[Paul Hynes]

Hi Daygloworange,

I tried to post a pic on the forum but couldn’t for some reason, so Audiotone posted it for me on page 4 of Zobsky’s  “open baffle line array-need advice” thread.

It’s basically 8 x B200 drivers per side all wired in parallel to give a 0.75 ohm load. My current amplifier is a 2.5 watt class A mosfet follower configured to drive the 0.75 ohms load. The agregate efficiency of each line is 105 dB for 1 watt at one metre, so I can get to around 109 dB before clipping, which is pretty loud. I will be uprating this to 20 watts soon, to ensure that dynamic peaks are not clipped listening at realistic levels. I am also looking at adding a super tweeter array to fill in the top end a bit as the upper treble is slightly subdued, although this isn’t bothering us as the sound is so good.

The baffle is made from machined MDF reinforced with aluminium girders. The stands are also fabricated from aluminium girders. There are three heavy duty turned brass spikes with a triangular footprint to sink the stand resonance energy to the floor.

It’s dead simple really, and no crossover to mess up the phase response. If the super tweeter array messes up the phase response, then it will have to go, as my absolute priority is a coherent phase response (it’s part of the ability to create the illusion of a live performance). I can live with a slightly subdued high treble resonse. In fact it can be a bonus with some recordings.

Alas, my days of picking a tune are probably over, but thank you for the offer. I was never good enough to boast anyway, but now my finger joints are suffering with the onset of arthritis, so I am reduced to playing air guitar. The vintage Strat went a long time ago when cash flow was not good (excuse me while I kick myself up the ass). I have recently bought my daughter a Keyboard and a Beringer USB Strat copy so she can be a computer rock chick and I can help her get started with music. The Beringer has reasonable action and surprisingly good sound through the line souce array, but it needs better strings. Any recommendations? If she continues with the music I will get her something decent to play.

Ah, those Marshalls. I’m dribbling. There is no other amp quite like them. Thank you Jim.

Regards
Paul.

[Paul Hynes]

Hi Daygloworange,

I noticed you have been listening to mcgsxr’s B200 based OB over the weekend. How did it go with a woofer and crossover in the mix? Did the speaker manage more weight and scale with the woofer involved without losing coherence?

Guitars have some guts through the B200 line. If this drive unit had been around when I was a teenager I would have loved to have a pair of these lines for my guitar. We used a pair of 4 x 12” lines for vocal PA. I just didn’t think to try it for the guitar at the time.

I had a look at your photo gallery. Very impressive woodworking.

I noticed the Whitesnake album on your daytime gallery. It reminded me of an old friend called Nik Green. He was the mix engineer while I was the studio technician at the Boilerhouse studio in Lytham St Annes in the eighties. He was really into sonic upgrades after I wired the whole studio with anealed copper data transmission cable. The studio was owned by Roy Harper and Tony Beck. Nick played all the keyboards on Harper’s Jugula album, which was recorded there. Jimmy Page collaborated on the album. Dave Gilmour and Tony Franklin worked on it as well. Sadly Roy and Tony (Beck) parted company after that album was recorded and the studio closed shortly after. Nick went to America to join David Coverdale in Blue Murder. I’ve not heard from him since he left. I digress, this is the wrong thread to talk about music.

Anyway, it’s sleep time. Goodnight all.

Regards
Paul

[Daygloworange]

Hi Paul,

It does sound different with the subs added. I heard a pair of Visaton B200 open baffles last year as one of our TAAS get togethers. mcgsxr's are very similar, but with the addition of phase plugs, and the added subwoofer drivers.

I'll give you unbiased impressions. mcgsxr's open baffles have a really wide sweet spot. As you are sitting, you can swing side to side as much as you want, and you never have the center image go away. Very neat.
Like I said before in another thread, they sound really nice on electric guitar. It reminds me of the Celestion speakers I'm so used to in guitar amps.
I noticed some sibilance in the high mids, and high frequencies. Certain cymbals have a bit of an aggressive bite and could use some more body or timbre. It seems to beam a little in the highs.

