Some 5E3 questions (too loud/hot?!)

[Meshugana]

It would have to be a very high value resistor (25-30W minimum) ...you'd have to tell us what the effect on sound would be...I would imagine a drop in efficiency. Why do you want to do this?

I've got a cabinet with two 8 Ohm speakers in it wired parallel. (so 4 Ohm impedance right?). That's why I need a 4 Ohm output. I could buy a 150 W 4 Ohm resistor ( Tonefactory Voor al uw versterkerbuizen, gitaaronderdelen en meer! ) to try it.

Or can I just connect the speaker cabinet on the 8 Ohm output without getting any troubles?

[MWJB]

"Or can I just connect the speaker cabinet on the 8 Ohm output without getting any troubles?" Yes, this is what would happen effectively if you plugged the 8ohm in-board speaker in the regular speaker jack, as well as another 8ohm cabinet in the ext speaker jack. It halves the OT primary impedance to 4K or so, there might be a slight noticable loss in power, but won't hurt anything.

To run the 4ohm cab at peak efficiency the new OT with multiple taps is required.

[Chuck H]

Building yourself one of these would be a good start for volume control. It's a simple and inexpensive attenuator. But it's very safe for the amp and sounds good. FWIW it's been tried and proven with the 5E3 circuit. The diagram represents those screw mount aluminum housed resistors but the cement block type will work fine. Layout is not important.

Don't use the ext. jack with nothing on the main output.

Chuck

[Meshugana]

Building yourself one of these would be a good start for volume control. It's a simple and inexpensive attenuator. But it's very safe for the amp and sounds good. FWIW it's been tried and proven with the 5E3 circuit. The diagram represents those screw mount aluminum housed resistors but the cement block type will work fine. Layout is not important.

Don't use the ext. jack with nothing on the main output.

Chuck

Hi Chuck, thanks for your input. This is wonderfull. But. I was still wondering why it is nessesary to have 3 resistors as attenuator instead of just one. Can't I just put a 4 Ohm 25 W resistor in serie with the speaker lead and connent a 4 Ohm speaker?

Please let me know.

[Wrnchbndr]

The '57 Deluxe Reissue owner's manual is available from fender.com. They claim that this is original 5E3 circuit. The manual clealy states that the speaker jacks are in parallel. The way that I read their explanation of the extension speaker jack it seems that you must maintain an 8 ohm total impedence load. This would indicate that in order to use the extension jack at all, both of your speakers need to be 16 ohms and there is no latitude for this according to Fender. And yes, I looked at the original Fender 5E3 schematic and the OT is shorted when the main speaker jack is disconnected so it is certainly a bad idea to unplug the main speaker at any time. A few seconds probably didn't hurt anything.

If you want to have some more speaker jack flexiblity, you'd need to replace your OT with a multitap version. I looked at my normal transformer supplier and was surprised that they didn't have such a thing for a Deluxe. I'm absolutely sure that either Hammond or Mercury Magnetics have exactly what you are looking for. You would use the multitap OT with a rotary selector switch to change the total impedence load setting.

I have built a couple of 5E3s and they can seem to run hot but double check that your 6V6s aren't glowing red on the plate. Mine are loud also. You should check to see that you have used the correct volume pots. They should be a 1 Meg audio taper or log pot and not a linear pot. Even your supplier may have made a mistake in packaging your kit