Hello guys,
I have two technics brand loudspeakers which i got from a bargain, the model is sb-eh550, each cabinet has a 6cm tweeter, 12cm bass and a 14cm bass.
Each loudspeaker has 4 wire connection behind, two going to the 6cm tweeter and the 12cm bass in parallel, tweeter has a 2.2uf high pass cap; another two wire is going to the 14cm bass alone.
I checked the service manual and it lists 200Hz and 4kHz as crossover frequencies. I assume that 4kHz cut is achieved by the 2.2uf high pass cap and 200Hz low pass is intended to be on the original amplifier of the whole system, but i just have the speakers.
Should i be okay just putting a passive 200Hz low pass filter before the input of the 14cm driver and drive the mid-high input directly from the amplifier? Or should i split the amplifier output at 200Hz with a two way crossover, feed the low to the 14cm input and high to the 12cm-6cm combo?
The schematic of the loudspeakers taken from the service manual is in the attachment.
I know active crossovers before the power amplifier would be the normal way to go but simply increasing the amplifier power and using passive crossovers is much cheaper for me right now.
Thanks for any help!
Edit: on a second thought, my question also applies for the active crossover configuration. i just need to be sure which frequency ranges should i feed to the each drivers, or the inputs behind the loudspeakers to be more accurate.
I have two technics brand loudspeakers which i got from a bargain, the model is sb-eh550, each cabinet has a 6cm tweeter, 12cm bass and a 14cm bass.
Each loudspeaker has 4 wire connection behind, two going to the 6cm tweeter and the 12cm bass in parallel, tweeter has a 2.2uf high pass cap; another two wire is going to the 14cm bass alone.
I checked the service manual and it lists 200Hz and 4kHz as crossover frequencies. I assume that 4kHz cut is achieved by the 2.2uf high pass cap and 200Hz low pass is intended to be on the original amplifier of the whole system, but i just have the speakers.
Should i be okay just putting a passive 200Hz low pass filter before the input of the 14cm driver and drive the mid-high input directly from the amplifier? Or should i split the amplifier output at 200Hz with a two way crossover, feed the low to the 14cm input and high to the 12cm-6cm combo?
The schematic of the loudspeakers taken from the service manual is in the attachment.
I know active crossovers before the power amplifier would be the normal way to go but simply increasing the amplifier power and using passive crossovers is much cheaper for me right now.
Thanks for any help!
Edit: on a second thought, my question also applies for the active crossover configuration. i just need to be sure which frequency ranges should i feed to the each drivers, or the inputs behind the loudspeakers to be more accurate.
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First you need some sense of what you've got. Are they quality pieces worth investing in? Can you run freq responses using REW and your laptop mic, esp with the drivers directly powered individually?
My guess would be that the top feed is full-range and the bottom feed is crudely below 200 Hz. Not likely to too good quality but then some small ambition is evident.
Bi-amping is almost always smart and here might be used by Technics so that two modest chip amps drive the two feeds instead of a single large amp with passive crossover.
B.
My guess would be that the top feed is full-range and the bottom feed is crudely below 200 Hz. Not likely to too good quality but then some small ambition is evident.
Bi-amping is almost always smart and here might be used by Technics so that two modest chip amps drive the two feeds instead of a single large amp with passive crossover.
B.
I think the loudspeakers are decent quality, they physically look okay, and i trust Technics. But i do not plan to invest in them too much, i just want to spend minimum to get them properly working with an acceptably flat response. Like i mean, i dont want to invest on highest grade components but i also wont use discrete components which are not suitable for audio use. I also want to get my math right and build a proper but easy amp+crossover combination.
I'm able to do frequency sweep through the speakers and monitor the response graph through a few softwares i use. I already ordered wm-62c electret microphone capsules and gonna build a measurement microphone with them, to use it in frequency response graphing of audio equipment. The electret condenser microphones i mentioned are known for their pretty decent flat response out of the box with +-0.5db.
