Hi All.
Another unfinished project from me. Actually hoping to finish this one, but so far unfinished ;-)
Project goals: Small, LOUD, active, cheap.
This is my first speaker designed from scratch (outside school-projects). "Designed" as in: will be using simulation and ARTA and actually thinking a little about the choices.
Small is in this context around 14liters.
Loud is defined as: not too fragile and shall take a little "beating" for the occasional birthday. Designed to be used with a sub for party-levels.
Active: build-in amplifiers and electronic crossover. Still considering the option for a limiter of some sort. Clip-indicator is also on the wishlist. Will probably buy the (ClassD amps from ebay) and do the other PCB's myself.
Cheap: all cost kept to a minimum. Dont have a budget, but guessing below 50EU for a single cap.
Bass: Dynavox DY166. Used in a few constructions on the web with good results. Relatively efficient according to datasheet. Big magnet. VERY cheap. Tieftöner DYNAVOX DY166-9A - HiFi/Car-HiFi/Video/TV - Lautsprecher - Lautsprecher-Chassis - Pollin Electronic
Treble: Rockwood PT25B-1. A small treble-horn. Horrible response. Hopefully this can be equalized. Efficient and should be able to play loud. Cheap. A bit of a gamble, but cheap enough to fail and dismiss. Hochton-Horn ROCKWOOD PT25B-1 - HiFi/Car-HiFi/Video/TV - Lautsprecher - Lautsprecher-Chassis - Pollin Electronic
Amp: TDA7498 complete board from ebay/aliexpress.
PSU: laptop-SMPS + boost converter or maybe a printer-SMPS (HP) with 32V/900mA.
More to follow.
TroelsM
Another unfinished project from me. Actually hoping to finish this one, but so far unfinished ;-)
Project goals: Small, LOUD, active, cheap.
This is my first speaker designed from scratch (outside school-projects). "Designed" as in: will be using simulation and ARTA and actually thinking a little about the choices.
Small is in this context around 14liters.
Loud is defined as: not too fragile and shall take a little "beating" for the occasional birthday. Designed to be used with a sub for party-levels.
Active: build-in amplifiers and electronic crossover. Still considering the option for a limiter of some sort. Clip-indicator is also on the wishlist. Will probably buy the (ClassD amps from ebay) and do the other PCB's myself.
Cheap: all cost kept to a minimum. Dont have a budget, but guessing below 50EU for a single cap.
Bass: Dynavox DY166. Used in a few constructions on the web with good results. Relatively efficient according to datasheet. Big magnet. VERY cheap. Tieftöner DYNAVOX DY166-9A - HiFi/Car-HiFi/Video/TV - Lautsprecher - Lautsprecher-Chassis - Pollin Electronic
Treble: Rockwood PT25B-1. A small treble-horn. Horrible response. Hopefully this can be equalized. Efficient and should be able to play loud. Cheap. A bit of a gamble, but cheap enough to fail and dismiss. Hochton-Horn ROCKWOOD PT25B-1 - HiFi/Car-HiFi/Video/TV - Lautsprecher - Lautsprecher-Chassis - Pollin Electronic
Amp: TDA7498 complete board from ebay/aliexpress.
PSU: laptop-SMPS + boost converter or maybe a printer-SMPS (HP) with 32V/900mA.
More to follow.
TroelsM
The amps sold here on ebay using TDA7498 use either a 32V/4.5A or 36V/5.7A SMPS.
Not sure 0.9A will be sufficient.
Not sure 0.9A will be sufficient.
Well it will depend on a lot of things. For sure the amp will never use 32V and 4A. That would be 100W rms to the speaker. Max average with pop-music to these drivers and 32V supply is perhaps 15-20W? I'll give it a try and see.
raw driver response
Both the chosen drivers have some serious challenges. The bass have a massive peak at 5K and the treble/horn is very non-linear.
Heres a ARTA measurment with a uncalibrated Mic and a cheap USB soundcard:
Blue is bass. Red i horn. Not a very ideal setup and a lot of the smaller ripples are probably measurement error. Notice the 10dB peak around 5K and the falling treble response.
Note: the bass-response looks like what others have put online. The treble-response has a small peak at 16K, but others have measured massive peaks here. I'm not trusting my simple mic and the peak I measure might very well be larger. The treble response is measured with 22uf in series with the driver to limit power.
Here is the response from the driver in approx 12Liters closed box with and without an 4order LP filter around 2.7K. This puts the 5K peak 20dB below passband.
Both the chosen drivers have some serious challenges. The bass have a massive peak at 5K and the treble/horn is very non-linear.
Heres a ARTA measurment with a uncalibrated Mic and a cheap USB soundcard:
An externally hosted image should be here but it was not working when we last tested it.
Blue is bass. Red i horn. Not a very ideal setup and a lot of the smaller ripples are probably measurement error. Notice the 10dB peak around 5K and the falling treble response.
Note: the bass-response looks like what others have put online. The treble-response has a small peak at 16K, but others have measured massive peaks here. I'm not trusting my simple mic and the peak I measure might very well be larger. The treble response is measured with 22uf in series with the driver to limit power.
Here is the response from the driver in approx 12Liters closed box with and without an 4order LP filter around 2.7K. This puts the 5K peak 20dB below passband.
An externally hosted image should be here but it was not working when we last tested it.
You could probably linearise the tweeter considerably with a carefully chosen in-line capacitor but I'm not sure what exactly that would do to your envisaged crossover point.
If you can try and simulate the tweeter with a 6dB high pass at 10k and see where it gets you.
If you can try and simulate the tweeter with a 6dB high pass at 10k and see where it gets you.
Hi.
I'm thinking of crossing around 2.5K. Yes, - first order HP around 10-15K looks correct. This will probably be combined with a 2order HP at 2.5K
Thanks for the input.
