Speaker Wattage vs Amp wattage?

[mgreene300]

I'm rebuilding my 67 Skylark GA5T and need to know what wattage would be optimal for a replacement speaker. I'm not necessarily trying to recreate the original tone. Since the amp is only 5 watts, I'm wondering if it would push a 30 or 50W speaker enough to even get a decent sound? I have a 15W Weber on order from MF, but it's backordered and me being impatient, I'm thinking of cancelling the order, but 30w is the lowest I can find around here in the short term. I called a store here in Nashville that has an Eminence Legend and a Ragin Cajun. They didn't know the model of the Legend, but the Cajun is 75w.

 

All I know on this topic is to make sure the max rating of the speaker does not exceed the output rating of the amp (sort of like plumbing knowledge that begins and ends with knowing that crap runs downhill), So any advice will be appreciated! When I got the amp years ago, the original alnico speaker was blown and I put a 30w Jensen c10q (ceramic) in but was never happy with the tone. Of course that problem may not have been the fault of the speaker.

[stein]

Higher wattage speakers are not only able to handle more power without blowing, but they are also inherently more efficient. That means you can get a lot more volume from it with the same amount of power (watts) using them as opposed to using a lower power rated speaker.

 

As far as I know, there is no limits to using a high power speaker in an amp.

 

A disadvantage would be that some amps get power tube distortion partly from a speaker reaching it's limit and giving a sort of "feedback" toward the power amp, helping the tubes to overdrive. So while going to a high powered speaker is safe for the amp, it can cause the amp's power-tube section to have enough headroom as to not distort.

 

I am guessing the Jensen C10Q you used was the Italian reissue? the origonals were not really rated at 30 watts, but the speaker itself in reissue form is rated higher because it is thought to be able to handle more power. It SHOULD be the same in sensitivity and power output as the origonal, although when used as a replacement for an actual Jensen, they tend to be a lot brighter. They often don't work well as replacements for this reason. The webers on the other hand, PARTICULARLY the low powered ones such as the "q" and "R", sound very close to actual Jensens, both in sound and how they react with the amp.

 

The Eminence "Legend" series are unofficially copies or simulations of Jensen ceramic types, and they work very well in that context...as in amps where you would want a ceramic Jensen. So the question is how would the amp sound with a ceramic Jensen at 30 watts? Or any ceramic 30 watt? One thing you can do is if you have other amps, try plugging the speakers of them into the amp you are wondering about. That will help to get a handle on what the amp sounds like compared to other amps, as well as a better picture of what speakers it likes and doesn't.

[mgreene300]

Yeah it was a reissue c10q. The original was a Gibson Ultrasonic alnico 10. Not sure what the power rating is on those. Unfortunately I don't have another amp right now (except a Roland Micro Cube) so I cant borrow any speakers to try. Like I said though, I was never happy with the ceramic jensen- the only decent tone I ever got was some super fuzz w/ the Big Muff. I don't play clean very often, so I definitely don't want to do anything that would keep the power tube section from distoring. On it's own though it just never sounded good to my ears. So maybe I just need to suck it up and wait on the 15W Weber signature Alnico 10. I ordered the regular 10 instead of the '10S' because Weber says the S has a later break up. Thanks for the info. One more question- do you have any idea which of these caps is considered the 'death cap'? I believe it's the black Sprague .022uf conected to the On/Off/Standby (in the picture it's the one in the upper left corner, closest cap to the fuse).

[mgreene300]

Well I finally got my speaker from MF- I went with the Weber 15 watt Signature 10S. Except for the hi gloss poly and a new handle on top, the cabinet is complete. It's open right now- not really sure what I'm going to do on the back side yet. I have the new Mercury Magnetic OT and the caps, but haven't put them in yet. I thought I'd hook it up with just the new speaker and cab first & see whats up. Let me say I was shocked (in a good way). It sounds so good that now I'm skeptical of even messing with the caps or transformer yet. There is a little bit of hum, but it's not overpowering. I'm not sure if the Weber Alnico is just that much better than the reissue 30W Jensen ceramic, or if it's the solid pine cabinet over the old MDF, but I'm getting tones so good that it really is a shame I'm not a better player! I really want to take this baby somewhere and just listen to someone good jam for a bit. I'm guessing everyone here is going to say if it aint broke don't fix it & leave the original electronics alone for now. Not sure which way I'm going to go yet. It sounds fantastic, but what if I could make it even better (the eternal question)? The only thing that really doesn't sound good, like maybe it has some component failure is the tremolo circuit, which I don't use anyway.

[hellion102792]

Hey mgreene, I'm posting this in regards to the comment on your profile.

 

First of all I like what you've done with it, is that a veneer or real wood on the cabinet? Very classy looking and compliments the front panel's fake wood nicely!

 

Secondly have you replaced the filter caps yet? You said your hum is not that loud which could mean they haven't quite failed yet. When I powered mine on before any repair there was a loud tone that sounded like a bass playing an infinitely sustained B note. No matter where the volume was the hum was there, same noise level. That paper multicap you see is the culprit and they do fail after so many years (most electrolytic caps have a lifespan of around 15-20 years I believe).

Replacing them now could not only improve the tone of the amp (I can vouch for this, the tonal quality really came out in my '67 after the replacement) but can prevent the whole circuit from failing when they do finally give way.

 

As you probably saw in my thread, Searcy gave some great info about replacing them:

 

First I would get it working by replacing the big orange multistage cap three new caps. Your multistage is a 10-10-20. You can replace that with two 22uF caps and one 47uF. The grounds of the three caps would be soldered together to the black lead from the original multistage cap and then connect one of the 22uF caps to the green wire. Connect the other 22uF to the blue wire and finally connect the 47uF to the red wire.

 

Once that is done and the amp is working I would move on to job #2. Replacing the cord and deleting the death cap from the circuit.

 

I advice discharging the caps. Better safe than stupid. Here is a common method for big caps but I just used a jumper lead with a 500K resister soldered to the end of it to short the caps to ground.

 

The caps you'll need look something like this.

 

Buy these two 22uf caps

http://www.ebay.com/...=item3cb6967433

 

and this one 47uf cap

http://www.ebay.com/...=item415ec304ba

 

Those links still work which is good, nice and cheap and they came in quicker than advertised (said mid-July, came end of June/early July).

 

Third, yes the death cap is that black Sprague you see on the power knob. Until I saw the picture I wasn't sure, as mine was a red Erie cap. Clip it out when you convert the plug. When I get home from work I can open mine back up and show you how to wire the 3-prong cord if you'd like.

 

I feel like "if it ain't broke, don't fix it" doesn't apply so much for old electronics. Sure a hardcore collector might only want it if it's all original, but at this point you've already modified the exterior quite a bit. You seem like you want this amp to play rather than to sell so switching out some internal components before failure is a good move that will extend the life of the amp. Especially those filter caps, the originals just weren't meant to last this long and replacing them is a really good move towards getting the full potential out of this cool little amp.

 

Hope this is helpful, if you have any questions I'd be happy to help the best I can. I'll try to get those wire pictures on here by tonight. Good luck!