So I just put an Artec 2 w amp in an old wall mounted speaker cabinet with a 8" speaker, like what you used to see in a school. The speaker has no makings on it at all so I do not know what the impedance or wattage ratings are. It works and sounds good but the volume is pretty weak, even with the vol and gain cranked.
1. Does that mean the impedance of the speaker is too low?
2. Do you think I will burn out the amp pushing the wrong speaker with it, or will it just not get loud?
I'm not electronics guy, but is there a way I can test the speaker to figure out the impedance ?
I had high hopes for this project but so far am rather bummed about the weak output.
Thank you for the help!
Replies
The speaker probably has an impedance marking directly on the magnet, 4 or 8 ohms. If, however, there is a transformer gizmo in there, the transformer is to allow the speaker to be connected to a high voltage PA line. If there is a transformer, disconnect it from the hookups directly on the speaker back and hook your little amp directly to those hookups, and you should be ok.
Most of those wall mounted speakers had transformers for high voltage lines, and I'd be surprised if you could hear the speaker at all if you're connected through one of those.
I used to do commercial PA as part of my livelihood and put in a bunch of those.
Thanks for the tips Jeff but there are no markings or a transformer or resistors or anything. I verified with my ohm meter that it is 8 ohms. I also connected a couple of other, smaller and newer 8 ohm speakers and got pretty much the same output levels. I'm not even sure if this is the original speaker or not since the cover over the magnet sticks out in back, it would not mount flat on the wall. I really think it is just a matter of having the right kind of input level as using a preamp helped some and using my harp mic (w/o the pre amp) gives the volume levels I was expecting. I imagine if I plug in a guitar with magnetic pickups I'll get output similar to the mic. Seems that piezos don't do so well with it. I do not experience that with my Honeytone amp though, it seems to be able to crank no matter what I connect to it.
Open mic night, here I come!
Oh wow, now that is more what I expected! There ain't nothin' wrong with the speaker, that is for sure! My "Shaker" harp mic got all the dogs in the neighborhood howling! No pre amp. So I guess I just have a lot to learn about the output of various kinds of pickups. I do not have a "regular" electric guitar with a magnetic pickup but I guess it would be similar to the volume I'm getting with the mic? I'm more likely to use it as a harp amp anyway and not a guitar amp so I guess I should consider it a success. Now I just need to find a place away from the dogs so I can open her up !
Thank you for all the help!
The pre amp helps but still not at all I guess what I was expecting. I'm going to try my harp mic through it and see where that gets me.
OK thanks, so it is an 8 ohm speaker (reads 7.2 on meter) . That is what is recommended. SO do I just have unrealistic expectations of how loud it will be. I have a ruby amp I made with a 3" speaker that cranks! Also a Honeytone through a 3" speaker and it is really loud ( for a small amp) . Maybe this speaker is defective??
Maybe you need a pre amp in the chain?
http://www.wikihow.com/Measure-Speaker-Impedance This gives a step by step method with pretty pictures#