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Vintage threads from the first ten years

P8R vs. P10R in a VIBROCHAMP

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7/12/2000 4:09 PM
Deltablues	P8R vs. P10R in a VIBROCHAMP Just recently picked up my first VibroChamp. It's a 1975 Silverface. First question, will a P10R fit in a VibroChamp cabinet without modification to anything other than the baffle? Second, what tonal difference could I expect using a P10R vs. a P8R in this amp?

7/12/2000 6:20 PM
Don	I've got a 10" speaker with a HUGE ceramic magnet in my VC and it fits OK. I had to move the speaker a bit off center to do it, which wasn't a problem because I made a new baffle anyway. The Champ sounds much better with the 10. Cheers, Don

7/12/2000 6:27 PM
Deltablues	How has the tone changed over using an 8" speaker in relation ship to breakup level, treb/mid/bass response, darker, brighter, etc... ?

7/12/2000 6:40 PM

I think the tone has changed, and it's different from that offered by the 8, but it sounds a bit better all around. I never cared all that much for all the speaker distortion with the 8 (some folks like it a bunch, I'm just not one of them). With the 10, you get more of everything; that is, you hear more of the amp's distortion than the speaker's (my guess is this will depend on what 10 you use--mine is way overrated for this application), and you get a lusher frequency reproduction (bass, mids, treble has more depth). As for darker or brighter, I think that'll depend on what you use. Predictably, there definitely is more presence.

I like the mod. I have both baffles handy, though, in case I need that extra crunch the 8 supplies for recording. Gotta admit, though, that I haven't gone back to the 8 since I put the 10 in.

Cheers,

Don

7/12/2000 7:42 PM

I've put the Jensen 10" in a few champs (see website: www.fuchsaudiotechnology.com), and it works well and sounds better. If you rear mount it, it's fine, unless the amp is modified and the power tubes or filter cap might bump into the frame or magnet. If you front mount the speaker you can get around this, but you need to rout a slight notch into the top and bottom of the grille frame to make it fit properly.

7/13/2000 10:39 AM
Deltablues	I'm assuming that using the bell cover on a P10R would be out of the question due to clearances. Are there any issues with having the alnico magnet come that close to the tubes? I'll have to admit ignorance on this one. I really don't know what the bell cover is designed to do. Is it just for protection of the magnet? Or is it for shielding the magnetic field from the rest of the amp?

7/13/2000 6:04 PM
Doc	The dome cover can act as a magnetic field shield. Might be advantageous around video monitors and magnetic tape, but shouldn't make a difference in a guitar amp with tube shields. Originally it was a safety cover when there was a high voltage field coil instead of a permanent magnet. I consider the Jensen bell as just a cool-looking hub cap.

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