I'm thinking of crossing around 2.5K. Yes, - first order HP around 10-15K looks correct. This will probably be combined with a 2order HP at 2.5K
Thanks for the input.
If the 5k woofer peak 20dB below bothers you give it a passive notch filter which will be nicely out of the pass band by an octave.
Well the family is out of the house and I can do some high volume testing in the living room🙂
First try with a 4.order LP at 2.7K and 2.order HP at 2.7K. There is also a 1.order HP at 14K to flatten the cracy horn response.
The extreme peak at 16K is back! arghh! Well, I'm pretty sure my hearing is 10-20db at 16K so not a major problem. Still dont know if it some measurment artefact.
There's a dip at 2.7K. It becomes a lot deeper if a single driver-phase is inverted
Sound is better than I had expected for a first try. Not as loud as I had hoped, but OK.
Below 500Hz is not correct.
First try with a 4.order LP at 2.7K and 2.order HP at 2.7K. There is also a 1.order HP at 14K to flatten the cracy horn response.
An externally hosted image should be here but it was not working when we last tested it.
The extreme peak at 16K is back! arghh! Well, I'm pretty sure my hearing is 10-20db at 16K so not a major problem. Still dont know if it some measurment artefact.
There's a dip at 2.7K. It becomes a lot deeper if a single driver-phase is inverted
Sound is better than I had expected for a first try. Not as loud as I had hoped, but OK.
Below 500Hz is not correct.
More measurments. I'm probably doing something wrong because some of the artifacts are hard to reproduce.
This is the two drivers alone and the combined response.
Looks like the horn-drivers resonance at 1.5-2K is showing up.
These measurment are done with ARTA, impulse response and 1/6 smooting
This is the two drivers alone and the combined response.
Looks like the horn-drivers resonance at 1.5-2K is showing up.
An externally hosted image should be here but it was not working when we last tested it.
These measurment are done with ARTA, impulse response and 1/6 smooting
filter response for the the above measurment
An externally hosted image should be here but it was not working when we last tested it.
Oh, well. It appears I made a small mistake on the last filter-setup. Like in not supplying a 5532.
Things look a little better with power to all parts:
Things look a little better with power to all parts:
An externally hosted image should be here but it was not working when we last tested it.
This is the combined response at different angles. Approx 0-10-20-30-40 off axis.
The difference to the previous graph is due to a small change in mic hight. Either this horn is extremely sensitive to angles (and/or elevation) or I'm doing this wrong.
To My ears the sound is OK and do not change THAT much when moving around in the room.
The difference to the previous graph is due to a small change in mic hight. Either this horn is extremely sensitive to angles (and/or elevation) or I'm doing this wrong.
To My ears the sound is OK and do not change THAT much when moving around in the room.
An externally hosted image should be here but it was not working when we last tested it.
Test-setup:
An externally hosted image should be here but it was not working when we last tested it.
I think the off axis response looks pretty good.
No gross variations in the curves, just reduced level. That's what you want.
The 16k peak looks like it might be annoying long term though.
Still can't get over how cheap those drivers were! ;-)
No gross variations in the curves, just reduced level. That's what you want.
The 16k peak looks like it might be annoying long term though.
Still can't get over how cheap those drivers were! ;-)
The off-axis may be OK ( I really have no experience on this). What annoys me, is that the response varies so much with every small mic-movement. I'm probably doing something wrong.
Looks like there is a consistent 5dB dip around 2K. May have to move the crossovers a bit closer together. Still, its not highend for critical classic listening.
Yes, the drivers are stupid cheap. The finish on the woofer is actually pretty good. The horn looks cheap, but sounds OK to my ears.
Looks like there is a consistent 5dB dip around 2K. May have to move the crossovers a bit closer together. Still, its not highend for critical classic listening.
Yes, the drivers are stupid cheap. The finish on the woofer is actually pretty good. The horn looks cheap, but sounds OK to my ears.
The whether in Denmark is wet, windy and miserable right now. Not exactly ideal for outdoors lab-exercises 🙂
When looking at the un-filtered response for drivers (page 1) there seems to be a decent overlap. The treble has a bump around 2-3K and not a dip. As there is a dip in the combined (filtered) response I wonder if its maybe a phase/cancelation-issue?
When looking at the un-filtered response for drivers (page 1) there seems to be a decent overlap. The treble has a bump around 2-3K and not a dip. As there is a dip in the combined (filtered) response I wonder if its maybe a phase/cancelation-issue?
Cross-over (phase) problems
I could use some help.
LP is 4.order around 2.7K. HP is 4.order around 2.7K + a 1.order around 14K.
Here is a plot of each driver and total output. Approx ½meter from speaker. Midway between drivers:
Same setup. Woofer-wires reversed.
The strange thing is that these plots change ALOT when the mic is moved up and down.
Here the last plot again, but mic at 3 different heigths: horn, mid woff. Still approx ½meter away.
All plots done with ARTA "impulse-response".
Is this normal?
Is the problems due to the phase introduces by the 1.order at 14K?
I could use some help.
LP is 4.order around 2.7K. HP is 4.order around 2.7K + a 1.order around 14K.
Here is a plot of each driver and total output. Approx ½meter from speaker. Midway between drivers:
An externally hosted image should be here but it was not working when we last tested it.
Same setup. Woofer-wires reversed.
An externally hosted image should be here but it was not working when we last tested it.
The strange thing is that these plots change ALOT when the mic is moved up and down.
Here the last plot again, but mic at 3 different heigths: horn, mid woff. Still approx ½meter away.
An externally hosted image should be here but it was not working when we last tested it.
All plots done with ARTA "impulse-response".
Is this normal?
Is the problems due to the phase introduces by the 1.order at 14K?
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