Quarter Wave Loudspeaker Enclosures

[MALIK_BRODER]

Does anyone here have experience with Quarter Wave Loudspeaker Enclosures or can point me to suitable resources as how to build one?

Cheers

Malik

 

[MJK]

I have been working on/with quarter-wave enclosures for over 25 years. You can find my take on the design of these types of speakers at www.quarter-wave.com and if you look at the gallery linked from the homepage there are many examples of speakers designed and built using my methods.

 

[MALIK_BRODER]

Wow, the Martin King. Blushing right now. Thanks for an amazing site and so much passion for what we do. I have been trying to get my head around back loaded horns. Can you explain the underlying advantages and principles in layman terms? I imagine they "bundle" the rear radiating sound in a similar way as a front loaded horn does making them rather efficient? Wouldn't they emit all frequencies backward and out the horn compared to say a well stuffed quarter wave leading to cancellations and superpositions with the output from the front? Do they help with bass extension at all? If so, how? Also do you know of a good reasonably priced quarter wave that is commercially available?

 

[MJK]

My latest thinking on back loaded horn design is contained in this article from 2012.

http://www.quarter-wave.com/Horns/BLH_Design_Article.pdf

For many years I dabbled in back loaded horn designs and never came up with a design I thought was worth building. The light bulb above my head started to flicker 3 years ago when I realized that almost all of the BLH designs found on the Internet were really just expanding TLs at low frequencies due to the grossly undersized mouths (I was very slow to recognize this fact). Applying horn sizing equations to design these BLH is really misguided, the inherent assumptions used to derive the horn equations were not met for most of these BLH designs at bass frequencies. I am still working on back loaded horn designs and have a few ideas that extend what I wrote in the linked document, I continue working on these ideas on and off as time permits. At this time I have no recommendations for a good BLLH design that can be found on the Internet. Sorry not much help.

 

[MALIK_BRODER]

Thanks so much for such a detailed reply. If you can't do it I am going to go with "can't be done". Do you know of any reasonably priced commercial quarter waves that you can recommend?

 

[MJK]

Can't be done might be too sweeping a conclusion, MJK has not yet found the right combination of driver and geometry is a fair statement. Other people might feel differently with respect to the various DIY BLH options on the Internet.

Not sure what is reasonable for you, but take a look at Jim Salk's or Dennis Murphy's speakers. They are both highly regarded TL variants.

 

[Swerd]

For your info, the following speakers are the ones that MJK referred to. They are all floor-standing speakers with mass loaded transmission line (MLTL) cabinets designed using MJK's methods and software. All of them make use of crossovers designed by Dennis Murphy.

Philharmonic Audio http://philharmonicaudio.com/
Philharmonic 3
Slims Tower

Salk Signature Sound http://www.salksound.com/
SongTower
SongBird
SuperCharged SongTower
Veracity HT1-TL
Ellis 1801-TL
Veracity HT2-TL
Veracity ST

 

[lsiberian]

I'd not give up on a design because one guy couldn't figure it out or finish his project. If I'd done that with bipolar fronts I wouldn't have the amazing front speakers that I currently do.

 

[slipperybidness]

I'd not give up on a design because one guy couldn't figure it out or finish his project. If I'd done that with bipolar fronts I wouldn't have the amazing front speakers that I currently do.

True, but check up on who this "one guy" MJK really is. Click on that link that he provided.

 

[MJK]

True, but check up on who this "one guy" MJK really is. Click on that link that he provided.

He's right, just because I have not found a recipe I am happy with does not mean that somebody else looking at the problem from a different perspective would not find a winning combination of driver and BLH geometry.

 

[KEW]

For your info, the following speakers are the ones that MJK referred to. They are all floor-standing speakers with mass loaded transmission line (MLTL) cabinets designed using MJK's methods and software. All of them make use of crossovers designed by Dennis Murphy.

Philharmonic Audio http://philharmonicaudio.com/
Philharmonic 3
Slims Tower

Salk Signature Sound http://www.salksound.com/
SongTower
SongBird
SuperCharged SongTower
Veracity HT1-TL
Ellis 1801-TL
Veracity HT2-TL
Veracity ST

Swerd,
Do any of those have design plans available?
Since the OP is looking for DIY, he may want to use the plans as a starting point to design his own, or simply build one of those designs, if plans exist.
I'm kinda assuming you would know this off the top of your head.

 

[rojo]

Swerd,
Do any of those have design plans available?
Since the OP is looking for DIY, he may want to use the plans as a starting point to design his own, or simply build one of those designs, if plans exist.
I'm kinda assuming you would know this off the top of your head.

http://forums.audioholics.com/forums/threads/new-diy-mtm-towers-designed-by-dennis-murphy-and-paul-kittinger.68531/

But it appears that OP already found that thread.

 

[MJK]

For a single driver design consider Bob Brines.

http://brinesacoustics.com/

He sells everything from plans to flat packs to finished speakers. His designs are very well thought out and engineered to get the most from a single full range driver.

 

[KEW]

http://forums.audioholics.com/forums/threads/new-diy-mtm-towers-designed-by-dennis-murphy-and-paul-kittinger.68531/

But it appears that OP already found that thread.

So are the ER18's the only ones from Swerd's list?
Actually, they are not on the list.

 

[Swerd]

The list above are commercially available MLTL speakers from Philharmonic or Salk.

The DIY design that I know is their close cousin is the ER18 MTM.

I believe a DIY designer/builder named Paul Kittinger did the cabinet design for all those speakers. He also has his own designs, and he can be contacted through the Parts Express Tech Talk forum.

 

[TheWarrior]

And the Seas Thor!

I've got half the mdf cut, the other half still needs to be bonded. And theoretically, because I have health insurance, I'll be getting a tax refund soon!