Achieving full range sound in typical British living rooms - IPL Speakers S2TLK CD3.0

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Just a little further documentation regarding the 3kHz dip in the IPL speakers. Linkwitz does the same:

Linkwitz the Psycho-acoustic 3 kHz dip

"Our perception of loudness is slightly different for sounds arriving frontally versus sounds arriving from random directions at our ears. The difference between equal-loudness-level contours in frontal free-fields and diffuse sound fields is documented, for example, in ISO Recommendation 454 and in E. Zwicker, H. Fastl, Psycho-acoustics, p. 205.
Diffuse field equalization of dummy-head recordings is discussed in J. Blauert, Spatial Hearing, pp. 363, and headphone diffuse field equalization by G. Theile in JAES, Vol. 34, No. 12.
Reference to a slight dip in the 1 to 3 kHz region for loudspeaker equalization is made in H. D. Harwood (BBC Research Department), Some factors in loudspeaker quality, Wireless World, May 1976, p.48.

Around 3 kHz our hearing is less sensitive to diffuse fields. Recording microphones, though, are usually flat in frequency response even under diffuse field conditions. When such recordings are played back over loudspeakers, there is more energy in the 3 kHz region than we would have perceived if present at the recording venue and a degree of unnaturalness is introduced.
This applies primarily to recordings of large orchestral pieces in concert halls where the microphones are much closer to the instruments than any listener. At most listening positions in the hall the sound field has strong diffuse components.
I use a dip of 4 dB (x1.gif, 2760NF) to equalize for this. The circuit consists of R, C and L in series, forming a frequency dependent ladder attenuator in conjunction with the 5.11k ohm source resistor. You may choose to make the notch filter selectable with a switch for different types of recordings.

I have found through my own head-related recordings of symphonic music that the dip adds greater realism, especially to large chorus and to soprano voice and allows for higher playback levels."
 
I think it's quite plausible that the dip at 3Khz is a diffraction effect from the cabinet edges. I got something almost identical doing a sim for Wilbur-x with a tweeter placed at the top of a 20cm wide cabinet.

Your IPL is close to the driver placement I was using. S2tlk Ribbon

Moving the driver down and putting it off centre seemed to fix it in the sim. 10 cms is approx. a wavelength at 3kHz.
 
Here's the sim restored to all its horrible glory.

Tweeter in middle of 20cm tower cabinet, 10 cm from top.

I really wondered what was going on with an ostensibly flattish tweeter! 3kHz, 6kHz, 9kHz. :confused:

I don't really understand why whole wavelengths cancel, but I am sure it is easily explained.
 

Attachments

  • 3kHz dip on 20cm cabinet..PNG
    3kHz dip on 20cm cabinet..PNG
    14.6 KB · Views: 206
This thread I just came across, just read through and actually agree with @Stretchneck. My problems of bass boom are gone after buying the IPL S2 TLK speakers. So much deeper so much deeper with almost no bass boom. I don't know about the BBC deep at 3kHz but these also sound less shouty not sure if Has anything to do with that. I have tried a lot of mass produced speakers nothing has sounded as even hand to me as the IPL S2TLK speakers. My Opinion of course.
 
This thread has been dormant for some time, but I thought I’d add some of my recent experiences.

I have changed many things to my setup since completing the S2TLK speakers - ncore amplifiers, Naim DAC V1, NUC running Euphony and a tx-USBUltra. I am now a believer of how important source is to a music system, it has made a significant difference and I now feel that my system sounds better now with a streaming source than it did playing CD’s. This was a major challenge for me, but the guys over at audiophilestyle gave me guidance.

I am happy to report the the S2TLK scaled nicely with these upgrades. But now that my source and amplifier is really top notch I felt the need to try something else. I tried the KEF R3 out of curiousness and it sounds really quite amazing, one of the best speakers I have ever heard (I am not a fan of the LS50). My aversion to ports has also been softened as I really don’t notice their potential downfalls in the R3.

Anyhow, S2TLK is still a marvellous speaker and I’m so grateful to Ivan for putting out kits that people can build with only basic skills. S2TLK offers smooth all day near full range listening. But looking at some of the commercial offerings out there now I would encourage people to look at other designs, for example the KEF R3 that I have now pretty much beats the S2TLK in all areas.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.