Replacing an 8 ohm speaker with an 16 ohm speaker

MilanPan!c

Basically, my amp has an 8 ohm speaker fitted.

I have an external extension cab with a 16 ohm speaker.

The amp pushes the 16 oh. cab, seemingly with no problem.

The question is, could I simply swap out the I ohm speaker with the 16 ohm from the extension cab.

Will I be running any risks, etc.?

I know almost nothing about ohms.

Rigsby

I found this site helpful in this situation.

http://www.tunemybass.com/bass_amps/how_to_hook_up_heads_and_cabinets.html

Paolo_M

MilanPan!c wrote: »

Basically, my amp has an 8 ohm speaker fitted.

I have an external extension cab with a 16 ohm speaker.

The amp pushes the 16 oh. cab, seemingly with no problem.

The question is, could I simply swap out the I ohm speaker with the 16 ohm from the extension cab.

Will I be running any risks, etc.?

I know almost nothing about ohms.

The answer depends entirely on the amp.
Moar details pls.

MilanPan!c

Paolo_M wrote: »

The answer depends entirely on the amp.
Moar details pls.

Ahhhhh ok.

Amp is reissue Fender Blues Deluxe 40w with 1x12.

Replacement speaker is a McKenzie 16ohm 12" speaker from a 70s Vox extension cabinet.

I have used these in parallel in the past and though the main speaker seemed quieter than normal both seem to work fine... That link that Rigsby provided (thanks man!) seems to say that I shouldn't be doing that, so I hope I haven't screwed anything up!

Thanks for the offer of more info! Can't tell you the exact model of the vox cab, because I can't find it online..,

Paolo_M

MilanPan!c wrote: »

Ahhhhh ok.

Amp is reissue Fender Blues Deluxe 40w with 1x12.

Replacement speaker is a McKenzie 16ohm 12" speaker from a 70s Vox extension cabinet.

I have used these in parallel in the past and though the main speaker seemed quieter than normal both seem to work fine... That link that Rigsby provided (thanks man!) seems to say that I shouldn't be doing that, so I hope I haven't screwed anything up!

Thanks for the offer of more info! Can't tell you the exact model of the vox cab, because I can't find it online..,

Yep, you really oughtn't be doing that if you can avoid it.
It's unlikely to cause immediate damage, and may never damage anything, but it's putting the amp under conditions it wasn't specifically designed for.

Fender do tend to use better transformers and so I'd say the risks are lower.
Mesa use good quality stuff and promote you doing this.

A higher impedance on a valve amp cause higher fly-back voltages than otherwise expected.

When I say "quality", most quality companies over-specify their components and these amps are well able to tolerate mis-matches.
I'd put both Mesa, and to lesser extent Fender these days, in that category.
Marshall spec their components on the limit, mis-match a Marshall at your peril.

If you're not running the amp near flat out, I'd say belt ahead.
If you're gigging or recording at loud volume regularly I'd get a matching speaker.

MilanPan!c

Paolo_M wrote: »

Yep, you really oughtn't be doing that if you can avoid it.
It's unlikely to cause immediate damage, and may never damage anything, but it's putting the amp under conditions it wasn't specifically designed for.

Fender do tend to use better transformers and so I'd say the risks are lower.
Mesa use good quality stuff and promote you doing this.

A higher impedance on a valve amp cause higher fly-back voltages than otherwise expected.

When I say "quality", most quality companies over-specify their components and these amps are well able to tolerate mis-matches.
I'd put both Mesa, and to lesser extent Fender these days, in that category.
Marshall spec their components on the limit, mis-match a Marshall at your peril.

If you're not running the amp near flat out, I'd say belt ahead.
If you're gigging or recording at loud volume regularly I'd get a matching speaker.

Brilliant advice! Thanks a lot!

eagle10

You will be fine.
It poses no risk to the amp.
If you were driving a speaker of a lower impedance then your amp could come under pressure.

Generally higher rated impedance speaker less output but no danger to output transformer.
Lower rated impedance speaker more power and may blow your output transformer.

Dont go below 8 and you'll be sound.

It does not matter what make or model an amp is, it does not change for different manufactuers.

Paolo_M

eagle10 wrote: »

You will be fine.
It poses no risk to the amp.
If you were driving a speaker of a lower impedance then your amp could come under pressure.

Generally higher rated impedance speaker less output but no danger to output transformer.
Lower rated impedance speaker more power and may blow your output transformer.

Dont go below 8 and you'll be sound.

It does not matter what make or model an amp is, it does not change for different manufactuers.

That's a surprisingly common but incorrect theory.

