A new Linear TL Floor Standers for my next upgrade to 845 tubes

[Hari Iyer]

Measured the speaker using an RTA with pink noise over the weekend. The near field response (microphone around 1" away from the woofer dust cap) is as below,

Observing the peak in response from 4KHz to 16KHz range modified the cross-over to tame the response in that region and below is the final cross-over simulated response.

Will be again measuring this response in the evening and will post them.

 

[mpw]

the responses will be better with wooden blocks under the equipment.

Please try it.

There is a long thread going on as well in another part of the forum.

Maybe your measurements with visual results will be interesting for all to see and box over.

mpw

 

[ANNA]

Hi Hari,

Congratulations !
Have read you posts earlier and love reading your posts as they have technical information as well. Hats off to your enthusiasm and time devoted to make quality speakers.

 

[kanwar]

Hari,

Why there is a slight hump around 200-300 hz ?

Also if possible kindly plot a mid-field data. Would love to see the effect of TL+woofer in combo.

 

[Hari Iyer]

Slight hump in the 200 -300Hz region is delibrate to improve the mid-bass response. Will post the mid-field response later once done.

 

[kanwar]

Slight hump in the 200 -300Hz region is delibrate to improve the mid-bass response. Will post the mid-field response later once done.

But in doing so have you taken account of the large variation in phase-shift in lower octaves of that region.

 

[Hari Iyer]

But in doing so have you taken account of the large variation in phase-shift in lower octaves of that region.

I have not done any modification in the cross-over for achieving that. The peerless M13KH kevlar woofer free-air response is such that it has a SPL increase from 150Hz till 500Hz and the is flat from 500Hz till 3KHz after which it rolls-off into cone break-up mode. Hence did not have to compensate with a inductor and resistor for that mid-bass region. The design being a TL have to take care of the odd harmonics with sufficient damping in the region to prevent standing waves.

The driver response and the filter phases are in the below figure,

Orange - Woofer free air SPL
White - Tweeter free air SPL
Yellow - Speaker system SPL
Golden - Filter Phase
Light Blue - Low Filter Phase
Dark Blue - High Filter Phase
Green - Impedance phase
Red - Impedance


As you can see, the filter phase is relative constant from 20Hz till 10KHz, being an Aluminium Dome tweeter it kind of resonates at around 13KHz to 16KHz region and needs to be compensated for the resonance else will suffer from ringing, due to this compensation the filter phase shift is evident from 10KHz till 20KHz. This phase shift trade-off is better than the resonance and ringing trade-off as per my findings with my listening test.

 

[mpw]

so does it not measure good ?

does it not sound good ?

mpw

 

[Hari Iyer]

so does it not measure good ? does it not sound good ?

mpw

As you can see in the measured response there is a peaking in the response in the nearfield from 4KHz till 16KHz. This was also evident in the listening test which kind of masked the mid-bass and the mid frequencies a bit. The measurements confirmed with the listening test and hence i tweaked the crossover a bit to reduce the tweeter high freq resonance to bring them in level of the lows and the mids.

Doing this change made a massive improvement in the overall sound stage and reduced the brightness from the speaker a lot. I have yet to measure this change and will do them when i get time.

 

[Hari Iyer]

Changed my midn and now will order the 300B instead of the 845 for the following reasons,

- My listening room is very modest size - around 180sq.ft ( 18' x 10') and hence felt that the additional power of the 845 will not be of much use for 95% of the time which will be wasted as heat.
- 300B is a mono-block and have 2 sets of input and hence can pair two sources simultaneously.
- 300B has a very well balanced mid-range and highs which is smooth and mellow to hear. Also the lows are quite tight.
- 9w + 9w should be adequate with my speakers SPL of now averaged at around 90dB.
- Connected the Indeed 15W + 15W amp today today to the speakers and found them reasonably loud at 12'O clock position.

Ordered them today and should arrive by next weekend. Hopefully.

 

[koushikp]

Heard and saw the speakers today finally... sound quality is superb, similar to atish's and mine speakers, of course one needs to do an A and B tests with mine and this one to see where exactly the difference is real works listening tests... But I did feel that because of the aluminium dome tweeter the high frequencies have an added definition, but not sure if that was just my mind playing tricks on me knowing the changed configuration... After both mine and this speaker is broken in let's do a blind test one day...

Hari's carpenter has done a really good job with the speakers in terms of finishing... Kudos to them

 

[Hari Iyer]

After listening test with my class A mono amplifier will finally settle for this simulated response. Hoping this to achieve the accurate balance of lows, mid-bass, mids, mid-highs and highs for my listening room. Have not yet implemented and will plan and do this over the week if time permits. Will measure them over the weekend and post subsequently.

 

[Jatt_boy]

After listening test with my class A mono amplifier will finally settle for this simulated response. Hoping this to achieve the accurate balance of lows, mid-bass, mids, mid-highs and highs for my listening room.

Hari,
How did you reached to this conclusion using this measurement.

 

[Hari Iyer]

Hari,
How did you reached to this conclusion using this measurement.

This is a simulated response and not the actual measurement. The conclusion is based on both subjective listening test and objective measurements. The subjective test is based on far-field (about 9 feet distance with both speakers playing).

I have not yet implemented this and will be doing so over the week and post the measured response later.

 

[kapvin]

After listening test with my class A mono amplifier will finally settle for this simulated response. Hoping this to achieve the accurate balance of lows, mid-bass, mids, mid-highs and highs for my listening room. Have not yet implemented and will plan and do this over the week if time permits. Will measure them over the weekend and post subsequently.

Bring them over to my house, i'll measure everything for you. impedance, frequency response, impulse etc. your listening area will not allow for a proper measurements as reflections will come in too early and smear the measurement. using a smaller gate will help, but artificially smoothen the response curve.

I am in India for the next few weeks so weekends should be fine if you call in advance. and tomorrow I am at home for most of the the day.


best wishes.

 

[mpw]

Bring them over to my house, i'll measure everything for you. impedance, frequency response, impulse etc. your listening area will not allow for a proper measurements as reflections will come in too early and smear the measurement. using a smaller gate will help, but artificially smoothen the response curve.

I am in India for the next few weeks so weekends should be fine if you call in advance. and tomorrow I am at home for most of the the day.


best wishes.

================================

thats a great gesture kapvin..

mpw

 

[keith_correa]

This is a simulated response and not the actual measurement. The conclusion is based on both subjective listening test and objective measurements. The subjective test is based on far-field (about 9 feet distance with both speakers playing).

I have not yet implemented this and will be doing so over the week and post the measured response later.

I'm sorry but I do not understand. If these are simulations and you have not implemented this yet then how can you have listened and measured this?

 

[keith_correa]

The new TL is using a waveugide for the upper mid and the high-frequency for diffracting them behind the box.

Are you saying that the waveguide is aiding diffraction?

 

[Hari Iyer]

I'm sorry but I do not understand. If these are simulations and you have not implemented this yet then how can you have listened and measured this?

We can do a cross-over simulation even before building the speaker. It requires driver FR curve and Impedance values to simulate. We can build the cross-over using this simulator and understand its behaviour before you decide to even purchase any of the components. Can also be used as a tool for further adjustments to the cross-over components and tweaking.

Usually the measured and the simulated response are within 2% of accuracy.

 

[Hari Iyer]

Are you saying that the waveguide is aiding diffraction?

May be. Not measured this though.