Low cost Class D pro plate amps.

Is this amp OK?
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Bill Fitzmaurice
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Re: Low cost Class D pro plate amps.

#31 Post by Bill Fitzmaurice »

Grant Bunter wrote: Adding this capability to a new design would involve a structural engineer
+1, one with a very high dollar limit liability insurance policy. Our builder N.Webber is well qualified to do this sort of thing, as his posts show, and he'd be the first to say that this isn't something to be undertaken lightly, because speakers aren't light, and they really hurt when they land on your head.

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Charles Jenkinson
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Re: Low cost Class D pro plate amps.

#32 Post by Charles Jenkinson »

Professional Indemnity Insurance has those high dollar limits, providing you are a professional in the specific field required. Knowing what you personally can and can't do is the deal with engineering, ...and who to ask when it's something that is not up your street.

Commercial speaker manufacturers will likely have product Insurance, for product failures, but the design of those products for flying will require various other professional disciplines to substantiate the designs, including mechanical test pieces and structural calculations, with signed off reports and design documentation, all compiled into a technical file for design and implementation / use, covering all foreseeable risks, with a list of residual risks as well, I.e. danger of death if misused. This information is never available to the end user - some of it is however distilled down into the O and M manuals, but all of it is dragged into the court room, for expert witnesses to assess, if anything goes wrong in a big way, and corporate manslaughter charges apply. Specifically they will establish what exactly failed, and what were the margins of safety considered for those elements - were they to a code of practice or recognised standard, ...or did you just make it up as you went along, I.e. it looks right, so it is right, kind of rationale.

It's not difficult when split up into small chunks, but there is a reason why only the big organisations and players can afford to do it. It just depends on your business model, ambition, and where you want to play.
2xJ12L (3012HO) switchable/melded
2xT30

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chris_c_
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Re: Low cost Class D pro plate amps.

#33 Post by chris_c_ »

I would have to see the design details to comment. However, the path of the DR280 is 3 feet.
* RCF and (if I remember right) JBL make horn loaded compact line arrays. Probably several other makers also.
Here's one of RCF's the HL-2290. This is just one example, not saying this is the best example available.
Also HL-2260 (60 degree horizontal) and HL-2240 (40 degree horizontal) are variations.
http://www.rcf.it/installed-sound-systems/h-series
User manual with cabinet diagrams and plenty of cabinet flying hardware details:
http://www.rcf.it/c/document_library/ge ... pId=216492
These HL-2290 are obviously 2x the weight, and at $4500 each plus $1375 for the top Fly Bar, 15-20x more expensive than the DIY BF J array Otop12.

* A pic of the L'acoustics Kiva II line array - see how small they are.
http://www.prosoundweb.com/channels/liv ... velopment/

It'd be nice to have a fully horn loaded line compact array element design with provisions for an inexpensive pro quality class D plate amp, for the DIY sound system engineers.
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David Raehn
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Re: Low cost Class D pro plate amps.

#34 Post by David Raehn »

"Hold my beer.... I got this....." :D
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6 OT12
4 T48
4 WH8
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CoronaOperator
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Re: Low cost Class D pro plate amps.

#35 Post by CoronaOperator »

Powered SOS (speakers on sticks) are convenient when you just want to throw 2 up for a few hours. They are a PITA when you need to run power to a bunch. We run an 8 cab PK rig and running power sucks every time. Troubleshooting on stage in the middle of a show when an outlet gets overloaded, or the power gets kicked out by the performer sucks even worse.

Those big rigs are run by rental houses with all the bells and whistles to make that rig work with remote amp monitoring, and current draws.

I am a bit of a fan of powered wedges just because then the performer can reach over and adjust his volume if need be and there is always power on stage.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

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Re: Low cost Class D pro plate amps.

