My TL speakers with dual Vifa P17 and Heil tweeter

[Greg B]

You have to remember that Martin King's math model of TL's is relatively recent, and apparently hasn't been entirely accepted by the old guard.

The Thor and speakers like it are based on Augsburger's work, which until recently was about the best you could do.

I have found that MK's model gives very accurate results.

Regarding measurement, here in the US (and in the UK?) you can buy a radio shack SPL meter inexpensively. Which, with a test CD or computer tones, is good enough in most instances to tune a TL. For something more accurate, there are those behringer ECM8000 measurement mics, or you can DIY one from a panasonic capsule.

Greg B

 

[Greg B]

One more idea. Take a look at the Norman Fulmer and Raymond Bates tuned pipe articles at this site (under the articles tag):

http://home.planet.nl/~ulfman/

Cutting an exponential slot saved my butt once when I was having similar problems in a TL I built in the bad old days. I did a quick check in MJK guessing at your dimensions. I think your project is a good candidate for this technique. It should bring back the midbass.

Also, your impedance curve shows a fair amount of rise. You may want to use a zobel network in your crossover if you aren't already.

I think your project is potentially very good sounding, you'll just have to stick with it.

Greg B

 

[Andypairo]

One more idea. Take a look at the Norman Fulmer and Raymond Bates tuned pipe articles at this site (under the articles tag):

http://home.planet.nl/~ulfman/


Cutting an exponential slot saved my butt once when I was having similar problems in a TL I built in the bad old days. I did a quick check in MJK guessing at your dimensions. I think your project is a good candidate for this technique. It should bring back the midbass.

Also, your impedance curve shows a fair amount of rise. You may want to use a zobel network in your crossover if you aren't already.

I think your project is potentially very good sounding, you'll just have to stick with it.

Greg B

I will give a look at these articles, the slot should be cut at the end of the line if I understand correctly, but what makes you conclude that it can be a good candidate for this kind of mod?

PS the impedance measurement only shows the midbasses (they are wired in parallel)

Cheers

Andrea