[nickyboy]

Hi folks
I've had a silverface champs for years..i really like it but would like to try a larger "fancy" speaker.

Does anyone know the procedure for getting a 10 inch speaker in the cab?

also what's the "best" speaker to use?

many thanks

Nick

[montereyjack66]

Might suggest as an alternative that you install a line out and run it into the amp/speaker combo of you choice(s) as a slave. Just a thought that occurred before coffee.

mj

[Jimmy Rocket]

You could go a couple of routes. If you wanted to preserve the integrity of the cab for future resale you could get a whole new cab (in whatever tolex/cloth floats your boat) from mojotone.

You may be able to just get them to make you a new baffle and pop it in your old cab depending on how it fits in there (I'm sure they've done it).

[Bob M]

The big issue will be impedance. The Champ is 4 ohm, hard to find a 10" 4 ohm speaker. I'm told that you need to upgrade the tranny to safely go to 8 ohms. Some folks will say that is unnecessary, but they are probably wrong. I tried a 10" eminence in my Blackface Champ and didn't note enough of a difference to pursue it. It will fit, just needs a new baffle.

Try upgrading to a high end 8 incher. Weber makes some just for Champs and that was a positive in my Champ.

[stevo]

Originally Posted by Bob M

The big issue will be impedance. The Champ is 4 ohm, hard to find a 10" 4 ohm speaker. I'm told that you need to upgrade the tranny to safely go to 8 ohms. Some folks will say that is unnecessary, but they are probably wrong. I tried a 10" eminence in my Blackface Champ and didn't note enough of a difference to pursue it. It will fit, just needs a new baffle.

Try upgrading to a high end 8 incher. Weber makes some just for Champs and that was a positive in my Champ.

Maybe I have this wrong, but adding an 8 ohm speaker to a 4 ohm system should be fine although you might lose something in tone or volume. It's the other way that would be problematic - you wouldn't want to wire something for lower reactance than it's rated for since that would actually increase the current that it sees. So if the amp is actually rated for 4 ohms, it doesn't get much more robust than that.

[Bob M]

Originally Posted by stevo

Maybe I have this wrong, but adding an 8 ohm speaker to a 4 ohm system should be fine although you might lose something in tone or volume. It's the other way that would be problematic - you wouldn't want to wire something for lower reactance than it's rated for since that would actually increase the current that it sees. So if the amp is actually rated for 4 ohms, it doesn't get much more robust than that.

I don't know enough to comment, but it makes sense because running my 10" emenence at 8 ohms made no significant change. The Weber 8 inch Champ speaker did make a solid difference.

[cybermgk]

Originally Posted by stevo

Maybe I have this wrong, but adding an 8 ohm speaker to a 4 ohm system should be fine although you might lose something in tone or volume. It's the other way that would be problematic - you wouldn't want to wire something for lower reactance than it's rated for since that would actually increase the current that it sees. So if the amp is actually rated for 4 ohms, it doesn't get much more robust than that.

For tube amps, SPECIALLY older amps, there are problems either way. Mismatch one way and you risk arcing on the OT, eventually failing it, the other arcing over the tube sockets, getting tube failure eventually. SOME newer amps have circuitry to handle reflected signal and over voltages caused by impedance mismatch, and can thus handle a small impedance mismatch (i.e. 4 and 8, or 8 and 16). Some even can switch the OT tap automatically.

But older amps you run aa real risk of damage mismatching impedances.

[tguen63]

Originally Posted by stevo

Maybe I have this wrong, but adding an 8 ohm speaker to a 4 ohm system should be fine although you might lose something in tone or volume. It's the other way that would be problematic - you wouldn't want to wire something for lower reactance than it's rated for since that would actually increase the current that it sees. So if the amp is actually rated for 4 ohms, it doesn't get much more robust than that.

The general consensus over on the Weber amp building forum is that in a tube amp you can run between 1/2 or 2X the amp's rated impedance with no risk of damage, but there may be a slight impact on tone/performance. It's SS amps where you don't want to go below the amp's rated impedance. Actually in tube amps running below the rated impedance is somewhat less risky than running over the rated impedance (which is why some tube amp speaker outputs use switched jacks to short when a speaker is accidentally not plugged in. There's less risk of damage running a tube amp on a dead short than an open circuit).

Weber has great 10" speakers available in 4 ohms.

[stevo]

Originally Posted by cybermgk

For tube amps, SPECIALLY older amps, there are problems either way. Mismatch one way and you risk arcing on the OT, eventually failing it, the other arcing over the tube sockets, getting tube failure eventually. SOME newer amps have circuitry to handle reflected signal and over voltages caused by impedance mismatch, and can thus handle a small impedance mismatch (i.e. 4 and 8, or 8 and 16). Some even can switch the OT tap automatically.

But older amps you run aa real risk of damage mismatching impedances.

I wouldn't think 8 ohms would kill it.

[cybermgk]

Originally Posted by tguen63

The general consensus over on the Weber amp building forum is that in a tube amp you can run between 1/2 or 2X the amp's rated impedance with no risk of damage, but there may be a slight impact on tone/performance. It's SS amps where you don't want to go below the amp's rated impedance. Actually in tube amps running below the rated impedance is somewhat less risky than running over the rated impedance (which is why some tube amp speaker outputs use switched jacks to short when a speaker is accidentally not plugged in. There's less risk of damage running a tube amp on a dead short than an open circuit).

