Big horn or pseudo-infinite baffle for bass reproduction ?

If the space is not a problem, which is the best speaker system for the bass (< 160-200 Hz) reproduction that may be associated with a high efficient horn (for mid-range)?
1) ...A big horn (i.e. or
2) a pseudo-infinite baffle (i.e.
3) ...or others ?

Low-end scale is essentially represented by two types of basses: deep, slow, and continuous basses and fast, percussive, and violent basses.
I think that a speaker system that may reproduce both does not exist.
So, which bass speaker system is the best in this area?


2002-01-07 6:02 pm
A properly designed horn will be the best. It will have lower distortion and superior transient abilities. A horn doesn't need to be huge. Properly implemented 30-40 cu ft/channel will give you all the bass you can use domestically. Built into a basement / loft space, it won't take up any living area.

Dr Bruce Edgar has a sub he sells, depending on finish, for peanuts compared to it's performance. It uses a small amount of EQ to get it flat into the 20's. Tom Danley has one too, and Jeff Robinson also has a corker design.

I've built a couple of systems similar to the 'pseudo infinite baffle'/ Infinity / Genesis, and even using the best direct radiators we could find (pro units, with huge motors and excursion), a horn is simply better IME. you really have to hear the difference to know how vast it is.

PWK knew what he was doing.

Bill F.

2001-11-15 5:25 pm
No argument on the sonics of horns (within passband) from me.

Just two questions:

1) How do you plan to get proper phase alignment from a big folded horn? It seems to me you'll need active delay on everything above it. Is adding that into the signal path acceptable to you?

2) Will practicality ever enter the equation? If you're thinking of cutting into your floor/ceiling, then a true infinite baffle is a snap to make. For the cost/complexity of a good, non-coloring bass horn, you could buy a bunch of quality bass drivers and mount them in a manifold venting into your basement/crawlspace--simple. You'd have high efficiency, low distortion, and deeper response than a horn. By tailoring inline resistance (or putting a pot on one coil of dual VC drivers,) you can dial in your preferred Q and transient behavior. You could even leave it adjustable to tailor to any program material.

Another thing about horns: Below cutoff, I believe their transient response goes kablooie along with their phase, right?



2002-01-07 6:02 pm
Hi Antonio,

Here are some ideas for bass horns for you.
Note, these are just the drawings, more details and data can be found on Jeff's mainpage, then navigate around.
(this is a big matching Tractrix midrange)
These designs are by John Inlow (posts here as carpenter)

And finally, the LAB subwoofer, designed by Tom Danley of Servodrive. Designed to be used in groups of 6 a side for PA, one per side eq'd, should get to 20Hz and (I calculate) 120+dB. Should be enough for most people. I'm going to build a few, two for home when the custom drivers become available.

A couple of these a side, driving through your front wall with some big amps should be able to cause arrythmia. Live the Maxell ad!. And at very low distortion too.

Sorry for the delay in replying, I,
Just as thought, since you are only looking for around 30HZ, is a transmission line ported out the back. Not as large, easier to build and move. Back loaded so its easy to change drivers. Using a quarter wave to figure length, if I remember correctly 3.6 meters=30HZ if the speed of sound is 433 meters/second. I also have a horn I built that is a single chambered squashed down version of a Jensen Imperial. I have also heard that the Karlson Horn is exellent for low frequency but haven't had the chance to listen to any. Klipsch horns have great bass, fast and furious they won't do as well as the long drawn out notes, at least the one I listened to, so folded corner horns don't seem to be what you would want. No experience with built ins so no comment.

i have an open baffle subwoofer running very soon together with my FR open baffle speaker. Have a bit patience please, i will report then.

What i heared from open baffle basses so far, they may not have the transients a harn can hand out (above its cutoff frequency only, of course) but they have the ability to make the bass sound as clear as the mids and the treble. Ever heared a plucked double bass having the same clarity and "stringiness" as Julian bream playing his classical guitar? That's open baffle bass.

me knows how a good bass horn can sound. And you do not see me building one. Horn bass is fantastic. Open baffle bass is better to my ears.
I believe that an open baffle may offer good results. However, since the bass unit should be associated with a horn system for the mid-range (Hedlund or Oris), I think that a high sensitivity is important to match the two unit.
In this view a horn system should fit better.
I'm convincing that K-horn bass unit could be a good choise. I do not know if it is better to buy an used couple or to build them by my self.
All three suggestions, TL, IB, & Horn have merit. System matching will play a big role.

