Hi. I'm a newbie DYI speaker builder and I'm currently designing a transmission line (TL) speaker using a 5.25 woofer and tweeter. My inspiration is the the PMC twenty5 series.
I understand that a TL speaker (when properly tuned) accentuates the bass which is why it can be an attractive concept in speaker design.
However, I have also been reading a lot into baffle loss where by bass energy is attenuated (up to 6db) via baffle diffraction.
My question is, when trying to model the speaker frequency response using available software tools, how do these to concepts compete with each other? At what point does the TL bass effect offset baffle loss?
Would be good to get your feedback on this...
cheers
I understand that a TL speaker (when properly tuned) accentuates the bass which is why it can be an attractive concept in speaker design.
However, I have also been reading a lot into baffle loss where by bass energy is attenuated (up to 6db) via baffle diffraction.
My question is, when trying to model the speaker frequency response using available software tools, how do these to concepts compete with each other? At what point does the TL bass effect offset baffle loss?
Would be good to get your feedback on this...
cheers
Different range so no, one doesn't fix the other. Secondly, there's no loss. It's more of a redistribution. This is an internet myth.
You might be interested in this speaker - it sounds great.
Low-Cost PMC-inspired TL Monitor with DC130A and DC28F
When I simulate a speaker with a narrow baffle, I have found that I typically have a "loss" of about -5dB from the rated woofer sensitivity. So in order to have output that is balanced, you will need a baffle step correction. Either a shelving filter in your XO (typically a resistor parallel with a coil) or a filter in DSP to attenuate the highs above circa 900hz by 5dB give or take 1dB. This changes if you place the speakers on the floor or near a back wall as you will get some wall reinforcement and the bass will sound more powerful. But up on a stand mount, it is about -5dB in my experience. This says that the typical 87dB sensitive woofer will at most, provide you with a circa 82dB sensitive speaker. If you have woofers that are closer to 90dB sensitive then they can be as high as 85dB. This circa 82dB to 85dB sensitvity of 5.25in 2-ways is confirmed with my calibrated microphone measurements. So anytime I see a 5.25 in or 6.5in 2-way speaker advertised as 92dB sensitivity, I take that with a grain of salt unless they are using some special 5.25in woofer with 97dB sensitivity below 100Hz (I have yet to see one).
Low-Cost PMC-inspired TL Monitor with DC130A and DC28F
When I simulate a speaker with a narrow baffle, I have found that I typically have a "loss" of about -5dB from the rated woofer sensitivity. So in order to have output that is balanced, you will need a baffle step correction. Either a shelving filter in your XO (typically a resistor parallel with a coil) or a filter in DSP to attenuate the highs above circa 900hz by 5dB give or take 1dB. This changes if you place the speakers on the floor or near a back wall as you will get some wall reinforcement and the bass will sound more powerful. But up on a stand mount, it is about -5dB in my experience. This says that the typical 87dB sensitive woofer will at most, provide you with a circa 82dB sensitive speaker. If you have woofers that are closer to 90dB sensitive then they can be as high as 85dB. This circa 82dB to 85dB sensitvity of 5.25in 2-ways is confirmed with my calibrated microphone measurements. So anytime I see a 5.25 in or 6.5in 2-way speaker advertised as 92dB sensitivity, I take that with a grain of salt unless they are using some special 5.25in woofer with 97dB sensitivity below 100Hz (I have yet to see one).
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great thanks for the feedback. I'm using hornrsp already although I can see that I haven't been using to its potential yet...will check it out.