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Hi All,

I was just about to make my decision which speaker to purchase when something occurred to me. That was the proximity of speaker to the output valves.

Thinking back to my t/v repair days, I suddenly remembered the scan coils on the neck of the cathode ray tube deflecting the electron beam from the cathode across the screen. The modulated signal from these electromagnetic coils of course gave us our picture.

The stock speaker that is in the Pro Junior is 30 watts and the speaker depth is 4 inches. That leaves about 1.25 inches between the back of the speaker and the EL84 output valves (not a lot). The replacement speaker that I want to fit is about a 50 - 70 watt to give more headroom (for want of a better word)for the heavily plucked trebly notes instead of hearing that recognisable slap (or clash). All of the speakers I'm looking at are about 0.25 to 0.3 inches deeper that the stock speaker which makes all of them even closer to the output valves. Not only that, but the magnets are a lot stronger and the magnetic pull on the output valves will be considerably more (probably double or more). My thinking is that this very strong magnetic field could severely affect the electron flow within the valves leading to a distorted signal in the output stage.

If I decide to replace the stock speaker with a 30 watt speaker of another make (with the same depth), then I run the risk of paying out and having the same problem with the new one as with the old stock one.

I would welcome any thoughts, experiences, or views on this from you more experienced sorts.

Regards

I think the higher power speakers won't get driven sufficiently and you will end up with a clangy sort of amp.
I did it once on an AC 30, I fitted 2 Fane Crescendos ( because somebody gave me them ! ) and the amp then sounded dreadful.
I doubt you'll hear much difference with any speaker replacement.

Hi Eric,

Thanks for that. Another reason I was going for a larger wattage speaker was that I have a friend who has a Pro Junior with a 60 watt speaker fitted and it sounds amazing. Perhaps the reason is more down to the speaker design rather than it's power rating.

Regards

dyker124 wrote:Another reason I was going for a larger wattage speaker was that I have a friend who has a Pro Junior with a 60 watt speaker fitted and it sounds amazing. Perhaps the reason is more down to the speaker design rather than it's power rating.

The speaker power rating only indicates the amount of power it can handle without damages. The sound volume will depend on the speaker sensivity which is independent from the power rating.
But the higher the speaker power rating, the less the speaker will be saturated.

Didier

Hi Didier,

Thanks for the reply. I do understand that the power rating is to do with what it can handle without damage. I was more thinking that it would handle the instantaneous transient hard plectrum strike, which gives a sound like the speaker 'bottoming-out', rather better than the lower power ones.

Regards

I would have thought that Fender worked out what was the RIGHT speaker for the amp when they were designing it?
No?
Ian

Hi Ian,

Your absolutely right of course, but different players look for different attributes from their equipment depending on their playing technique and the type of music. Sometimes the stock speaker doesn't fit the bill.

Regards

Stratpicker wrote:I would have thought that Fender worked out what was the RIGHT speaker for the amp when they were designing it?
No?
Ian

What's "right" depends a lot on the cost, this is why most budget amps don't a have a very good speaker, and why repacing it by a better speaker is the easiest and most efficient way to upgade such amps.

Didier

dyker124 wrote:I do understand that the power rating is to do with what it can handle without damage. I was more thinking that it would handle the instantaneous transient hard plectrum strike, which gives a sound like the speaker 'bottoming-out', rather better than the lower

This is exactly what I meant when writing : "But the higher the speaker power rating, the less the speaker will be saturated."

Didier

Stratpicker wrote:I would have thought that Fender worked out what was the RIGHT speaker for the amp when they were designing it?
No?
Ian

Fender choose speakers on some amps to keep the price right, the lower end amps sometimes have speakers that leave much to be desired.
Even in the mega bucks Fender Twin Reverb that I used in the early seventies, there was a choice between the bog standard Fender label speakers which were never up to the job as they broke up too early, or the JBL speakers that were the dogs doo dahs at that time. The difference in quality between the two was vast. I had the Twin Reverb with JBLs and was always too loud and clear - and it was too bloody heavy. . . .

I read somewhere that as an upgrade Fender recommend the Ragin Cajun (in fact they use one in one of the Blues Junior posh coloured models) as well as the Weber.