Higher impedance cause excessive voltages, lower impedance causes excessive currents. Either can damage an output transformer.
Valve power amps attempt to deliver the same power no matter what the load.
Solid State power amps vary the power out with load.

The manufacturer makes a big difference as quality of components varies greatly.

Where are you getting your information from?

eagle10

Paolo_M wrote: »

That's a surprisingly common but incorrect theory.

Higher impedance cause excessive voltages, lower impedance causes excessive currents. Either can damage an output transformer.
Valve power amps attempt to deliver the same power no matter what the load.
Solid State power amps vary the power out with load.

The manufacturer makes a big difference as quality of components varies greatly.

Where are you getting your information from?

Fair enough.
I'll take your word for it and be more vigil in future.
It must be a common belief that I have grew up with and practiced for years.
I could not really find any info on the web to support my theory so now I have changed my point of view.

When ohms law is taken into account and your impedance is raised I suppose voltage drops and current increases at the output transformer and depending on the physical size of it would some may cope under these circumstances better than others.

Cheers

Paolo_M

eagle10 wrote: »

Fair enough.
I'll take your word for it and be more vigil in future.
It must be a common belief that I have grew up with and practiced for years.
I could not really find any info on the web to support my theory so now I have changed my point of view.

When ohms law is taken into account and your impedance is raised I suppose voltage drops and current increases at the output transformer and depending on the physical size of it would some may cope under these circumstances better than others.

Cheers

Cheers,
Sorry if I came across all know it all.
It's just that a lot of these theories (a lot of which seem to originate with Gerald Weber, who's a meat trader by trade) confuse and mis-lead a lot of people.

MilanPan!c

Final question.. Is there a way, some sort of circuit or something, to use a 16 ohm speaker safely in an 8 ohm amp?

Really wanna use this thing as it's primo and sounds amazing with the amp... Just quiet. So, if there was a way that was safe I'd, look into it.

thanks!

68 lost souls

Firstly the reason it is quiet is becuse the reistance is more so you will not be delivering 40watts but more like 20-25watts, seconldy part of the sound could be the design of the cab rather than the speaker itself so you may loose that sound by moving it to the combo. Cabinet design has a big impect on the sound.

MilanPan!c

68 lost souls wrote: »

Firstly the reason it is quiet is becuse the reistance is more so you will not be delivering 40watts but more like 20-25watts, seconldy part of the sound could be the design of the cab rather than the speaker itself so you may loose that sound by moving it to the combo. Cabinet design has a big impect on the sound.

Yeah, I'm sure the cab is def helping the sound, but it's soooo heavy I hate to lug it around and therefore it doesn't get used a lot. Which is sad.

Hmm... Maybe I should just give up.

ciaranmac

If you have time in your hands you could try the swap temporarily - it shouldn't cause any problems (i think) running it for just long enough to tell which sounds better. Then you'll know if the good sound is due to the cabinet or the speaker. If it's the 16 ohm speaker then probably your best option is to get yourself an 8 ohm speaker of the same model and use that in your amp.

MilanPan!c

ciaranmac wrote: »

If you have time in your hands you could try the swap temporarily - it shouldn't cause any problems (i think) running it for just long enough to tell which sounds better. Then you'll know if the good sound is due to the cabinet or the speaker. If it's the 16 ohm speaker then probably your best option is to get yourself an 8 ohm speaker of the same model and use that in your amp.

Yeah, not even sure where I'd get an 8 ohm 70s McKenzie Speaker

The difference is pretty amazing... Especially the low end, which from the amp is really flabby and loose... from the cab it's super tight...

Paolo_M

MilanPan!c wrote: »

Yeah, not even sure where I'd get an 8 ohm 70s McKenzie Speaker

The difference is pretty amazing... Especially the low end, which from the amp is really flabby and loose... from the cab it's super tight...

The Fender amp is open backed, right?

I'm guessing the cab you have is closed back?

Putting a new speaker into the amp itself will give the same flabby results in that case.

It's down to the amp/cab construction. Open backed designs allow for quite a bit of phase interference, especially in the lows. Some frequencies get nulled, others getting unnaturally boosted. Some say chewy, others say flabby.
Good for blues and classic rock, not so hot for modern rock, funk or metal.

From memory the valves hang down into the speaker area in that amp so closing up the back is not really an option as you'll be frying valves regularly.

MilanPan!c

I've read a lot of people saying that you can greatly tighten up the low end with different speakers and tubes.

I'm really gutted I can't use that speaker cab; I recorded it for a few hours tonight an it made the amp sound like an amp worth 3x-4x as much. It's that different.

Maybe, an 8ohm capacitor in front of the speaker cab??? Read a few people have done that.

Maybe?