Disco Speaker Cabinet

[tor]

Good evening Patrick,

I've watched your disco speaker cabinet video several times, and I must say I'm intrigued.

Please allow me to explain:

Purely by coincidence Jim Marshall discovered that slanting the upper half of his speaker cabinets slightly upwards did indeed help to spread the sound more widely than with a straight cab.
Charlie Watts did the same by placing the speakers in the cabinet at an angle facing outwards.

Now I see that you have been doing the exact opposite by concentrating the sound in a beam by placing the speakers in a 90 degree angle facing inwards.

As the speakers that you used are extremely powerful, it's absolutely amazing that you were able to have a normal conversation behind the cabinet while in front of the cabinet the sound must have been extremely loud.

Now here are my questions to you:

1. By concentrating the sound in such a strong forward beam, wasn't the concentration of sound straight in front of the speaker overly powerful (bleeding ears), while further away from the center of the beam the strength of the sound deteriorated significantly and rapidly?
2. Wasn't there a possibilty of the sound oscillating at certain powersettings?
3. Did you find that this 'beam of sound' carried a lot further than you expected? Imagine the possibilities...

I would love to experiment with these cabinets, as personally I have never seen this approach before.

During my younger years (about 100 years ago) I used to dj for "The Radio Caroline Drive-in Show", maybe you remember that station. I remember many an occasion where we weren't able to hear properly for several days as a result of the loud music. Unfortunately nobody ever thought of placing the speakers at an inward angle.

I'm looking forward to your reply.

Tor

[tor]

I see that I said Charlie Watts. Of course I meant Charlie Watkins.

[Sparky]

Sorry for the delay, the forum isn't that busy so i check occasionally.

We never played the music too loud for the audience, we were often asked to turn it up rather than down, when i say 'normal conversation' sure we raised voices a little, but didn't need to shout or mouth the words while behind them.
One of the things we used to do was outdoor PA, mostly for the local football clubs when they ran 6-a-side tournaments in a large park, we were able to cover that quite nicely, though having the motorola horns (tweeters) helped too, so we didn't have big 'drop off' problems at distance.

When we first built the cabs, we added a little too much padding, and sure enough we had problems with resonance, so we removed about half of it, leaving a light lining to the enclosure, plus a light roll of insulation, never have a problem after that.

We call the design 'horn loaded' because it almost takes on the characteristics of a horn speaker, but instead of driving the air forwards from the end, it's done from the sides, this creates a wedge pushing forward.

Here is the design sparky-projects.co.uk/hosted/discocabs.gif

A word of warning, because of the pressures inside the enclosures, use good quality speakers with a good cone and suspension,
also note that the magnets came within 1/2 inch of the case, so check measuements carefully.

the 2 XLR's were because we looped through the cabs to the horns, original intention was to have 2 cabs plus 4 horns each channel giving a total capacity of 400W per chan, but drive them at no more than 300W.

Yes i grew up with Caroline, heard some of the raids that went on, and was listening right up to when it grounded on the sands, then i later discovered they were back with an online channel, and often listen to it.

If you have further questions, please feel free to ask.

[tor]

Hi Patrick,

Thank you for your reply. And also, thank you very much for posting your designs.

Sorry that it's taken me a while to respond, but at the moment we're travelling all over Europe. We'll be back in the UK as from September.

Please allow me to lift some of the veil: we have a singer who is suffering somewhat from the noise originating from behind her. Your speakers might just be the solution to the problem to direct some of the decibels away from her. Personally I've never seen it done this way in this sort of situation, so this would be a novel approach. We're willing to learn.

I appreciate your point with regards to the pressure build-up inside the cabinet: have you ever torn up any speakers? After all, the cones are only paper...

Rather than starting off straight away with building two of your cabinets for myself, would it be at all possible to see/hear your design in action at your place first? If you would be agreeable to this, we could choose a time that is agreeable to you; I'm flexible.

I'm looking forward to hearing from you.

Kind regards,

Tor

[Sparky]

Unfortunately i don't have an amplifier suitable for testing, besides, the neighbours would complain at the powers that would let you see what the difference is.
The speakers are original, no problems with blowing cones, we used them on average over the 10 years or so about once every 2 weeks (disco was more about having fun than making money), and even did a few PA events at football matches in the park where we turned up the power, though only for mic.
Cabinets have had a hard life, but are still solid.

Just wondering where you are located

[tor]

Hi Patrick,

At the moment we're in the north of Spain. But from the beginning of September we'll be staying in Wells, Somerset, until the following May; by our standards 'around the corner' from you.

By coincidence I'm flying into Bristol on 11 July. I'm only staying for a day. We could meet up and have a chat. Fancy a curry and a beer? My treat.

Regards,

Tor

[Sparky]

A day may be a bit tight for you to get to me and back, i live close to Maesteg which is close to Swansea and Bridgend, Maesteg would be the closest station to me (about 3 miles), and i know it's about an hour from Cardiff.

[tor]

Hi again Patrick,

Thank you for your reply.

On Thursday the 11th I'm arriving early in the morning and I've got a rental car anyway. From the airport it's only an hour and 15 minutes drive to Maesteg. There's not much I need to do that morning and the early afternoon. My appointments are for the evening and the following day. I'm flying off again, into the wide blue yonder, later that Friday. So paying you a visit on Thursday really is quite possible. That is, if it would be convenient for you. And of course if you think it would be fun.

I'm looking forward to hearing from you,

Tor

[Sparky]

I have PM'd my contact details, let me know for definite closer to the time.
Remember that i haven't got anything much to power the speakers, though i may rig something up on my hifi

[tor]

Hi Patrick,

Thank you for your contact details.

Would it be convenient if I arrived at your place somewhere between 11am and midday on Thursday?
Please let me know.

I'm looking forward to meeting you.

Regards,
Tor

[Sparky]

That will be fine

[tor]

Hi again,

Excellent.

I'll give you a call once I've arrived at Bristol Airport.

See you in a few days,

Tor

[Sparky]

Went a bit further than doing a diagram as we discussed

www.youtube.com/watch?v=tLOf3UTfCu8

[tor]

Hi Patrick,

Thank you once again for the very friendly reception, and of course for all the information that you so generously volunteered.

Now you've done it again: you invested quite an amount of time and work explaining the physical aspects of your cabinets!
Thank you so much: you've presented it all very clearly.

You're a kind and helpful man.

Regards,

Tor

[Sparky]

Not a problem, only took me 10 mins to make (plus glue drying time), and the video doesn't take a lot of time to make, it's worth doing if others are able to learn from it.