Overclock.net banner
Cancel
Create thread New Forums

Need to power 2x 50w speakers on the cheap

Jump to Latest
1 - 17 of 17 Posts
T

TA4K

· Registered
Joined
·
762 Posts
Discussion starter · #1 ·
So I found two old (think 30yrs) 12" twin cone speakers that used to be my Dad's. They are already in a cabinet, and I just need to wire them and power them. What would be the best solution for doing 100w on an amp, on the very cheap?

I found this:
http://www.jaycar.co.nz/productView.asp?ID=KC5470&keywords=amplifier&form=KEYWORD

but I'm not sure if that would be suitable, or easy enough to set up. I have access to transformers to go form 240 to other voltages if need be.
 
#2 ·
For that price and if you are looking for a project, build a LM3875 or LM3886 or LM4870etc. amplifier.

The LM3875 is arguably the best sounding, the other models get higher in power.

You can get kits, maybe avoid the China Ebay ones and go for something from audiosector.

Less money and you will be hard pressed to beat those chips for sound quality.

Here is an example for a stereo pair. Highly recommended, no affiliation. This amp is pretty simplistic, so don't be shy to add lot's of capacity to the PSU. (More or bigger filter caps, helps with the bass a bit cause that's how people are lol)

http://www.audiosector.com/lm3875.shtml

When you are building a "real" stereo, you don't need as many watts. Your speakers efficiency would dictate weather you need 135 w per channel or not. I never use more then 15w or 20w myself, and it is loud.

See if you can find out and specifications on the speakers.
 
Discussion starter · #3 ·
I actually have no idea when it comes to amplifiers. I was wondering if the one I linked was easy enough to setup. all the prebuilt ones are too expensive.
 
#4 ·
#7 ·
Make sure you take the cover off of those speakers and look at the drivers - if they have foam surrounds, it's likely that the foam has disintegrated. If they're not foam surrounds, its likely that they're not very efficient and you'll need at least a 100W to make a lot of noise. If the foam is intact, then you're good! I wouldn't go below 50Watt, no matter what. 12" speakers are not easy to move.

You could always go used.... This would be awesome:

http://www.ebay.com/itm/Vintage-FISHER-RS-2010-Stereo-Receiver-/130839028496?pt=Vintage_Electronics_R2&hash=item1e769d2310

Do not even think about the amp kit you posted. While I'm sure it'd sound amazing and have immense power, you'd likely spend over $300 getting that set up. Its class A, so you'd need a heat sink and fan system capable of dissipating over 400W, and I'd be shocked if you have a 60-0-60 volt, 600VA transformer laying around to drive it.

The most expensive part of any amp is the power supply. The transformer, if you don't have it, will probably be about $150. Heck, you're probably looking at $40 or so just in the filter caps! And then there's the matter of a case...
 
#8 ·
Quote:
Originally Posted by kevmatic View Post

Make sure you take the cover off of those speakers and look at the drivers - if they have foam surrounds, it's likely that the foam has disintegrated. If they're not foam surrounds, its likely that they're not very efficient and you'll need at least a 100W to make a lot of noise. If the foam is intact, then you're good! I wouldn't go below 50Watt, no matter what. 12" speakers are not easy to move.

You could always go used.... This would be awesome:

http://www.ebay.com/itm/Vintage-FISHER-RS-2010-Stereo-Receiver-/130839028496?pt=Vintage_Electronics_R2&hash=item1e769d2310

Do not even think about the amp kit you posted. While I'm sure it'd sound amazing and have immense power, you'd likely spend over $300 getting that set up. Its class A, so you'd need a heat sink and fan system capable of dissipating over 400W, and I'd be shocked if you have a 60-0-60 volt, 600VA transformer laying around to drive it.

The most expensive part of any amp is the power supply. The transformer, if you don't have it, will probably be about $150. Heck, you're probably looking at $40 or so just in the filter caps! And then there's the matter of a case...
Click to expand...
Not necessarily. I had some vintage Sony speakers from the early 70's. When I got them in I can't remember 2000 or something they where in perfect working order. In daily heavy usage they lasted to around 2007 when after some spirited use of volume the foam gasket finally gave out and ripped.
 
Discussion starter · #9 ·
Quote:
Originally Posted by kevmatic View Post

Make sure you take the cover off of those speakers and look at the drivers - if they have foam surrounds, it's likely that the foam has disintegrated. If they're not foam surrounds, its likely that they're not very efficient and you'll need at least a 100W to make a lot of noise. If the foam is intact, then you're good! I wouldn't go below 50Watt, no matter what. 12" speakers are not easy to move.