#36 Post by chris_c_ »

CoronaOperator wrote:Powered SOS (speakers on sticks) are convenient when you just want to throw 2 up for a few hours. They are a PITA when you need to run power to a bunch. We run an 8 cab PK rig and running power sucks every time. Troubleshooting on stage in the middle of a show when an outlet gets overloaded, or the power gets kicked out by the performer sucks even worse.
I guess the solution to power disconnects and overloaded power outlets, is the locking IEC ends, or the locking Neutrik PowerCon ends. And carefully check each plate amp's max power draw and do not not plug in devices with total current draw greater than the capacity of the given AC breaker.

Probably the best advantages of class D plate amps, besides less weight, fewer racks to deal with, less pack space, are:
1. Their power supplies can take anywhere from 90 V AC to 250 V AC input. World power supply, and don't care if the voltage is sagging low due to other devices drawing power ie lights.
2. The power cable feeding the plate amp can be thinner gauge wire than the audio power amp output cable it replaces. Because of the higher voltage. So cheaper easier to roll up cable.
3. Less power loss, and therefore less risk of heat melting the cable, for any given longer cable run length. Due to less amperage carried on the cable, due to higher voltage being carried, compared to audio power amp output cables.
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DJPhatman
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Re: Low cost Class D pro plate amps.

#37 Post by DJPhatman »

chris_c_ wrote:I guess the solution to power disconnects and overloaded power outlets, is the locking IEC ends, or the locking Neutrik PowerCon ends. And carefully check each plate amp's max power draw and do not not plug in devices with total current draw greater than the capacity of the given AC breaker.
As you have to check when using ANY electric draw. But, that doesn't take into account the "bursts" of power (crest factor) that is prevalent to audio amplifiers. For my rig, it was all Neutrik Speakon cables, so there was never a disconnect. But, in your scenario, 4 speakers would require 2 plate amps, but only a single rack mounted amp. And, if/when an amp channel smokes, most rack mounted amps can safely run at 2 Ohms to finish a show. No prosumer plate amp, that I am aware of, can run super-low impedance loads like that, in case of an emergency.
chris_c_ wrote:Probably the best advantages of class D plate amps, besides less weight, fewer racks to deal with, less pack space, are:
1. Their power supplies can take anywhere from 90 V AC to 250 V AC input. World power supply, and don't care if the voltage is sagging low due to other devices drawing power ie lights.
2. The power cable feeding the plate amp can be thinner gauge wire than the audio power amp output cable it replaces. Because of the higher voltage. So cheaper easier to roll up cable.
3. Less power loss, and therefore less risk of heat melting the cable, for any given longer cable run length. Due to less amperage carried on the cable, due to higher voltage being carried, compared to audio power amp output cables.
1. All amps are susceptible to power droop. And, almost all modern amps contain around-the-world usable power supplies

2. This still doesn't negate the fact that you have to run 2 lines to each one! Signal and power. Add up the extra weight of the 2 cables, and it could be a wash, but the advantage goes to speaker wire, for easy, single cord setup.

3. Again, they all suffer from power loss. Be it from the mains to the amp, or from the amp to the driver. But, again, you are running 2 separate wires all the way to the cabinet.

Conclusion: is there a place for amps built-in to the cabinets? Of course there is. If you want to put a plate amp(s) in your cabinets, chris_c_, you do so at your own peril. Bill's cabs were never designed for, and he has always been against, installing built-in amps. The guide lines are the designs must remain air-tight, you must not block and pathways, and you cannot change internal dimensions.
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice

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Charles Jenkinson
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Re: Low cost Class D pro plate amps.

#38 Post by Charles Jenkinson »

Plate amps could be part of the fascist world order,...trance inducement as the commercial speaker manufacturers wave them before your eyes.

I was on Yahoo mic builders group the other day and read that the primo EM200 electret capsule was only available from the manufacturer to other OEMs, and not to DIYers. It was constrained for business to business supply only. The desirable trait is its frequency response.

Could it be the same with sensibly priced and adequate features on plate amps to the DIY community?

If it smells like a fish, it usually is a fish. But it will only be a matter of time till someone break ranks.