I take this as a DIY project to improve myself and i have another option in my mind, i can also build a 3 way crossover with matching orders to keep all three drivers in phase. I think that the 2.2uf capacitor before the tweeter might phase lag the tweeter behind the mid bass driver.
questions:
If you guess that top feed is full range and the bottom feed is crudely below 200Hz, then why do they mention another cutoff frequency of 4000Hz in the service manual?
So do you suggest me to analyze each driver for their frequency response and decide on crossover frequencies solely according to that? I definitely can do that but i also kind of trust on what Technics engineers have already done and decided on those two cutoff frequencies.
And also, would i lose too much in terms of quality if i just use one big amp with crossovers instead of bi-amping? It might be efficient and smart but it's that i find it more complicated for me.
thanks
I'm able to do frequency sweep through the speakers and monitor the response graph through a few softwares i use. I already ordered wm-62c electret microphone capsules and gonna build a measurement microphone with them, to use it in frequency response graphing of audio equipment. The electret condenser microphones i mentioned are known for their pretty decent flat response out of the box with +-0.5db.
I take this as a DIY project to improve myself and i have another option in my mind, i can also build a 3 way crossover with matching orders to keep all three drivers in phase. I think that the 2.2uf capacitor before the tweeter might phase lag the tweeter behind the mid bass driver.
questions:
If you guess that top feed is full range and the bottom feed is crudely below 200Hz, then why do they mention another cutoff frequency of 4000Hz in the service manual?
So do you suggest me to analyze each driver for their frequency response and decide on crossover frequencies solely according to that? I definitely can do that but i also kind of trust on what Technics engineers have already done and decided on those two cutoff frequencies.
And also, would i lose too much in terms of quality if i just use one big amp with crossovers instead of bi-amping? It might be efficient and smart but it's that i find it more complicated for me.
thanks
The 4000Hz is the 6dB/oct high pass/low cut filter (C1) for the tweeter.
I would measure their resistance and hook them up to a stereo amp and listen if they sound ok on both top and bottom connection. If so, use them as they are.
This cheap Class D board which has a 150hz high pass and a variable low pass filter (80-250hz) for the sub, which is cheaper then getting passive crossovers, and an old 19V laptop power supply are probably going to drive them very nicely.
I would measure their resistance and hook them up to a stereo amp and listen if they sound ok on both top and bottom connection. If so, use them as they are.
This cheap Class D board which has a 150hz high pass and a variable low pass filter (80-250hz) for the sub, which is cheaper then getting passive crossovers, and an old 19V laptop power supply are probably going to drive them very nicely.
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This solution looks awesome, thank you! But there is one thing, i'm not sure if my loudspeakers are each 70W or 70W combined, i bought them at a different location and shipped to my address so they will arrive in 2 days, can't examine further for now.
Should the amplifier be more powerful than the speakers or should the speakers wattage should be higher than the amplifier? My intuition says power amplifier should be more powerful and used below maximum so it'll stay more linear, am i right?
edit: i just saw that the amplifier you linked looks like to have 2 full range output + 1 low pass woofer output. i think i need 2 low pass woofer outputs + 2 high pass or full range outputs. am i missing something?
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These are the speakers from the boombox of the same #? If so you may be spending money where not wise. They might be good for the workshop but you might find them not suitable for the living room. Maybe hang a coil on the lower woofer to prevent too much midrange.
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Yes these are the speakers i'm talking about. Do you think they are worse than common 2.1 speaker systems that can be found at any electronics shop? if not, they'll cost less and i'll be learning stuff from diy.
@gezzer
You can actually never really have to much power - well - ofcourse you can - and the coil in the speaker will melt.
But chances are mostly better with a big amp, then a small, when it comes to fidelity and control. But again - it's not always that simple.
Sometimes you will get a better result by using your money on a better quality, but lower output amp, than a brute that plays roughly.
The 70W on your speakers tells you nothing really. It might just be the total amount of power that they can absorb, before they start to smoke or smell badly.
