few '90s compact stereos had speakers connected via multiple pairs of twin lead.
Hi, from my experience the signal path you describe is not the one used in powered monitors ( especially budget ones like the Maudio in question): cross over duties are performed at line level not after the amplifier in passive.
Signal path is typically: line input( line receiver) > volume control> xover > treatment ( eq, phase manipulation,...) > dedicated amplifier for each driver.
There is economic reason for that kind of schem: line level filtering needs cheaper parts than going passive post amplifier filtering.
That said nothing stop you to use line level filter then use multiple tube amps ( instead of chipamps commonly used in this kind of monitors - tda7293, lm3886,...).
Since it is a 60W speaker, I believe a cheap crossover (just a 3.3 or 4.7 Uf cap in series ) will do the job. Test at low volume. If they are too bright, put a resistor before the cap.
I use these but my speakers have 18Sound 500W RMS drivers
Beyma Crossovers - Beyma FD-250 crossover - Beyma FD-250 2-way passive 2.0kHz crossover. The Beyma FD-250 crossover is rated at over 500 watts RMS. Beyma crossovers here.
I use these but my speakers have 18Sound 500W RMS drivers
Beyma Crossovers - Beyma FD-250 crossover - Beyma FD-250 2-way passive 2.0kHz crossover. The Beyma FD-250 crossover is rated at over 500 watts RMS. Beyma crossovers here.
Oh, you could still use this 3 years later?
What makes you so sure that you will be unable to find and fix the problem? Traditional active speaker electronics may be partially surface mount and compact but they're hardly rocket science. (Rokit science?) Mostly a buncha opamps and a chipamp power amplifier (with only about 3 or 4 candidates for types in terms of Class AB - I'd guess it would be that critter with 6 legs and staggered pins here, could be a TDA2052 as also used in KRK Rokits). Nothing that you really need more than a multimeter for to troubleshoot (and datasheets for the parts used, for pinouts - dual and quad opamps generally tend to be all the same but power amps differ). Finding good probe points may be the biggest challenge - clip probes may be helpful.
I would:
* Listen to the tweeter (closely). Is there any noise emitted from it at all? If absolutely nothing yet the tweeter is not open, either the connection from power amp output has been lost or the chipamp is just bad. (Measuring out-of-spec output DC voltage may confirm this.)
* If there is some noise, see whether you can put your finger on components in the input tweeter power amp section and if so, whether that gives any noise in the tweeter. (You could temporarily replace the tweeter by a larger speaker driver to better reveal hum.)
* Inspect the board for the dreaded black circuit (fixing) glue. If found, this corrosive stuff needs to be scraped off and any damage found underneath repaired. Also inspect the underside for bad solde joints. Things mounted off-board like power amplifier ICs are somewhat prone to them.
* Measure supply voltages on power amplifier and opamps. Also try to measure output DC voltage on all opamps found to be connected to tweeter function. (Dead opamps often latch up with the output near one of the rails, though other factors such as loss of feedback may also cause this.) Identify pins in datasheet.
I'm not saying that you are guaranteed to find the problem this way but at least you'd have a fair chance. Trying to come up with a good passive crossover would take a lot of work, time and measurements, and may still yield worse results than the original. Save for noise, perhaps, the TDA2052 is noisier than some other parts. (Finding out where to adjust tweeter level after adding an L-pad is probably a bit much to ask for without service docs.)
Oh i see... i've not heard them but i bet they are good AS IS. I understand your willing for tube amp but the truth is a monitor result is a whole and there is chance Tannoy have done a good job. How does i know?
Tannoy System 800a crossover
As you can see there is more than just a crossover and eq used to gain good results with the system800A versus the S800 passive... you can study the schem to understand how it's done and read the S800 manual too as there is usefull info about the philosophy beihind choices made by Tannoy for the chipamp choice ( tda7293).
You could redo the whole filter amp outside the monitor though ( and using tube based active filtering and tube amp too!) but believe me this will be a lot of work and won't be cheap! It is cheaper for my effort with the S800 filter as i stick with opamp and chipamp but this is a lot of work ( i'm in the midlle of my rebuild for now)...
As i said i've not heard the new Tannoy but i bet they sound very good. You could consider the Kali in8 too as they push the concept even further being a 3 way with coax in same price range. I bet they are very good too, maybe even better than the Tannoy.
Wise words from a wiseman imho.
I fixed an Maudio monitor some years ago from same serie, probably an mk1. Issues was typical: no more sound from woofer after a party... outcome was a tda7293 blown from overpowering the monitor for too long.
This was an easy fix and easy to find as there is not much components involved ( no smd used all were thru hole) and most of them were in great shape. The only thing bothering was the pcb which had pad lift/cut track during desoldering of the tda7293 ( my soldering iron was set to high in temp! Such a fool i am!). The lifted track was a ground so i had to find a place to resolder it on pcb ( using some wire) and the only easy spot was a capacitor negative lead. It worked but there was a faint hum as you can expect from such a place... i ended scratching the surface ( there is some coating over pcb tracks) of a track closer to the tda an resolder the wire there.
Lesson learned, next time i'll cut tda's legs right at the chip and desolder carefully from there.
Oh and i exchanged tda7293 for 7294 as this was what i had at hand ( after checking for compatibility from schematic and datasheets).
As Sgrossklass told this isn't rocket science and as your monitors are faulty anyway you haven't nothing to loose to try to fix it. Worst case you'll destroy the pcb...
From there if you have a multiple out soundcard ( 4 outs) and the schematic is availlable you could redo an external filter using dsp ( plug ins or jriver internal filter option for example) and a pair of stereo amp and there you go... reverse engineering the filter implemented on pcb and Voila!
May sound daunting but not as much in reality. You could have help from here too if you don't know how to do it...
Sgrossklass i like the humour about rockit monitors! Not sure everyone knows Krk though...
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