[JohnR]

Hi Paul, got any pics?

I think your project is interesting and enlightening, I was trying to suggest that the concern about theory and measurements expressed earlier in the thread might have more validity and interest if the actual combination of factors under consideration were taken into account.

One doesn't necessarily amps capable of driving 0.75 ohms, though - multiple amps would do the trick as well.

[FullRangeMan]

Dear Mr. Paul,
I also like FR, LA and OBs. When I see the B200 at the Visaton Site I was very excited, but when I found its Freq. x dB chart I was sad why the Bass is very attenuated.
But as you said the Bass performance of your B200 LA OB are good, Iam curious as you managed to get a hi dB Bass response of the B200?
Do you use a active SubWoofer?  Tone Controls at Preamp?  A filter to boost the low freq.?
Please inform us, as Iam in search for a FR + LA + OB loudspeaker afew years...
Gustavo

[Browntrout]

If drivers with 16ohm impedence were used  would I be right in assuming the amplifier could be a SET 300B type and not need to be purpose built for very low values?

[Paul Hynes]

Hi JohnR,

If you copy the following link to your web browser it should take you to an old photo of the line array taken at our old house in Cumbria, England.

http://s700.photobucket.com/albums/ww7/paulhynes/th_Picture036.jpg

It is certainly more sensible to consider all the factors of a design when making an assessment. Comb filtering effects are only one factor, and in my system they are not giving me any real concern. It could be that the cumulative benefits of all the design parameters are far outweighing the effects of comb filtering.

You can easily use multiple amplifiers to drive the parallel-wired line array, if you happen to have them. However if you are building from scratch it is easier to build a stereo amp, or two mono power amps with the design adjusted for low impedance loads. I am happy to help DIY enthusiasts to do this and I have freely published the two depletion mosfet designs in the lab circle. This will be followed with the lateral enhancement mosfet version, shortly, when I can find a little time to prepare the drawing.


Hi Gustavo,

I am not using and electrical compensation or subwoofers on the line array. Mutual coupling between the drive units increases the efficiency at low frequencies and this reinforces the low frequencies. Danny kindly explained the reasons for this in his earlier posts. The bass sounds very natural and has very good extension. You can feel the deep bass as well as hear it. Distortion is low as the drive units are barely idling under normal listening conditions and there is certainly no confusion with regard to the type of instrument being played. If you like your bass larger than life then you may prefer to implement some bass boost by whatever means you like. There is plenty of scope for this as the power handling of each array is 320 watts continuous and 560 watts for transient peaks. I am very happy with the bass as it is well balanced with the rest of the frequency spectrum. Whilst I have stated that I only use live acoustic music as a reference, I do listen to all types of music and the line is equally at home with rock, jazz, and classical.

Hi Browntrout,

It would depend on the taps available on your output transformer. Incidentally I have driven the SE current amplifier output stage from a current source loaded 300B valve with no output transformer (capacitor coupled) and really liked the resulting sound quality.

Regards
Paul

[FullRangeMan]

Many thanks Paul.

[Retsel]

I have seen more than one set of Lowthers in a baffle (one the Web).  The design that I saw had one set of drivers mounted facing forward, and the other set facing backward (one forwarrd, one backward on each side).  I e-mailed the guy about his design but I never heard back.

But I don't think that it would be desirable to have more than one Lowther per side.  Although there may be benefits, the downsides would likely dominate.  Lowthers are pretty good drivers so a single set of drivers can handle the job, providing that a couple of adjustments or accomodations are made to the drivers. 

First, I would use a Lowther line with a stronger set of magnets.  This provides more detail in the music.  For example, the DX4 line is excellent, although a guy named Chopper has compared different Lowther drivers and swears that the PM2AMKII drivers are the best in open baffle.  I cannot confirm his claim.  However, I did try DX4 drivers with and without an enABLE treatment and the effects of the enABLE treatment are worth the time and effort.  The sound is more dynamic and more focused and the tone of the drivers is improved as well (they sound less like paper drivers).  I would opt for the 15 ohm drivers because of the greater x-max.

I would roll the drivers off at 150 hz, and rely on a good woofer to handle the low frequencies.  This reduces the doppler distortion of the midrange amps and drivers (the Lowthers), and allows for the use of a sand amp where it is best.  The complexity with this approach is that getting a good blend between the two drivers is very challenging.

I hope that this helps.  EnABLEd Lowther drivers are probably some of the best sound that I have heard in audio.

Retsel

[Mr Content]

Interesting discussion.......... One thing that is sometimes overlooked is that what we hear can be very different. Some find the B200 to hot, I dont, well my ears dont. But they must be put into a baffle that does them justice, thats IMHO anyway. Other dont like them, still other say they are no good without even hearing them. Thats OK, but none of us has the last word on what is right or wrong. Its is just personal preference. I would like to comment about the Lowthers  drivers, but because I have never heard them, there is not much I can say, other than I would like to listen to them.

I agree, that if you have a great point source driver, I dont see much point in a line array of them, but I would still like to try a line array.......well a true floor to ceiling array anyway. But there are as many minuses as the are pluses for any alignment of driver/drivers, nothing will be perfect.

I think that for a line array to work properly, you may have to consider power tapering, or building a top to bottom curved baffle. 

Mr C