Princeton Reverb with 4ohm output?

[evancorylevine]

Is this an option? Can I do this just by changing the output transformer? Are there tonal (or functional) ramifications to this? Could I use a switchable output transformer?

[bnwitt]

Of course you can use a multitap OT.  Some folks do report you get the best tone when using the entire secondary winding of an OT.  So for instance a 16, 8, 4 ohm OT would supposedly sound it's best on the 16Ω tap with matching load.  I've never confirmed that myself.

[evancorylevine]

Of course you can use a multitap OT.  Some folks do report you get the best tone when using the entire secondary winding of an OT.  So for instance a 16, 8, 4 ohm OT would supposedly sound it's best on the 16Ω tap with matching load.  I've never confirmed that myself.

how could you even test that? you'd need three magically identical speaker cabs of different impedance.

[92Volts]

The very same 2x 8 ohm speakers can be wired in parallel or series for 4 or 16 ohm overall impedance. Parallel/series connection itself shouldn't cause any electrical or tonal changes (except a 4x greater impedance)

You can also get the same brand/model speaker in different impedances, though these won't be totally identical. Jensen actually acknowledges that different impedance ratings for the "same" speaker behave slightly differently, other companies don't mention this but I assume there are very slight differences.

[evancorylevine]

So the cat remains out of the bag as to whether or not an OT sounds different when tapped.

At any rate, I wouldn't mind straight up setting my princeton reverb up as a 4ohm device. my other three amps and my cabs are all four ohms.

[sluckey]

At any rate, I wouldn't mind straight up setting my princeton reverb up as a 4ohm device. my other three amps and my cabs are all four ohms.

So just plug one of your 4Ω cabs in to see what you think. The mismatch can be tolerated.

Or, get a multi-tap OT and run whatever you chose. Hoffman has two multi-tap OTs that should work fine with your PR. One is a 25W for use with the Deluxe. The other is the 18W OT for the Marshall 18W amps.

[evancorylevine]

At any rate, I wouldn't mind straight up setting my princeton reverb up as a 4ohm device. my other three amps and my cabs are all four ohms.

So just plug one of your 4Ω cabs in to see what you think. The mismatch can be tolerated.

Or, get a multi-tap OT and run whatever you chose. Hoffman has two multi-tap OTs that should work fine with your PR. One is a 25W for use with the Deluxe. The other is the 18W OT for the Marshall 18W amps.

This is a build which I'm planning but have not yet begun. Which OT would sound most like a standard Princeton Reverb?

[sluckey]

Which OT would sound most like a standard Princeton Reverb?

I have no idea. I owned a '64 PR back in the late '60s. It was a good practice amp but did not have enough balls for rock clubs. And the single 10" speaker always had a thinner sound (lacking bottom end) when compared with the popular 2x12 or 4x10 amps of the era. I realize that's not a big deal today.

You may have to buy one of each and decide for yourself. If I were gonna build a non-standard PR I would use the 25W multi-tap OT for the most options. The bigger OT would probably have a stronger bottom end. I like that.

It's really gonna be a personal choice thing. You will likely be pleased with any PP 6V6 OT. Bigger is better IMO.

[tubeswell]

I did a Weber 6A14 kit with a 12" 12A125A speaker and a DR OT (25W rating reflecting 6K6). Has incredible bandwidth. Awesome studio amp.

[bnwitt]

I did a Weber 6A14 kit with a 12" 12A125A speaker and a DR OT (25W rating reflecting 6K6). Has incredible bandwidth. Awesome studio amp.

+1 on that.  I've done a few Hoffman style PRs with a 12" speaker and a DR OT/PT and the sound great

[tubeswell]

Also the stock PR has an extn speaker jack wired in parallel to the main jack, so assuming you are running an OT with only one tap, you will automatically halve the reflected load seen by the tubes if you plug in another matching speaker.


You can wire these output jacks differently with a multi-tap OT, (but you also need to change the type of output jacks to do this). (Can't remember which site diagrams came from):

[evancorylevine]

Also the stock PR has an extn speaker jack wired in parallel to the main jack, so assuming you are running an OT with only one tap, you will automatically halve the reflected load seen by the tubes if you plug in another matching speaker.


You can wire these output jacks differently with a multi-tap OT, (but you also need to change the type of output jacks to do this). (Can't remember which site diagrams came from):

Gosh all those options seem like they can introduce a lot of variables between impedance mismatching etc. I think I'd like to just have a 4ohm speaker in the combo, and be able to alternatively use an external speaker.

What's a DR transformer?

[SILVERGUN]

DR = Deluxe Reverb

[mresistor]

You could build your Princeton Reverb with this OT and be able to adapt to any load.  http://www.classictone.net/40-18087.html  This is the one that I have in my Hoffman Single Channel DR and now I want one for my Hoffman Princeton.  I recently started using the 16 ohm output on the DR through a 2x12 with two 8 ohm speakers wired in series and I really like it.

[evancorylevine]

Alright! Thank you all so much for the great help! I've started a bookmark folder and I hope to start buying parts soon!