Boosting a PA AMP?????

[abunaitoo]

Any electronics guys here????
I have a Radio Shack PA AMP that is 20W.
Is there a cheap way to boost it up to 100W??????

[10x]

Any electronics guys here????
I have a Radio Shack PA AMP that is 20W.
Is there a cheap way to boost it up to 100W??????

Short answer, it will be far less expensive to purchase a used 100 watt amp than tinker with an amp engineered to supply 20 watts.

When my kids were in junior high and interested in music I started to collect sound gear, amps, mixers, speakers.
expect to pay 50 cents to a dollar a watt for a used PA stereo amp. A 100 watt 2 channel amp is 50 watts a side. There should be a means to bridge the wires to give 100 watts to a single speaker. Bridging is hard on the amp . If you find a used amp, download the manual.
Run an inexpensive mixer as a pre amp for microphone and music - run the power amp at full volume and the mixer to control the volume.

The biggest problem with more watts is keeping the amp cool.
I have a Radio Shack 20 watt amp - it weighs about 8 pounds - I also have a Peavy 200 watt (100 a side) 2 channel - it weighs close to 60 pounds. Much of that weigh difference is heat sink and cooling. And the 200 watt gives cleaner sound with less clipping and distortion.
JMHO

[gsdelong]

Couple of important questions. Is this a 70V output amplifier ? are you using 70 V speakers? if so how many? do the speakers have taps and what are they currently set at?

I am assuming you want it louder, with a true 70V system that does not allways mean more watts

gsdelong

[10x]

Also a bigger speaker will move more air and cover a larger area at a volume folks can tolerate than a small speaker at high volume.
Just make sure the resistance (OHMs) and watts of the speaker match the amp.

[abunaitoo]

The Radio Shack AMP is small and light.
Perfect for what it's doing.
It's just not loud enough.
I'll look around for something in the 100W range, hopefully around the same size.
Would it be possible, and how hard would it be, to adapt a Auto stereo AMP to work as a PA AMP?????
We use it only four times a year, for about three hours at a time.
Looking for something really cheap, easy to carry and store away, and loud enough to hear over gunfire.
The speakers I'm using are two of those small house stereo type.
Would bigger speakers make that much of a difference?????
I have two old school house speakers. When I tried them, it didn't seem like it made that much difference.

[shredder]

The Radio Shack AMP is small and light.
Perfect for what it's doing.
It's just not loud enough.
I'll look around for something in the 100W range, hopefully around the same size.
Would it be possible, and how hard would it be, to adapt a Auto stereo AMP to work as a PA AMP?????
We use it only four times a year, for about three hours at a time.
Looking for something really cheap, easy to carry and store away, and loud enough to hear over gunfire.
The speakers I'm using are two of those small house stereo type.
Would bigger speakers make that much of a difference?????
I have two old school house speakers. When I tried them, it didn't seem like it made that much difference.

There is something you should know about power amps and speakers. You have the home variety like your home stereo and your radio shack amp, and then you have pro audio gear for live sound reinforcement PA work. They are not the same in very many ways. They operate at different input,and output levels and the power ratings on the home audio are laughable. The pro stuff made for PA work are rated in watts RMS and have the ability to amplify microphones and line level inputs. As you are discovering, the home stuff does not perform in that application. More watts will not make your home speakers more suitable. It will destroy them if you keep it up.

You should really look at an actual small PA for this type of thing. In an outdoor situation it takes a lot of power to be heard. 100 watts for vocal amplification is just not realistic. You do not say how many people are at the venue of how far away they will be or what other noise you my have to overpower to be heard. This is critical information to make a PA size recommendation.

Have a look at the Peavey website for some excellent starter PA systems. The little Peavey escort is quite capable for very small venues.http://peavey.com/products/escort/

[jsizemore]

I used to run a silhouette match. The firing line was 150 feet long. I used the same amp you have with speakers similar to this:

http://www.ebay.com/itm/2-Pyle-PHSP4-6-50-Watt-Indoor-Outdoor-Waterproof-Home-PA-Horn-Speaker-White-/231361609565?hash=item35de39ff5d:g:NsQAAOSwBahVCaT 2

Also used an answering machine tape in a portable tape player for range commands. The 4 speakers and speaker wire were permanently mounted. The speakers put out 100db at 1 watt/at 1 meter. At mid volume setting it should be enough to get folks attention.

Another range used a vehicle cb to run the same speakers that used a car battery for electrical power.

[MaryB]

I used to run an outdoor PA system when I was catering BBQ. People would provie a DJ and CD's and I provided the amplifier and speakers. It too a 200 watt system and big stage speakers to be heard outside...

[Tackleberry41]

Music amps are usually pretty cheap used. A bass amp for this use would probably be better than a guitar amp. Guitar amps the EQ controls only cut, a Bass amp generally boosts. I have a 50watt Bass amp I used with guitar for a while. Got it for free as the pots were bad. Stays clean even cranked up, cheap guitar amps wont. And a bass speaker is made to take a wider freq response than one for guitar.

But no you cant just make an amp bigger. More power requires more heat sink, which means more cabinet to hold it. A trick with guitars was to boost it going in, I have a pedal I built that would boost a small amp to frightening levels, but its going to clip, desirable when it comes to guitar. Not so much in a PA system. Can you cobble together a car amp, yes, but they generally run off 12v, so is another issue to deal with.

