Blues Jr. Question

[eldungo]

Hi All. I have a Blues Jr. question. I have a little USA made beauty with the standard Eminence/Fender speaker. I have put my hands on a Celestion V-30 (Yay!) and IT is a 16 Ohm speaker. Says so right on it. From reading here, I gather the amp is perfectly able to handle the 16 Ohm speaker. However, I would like to hear it for myself from someone. Know what I mean? Doesn't matter where you look, everyone says "try the V-30 in the BJ"! I'm all like...OK! I like the stock sound but I have this V-30 just sitting here! Thoughts? Answers? Thanks.

In Walked My Past, and My Past Was pd!

[JohnH]

Welcome to GN2. I don't know about BJ's, but doesn't the current speaker have an Ohms rating (8 or 16 Ohms) written on it? - If you match it, it will work. Vintage 30's are great speakers, I just put one in my Marshall combo.

John

[ChrisK]

The Blues Junior only has one output winding on the output transformer.

It is for 8 Ohms.

Since the Blues Jr is kind of loud anyway (too loud for keeping your lease), you might try adding a 16 Ohm 25 Watt power resistor across the speaker terminals on the 16 Ohm V-30. This will present an 8 Ohm load to the output transformer, work the output tube plates just as hard as the original speaker, but only be half as loud.


If you connect a 16 Ohm load up to the 8 Ohm winding, the output tubes will be presented with a plate load twice as high. I don't know what effects will occur in the Blues Junior.

[eldungo]

Thanks for the info you hip cats. Yeah John, she sez 8 ohms. And ChrisK, you Global Moderator you! That's the BEST answer I've gotten. I posted on "other" forums and did not get this info. OUTfreakingstanding! Wanna buy a 16 Ohm V-30? Anyone? (I know, another thread).

[ChrisK]

Seriously, try the resistor trick. That's how simple speaker attenuators work.

I'm building an Allen Amps Encore kit with 6V6's instead of 6L6's. To effect the proper higher (or at least better) plate impedance, I'll be connection the two 8 Ohm speakers in series and hooking them to the 8 Ohm output winding.

I don't remember what the effect will be from doubling the plate impedance but you can try it. If you don't like it, use the resistor.

[sumgai]

Chris,

.....
I don't remember what the effect will be from doubling the plate impedance but you can try it. If you don't like it, use the resistor.

Since the ratio of impedance transformance remains the same, any increase on the primary side will present an equal increase (percentage wise) on the secondary side.

This is why simply pulling two of the four tubes in a standard Fender higher-power amp causes problems for the tone. The now higher plate impedance across the primary doubles the secondary impedance. It is my observation that at moderate volume levels, this isn't a problem, though the tone might be a touch darker, depending on one's tastes. But at higher levels, one should connect a second speaker of the same impedance in series, or one speaker that is rated at twice the labeled output impedance.

For example, if your amp is rated at 4Ω, and you pull two tubes, the 4Ω output jack now wants to see an 8Ω load. Hook up another 4Ω speaker in series, and at higher volume levels, the tone will sound 'just right'. ;D In 2x12 amps like an FTR, simply disconnect one speaker or the other, and you're all set. (But then, you have the world's heaviest low-power amp! )

HTH!


sumgai