I've probably rambled and got off topic enough.

Later,

Dave

There is also increased dynamics inherent in the characteristics of horns. Again, if you choose to ignore this, this is your choice, but it is there.

For these reasons, if I am going to put my Lowther DX4s into a box, it will be a back horn, not a reflex box, which Lowther owners say suck, nor transmission lines, which are a step above reflex boxes, but still not as good a match.

Retsel

You also wrote :

"For these reasons, if I am going to put my Lowther DX4s into a box, it will be a back horn, not a reflex box, which Lowther owners say suck, nor transmission lines, which are a step above reflex boxes, but still not as good a match."

I own seven pairs of Lowther drivers, including a pair of DX4's, and find they perform very well in TL and ML TL style enclosures. So this Lowther owner definitely does not feel that this design option "sucks". It is one compromise that can be considered for Lowther drivers. I also use 200 watts of SS power and can report that does not "suck" either.

Martin

• Quarter Wavelength Loudspeaker Design

If you reread my post you will see that I did not say that transmission line speakers suck. I did said that reflex boxes suck. I own a pair of transmission line speakers. They are the premier speakers made by Irving "Bud" Fried. They were originally sold with the name of C3Ls and then when he upgraded the speaker drivers and crossovers, he renamed the satelites as C5s (as part of his Vahalla system which sold for $10,000 in the 80s). I upgraded to the C5s. They are very excellent speakers. It is just that the Hedlund Horns are better, as they start with better quality drivers. Bud did say that the woofers in those speakers are higher Q drivers.

I am sure that the Lowther DX4s are excellent in transmission lines. I bet that you could duct tape a pair to the wall and if coupled with a suitable crossover, they would have respectable sound in that application too. But the point being made by this string of posts is that back horns are the best way to get the most efficiency and dynamics from full range speakers. My experience has confirmed this with Lowther DX4s and particularly so since they have such a low Q.

Transmission line speakers probably have a higher WAF then back horns, and you could sell them on that basis, but I doubt that transmission lines will have the dynamics and efficiency of back horns. They may not be different by a lot, but side by side, they would be a notch lower. My question to you is when you put a pair of Lowther DX4s into transmission lines, do you need to pad down the upper frequencies, or is the frequency response relatively flat (I doubt that Lowthers are "flat" in backhorns, but they are so when averaging over the frequency response and they sure sound great without crossover components in the signal path)?

Retsel

Can't agree with you on bass-reflex either. To say bass-reflex sucks is like saying LC oscillators suck. They do just fine when tuned right and used in the right situation. I don't think I'd want a bass-reflex midrange or tweeter and I don't think I'd want a highly underdamped bass-reflex woofer either. But I think bass-reflex is perfect for high efficiency woofers where low extension and relatively small cabinet size is required.

I think that back-loaded horns are a great idea for single driver speakers. But the thing I think is very important to make clear, is that size matters. If a backloaded horn is small, it acts very similarly to a transmission line. This can be seen in both the impedance plot and the frequency response. This also affects excursion, which limits maximum SPL on a single driver speaker.

Where efficiency is concerned, backhorn loudspeakers generate midrange and treble from direct radiation, so that sets the limit. You would not want to build a horn that raised the bottom octaves above that of the midrange, so the average SPL of the driver itself is the average SPL of a good single driver loudspeaker. Speaker voicing is a different matter entirely.

I understand what you and others are saying, that you would rather use the backhorn as an acoustic filter, to use it instead of a electrical network. But I've heard some very fine transmission line speakers that needed no electrical filter, so I consider the two issues separately. I've also heard some very nice bass-reflex single driver speakers that needed no electrical filter. So I would ask you to understand why I would suggest that the issue of electrical filters be separated from the rest of the discussion, and just look at the similarities and differences of the acoustic chambers themselves.

Lastly, consider the amp driving these speakers. The electrical impedance becomes very important on amps with high output impedance. Loudspeaker impedance peaks cause response peaks when used with tube amps, the "First Watt" Pass Amp and others that act like constant current sources. Look at the impedance charts of all these loudspeakers in question and you'll see that some are more friendly than others in that situation. A moderate peak or two is much better than several notches, so it is important to the overall sound quality to pay attention to that when used with current sources. This is overlooked by many people, and ironically, it is probably more important than anything else when using some amps.

My question again to Martin is does his transmission designs allow forgoing all crossover components because the bass boost brings up the bass to match the high frequencies, and is the tipped up response smoothed out? That is the magic of a well designed back horn.

I have never had a reflex bass cabinet. I have heard some say that the design is flawed. I am heard from so many that the bass reflex design sucks for Lowhters, so I am convinced of that.

Retsel

And again, bass-reflex cabinets are like LC circuits. There is nothing flawed with them. There are a lot of people spouting nonsense on the internet, and I would suggest to you that comments about reflex designs being flawed are the remarks of a person that doesn't know what they are talking about. It's kind of sophomoric really, like a sticker on the back of a Camaro that has a kid pissing on a Ford logo.

Based on what others say you are already convinced. Based on that, I see no real reason to continue the discussion.

Martin