The TL probably represents the smallest of these and has the advantage of being a non-resonant system with a very benign impedance making it the nicest one from the amplifier's point-of-view. A set of 4 Lambda high-efficiency 15" TDs in push-push enclosures would give you something like 98 dB sensitivity and very low distortion.

The IB, if implemented as a hole into another space, would also be very good, easier to implement, but would not have as nice an impedance as the TL.

The horn would provide the greatest efficeincy, and probably lower distortion due to the better impedance match with the air (i say probably because this is VERY dependent on actual implementation). This will have the nastiest impedance -- particularily below cutoff. The big problem, as mentioned by Bill, is getting the phasing right. If you use a digital delay you have to put it on the mid/hi units and IMHP these still have a ways to go before they are transparent enuff to be HiFi. One way of getting around this is to mount the bass drivers at about the same plane (or slightly ahead0 of the mid/hi and have the horn expand under the floor (or in the walls) with the mouth opening out into the room the apparopriate distance. If the plane of the bass is too early, it can be delayed digitally (where their performance is less intrusive) or since it is much smaller, with an analog all-pass filter. And for really good performance you can't stint on the mouth size -- BIG.

You could use the new Lambda TD field-coil unit in these thou which would be a really cool project -- variable TS parms just by adjusting the field-coils PS.


Bill F.

2001-11-15 5:25 pm

>You could use the new Lambda TD field-coil unit in these thou which would be a really cool project -- variable TS parms just by adjusting the field-coils PS.

Hey Dave,

Never heard of these. How bout a link?

My google search turned up nought. Lambda has turned so danged opaque recently...

Re: drewl!

Bill F. said:
>You could use the new Lambda TD field-coil unit in these thou which would be a really cool project -- variable TS parms just by adjusting the field-coils PS.

Never heard of these. How bout a link?

I suspect you need to be on the mailing list to hear about any of this stuff -- availability will also be hit & miss, because market pressures are pushing lambda out of DIY and into OEM -- pretty much one man, he has to go where it allows him to put bread on the table -- the project may even have died a still-birth (all it would take, i expect, for a resurrection would be for someone to organize & execute a buy of 50-100 units. There are a whack of posts, you will have to poke thru the archives, but i'll attach a teaser.]Lambda List[/URL]

"I received the estimated parameters for the TD15M field coil. With a
target of 5000 amp turns to generate a theoretical maximum 2 Tesla in the
gap, we need 38V with 1.612A and 61.25W of power consumed continuously.

Now first we will saturate in the center pole before I can get 2 Tesla
across the gap, no way around it without using Permendur (FeCo alloy), and
no one wants to pay the bill for that stuff! From what I remember the TDM
is pushing around 0.6T in its gap so even going to 1.2T is a radical
increase (~double Bl), 2.0T might push the Qes to near zero.

By the way, if we just double the Bl the Qts of the woofer drops down to
~0.071 and the 1W spl goes to 104dB, I don't know where this would work
other than a horn load.

Second, we need to compute the expected DCR rise of the field coil to
figure the extra voltage needed to keep the 1.612A running through it once
heated by the constant 61.25W. The field coil is wound with 20awg copper
wire with a 24 ohm DCR cold (~72F I would imagine), and that info can tell
us what sort of length of wire we are dealing with as well.

Once armed with this knowledge, we can get the power supply designed. The
above numbers are for maximum power into the coil, I imagine we will run
much lower in reality.

I leave this to any of you tech types that can help out.


PS - 1.2T works out to about .939A with 22.53V applied for 21W into the
field coil, this is probably the maximum needed for most anybody as
indicated by the above TS changes I noted, and is probably pretty close to
saturating the motor anyway

PSPS - I am designing the field coil to absorb 100W+ for those that want to
really experiment "

Bill F.

2001-11-15 5:25 pm
>By the way, if we just double the Bl the Qts of the woofer drops down to ~0.071 and the 1W spl goes to 104dB, I don't know where this would work
other than a horn load.

...or a linkwitz transform, eh?

Oops..just drooled again. I think there should be a section on this forum for those who venerate big, beautiful magnetic circuits for their their own glorious sake...sorta like this guy