The one thing that I pointed out to mcgsxr was that there was a comb filtering issue. There was  like an out of phase honking that I noticed in the mids. I'm not anywhere near an expert in speaker design, but as a long time recording engineer, I can spot comb filtering, and phasing issues. I mentioned it to mcgsxr, and hopefully one of the guys in the open baffle forum can help figure out where it might stem from. Perhaps the spacing between his Visaton's and the sub drivers is causing an issue.

I chose to mention it to him, and I hope he takes it in the spirit it was intended. I know there are a lot of guys here that could probably help him ameliorate the issue causing it. I wish we had more time to run the Visaton's full range without the subs, that might have helped in trying to locate the source of the issue. But considering that he is running all this with no network at all on the Visaton's, the drivers have a lot of cool characteristics.

I brought along my little Trends TA 10.1 and left that with him. We'll see what mcgsxr thinks of that in his setup. Maybe some of the issues I heard were a synergy issue.

Yeah, big fan of John Sykes and Blue Murder. Killer players in that band, with Carmine Appice and Tony Franklin. Some of the best players in the business.

Cheers

[Paul Hynes]

Hi Daygloworange,

Thanks for the impressions. I thought, from your post no 12 on this thread, that here’s a guy with good ears and a lot of experience. You don’t get to be a recording engineer unless you have a good ear and understand the recording/reproduction process. Your insights are a valuable resource.

It would be interesting to know what difference the phase plug is making to the B200 against standard issue. Can you comment here mcgsxr?

The sweet spot spread you noticed with mcgsxr’s speakers is similar with the B200 line. Moving across the listening position is like moving across in the audience of a live event. All that changes is the perspective. This is probably a major reason why the whole family are enjoying the system. And there are no squabbles about who sits where.

Recorded guitar does sound very good. You can imagine the event from a musician’s point of view. Interestingly, if I feed the Beringer guitar directly into the line preamp, it just sounds very clean. So I think that it is just that the drive units are very transparent to what you feed them. A good guitar recording comes through sounding good. The amplitude/frequency response tilt could also favour guitar a little although in practice the tilt is gentle and smooth through the main area or operation. I have seen a few high-end loudspeakers with much worse response anomalies. The response above 12 KHz is a bit ragged, particularly with brand new drive units. This does smooth out somewhat with time and I think that adding a super tweeter may well fill out the body and timbre at the top end. Time will tell if there is a down side with this. I will experiment and report on this in the near future when I have caught up with a backlog of work.

Have you noticed any phasey, comby stuff with B200’s on their own when you heard them previously in other systems? Perhaps mcgsxr could tell us more about how high any response overlap of the bass unit goes?

Just had a two hour phone call so better go and do some work.

Regards
Paul

[mcgsxr]

Firstly, I take no issue at all with what Denny is hearing, I am very open minded about what my system does well, and where it needs improvement.  Period.  The tone of the b200 is what keeps me there, and the simplicity of it all - two stroke vs four stroke in my books.  My early bikes were two stroke twins, and when happy in their power band, there is no better fun for me.  Then I graduated to four stroke fours, and found that a GSXR750 has the peak power of an RD350, at all times - speaking in broad strokes.  But there are complications.  So too with the b200.

I have respect for Denny's ears also, and even more for the manner in which he shares.

As for regular cones vs with phase plugs, I have posted here about it - I find the beaming has moved significantly up in the FR, so that it only does so in the higer treble region.

With respect to Xover, I am using the Reckhorn F1, and have it set around 100Hz, so the mids that Denny is commenting on SHOULD be unaffected.  I draw into question floor bounce, or rear reflections off my corner placement?

I will do some comparison listening to the Trends amp vs my old Magnavox EL84 amp, running the b200's alone, and see if I notice anything related to the phasey/honking nature that Denny is raising.

More when I know more!

[Daygloworange]

I will do some comparison listening to the Trends amp vs my old Magnavox EL84 amp, running the b200's alone, and see if I notice anything related to the phasey/honking nature that Denny is raising.

