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Achieving full range sound in typical British living rooms - IPL Speakers S2TLK CD3.0
Achieving full range sound in typical British living rooms - IPL Speakers S2TLK CD3.0
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Old 17th March 2018, 07:12 PM   #1
stretchneck is offline stretchneck  United Kingdom
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Default Achieving full range sound in typical British living rooms - IPL Speakers S2TLK CD3.0

Completed my IPL Transmission Line project and have written a huge 12 page review. Lots of stuff on forums elsewhere, which I've tried not to replicate, instead I'm trying to pass on the knowledge that I've gained as a beginner to DIY speaker building.

I hope this helps everyone, and if you're in the UK I really recommend these IPL kits.

Thanks
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Old 17th March 2018, 07:52 PM   #2
planet10 is online now planet10  Canada
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Achieving full range sound in typical British living rooms - IPL Speakers S2TLK CD3.0
Thanx for that… i haven’t read the whole thing, but this bit seems like non-sense:

Quote:
The transmission line speaker design helps by effectively stopping the
sound wave from the back of the speaker driver reflecting off the wall behind the speaker (the front wall) and then bouncing back towards the front of the speaker causing an acoustic null – this reflection is a major factor in good sound production.
dave
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Old 18th March 2018, 08:10 AM   #3
stretchneck is offline stretchneck  United Kingdom
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Hi Dave - yes I struggled in writing this part. Basically what I'm trying to say is that the sound from the rear of the speaker driver is effectively eliminated in a transmission line design, with only frequencies 200Hz and lower leaving the front termination of the transmission line. This means that the bulk of frequencies 200Hz and higher are not emitted towards the wall behind the speaker (the front wall that the listener is facing) - and therefore cannot go on to produce acoustic nulls. I hope this makes sense?

Achieving full range sound in typical British living rooms - IPL Speakers S2TLK CD3.0


For someone like me who is trying to achieve good sound quality, but in near wall placement, it made a big difference.
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Old 18th March 2018, 09:39 AM   #4
Jerms is offline Jerms  United Kingdom
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Quote:
Originally Posted by stretchneck View Post
Hi Dave - yes I struggled in writing this part. Basically what I'm trying to say is that the sound from the rear of the speaker driver is effectively eliminated in a transmission line design, with only frequencies 200Hz and lower leaving the front termination of the transmission line. This means that the bulk of frequencies 200Hz and higher are not emitted towards the wall behind the speaker (the front wall that the listener is facing) - and therefore cannot go on to produce acoustic nulls. I hope this makes sense?

http://arqen.com/wp-content/gallery/...e-response.jpg

For someone like me who is trying to achieve good sound quality, but in near wall placement, it made a big difference.
That it is a TL has some advantages. Those 180 bends the sound waves transit act as filters to reduce/remove higher frequencies. The lining and stuffing of the TL also tend to do this. Some reduction in reflections through the driver and some reducing higher frequencies passing through the line to exit the port.

The front foot placement of the port helps. It is physically remote from the woofer and close to a dispersing surface, the floor. Could also be an absorbing surface if carpetted.

What you are left with in terms of a problem(?!?) or not.... Is the group delay inherent in the sound reinforcment through the port. Which will be at its maximum at the TL tuned frequency. If that frequency is low enough, however, all manner of other room and furniture effects might make more of an impact.

J.
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Old 18th March 2018, 10:41 AM   #5
Scottmoose is offline Scottmoose  United Kingdom
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Quote:
Originally Posted by stretchneck View Post
Hi Dave - yes I struggled in writing this part. Basically what I'm trying to say is that the sound from the rear of the speaker driver is effectively eliminated in a transmission line design, with only frequencies 200Hz and lower leaving the front termination of the transmission line. This means that the bulk of frequencies 200Hz and higher are not emitted towards the wall behind the speaker (the front wall that the listener is facing) - and therefore cannot go on to produce acoustic nulls. I hope this makes sense?

http://arqen.com/wp-content/gallery/...e-response.jpg

For someone like me who is trying to achieve good sound quality, but in near wall placement, it made a big difference.
Er -that's still nonsense I'm afraid. Unless your speaker is built into the room & is entirely flush with the front wall, it is a nominal monopole attempting to radiate into 2pi space below the baffle-step frequency. It doesn't matter whether it is a TL / QW, vented box variation, horn, sealed or anything else. Above the baffle step frequency, where the drivers are nominally emitting in 4pi space, it makes no difference what the enclosure internal load is and the radiation angle is governed by the driver characteristics & the baffle size & shape. Identical drivers on an identically sized & shaped baffle will behave the same way.
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Old 18th March 2018, 10:57 AM   #6
stretchneck is offline stretchneck  United Kingdom
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Hi ScottMoose - definitely agree that “Unless your speaker is built into the room & is entirely flush with the front wall” statement, but the transmission line design does tend to help with this aspect, probably more so in the lower frequencies. This is my subjective opinion
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Old 18th March 2018, 11:02 AM   #7
scottjoplin is offline scottjoplin  Wales
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My experience is distance from the front wall either has to be small as possible, soffit mounting being the ultimate in this regard, or as far away as possible so that reflections are delayed, attenuated and diffused, and appropriate baffle step compensation. A transmission line is still a monopole source, a cardioid speaker can help with close front wall positioning
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Last edited by scottjoplin; 18th March 2018 at 11:19 AM.
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Old 18th March 2018, 11:24 AM   #8
JimT is offline JimT  Canada
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Nice article.

Thanks
Jim
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Old 18th March 2018, 12:05 PM   #9
stretchneck is offline stretchneck  United Kingdom
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cardioid speaker - being a newbie I’ve never heard of this before. You’ll get me building another project!
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Old 18th March 2018, 12:25 PM   #10
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