Tapped LAB, or something like that...

I have been aware of these tapped horn plans, but have been reluctant to post them. I would have expected Danley Sound Labs to be a bit edgy about these plans leaking out, but they don't seem to put much effort in having them taken off line. So hurray!

This thread is a building report of the TH-SPUD by Danley, a regular production model. I always think that DIY-ers can do very good designs by themselves, it is very interesting to see what practical design choices professional make and what the end result is. While I can produce any number of design variations with a linear simulated response graph, Tom Danley knows which variation will deliver in the situations his customers will use his product in. Before tapped horns, Danley gave the DIY horn community the LAB horn, a detailed and perfected design for a bass horn. It gave DIY-ers the chance to build and experience a state-of-the-art horn with predictable performance. "It still is a popular ultimate DIY horn project."

However, we're now in the age of tapped horns and while we have plenty of simulation abilities and there is considerable experience with the tapped horn principle, there has not been such a professionally designed reference tapped horn, such as the LAB is for the conventional horn principle. This is where the TH-SPUD comes in. I am not sure how these plans leaked out, perhaps they were sent to a potential customer to illustrate options and sizes. In any case, they ended up online, including several recommended drivers. Tom Danley even chimed in, in this thread and another, to offer background and advice! Apparently, DIY-builds have his blessing (quite possibly as an afterthought). I guess this is a similar gift as the LAB and I think DIYers will certainly enjoy this one!

I will it to the linked thread to give specifics, I just want to point out the following things:

- it is little deeper as an 8 inch driver (it uses two 8 inch drivers)

- it will work in many locations, but Danley's favorite placement for it is corner placement

- it has breathtakingly extended response

- it has very linear response (check the response graph underneath)

- your room will probably mess that up big time...

Jubilation, again!

The wonderful Klipsch Jubilee build report is back! A new URL, though.

Klipsch Board

It is hard to describe how proud this makes me feel: my list of Klipsch plans mentioned as a resource on the Klipsch board. Grin!

I found it through the referrals section of the hitcounter. The post is also mentioned in this simulation thread, where several woofers are considered in simulations of the Klipschorn, the LaScala and the Belle. It's good stuff. Maybe we can get them to model the Jubilee as well in that thread.

Fixing Bass

I stumbled on to these two examples of multiple subwoofer use. One is the Geddes approach, basically limiting oneself to random placement and playing with cutoff, phase and volume on the submodules. The other, by BD-Design, is more specific, precisely selecting the issue to be dealt with and using a digital crossover and a sub to mirror and cancel the unwanted effect.

Both are effective and interesting.

Impulse resp in Hornresp

A wonderful update of Hornresp. There has been a long list of updates in the tapped horn wizard, but this is (currently) only available for frontloaded horns and direct radiators: simulated impulse response.

Modern Vintage Build, the RT-2/Klason horn

As I have shown, I have a love for vintage designs. I recently posted a link to a thread elsewhere, concerning the Swedish RT-2, otherwise also known Klasonhorn elsewhere. The reason for that thread, was the build by Elbert.

In all the commotion about peceived response etc., the practical and visual side of the project was somewhat neglected. Elbert opened another thread, showcasing his work. He took a very thorough approach to building this horn. Respect!

Geddes and Harman Kardon on subwoofers, bass response

I am thinking hard about my system revision, and particularly the cornerhorn situation. I am reading a book by Floyd Toole, which I will be coming back to later. I have to finish reading it. :) The book is very interesting and is giving me quite a few concept changes about audio reproduction in the home. To paraphrase him shortly, you just have to do what you have to do to make it sound good and then it does sound good. There's a load of data and discussion to back it up, but that's not what I want to talk about. It just triggered me into realising that smooth bass response is a big issue for me (and music in general) and I need to adress it well.

With a single subwoofer or bass source, reflections and resonances in the room lead to peaks and dips in the frequency response, that also differ at varying listening positions. You can try to even them out with an EQ, but whatever is fixed in listening position A makes something else worse in listening position B. And you can take out a peak, but it's impossible to fully fill in the dips as they are cancellations. More power just means more cancellation.

Harman Kardon has a whitepaper about the use of multiple subwoofers and pre-determined, regularly spaced, placement in rooms, which leads to a similar frequency response in the bass range, for all listening seats. This response may be irregular, but it can be equalized flat and the result will be similar and linear bass response throughout the room. The strategy relies on a rectangular room and processing to get the final result right.

Earl Geddes suggests that listening rooms rarely are as predictable in their lay-out and characteristics as the testroom used by Harman Kardon and that this randomness will reduce the positive effects. He also points out that subwoofers placed in regular locations means they will have to be in sight and be very conspicuous. He suggests that randomizing subwoofer placement will work better in the random environment of the listening room, producing a better frequency response in all locations. Randomization basically means put the subwoofers where you think they are convenient. Also, this apparently gives a smoother frequency response even before final EQ and it seems people are getting by without final EQ.

Geddes has a simple approach to get started with placement and to work from there. There is a thread on diyaudio that describes the methodology and Earl Geddes participates in the discussion. There's also some measurements of results. I refer to thread that for the full background. One thing that I do want to mention here, is that Geddes advises to have one main subwoofer, that plays loudest and becomes the source, or the reference subwoofer. Other subwoofers are only there to break up roommodes etcetera, so are all adjusted to disappear into the main response. It is pointed out in the thread that dissimilar subs add to the randomization.

I want to employ this. A big hornsub in the corner and some frequency response smoothing via smaller subs here and there.