Yeah, if we had listened to the Visaton's minus the sub drivers, that would have been helpful.

Have you noticed any phasey, comby stuff with B200’s on their own when you heard them previously in other systems?

It was a while ago, but I don't think so. I did find however that there was a peakiness in the midrange, and a bit of beaming. I also remembering that after a few minutes, that the peakiness didn't stand out for me as much. It's a different thing that what I'm used to. Same thing when I've heard single driver Fostex based speakers. They have a character that I'm not used to. Just my impressions, YMMV.

Hey Mark, Wayne is sending his modded version of the Trends TA 10, with a tweaked P.S. Should be here next week sometime. It'll be fun to compare to the stock one.

Cheers

[Paul Hynes]

Hi mcgsxr,

I understand your liking the tonality of the B200. It isn’t a perfect drive unit (I don’t know of one) but it is capable of a first class musical performance with the emphasis on emotional stimulus. It allows you to easily understand what instruments are being played, how they are being played and what the musician’s message is. Not a lot of drive units can do that so well.

Forgive my ignorance about your previous posts. I’m new to the forum and there are a lot of threads that I find interesting, but not enough time to go through them all, as work is very busy at the moment.

I have been pondering about your comments (and Daygloworange’s) about beaming and phasy, comby sound effects. If it is level related, it could be caused by cone break-up, when pushed a little too hard. Under break-up conditions the cone can generate irregular resonating nodes across it’s  surface. I worked with Badger Sound Services (UK) in the early eighties with Phil Goymer, who designed the HIFI Answers Compact Monitor. He explained to me that they doped the cone of the 10” Audax and the 4” Peerless units used in this design (both paper coned), to reduce cone break-up and resonance effects. He said that without the treatment, the drive units could be a little shouty and singers could sound like they were singing through cupped hands. The effects were not dramatic but it was worth treating.

I also considered the differences I noted, when changing from single B200 to the eight-driver line array. The array didn't have the edginess of the single B200 from the mid upwards. I was thinking about how much more effortless the array was, so I had another look at the Excel program I set up to calculate efficiency and power requirements for any given SPL.

For the single drive unit the efficiency is 96 dB for 1 watt at one metre through the upper mid and treble range out to around 12 KHz. The wave front is hemispherical and sound pressure level falls off at the rate of 6 dB per octave for every doubling of distance from the drive units. From a four metre listening position 1 watt would get you to around 84 dB. The efficiency of the line is 105 dB for 1 watt at one metre through the same range because of the coupling effect of adjacent drive units increasing efficiency by 3 dB per doubling of drive units. Additionally, due to the almost hemi-cylindrical wave front from the line the sound pressure only falls off at the rate of 3 dB per octave until the wave front expands and approaches a hemi-spherical wave front. So 1 watt should get you to around 99 dB at four metres. With a single drive unit you would need 32 watts to reach this level. This is a hell of a difference (15dB), and, as Daygloworange pointed out, this would account for the dramatic reduction in amplitude distortion cone break-up and resonance with the line over the single drive unit. It’s a great shame that these drive units are so expensive.

Oh-oh. It is time for the annual school play. Got to go.

Regards Paul

[scorpion]

mcgsxr,

Please note that the Trends are phase inverting. To get things right you have to reverse speaker leads to integrate with subs for instance.
Perhaps I also can advice you to check your baffle design with 'The Edge' from http://www.tolvan.com/ to see effects of
diffraction from the baffle shape.

My design as seen in 'the wide Open venetian Blind' thread http://www.audiocircle.com/index.php?topic=40594.0 is not
that different from yours and I don't think I have any adverse mid-lowbass effects. Frankly, I would be surprised if the effect was connected to your baffle.
The Reckhorns just cut 12 db/octave but I got the impression you also used a plate-amp LP so the cut off would be sharper.

My impression with the B200 is that you should really be in the sweet spot. Not so much for the stereo but absolutely for depth information to
be correct.

