Yes; usually we are trying to avoid boomy bass when designing our loudspeakers. I’m looking in opposite direction with my project. It’s amusing and entertaining and I learned a lot fooling around with this project.
Yesterday evening I got an idea. I played music from my cellphone with Neutron player and 20 band equalizer. It has this sliders at the bottom: 28Hz, 39Hz, 55Hz, 78Hz, 110Hz, … etc.
Looks like the magic frequency is 55Hz or I should say somewhere between 50 to 60Hz.
Moving 28Hz and 39Hz slider didn’t make much difference. When pushing 78Hz slider I got more shallow ‘’tup-tup’’ and not deep round ‘’bum-bum’’ bass.
When I pushed 55Hz slider the bass started to move in direction I was looking for. It became more rounded and fat but not exactly one note. It was quite enjoyable. Pushing slider from +5 to +8dB I got it.
First let me say something about WinISD software.
When designing my main loudspeakers with full range unit I discovered that WinISD usually calculates bass reflex port longer as they are later in reality. This goes with the results Troels got when doing measurements:
vent tuning
Taking all this in account I started thinking about my boombox tuning.
First thing:
If according to my equalizer test 55Hz is the frequency I’m looking for should I tune bass reflex port to this frequency?
I can’t calculate the ports because those calculations are not exact and I can’t measure it because I don’t have equipment. So the only thing I can do is to play 55Hz with my finger on the woofer and slowly change port length. When woofer makes the smallest movement playing 55Hz this is the port length I’m looking for. In other words – the ports are tuned to 55Hz.
Second thing:
Will I be able to increase bass for 5 to 8dB this way?
Probably not so I guess I will need some sort of bass boost to get the result I want. Passive circuit will increase 55Hz by lowering the rest of the range so I will lose gain. This Bluetooth module does not have a lot of gain so better option would be to make active bass boost.
One option is preamplifier – basically CMoy amp with bass boost on feedback loop. I did the same thing on my gainclone amp with good results - an additional resistor in parallel with a cap and in series with feedback resistor to increase the gain at low frequencies..
Any other options?
What is passive twin T filter at line level?
Yesterday evening I got an idea. I played music from my cellphone with Neutron player and 20 band equalizer. It has this sliders at the bottom: 28Hz, 39Hz, 55Hz, 78Hz, 110Hz, … etc.
Looks like the magic frequency is 55Hz or I should say somewhere between 50 to 60Hz.
Moving 28Hz and 39Hz slider didn’t make much difference. When pushing 78Hz slider I got more shallow ‘’tup-tup’’ and not deep round ‘’bum-bum’’ bass.
When I pushed 55Hz slider the bass started to move in direction I was looking for. It became more rounded and fat but not exactly one note. It was quite enjoyable. Pushing slider from +5 to +8dB I got it.
First let me say something about WinISD software.
When designing my main loudspeakers with full range unit I discovered that WinISD usually calculates bass reflex port longer as they are later in reality. This goes with the results Troels got when doing measurements:
vent tuning
Taking all this in account I started thinking about my boombox tuning.
First thing:
If according to my equalizer test 55Hz is the frequency I’m looking for should I tune bass reflex port to this frequency?
I can’t calculate the ports because those calculations are not exact and I can’t measure it because I don’t have equipment. So the only thing I can do is to play 55Hz with my finger on the woofer and slowly change port length. When woofer makes the smallest movement playing 55Hz this is the port length I’m looking for. In other words – the ports are tuned to 55Hz.
Second thing:
Will I be able to increase bass for 5 to 8dB this way?
Probably not so I guess I will need some sort of bass boost to get the result I want. Passive circuit will increase 55Hz by lowering the rest of the range so I will lose gain. This Bluetooth module does not have a lot of gain so better option would be to make active bass boost.
One option is preamplifier – basically CMoy amp with bass boost on feedback loop. I did the same thing on my gainclone amp with good results - an additional resistor in parallel with a cap and in series with feedback resistor to increase the gain at low frequencies..
Any other options?
What is passive twin T filter at line level?
Last edited:
As already mentioned take a speaker which is tuned flat and neutral and then tune it higher. This can give you a hump up to +6dB (i.e. fourfold sensitivity over a small frequency range). Then use some subsonic filter - or reduce some coupling cap - below the new tuning frequency. Et voila: there is your Teenie stereo.
Regards
Charles
Regards
Charles
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