I am looking to build a portable speaker for auctions and need some help. I would like to build something similar to the Lectrosonic Voice projector. https://www.lectrosonics.com/phocadownload/vp18rman.pdfThis would be for auctions so voice only. It needs to be fairly compact and have sound enough for a crowd of 20-30 people. If possible I would like to power it off of a Milwaukee drill battery (18v). All this and be cost effective. Any help would be appreciated.
what advantage would diy'ing this have over the many low cost ready made units you can easily find on Amazon?
I think with some help I can build a better sounding one. I have heard some of those and I am not very impressed. There is a reason the Lectrosonic’s are sought after. And there’s also the part of I just want to build my own.
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well there's a reason Lectrosonic stopped making portable paging systems and concentrated their company focus on wireless mic technology...
it comes down to the simple fact that size and efficiency combined with the requirement of self powered all place severe constraints on what's possible, and providing intelligibility to an auctioneer whose style relies on slurring phonetics and using the dynamic capability of the human voice to create a fervor pitch are not elements that are easy to reproduce or amplify faithfully without issue so, no easy task...
if you could define limits such as physical size, max SPL , coverage angle, expected duration of operation, then it would be easier to guide you towards the potentially correct solutions.
it comes down to the simple fact that size and efficiency combined with the requirement of self powered all place severe constraints on what's possible, and providing intelligibility to an auctioneer whose style relies on slurring phonetics and using the dynamic capability of the human voice to create a fervor pitch are not elements that are easy to reproduce or amplify faithfully without issue so, no easy task...
if you could define limits such as physical size, max SPL , coverage angle, expected duration of operation, then it would be easier to guide you towards the potentially correct solutions.
There is small and small... 🙂
A 8" PA full range or coax could be enough for voice.
You need maybe 80hz in low ( maybe 150hz is enough?) So the box could be closed high qtc ( compensated by small eq in front of amp), depend if the driver will need cooling or not ( duration of operation).
Something like the Beyma 8cx20 with accompanying xover board.
Or Beyma 8ag/n.
A 8" PA full range or coax could be enough for voice.
You need maybe 80hz in low ( maybe 150hz is enough?) So the box could be closed high qtc ( compensated by small eq in front of amp), depend if the driver will need cooling or not ( duration of operation).
Something like the Beyma 8cx20 with accompanying xover board.
Or Beyma 8ag/n.
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big problems that come to mind from past experience with providing reinforcement sound to auctioneers is #1 it's an open loop system, so any appreciable distance between the source mic and the loudspeaker can introduce a delay which can screw with auctioneer's timing and delivery and #2 close proximity to the speaker if it's directivity isn't well controlled can introduce the potential for feedback put a limiting factor to overall achievable SPL.
and i'm still not going down the rabbit hole of the acoustic environment, cattle auctions are held in metal barns, surplus auctions in warehouses with little care for acoustics, and the few held in a nice ball room still suffer from audience distribution, there's little chance competing bidders are going to sit anywhere near each other...
so sorry if i appear negative but there is a lot to consider in attempting this sort of build....
and i'm still not going down the rabbit hole of the acoustic environment, cattle auctions are held in metal barns, surplus auctions in warehouses with little care for acoustics, and the few held in a nice ball room still suffer from audience distribution, there's little chance competing bidders are going to sit anywhere near each other...
so sorry if i appear negative but there is a lot to consider in attempting this sort of build....
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For me the biggest advantage would be avoiding Amazon. OTOH, there are many other vendors one can order from. No need to make Mr Bezos even richer and bring him closer to his next space journey.
Best regards!
This would be used mostly outside as a shoulder carry unit. Mostly used in 30-45 minute shots but would want to be able to go longer. I would prefer it last a whole day (8-10 hours) but if I do a Milwaukee battery it would be simple to swap. I think 150hz would be a little on the low side. I am a little higher pitched. My biggest question is what amp to use.
my efficiency favourites are CIARE, a discontunued MR6.38 (6.5") gets you 100dB eff, the CMI200ND (8") has 98.5 and more low end. power handling is more than what you can carry
sorry could you expand on "as a shoulder carry unit" are you in fact thinking of something that is slung on your shoulders and meant to project outwards to the intended audience vs something pole or stand mounted in close proximity?
so a lightweight bullhorn but with better fidelity so to speak....i'll have to find it again but there was a recent thread of someone looking to create a sonic projector/cannon which might help.
so a lightweight bullhorn but with better fidelity so to speak....i'll have to find it again but there was a recent thread of someone looking to create a sonic projector/cannon which might help.
Yes, it would be attached to a single strap sling over the shoulder. This is a poor quality pic. but is how I would be looking to carry it.
You basically nailed it.
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not my first rodeo in trying to provide solutions for this sort of situation....
at 4 kilos this would be the sort of speaker i would try to emulate
being approximately 14 x 9 x 13 it's a little bigger then what's shown but i can't imagine better without going a little bigger
finding a class d amp module to power it with would be next but hey it's your project...
at 4 kilos this would be the sort of speaker i would try to emulate
being approximately 14 x 9 x 13 it's a little bigger then what's shown but i can't imagine better without going a little bigger
finding a class d amp module to power it with would be next but hey it's your project...
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and i may be going way over the top on this one but think it's a way better idea in terms of allowing a speaker to project unobstructed would be to adapt something like a camera support
I would suggest a pair of 8 ohm 4" neodymium PA drivers which will give you a sensitivity around 95dB/W 1m and a little more controlled dispersion than a single driver - every little bit helps. Use a low supply voltage-friendly cheap Chinese 15W digital power amp board and Karaoke microphone input board which will also give you tone controls and reverb. In the Uk this lot would cost under £60.00. Add a lightweight sealed enclosure and battery and there you go - an easy 100dB output device with good quality sound!
PS. Don't be a cheapskate with the microphone!
PS. Don't be a cheapskate with the microphone!
Thanks for the suggestions.
that was going to be my next question, what to use to power it.
That is going to to be my next project finding a solution that is a little more comfortable.
you many have to look at hypercardioid mic's as they have better rear and side rejection which would help keep feedback at bay and headset mics have the advantage for keeping your hands free, so don't overlook those.
I'm not a huge fan of the SM5X mics - probably just me! I agree with the great advice of turk 182 above. Hands-free 100%.
As a complete unit, the Western Safety 50 watt megaphone would probably do fine, and 18v would probably not be too much for the circuit. If you wanted more low frequency, you could replace the re-entrant horn with a 5'-8" cone, though for what you are doing (fast talking to old men..) the frequency response (and efficiency) of the megaphone and mic is probably just what you need.
The noise cancelling mic really works, loads of gain before feedback without needing to talk loud.
At $30, even if you only use the amp, hard to find anything close to it's performance- it's output is within a few dB of the Fanon MV-20s megaphone they copied that cost over $150 in the mid 1980's.
Art