Suggestions needed for Amplifier - Dance Team

spartan711

Member
2010-10-20 11:19 pm
Hi Everyone,

I've been on these forums nonstop for the past 2 days, and hunting ebay for a good deal on TA2020, or MK2050, and on Arjen Helder's store. I figure this will be a good place to ask this question.

Our dance team uses an old school boombox, but it has finally crapped out on us. I am in charge of getting us the new speakers. I found a good deal on passive bookshelf speakers (I think they are... feel free to judge!) at Radioshack here
Yamaha NS-6490 3-Way Bookshelf Speakers (Pair) - RadioShack.com

and I have been trying to find a low-cost way to amplify them - our budget for speakers is only around 80 bucks. Minus the speakers, so 50 for the amp. I would like to be able to use these at parties as well, as we are a dance team :) DIY is perfectly fine, as we are all engineers of some kind, but from what I have seen, project boxes, and switches, and everything add up too quickly...

In terms of audio quality, the most important thing is CLEAN and BALANCED sound. We need to hear the little things!

I am looking for any suggestions... the speakers specs are as follows on the last page. Thank you for all your time.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/4000103_PM_EN.pdf
 
They're 8 Ohm and 90dB/W - that indicates to me that you'll want to power these at 24V or higher, e.g. aiming for 50W or so to get good volume out of them. The ideal amp IMO would be a TK2050 amp running at 24-32V. Might be too expensive though.

However, if you can find speakers that have a 2 or 4 Ohm impedance, and preferably a little higher sensitivity - say 92dB/W - then you can use a lower-powered amp. Then you can save on the amp - and on the power supply! Plus you'll be able to realistically use a cheap battery power supply for loud playback for long periods of time. Then the cheapest suitable amp is probably the 41Hz Amp6-BASIC-Sneaky for $26: 41Hz Audio:AMP6-BASIC-SNEAKY

These are very very good. Easy to assemble, they sound simply EXCELLENT, cheap, rugged.
 
The Amp6 is nice, but once you add a box, transformer, power supply, etc. its getting tight. I'd probably suggest checking the local pawnshops, Craigslist, classifieds and Goodwill and look for a small PA amp, power amp, or old stereo reciever or integrated amp in good working condition. If you don't have to move it around much, you can probably find a pretty powerful solid state reciever (50 to 100 watts per channel) fairly inexpensively; the big thing is to test it out pretty thoroughly before you lay out the cash. You might also check the same sources for small PA speakers - if you find a small PA amp it probably will have speakers with it, and they will likely be more efficient than the ones you listed, although those look very good for the price. Its easier to modify PA speakers to sound better than it is to modify inexpensive stereo speakers to be more efficient. If you can find a box to mount them in, the Sure Electronics 25 watt per channel class D amp from Parts Express would be another possibility. Any of the options we've discussed will be a big step up in sound quality from a boombox.
 
That should work great. Just try it out before buying, check to make sure sound is coming from each speaker about equally, that there aren't any major "funny noises", crank it up to at least 2/3 power and make sure nothing blows. As thats a simple PA system, it will have a somewhat limited bandwidth and will likely be mono, not stereo. Just get some adapters from Radio Shack to go from the RCA plugs your CD player (or other source) probably has to the likely 1/4 inch phono plugs this thing has, and put each output into one input. It won't sound as good as a good home stereo as far as "true, accurate sound", but can safely play loud, is built to be hauled around if needed, and with a microphone can also be used to discuss the dances with an audience or be heard over boisterous kids. If it has some mild crackling noises only when one of the controls is turned thats probably okay and can be likely improved with some tuner cleaner. For the money we're talking, its a great solution, and should kick the snot out of your old boombox.
 
The Sonax is a vintage '70s set, possibly made in Canada by Traynor. Traynor made some really well built stuff. If it currently works well, it should be pretty reliable, at least until the electrolytic caps have to be replaced. Its definitely not "high end" by any stretch, but should be fairly well built. I've never seen a Sonax amp before in person, so thats a bit of an educated guess.

The Pyle amp is kind of a budget brand and will be cheaply built, but it is fairly recent and MAY be reliable. The 75 watt rating is likely to be quite optimistic. The speakers mated to it in that ad are basically very inexpensive car stereo stuff. I'd guess the sound output using that amp to drive those speakers will be on the lowish side - the fact the speakers are rated for up to 800 watts (probably also "optimistic") suggests the stated sensitivity of 93 is also unlikely under real conditions.

If I were making the call, I'd go with the Sonax, but that is partly based on my perception that the basic construction is more solid and that I could more easily update the drivers and "voice" the speakers to my liking, and that the amp circuitry will be simple and easy to repair. It is absolutely worth $60, particularly for your situation, if its in reasonable working condition. I'd definitely go check it out, and probably soon, as it will probably be snatched up by some kid trying to start a garage band. The other stuff you posted MIGHT be worth the money, I don't know.

Resale value on either set will be low, but to the right person the Sonax would probably be worth more.
 

spartan711

Member
2010-10-20 11:19 pm
Good news! I talked to our finance guy on the team, and he said he'll up to the budget to $200 (to match how much we spent on the last boombox). He said the other teams were using at the CM-30 from Roland, and to check it out.
Roland U.S. - CM-30: Cube Monitor
From what I see, this is a speaker and amp built in. Im trying to get away from that, as it will be easier to replace components rather than the whole thing. Can you guys imagine any setup that will be extremely portable? What I am picturing is a suitcase sort of thing, where the speaker has two wheels on the bottom, the amp on top, and I can extend something and roll it everywhere.
With this HUGE budget increase :-D , do you think something like this is possible?
 
The Roland would be okay. Its very portable, more powerful than a boombox, but not by much. If you buy it new from a vendor with a return policy I wouldn't lose a lot of sleep over any component part being separately replacable in this price range. You might also consider this - its portable (but less portable than the Roland), but more powerful.
Buy Kustom Profile 100 Portable PA System | Live Sound Packages | Musician's Friend
 

savenger1

Member
2010-06-29 8:53 am
^ that looks ok for $50... the only problem I see is the max SPL listed there is 103db... which may not be loud enough for your needs depending on the space you're in.

if you're thinking about getting a portable, powered mono unit anyway, you may as well get a single powered PA speaker. Chances are it'll sound as good if not better, plus you have the opportunity to upgrade to a proper stereo PA system in the future just by adding another one.

This is within your price range and exceeds your requirements... max SPL is 113db which is easily more than twice as loud as the polk audio unit:
Behringer B208D Eurolive Active 220W 8" 2-Way PA Speaker | Parts-Express.com