[windupman]

Hi everyone,

This topic probably has been covered ad nauseum, so please forgive me if that's the case. I'm trying to test out some OB speakers that I'm building with my kids. I'm completely new to things audio.

With an active crossover (dbx 233) to test the crossover points, I want to tri-amp my quasi-Lampizator-Px speaker idea. Please keep in mind that everything I'm talking about is based on what I've read. I've barely heard an open-baffle speaker, let alone a DIY system.

Drivers are:

High/mid: Jensen RP-108 horns. Supposedly originally crossed at 800hz with a full/mid-range. 12 ohm. I don't know the sensitivity, nor do I know how to test it.
Full/mid: Zenith 49CZ860/1. I have read that they are sensitive to 97db and 8 ohm. Again, I don't know exactly.
Low: 2x Eminence 292-2008. Early seventies 15", alinco-magnet woofers pulled from Allen Organs. I bought four of them on eBay probably after a drink or two and I don't know anything about them.

I've read that people are powering the Zeniths with 2 watt tube amps and I know that the Jensen horns were powered by a low-wattage Magnavox tube amp (I have it and may use it).

The idea I had was to buy a $100 used multi-channel power amp to test the crossover points. I looked at a few Elan Z series amps and the like. I worry that anything over 30watts/channel will be too much, but I don't know. Can anyone help?

Thanks,
David

[FullRangeMan]

These drivers are hi efficiency n o % and SPL, propable 96dB or more, you will need Little power indeed according your room size, for testing you will need even fewer W. There is no way to re-cone these beautiful drivers.

Please Note passive xovers eat some power from the amp as heat and lower the SPL from the drivers.

[JLM]

Your biggest challenges are not having much usable range on the volume control and the kids turning it up too much.

Actually too little power can be more of a hazard than too much.  Too little power can lead to over driving the amp to the point of distortion and clipping (where the smooth sine wave output gets flattened out at the peaks).  Those clipped signals are extremely hard on the drivers as they try to follow the signal, it forces them to try to come to an immediate dead stop/start which generates heat and can fry the voice coils.  Better to over drive the speakers with clean power than clipped power.

[windupman]

Thanks guys. I'll try it with the 30w/channel power amp and keep the volume down. I'm still waiting on a few things to arrive, so I'll let you know how it goes.

[windupman]

Over the weekend, my daughter and I put the drivers in baffles and wired them for a test. I ended up using an older Yamaha home theater amp just because that's what was around. It's 100W per channel.

To get to the point, it sounded terrible. There was a hiss audible and the speakers sounded tinny and thin. And we needed some volume to get any sound at all. We tried running each full-range and with some crossovers. We used those Dayton pre-wired crossovers from Parts Express just to try something. I checked the polarity, etc.

I'm guessing that this is a case where the amp is a mismatch for the speakers because there's no way they would sound this lousy. Either that or I have some setting on the amp wrong, but I'm not sure what it might be. I have only heard the Zenith speakers before, but they sounded much nicer when driven by the mono tube amp in the console.

Does anyone have any ideas? I know that most people are using tube amps with this kind of speaker, but I don't have one (yet).