/Erling

[ttan98]

scorpion,

"Perhaps I also can advice you to check your baffle design with 'The Edge' from http://www.tolvan.com/ to see effects of diffraction from the baffle shape."

what should one be looking for, pls give your design objectives?

thanks

[scorpion]

Regarding 'The Edge' as MJK also stated in another thread it will only give you an indication of the baffle's effect on the frequency response.
With the Edge program you can simulate very different baffle shapes and the precise placement of the speaker on the baffle. That can
be very important.

Depending on what speaker you have chosen you can estimate the combined effect of its stated frequency response together with the simulated baffle effect.
It is not unusual that a speaker placement in the center of the baffle results in a response peak in high bass/midrange.

/Erling

[ttan98]

scorpion,

"With the Edge program you can simulate very different baffle shapes and the precise placement of the speaker on the baffle. That can
be very important."

important you mean minimise diffraction? if not what then?

thanks

[mcgsxr]

Paul, here is a link to my posting about the phase plug, and my thoughts.

I hope I did not come across as an arrogant arse, suggesting that everyone has the time to ferret out the various topics I have posted on!   
 
http://www.audiocircle.com/index.php?topic=39536.0

I am loving your line array, and it is interesting to learn about what you have done, and why etc!

[Paul Hynes]

Hi mcgsxr,

I didn’t think that you are arrogant, but I did think that I may have offended you by breaking into your thread. It is not my intention to offend anyone. I do understand that forums develop into circles of friends with like-minded goals and that everybody here is looking to improve their musical enjoyment. It is a natural reaction to back off a little when a new kid on the block joins the forum. I wish I had joined it a long time ago as there is so much interesting stuff in progress that is beneficial to the common goal. You are all to be commended for sharing your experiences. If only the rest of the human race would share knowledge and help each other instead of shooting the shit out of each other.

I will look into the phase plug issue when I have a little free time as it may save me a lot of grief trying to meld a tweeter array with the line seamlessly.

Incidentally I missed one of my notes on the last post due to the abrupt family interruption. The actual power each drive unit in the line receives is only 0.125 watt whilst the line is generating 99 dB. So the difference in drive unit operating power between the single driver loudspeaker and individual drivers in the eight-driver line is 24 dB at the 99 dB operating level. I can’t under-estimate just how significant this is for distortion levels. The line is almost like electrostatic loudspeakers in its transparency, yet I haven’t heard an electrostatic loudspeaker that is this musical. The inner detail of musical instruments and voice is quite sublime on good program.

I’ve just checked the additional posts on the thread since my last post and the diffraction issue could be another possible cause of image interference. If the drive unit is centrally placed in a baffle with edges at 90 degrees to the baffle face, the diffraction wave caused by abrupt discontinuity of the left and right baffle edges (the most important edges) is reflected symmetrically into the sound-field (at a lower level than the direct driver wave-front), and it’s time delayed due to the additional path length. This is likely to interfere with image location clues. Moving the drive unit off centre will make the diffraction wave asymmetrical, which just changes the interference pattern. This may be better or worse depending on the effects of the interference. Rounding the edges of the baffle, with a router, will help reduce diffraction effects. The sound-wave doesn’t see a sharp discontinuity at the baffle edge and it just follows the curve round towards the back of the baffle where it is partially cancelled by the out of phase energy from the rear of the drive units.

We have had a series of power dropouts today and I am fed up with rebooting the computer so I am signing off until the power is stable again.

Regards
Paul

[mcgsxr]

Paul, you and everyone else trying, will have to work harder than that to offend me!   

I suggest reading about the phase plugs, and perhaps even reaching out to Doug D, he is a great guy to deal with, and is far from a guy seeking to sell something etc.

Knows a ton about a wide and varied number of things audio related.  A true experimenter.

[Paul Hynes]

mcgsxr,

Hi Mark,

From your links I have already read about the phase plugs and checked out Doug’s web site. Everything sounds sensible so I don’t need convincing, but it will have to wait a while, as I am about to relocate home and business to the Hebrides, and life is a little busy at the moment. I will contact Doug D as soon as things settle and give them a try.

Regards
Paul