Your speakers belong to an old complete stereo system, that was of modest quality, but you can ofcourse enjoy them anyway - fx in the garage or workshop, where they would fit great
You can actually never really have to much power - well - ofcourse you can - and the coil in the speaker will melt.
But chances are mostly better with a big amp, then a small, when it comes to fidelity and control. But again - it's not always that simple.
Sometimes you will get a better result by using your money on a better quality, but lower output amp, than a brute that plays roughly.
The 70W on your speakers tells you nothing really. It might just be the total amount of power that they can absorb, before they start to smoke or smell badly.
Your speakers belong to an old complete stereo system, that was of modest quality, but you can ofcourse enjoy them anyway - fx in the garage or workshop, where they would fit great
Thanks, i forgot to mention that i'm not an audiophile, due to my job in nightclubs for more than 3 years, i think my ears lost the ability to differ between a good audio amplifier and a mediocre one. I'll just trust customer ratings and popularity of a premade amplifier board i can find on aliexpress, and that's all. But i think crossover design in my case is essential because not doing so could cause easily noticable unwanted characteristics.
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You don't need more clean power from the amp then the speakers can handle / start to distort.
Measure the impedance of the drivers with a multimeter, or maybe you can find them in the specs. With 4 ohm drivers, you will get 2x50w+1x100w with a 24V power supply. The 2 lower woofers run as mono, connected in parallel to the sub-woofer connection. You will get half the power with 8ohm drivers and about 60% with the 19V adapter.
Double the power is only 3dB louder which is just noticeable.
There is a 150Hz high pass/low cut filter you can turn off for the left and right connection. I have two of these boards and listen a lot to 1 of them.
More info about these chips and similar boards is in this monster thread: TPA3116D2 Amp
Thank you so much! Running woofers in mono makes sense i'm not really sure why the spatiality of the lower end bass is neglected but it's like that everywhere, so ok i guess. I'll definitely go through most of that article.
At first glance i'm still not able to see the 150Hz high pass switch on the board but i'll continue on looking. If it's as you say so, that was what exactly i was looking for.
Thank you for sharing your experiences about those new amps
There is not much spatiality (?) / stereo signal in the lows on most recordings and if there is any, it won't add much. Separate sub-woofers boxes have some advantages with placement and are most often best used close together and with a mono signal.
The switch is in between the 2nd (treble) and 3rd pot-meter (volume highs) from the right.
You might even put the amp in 1 of the speakers and/or run it from batteries.
U can use some cheap ebay 'neutrik' 4 pole connectors ($1 each, sockets 40 cents) and 4 conductor (?) (4 coper wires) cable to hook them up easily, if you like to move them around.
The switch is in between the 2nd (treble) and 3rd pot-meter (volume highs) from the right.
You might even put the amp in 1 of the speakers and/or run it from batteries.
U can use some cheap ebay 'neutrik' 4 pole connectors ($1 each, sockets 40 cents) and 4 conductor (?) (4 coper wires) cable to hook them up easily, if you like to move them around.
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Now researching into the subject more, i found another option. And i think many of you already know this, its called line level passive crossover.
As you guys said splitting frequencies before the power amplifier, by the means of using an active crossover, would be the smart and efficient way.
But why couldn't i use a passive crossover before the amplifier? This way i can utilize 2 full range stereo amplifier boards which are cheaper and simpler, and i can bi-amp both my speakers.
I came accross to this webpage, it suggests using RC crossovers, because the required inductance values for butterworth and linkwitz-riley type passive power crossovers are way too high for high input impedance values of amplifiers.
Looking at that page, it seems logical that i measure the input impedance of the amplifier board i buy, design and build a simple passive line-level crossover, then drive the bass and mid-high parts of my loudspeaker independently by the left-right channels of a single amplifier board. For the other speaker i'll do the same thing.
Is it wrong? If it was feasible, why didnt i ever came accross this thing before?
As you guys said splitting frequencies before the power amplifier, by the means of using an active crossover, would be the smart and efficient way.
But why couldn't i use a passive crossover before the amplifier? This way i can utilize 2 full range stereo amplifier boards which are cheaper and simpler, and i can bi-amp both my speakers.