For now, I'm going with "Flying Amp Racks".
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Re: Low cost Class D pro plate amps.

#39 Post by chris_c_ »

Question for everyone:
Which is better - as in, less of a BAD THING - to have. Given a Class D pro amp with a modern switch mode power supply (it doesn't care input voltage as long as it's 90 V AC - 300 V AC):
1. Voltage drop in the MAINS AC CABLE feeding the power amp, due to slightly long mains AC cable run. Typical voltage is 120-220 V AC, 2-15 Amps, 50 - 60 Hz.
2. Voltage drop in the Audio Power Amp power output cable. Typical voltage is up to 60 V AC, 0.1 - 20 Amps, 20 Hz - 20,000 Hz.

I say #1 is less of a bad thing. Because the switch mode power supply doesn't care if the mains voltage sags or not. So, who cares if AC mains cable runs are a little long?? Nobody will hear it.
#2 is worse because sagging voltage on the power amp output will cause distortion in the audio signal to the speakers. Everyone will hear when the audio power output cable runs are a little long leading to sagging voltage.

* In conclusion, if you care about protecting your client/audience from distorted audio, you'll really try hard to get pro plate amps for your (new build) cabs, so as to benefit from the versatility of the SMPS mentioned above, and eliminate the chance of the distortion mentioned above. AND it's a good idea to double up on the thickness of the copper in the audio power amp output cables for your existing rig, BUT doubling your thick copper audio power amp output cables is super expensive.

* Flying amp racks is super risky, expensive for the added insurance and mechanical engineers and rigging gear and certified riggers, and just insane, in my humble opinion, when you can simply add a pro class D plate amp weighing about 5 pounds into each cab and incur no additional risk or secondary expense, beyond the plate amp itself, which can and should be had for relatively cheap.
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Re: Low cost Class D pro plate amps.

#40 Post by Grant Bunter »

Who says you need to double up thickness of speaker leads?
At worst, you might lose 1-2dB at the cab with speaker cables of insufficient gauge, and that's through resistance of the wire vs length. 1-2dB is not noticeable for most people.
There's no evidence that distortion will occur.

Use this to work out gauge when it comes to various lengths:
http://www.bcae1.com/images/swfs/speake ... istant.swf

Or make all your speaker leads 12G and less than 50 feet long and you will be fine, at not to much expense.

IMHO, power sag is the worse of the 2. IF the SMPS is truly global in voltage required, you will get more noticeable drops at the cabs when power sags.
Also, it depends somewhat on how you run your power to active cabs. If you power source is to one side of your rig, then, on a long run, power is lower on the other side. So output between the 2 sides may vary.
which can and should be had for relatively cheap.
That remains to be seen. You haven't posted up suitable examples of product, or pricing yet...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
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Re: Low cost Class D pro plate amps.

#41 Post by NukePooch »

To me, the advantages of having a powered speaker is in the limited circumstances where I am only using one speaker in a low-level no-microphone background music only event. I'm talking something similar to QSC K8's in this scenario. Lightweight, sets up quick. On a tripod, one power cable, music player hangs on the back of the speaker. Done.

The other advantages of powered speakers come at the other end of the spectrum. Huge concert rig, self-powered arrays. Using the software provided by the array manufacturer can help in ease of set up and tuning.
I've worked crew on concerts that have had high-dollar powered rigs and horrid sound, and I've worked concerts that have had 'old-school' amps and passive speakers, and phenomenal sound. It's all about the right tool for the right job, and most importantly, how that tool is used. It's all about how the system is tuned and adjusted.

I no longer work huge arena events with massive crews. I now work events from 50 to 500 people in attendance. I usually am my own crew...rarely do I have help. I love the BFM stuff because it is so efficient that I can do more with less. I don't need 6-8 store-bought speakers when I can do more with 4 Jacks. I can carry a healthy system in my tiny Honda hatchback, and only need to bring the trailer when I'm doing something bigger.