You could always go used.... This would be awesome:

http://www.ebay.com/itm/Vintage-FISHER-RS-2010-Stereo-Receiver-/130839028496?pt=Vintage_Electronics_R2&hash=item1e769d2310

Do not even think about the amp kit you posted. While I'm sure it'd sound amazing and have immense power, you'd likely spend over $300 getting that set up. Its class A, so you'd need a heat sink and fan system capable of dissipating over 400W, and I'd be shocked if you have a 60-0-60 volt, 600VA transformer laying around to drive it.

The most expensive part of any amp is the power supply. The transformer, if you don't have it, will probably be about $150. Heck, you're probably looking at $40 or so just in the filter caps! And then there's the matter of a case...
Click to expand...
Wow man, thanks for the help!
thumb.gif
Just to note, I did some digging, and they are Philips AD12100 HP8, which is a twin-cone 8ohm resistance, 50w. Also btw by speakers, I meant the drivers. They are perfectly intact, I've had them running off of an old radio head unit to test them. They are also already in a cabinet which my Dad used for PA stuff. I am just in the process of modernizing the cabinet with clamping latches and hinges etc. Another idea I had was to run it off a car head unit, since the driver I tested seems to do fine on an old radio that probably did 25w-ish.

EDIT: I can put pictures up if need be. I'm sure you'd love to see some vintage autio equipment.
 
#12 ·
It might be alright, I think it's only around 30 - 40 watts per channel though.

That Fisher RS 2010 is a slightly different level of gear, which is maybe why it he pointed it out.

That Onkyo is from the 80's, nothing particularly special, probably a IC amp module as opposed to separate discrete transistors. While there is nothing particularly wrong with it, it was early times for IC amps, they might not be as good as something like that Fisher RS2010.

Short answer, I myself would not pay $75 plus shipping for that Onkyo without hearing it first, or at least reading multiple positive reviews about it. If it was a local purchase maybe pay $50 tops for it.

I suppose your selection is limited though with the internet that is less of a problem.
 
Discussion starter · #13 ·
Quote:
Originally Posted by All3n View Post

It might be alright, I think it's only around 30 - 40 watts per channel though.

That Fisher RS 2010 is a slightly different level of gear, which is maybe why it he pointed it out.

That Onkyo is from the 80's, nothing particularly special, probably a IC amp module as opposed to separate discrete transistors. While there is nothing particularly wrong with it, it was early times for IC amps, they might not be as good as something like that Fisher RS2010.

Short answer, I myself would not pay $75 plus shipping for that Onkyo without hearing it first, or at least reading multiple positive reviews about it. If it was a local purchase maybe pay $50 tops for it.

I suppose your selection is limited though with the internet that is less of a problem.
Click to expand...
that is 63USD, with two extra speakers that I would probably end up selling.
 
Discussion starter · #15 ·
Quote:
Originally Posted by Electrocutor View Post

Remember to do all the math for that driver... ported, unported, cab volume, insulation, no standing waves, etc. The cabinet and cross-over are what really make a speaker.
Click to expand...
The cabinet was built when my dad was 18, with these exact drivers in mind. It has been running before, but the amp he had for it was sold long ago. I should only have to power it now, since all the maths has been done.
 
#17 ·
Those drivers are pretty... Meh. Those aren't foam surrounds. Anyway, I revise my recommended power level. 50W would probably be pretty stout for that, since they're only rated for 40 Watts

Another amp in the power range I recommend is the Pioneer SX-780, though they've seem to have taken a sudden spike in value recently. They're rated at 48WPC, and can easily do far more. My dad's used to literally shake pictures off of the wall!

I wouldn't let the IC driver thing put you off (The SX-780 is one). They were pretty good from the get-go. Discrete is better, but do you need better than perfectly fine? Besides, I don't think you're talking about true Hi-Fi or anything... Large full-range speakers are full of compromises.

Still, though, worth getting an amp for those!
 
1 - 17 of 17 Posts
About this Discussion
16 Replies
5 Participants
Last post:
kevmatic
Overclock.net
posts
28M
members
562K
Since
2004
The premier forum for overclocking experts and enthusiasts. Discuss hardware optimization, custom builds, benchmarking, cooling solutions, and pushing the boundaries of computing performance. From beginner guides to extreme overclocking, join our technical community to master system tuning.
Full Forum Listing
Explore Our Forums
Intel CPUs Hardware News NVIDIA PC Gaming Water Cooling