I came accross to this webpage, it suggests using RC crossovers, because the required inductance values for butterworth and linkwitz-riley type passive power crossovers are way too high for high input impedance values of amplifiers.
Looking at that page, it seems logical that i measure the input impedance of the amplifier board i buy, design and build a simple passive line-level crossover, then drive the bass and mid-high parts of my loudspeaker independently by the left-right channels of a single amplifier board. For the other speaker i'll do the same thing.
Is it wrong? If it was feasible, why didnt i ever came accross this thing before?
I'm aware that most recordings dont have channel seperation or phase difference on the low frequency end, but that is generally true if the recording is mixed that way(which still makes the majority).
Okay i just noticed whats in front of my eyes the whole time
Thats good to hear. In case of putting LLPXO's before the power amplifiers, how could i achieve volume level adjustment? My intuition says putting a potentiometer before or after an LLPXO could change the crossover circuits characteristics. Do i have to use buffer op-amps or is there any other easier solution? Or do the volume pot on amplifier boards already have no effect on the input impedance of the amplifier?
Using two of these dirt cheap tpa3116d2 amplifier boards and some other parts for LLPXO, the cost has been reduced to around $15.
Yes, you can make the parts to stitch 2 boards together your self and if you like add treble or balance control or buy it. There are many others but most like to have AC.
The board I linked is the best tpa3116 2.1 board ready to use (no mods required) and the only one I know of with variable low pass/high cut for the 'sub', a switchable high pass/low cut for the 'tops' and has a separate treble and volume control for the tops. There are cheaper ones like this one.
The board I linked is the best tpa3116 2.1 board ready to use (no mods required) and the only one I know of with variable low pass/high cut for the 'sub', a switchable high pass/low cut for the 'tops' and has a separate treble and volume control for the tops. There are cheaper ones like this one.
OK two of these caps
220uF 100V Electrolytic Non-Polarized Crossover Capacitor
to cross the mids somewhere near 250 Hz
and two of these coils
Dayton Audio 3.0mH 18 AWG I Core Inductor Crossover Coil
for the woofers to cross near 250 Hz
then you have spent 17.52 + shipping to fix these. That might be too much for them already. You will learn how they change the sound as you go so it might be worth it have to start somewhere.
220uF 100V Electrolytic Non-Polarized Crossover Capacitor
to cross the mids somewhere near 250 Hz
and two of these coils
Dayton Audio 3.0mH 18 AWG I Core Inductor Crossover Coil
for the woofers to cross near 250 Hz
then you have spent 17.52 + shipping to fix these. That might be too much for them already. You will learn how they change the sound as you go so it might be worth it have to start somewhere.
Hello guys, thank you all for your guidance, i finally decided on doing the impedance and frequency response measurements for each drivers, then designing a passive crossover through XSim.
I got the impedance measurements correct, got some temporary freq. response measurements with a cheap microphone to do a pre-design, but i also ordered some panasonic WM-61A capsules to DIY a decent measurement microphone.
Later i'll re-design the crossovers with correct measurements and build them.
I'll most likely wind the inductor coils myself, but about the capacitors, polar electrolytic capacitors are really not much of use, right? But what about bipolar electrolytics? Should i really just use film or propylene caps?
I got the impedance measurements correct, got some temporary freq. response measurements with a cheap microphone to do a pre-design, but i also ordered some panasonic WM-61A capsules to DIY a decent measurement microphone.
Later i'll re-design the crossovers with correct measurements and build them.
I'll most likely wind the inductor coils myself, but about the capacitors, polar electrolytic capacitors are really not much of use, right? But what about bipolar electrolytics? Should i really just use film or propylene caps?
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The term is polarized or non-polarized and yes you want non-polarized think AC not DC speaker moves both ways. Electrolytic's are fine to start with or for bass crossovers large polypropylene caps are vary big and cost lots. Film caps for the highs or to meet a perfect match micro farad for tweaking. Kudos for trying to wind your own coils.
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