To me, putting amps in the back of my Jacks would be a step backward.
I would need to run double (or triple) cables to everything, and roll up double (or triple) cables at the end of the night.
Amp adjustments now are made in one location... With powered speakers, I'd be looking at adjustments in at least three different locations. When stuff goes south, keeping it in one location makes it easier to fix.
I run 12ga 3-conductor power and 12ga 2-conductor speaker cables now. I'd have to buy/run all 3-conductor cables. More weight, more expense.

If flying the rig? I'd never run powered stuff unless I had instant access to a scissor lift or had the speakers on motors so that I could lower them (either would be impossible in the middle of a show). Flying amp racks is only done when the event requires a clean floor. I'll keep the amps where I can get my hands on them. Not a concern to me as I'm not gonna fly anything anytime soon. I'm done with big events.

I'd consider getting a couple plate amps to put in another pair of Jacks to use in the smallest, easiest events...the first scenario I mentioned. But they'd have to be light, small, cheap and have a built-in mini-mixer... and ideally be battery powered...
Built:
4 Jack 112L- 3012HO, melded array
17.5 wide AutoTuba with Infinity 860w
6 Wedgehorn W6 w/ Panel Mount Piezos
2 T48 Slims (15" wide) with 3012LF
4 T48 Fattys (32" wide) with 3015LF

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Re: Low cost Class D pro plate amps.

#42 Post by chris_c_ »

Thanks for your replies Grant and NukePooch.
EDIT: There exists an advanced version of switch mode power supply, which puts out steady power and voltage, even when the AC mains sags.
Grant, about pricing and product, your feedback would be a help: Which features would you require? Which features would you like to have but not absolutely require? How much would you be interested in paying?
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Re: Low cost Class D pro plate amps.

#43 Post by Bruce Weldy »

chris_c_ wrote: Grant, about pricing and product, your feedback would be a help: Which features would you require? Which features would you like to have but not absolutely require? How much would you be interested in paying?
So, how about you cut to the chase with what you are trying to do.

Is it your plan to design, build, and manufacture plate amps? Might get you some better answers if everyone understood just what you are trying to achieve and why.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


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Re: Low cost Class D pro plate amps.

#44 Post by chris_c_ »

Bruce Weldy wrote:
chris_c_ wrote: Grant, about pricing and product, your feedback would be a help: Which features would you require? Which features would you like to have but not absolutely require? How much would you be interested in paying?
So, how about you cut to the chase with what you are trying to do.

Is it your plan to design, build, and manufacture plate amps? Might get you some better answers if everyone understood just what you are trying to achieve and why.
Hi Bruce,

I'm exploring the possibility of making pro plate amps available at a reasonable cost.

If you'd be interested, kindly reply with:
1. Your required features,
2. Features you'd like to have but not absolutely required,
3. How much you want to pay,
4. How many you'd want.
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Re: Low cost Class D pro plate amps.

#45 Post by Bruce Weldy »

chris_c_ wrote:
Bruce Weldy wrote:
chris_c_ wrote: Grant, about pricing and product, your feedback would be a help: Which features would you require? Which features would you like to have but not absolutely require? How much would you be interested in paying?
So, how about you cut to the chase with what you are trying to do.

Is it your plan to design, build, and manufacture plate amps? Might get you some better answers if everyone understood just what you are trying to achieve and why.
Hi Bruce,

I'm exploring the possibility of making pro plate amps available at a reasonable cost.

If you'd be interested, kindly reply with:
1. Your required features,
2. Features you'd like to have but not absolutely required,
3. How much you want to pay,
4. How many you'd want.

I understand the info that you want, but I still don't understand why you are asking.....so, maybe you could answer these questions:

1. Are you a retailer trying to sell amps?
2. Are you a manufacturer's rep trying to determine the viability of the plate amp for BFM?
3. Are you an amp builder considering building and selling these amps?
4. Are you just a guy who is doing research to try and find a manufacturer would build these amps to suit?

Any of the above are fine - would just like to know which it is.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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