Weber has great 10" speakers available in 4 ohms.

But then, they are designing their circuits and controlling the plate voltages, voltage sag etc. All depedns on the amp design. Some are designed such that it WILL only take a 4 ohm load, else you will be shortening the life of the OT and/or tubes. Not to mention, it was likely designed to have 'it's' tone driving that particular load.

In fact, I had read that the Fender Champs/Broncos/VCs were VERY intolerant of any mismatch.

Depends on the OT on the Amp. Some can handle a 2x Mismatch and the reflective or flyback voltages. Champs/Broncos/VCs didn't have a TO capable of it. Lower than expected can still over work the tubes.

[cybermgk]

From an Amp tech/builder I REALLY trust
"If mismatching high there is a risk to the OT, which increases with the severity of the mismatch, & with how hard you are pushing the valve output section. The ultimate 'high' mismatch is no speaker load ie infinite ohms. If trying to pass a signal into this then there is a severe risk to the OT from high flashback voltages which can arc through the insulation layers & burn out the tranny. Mismatching between 1/2 & 2x the impedance the amp 'expects to see' is normally problem free for most amps with healthy OTs. It is never guaranteed safe though, & being manufacturer specific Marshalls fail much more often when doing this then Fenders do"

[tremelo68]

Get the Weber replacement speaker. It sounds way better than the original and bigger too. I did this for my 66 Champ, in order to preserve the speaker, and was immensely surprised and impressed with the new tone. I believe I have the Blue Pup in there (8" AlNiCo Blue style speaker at proper Champ impedance, which I think is actually 3.2ohms).

Actually just looked at the Weber site and they have 3.2 and 4 ohm 10" speakers if you really want a larger speaker. In that case, I would create a new baffle and preserve the old one or buy a whole new cab with a 10" baffle and spec'd to fit the Champ chassis.

[stevo]

Originally Posted by cybermgk

From an Amp tech/builder I REALLY trust
"If mismatching high there is a risk to the OT, which increases with the severity of the mismatch, & with how hard you are pushing the valve output section. The ultimate 'high' mismatch is no speaker load ie infinite ohms. If trying to pass a signal into this then there is a severe risk to the OT from high flashback voltages which can arc through the insulation layers & burn out the tranny. Mismatching between 1/2 & 2x the impedance the amp 'expects to see' is normally problem free for most amps with healthy OTs. It is never guaranteed safe though, & being manufacturer specific Marshalls fail much more often when doing this then Fenders do"

I've heard that Champs have wimpy OTs, but that doesn't mean it can't take it. You don't end up with too much problem by over-matching within 2x. It won't usually burn anything up, it'll just sound crappy.

Keep in mind, the amp has no ohms to speak of. The tubes want to see a certain impedance and the OT can tolerate a certain amount of current draw.

If using an 8 ohm speaker to an amp that likes 4 ohms, you will see a loss of frequency spectrum and it may not sound as loud.

All this being said, it sounds like he can / has found a nice speaker for his needs that has the proper impedance.

[stevo]

Originally Posted by cybermgk

Lower than expected can still over work the tubes.

Lower than expected is the bad one - more likely to burn things up.

[cybermgk]

Originally Posted by stevo

Lower than expected is the bad one - more likely to burn things up.

Disagree, issues CAN happen in both directions, imho. Only 100% certain safe is Impedance match.

[Jimmy Rocket]

Issues CAN happen for lots of reasons (especially in an amp that old if it hasn't been re-capped recently) but it's unlikely in the case of swapping in an 8 ohm speaker in that design.

That said, you will experience a decrease in volume and frequency response and given that you can snag just about anything you want in 4 ohm from Weber, there's no reason to push your luck.

Best plan of action, new 10" baffle from Mojo + new 10" 4ohm speaker from Weberland, and you're off and running.

[stevo]

Originally Posted by cybermgk

Disagree, issues CAN happen in both directions, imho. Only 100% certain safe is Impedance match.

I apologize - I'm not trying to argue for the sake of argument. Yes, it CAN happen. In practical experience, I've done it a lot and have met plenty who have and there have been no issues.

But it's never recommended - I always match when I'm not in a bind.

But if I'm in a club and didn't bring my cabinet because they told me they have one and I find out they have one that's 16 and one that's 4, I know not to choose the 4 for an 8 ohm amp.

[LittleRedRooster]

What do you expect to get from the larger speaker. What does fancy mean? If you like the sound of the amp don't mess with it. If you want a change of pace buy another amp. They aren't making anymore silver faces. If you screw up the output transformer you will regret it.

[TV the Wired Turtle]

tried a jensen mod 8", Jensen alnico 8" and weber 8" didnt make that much difference unless you want the Jimmy Page overdrive thing or want a harp amp..
If you want some nice head room a bit o' cash has to be spent. Simple upgrade was a drop in mercury magnetics fat champ 8ohm OT and opening the speaker baffle up for a celestion greenback 10" speaker. My champ now loves my gretsch something fierce especially with the solid state rectifier plug.