[Petrol & Powder]

The cheapest way to handle that is to just find a bigger amplifier. Stay away from music stores, they think their stuff is made of gold.
Keep an eye on Craigslist, there are always starving musicians in the world selling gear. Local government surplus auctions are good (schools use amps in PA systems and auditoriums), Pawn shops might be good but they will likely be costly.

Good Luck

[Blackwater]

You've gotten good advice above. One other thing that may help, is knowing that speakers can be a very big part of the problem. It's not just how much power (watts) you have, but how much of that power it takes to run the speakers. An old Fender Super Reverb amp, for instance, rated at 35 watts, will sound as loud or louder than a modern, solid state amp rated at 100-120 watts. The newer amps usually have high power rated speakers, that take a lot of power just to make them work at all. Older stuff often has speakers that don't take nearly as much power to make them work, so they just sound louder, even though you're putting less power to them.

A friend of mine is now building custom guitar amps of all types, but prefers making old Vox copies, correct for whatever period one wishes, and the speakers are a BIG part of the sound one gets, and the volume, from any amp of any type. And ironically, the cheaper speakers often sound the best! Will wonders never cease?

What happens is the old light, paper cone speakers don't take much power to move them, and with good flexible surrounds, they drive easily and produce more harmonics and over/undertones because they're so flexible and easy to move.

So one thing you might try is just getting some new, cheap speakers, but have spares handy, because the cheap ones do tend to "blow" more often than the ones that require a lot more power just to run them. Magnets, and the balance of all the components interplay with the power input to make all sorts of combinations. Most folks don't realize how important it can be to match the speakers to the amp, but it's a very significant factor in what kind of sound you get, and how much of it comes out.

[bangerjim]

Best bet is to invest in a REAL 100W RMS (very important) output amp. That RS thing you have is probably not a true RMS rating. (read the manual and see the different listings for rating the output!) RMS is the raw power an amp can put out driven by a sine wave until it starts to clip the sine wave to a square - distortion.

There is no way to "jury rig" a cheap amp (or expensive one) to increase the power.

You will drain a car battery in a matter of minutes with a powerful car amp. They are made to be operated off the alternator - not the battery - for extended periods of time. A friend has a 1KW/channel RMS car amp and it will make the headlights dim when driven hard on bass lines! And that is WITH the engine running.

Look around for an old tube type amp. I had one back in the day that cranked out 90W RMS and was a great PA amp (and hand warmer). Rugged and reliable.

Also as mentioned - speaker efficiency is VERY important! 20W RMS is very loud when driving good quality high-efficiency 8 ohm speakers (big magnets with big voice coils). I have build/assembled/modified a bunch of audio equipment in the past and it always pays to use good quality high-end stuff. Even if you use it only a few times a year. There is nothing more embarrassing than to be playing at a "gig" and have the audio system underpowered and distorting like crazy.

Good luck on your quest.

bangerjim

[Tenbender]

Any electronics guys here????
I have a Radio Shack PA AMP that is 20W.
Is there a cheap way to boost it up to 100W??????

I have a 3000 watt Crown I would sell !

[MaryB]

Speakers will have a label usually listing "sensitivity"

"Sensitivity
Sensitivity is most easily defined as the speakers’ ability to effectively convert power into sound. The traditional way of measuring a speakers’ sensitivity is using the standard of 1 watt/1 meter. Meaning a microphone is placed 1 meter away from the speaker to measure the sound output (in decibels) with 1 watt of sound played through it.

There is much room for error (or imposed error) with this type of measuring system and some manufacturers today take advantage of this."

The higher this number the louder the speaker is per watt fed to it.

[abunaitoo]

Are those horn speakers better than those home stereo speakers?????
We're not playing any music. Just instructions and a beep.
Cheap enough to try a set.
Thanks.



I used to run a silhouette match. The firing line was 150 feet long. I used the same amp you have with speakers similar to this:

http://www.ebay.com/itm/2-Pyle-PHSP4-6-50-Watt-Indoor-Outdoor-Waterproof-Home-PA-Horn-Speaker-White-/231361609565?hash=item35de39ff5d:g:NsQAAOSwBahVCaT 2

Also used an answering machine tape in a portable tape player for range commands. The 4 speakers and speaker wire were permanently mounted. The speakers put out 100db at 1 watt/at 1 meter. At mid volume setting it should be enough to get folks attention.

Another range used a vehicle cb to run the same speakers that used a car battery for electrical power.

[bangerjim]

The LARGE (20x10") horn PA speakers I have run with 70.7 volts line to voicecoil, not 8 ohms like your standard run-of-the-mill home speaker systems. And require an amp that uses that output impedance. Or matching xformers. That is done to allow long runs of realatively small gauge wire and not loose power. There is a lot of electrical and audio engineering "things" to consider when throwing a good powerful AND functional PA system together. And I am not talking thumping bass here......just good clear strong vocal audio.

Do some research on the net B4 just buying a more powerful standard amp. Those Pyle horns may do the job for you. I paid a lot more for my set of matching xformers and L-pads than a set of those cost.

[abunaitoo]

I'm waiting for them to let me know if the free shipping is for Hawaii.
If it is, I'll order them.
PA is not going to be used for any music.
Just range commands and a beeper.

[MaryB]

This

SPL(@ 1W/1m): 100dB

tells you they are pretty efficient! So they will be fairly loud with low drive.


Are those horn speakers better than those home stereo speakers?????
We're not playing any music. Just instructions and a beep.
Cheap enough to try a set.
Thanks.

[abunaitoo]

Looks like they don't send to Hawaii free shipping.
I found a pair on Amazon with free shipping and cheaper.
Same brand, but 65w instead of 50w.