Lowther Opus One Model B Build Thread

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#62
I am very impressed with your building skills.
How is the Jericho compared to Accousta 115 and your Opus, in the bass?

I have the same experience with the importance of solid horns. I moved Klipsch horns from solid concrete walls to corners were one wall was concrete an the other 13mm plaster board and lost about 6dB below 80 Hz.

I have built the Accousta 115 but I modified the back part to be similar to the Opus that is that the back was to parts each 45 degrees angle to the sides, if that makes any sense. The reason was to get rid of the "accousta sound" caused by resonances in the back plate. I used the Philips 9710 a driver that has a very forward sound so the end result was not good and they were later scrapped. :/
 
#63
Peter Huang said:
Hi, Horst Möller, thanks for your very positive suggestion. I measured the near-field responses and combined with previous far-field one to make a comparison, as shown.

There are three measurements, all on-axis, only for left channel. The far-field measurement is located at 4m, the same as the ordinary listen position. The near-field measurement at 2m is used to as a typical comparison base. The third measurement is located at 26cm from the driver’s cone center, almost just in front of the front horn mouth. The measured data are Levelized to the same value of 70db at 1Khz.

By examining the diagram, there are three essential phenomenons which I would like to emphasize. The first one I noticed is that the fare-field response around 8 kHz is attenuated about 12dB compared to the near-field one at 26cm. The front horn seems to have a strong performance to reduce the HF shouts, sometime criticized for Lowther’s stronger drivers.

In addition, the room resonant peak at 60Hz is almost disappeared at near-field responses.

The deep dip at about 1.1Khz of near-field measurement at 26m is quite difficult for me to understand.

Any comment or suggestion will be highly appreciated. Thanks.
Click to expand...

All very pretty and very good work but an awful response...
 
#64
Boscoe said:
All very pretty and very good work but an awful response...
Click to expand...

Hi, Boscoe
Please note that the frequency response is measured in a listen/living room, not in anechoic conditions. I think the frequency response of Opus 1b which I made, is quite excellent.

"While the very best modern speakers can produce a frequency response flat to ±1 dB from 40 Hz to 20 kHz in anechoic conditions, measurements at 2 m in a real listening room may be considered good if they are within ±12 dB, and efforts to produce anything like a flat response below 100 Hz are likely to provide endless scope for experimentation! This is where a real challenge to audio quality lies." The sentences are from Loudspeaker measurement - Wikipedia, the free encyclopedia. Becasue the opus 1B is placed in the corner, the actual listening distance in my living room is 4m. Referring to the freauency response diagram of opus 1B which I measured, the frquency variation between 100Hz to 10kHz is about within ±7dB.

Also please note the drawing scale is 60dB range. I would suggest that you read the article in http://www.audioholics.com/education/loudspeaker-basics/audio-measurements.Then, you would know what I mean.

Thanks a lot for your question. I am happy to discuss this issue futher.
 

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#67
DrBoar said:
I am very impressed with your building skills.
How is the Jericho compared to Accousta 115 and your Opus, in the bass?

I have the same experience with the importance of solid horns. I moved Klipsch horns from solid concrete walls to corners were one wall was concrete an the other 13mm plaster board and lost about 6dB below 80 Hz.

I have built the Accousta 115 but I modified the back part to be similar to the Opus that is that the back was to parts each 45 degrees angle to the sides, if that makes any sense. The reason was to get rid of the "accousta sound" caused by resonances in the back plate. I used the Philips 9710 a driver that has a very forward sound so the end result was not good and they were later scrapped. :/
Click to expand...

Hello, DrBoar,
If only comparing the bass performance, I think that the Jericho with Fostex 206 driver is the best one, the opus 1B placed in the corner is the second one but quite near the preceding, and the bass of Accousta is poor in my oppinion. The Accousta could not be placed near to the cornor, and I also heared of some church sound(resonances) from the mouth. Could you hear the resonance from the modified Accousta again?

Since you had build the Accousta, certainly you can build the opus, too. And it will be absolutely worthy of your hard working, if you have two solid corners. The opus is more complicated, but the skill of making horn has no much difference.

Best Regards,
 
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