amp and cab impendence matching

[chisa]

i have a dsl401 with a speaker rated 16ohm. i also have a 1922 cab with and 8ohm mono out.

 

can i run the two at the same time or do i need to stick a 8ohm in my combo and run it all at 8ohm.

 

cheers

[Totengott]

thats a safe match, its only really unsafe when you go below the amps impedance

[thinkpad20]

It's always best to match, but generally all is well as long as the speakers are rated equal to or greater than the impedance of the amp. You're unlikely to blow anything up if you go the other way around, but there's a comparatively much higher capacity to {censored} something up.

[chisa]

It's always best to match, but generally all is well as long as the speakers are rated equal to or greater than the impedance of the amp. You're unlikely to blow anything up if you go the other way around, but there's a comparatively much higher capacity to {censored} something up.

 

 

what about putting an 8ohm in the combo. i was thinking of getting a celestion v30 anyhow,

 

BTW the amp has a 8/16ohm switch on the back.

[GCDEF]

 

thats a safe match, its only really unsafe when you go below the amps impedance

 

 

How many times do people have to keep getting this wrong. Sheesh.

 

http://acapella.harmony-central.com/forums/showthread.php?t=1968612&highlight=ohms

 

Also, 8 and 16 ohms together = 5.33 ohms which is below the amp's minimum impedance, so even if what you said was correct, it wouldn't be safe.

[Totengott]

How many times do people have to keep getting this wrong. Sheesh. http://acapella.harmony-central.com/forums/showthread.php?t=1968612&highlight=ohms Also, 8 and 16 ohms together = 5.33 ohms which is below the amp's minimum impedance, so even if what you said was correct, it wouldn't be safe.

 

 

oh, i missed the whole part about his 16 ohm speaker in the 401....duh

[GCDEF]

oh, i missed the whole part about his 16 ohm speaker in the 401....duh

 

 

The whole as long as you don't go below the minimum impedance you're safe thing applies to solid state amps. Tube amps don't work that way.

[chisa]

oh, i missed the whole part about his 16 ohm speaker in the 401....duh

 

 

but an 8ohm in the 401 will allow me to run cab and combo at the same time at 8ohms?

[Totengott]

but an 8ohm in the 401 will allow me to run cab and combo at the same time at 8ohms?

 

 

no, a 16 ohm cab will allow you to run both at the same time at 8 ohms

[chisa]

no, a 16 ohm cab will allow you to run both at the same time at 8 ohms

i am lost.

the cab i have is 8ohm - i cannot change that. the amp has 2 speaker outs which can be set at either 8 or 16ohms. if i use the combo as a head and run out at 8ohms into the cab (what i currently do) i cannot use the combo speaker. but surely if i change the speaker to 8 ohms and then have 2 seperate 8ohms outs 1 to cab 1 to combo speaker i can use all speakers?

[Totengott]

if you buy an 8 ohm speaker to go in the 401 that will equal a 4 ohm load if im not mistaken, think of it like this 2 16 ohm loads will equal 8 ohms and 2 8 ohm loads will equal a 4 ohm load...

[rrrajo]

How many times do people have to keep getting this wrong. Sheesh. http://acapella.harmony-central.com/forums/showthread.php?t=1968612&highlight=ohms Also, 8 and 16 ohms together = 5.33 ohms which is below the amp's minimum impedance, so even if what you said was correct, it wouldn't be safe.

 

 

 

I believe this will come up time and time again. No use in fighting it.

[chisa]

if you buy an 8 ohm speaker to go in the 401 that will equal a 4 ohm load if im not mistaken, think of it like this 2 16 ohm loads will equal 8 ohms and 2 8 ohm loads will equal a 4 ohm load...

 

 

even out of different speaker outs? with 8ohm dedicated to each jack? i know wiring in parallel divides the impedance and series multiplies it - but that is not my real question. coming out of the amp is 2 outs so does this mean each out is treated separately and not as series/parallel?

[Totengott]

even out of different speaker outs? with 8ohm dedicated to each jack? i know wiring in parallel divides the impedance and series multiplies it - but that is not my real question. coming out of the amp is 2 outs so does this mean each out is treated separately and not as series/parallel?

 

 

nope,..you use to speaker loads you get the sum of both of them doesnt matter if you have 2 outputs, you use 2 8ohm speaker loads you get a 4ohm load overall, and dats baaaaad for da 8 ohm marshall

[Angry Grimace]

You need a 16 ohm speaker in your extension cab.

[Totengott]

You need a 16 ohm speaker in your extension cab.

 

 

well...he is kinda in a suck ass position, im sure he wants to use his cab more than the internal speaker,..

[chisa]

You need a 16 ohm speaker in your extension cab.

 

{censored}:mad:

 

yeah just thinking about this.

 

will have to run it without the combo's speaker as that would be 5.3ohms with 3x16ohm speakers.

 

interesting the cab can be set for stereo at 16ohms, but this is raising more problems than it is solving.

 

thanks anyhow guys:thu:

 

btw the speakers in the cab are 16ohms, but there are 2 of them

[petejt]

Is it ok to connect an 8ohm output to a 16ohm speaker?

[Totengott]

Is it ok to connect an 8ohm output to a 16ohm speaker?

 

 

yes

[GCDEF]

yes

 

Maybe You just can't make blanket statements about tube amps like that. Read the other thread I linked to earlier for a spirited discussion of why not.

[axepilot]

Is it ok to connect an 8ohm output to a 16ohm speaker?

 

 

 

Most modern amps can deal with a 2:1 impedance mismatch either way, but matching is always the safe way to go.

 

That said, you should be OK with 8 going to 16.

[JohnH]

I have your exact amp, the DSL401, and I also have an 8Ohm 4x12cab. I believe it is best to get a close match on impedances with valve amps and speakers. When you plug two speakers into the amp, they are both connected together in parallel. It is intended that you use a 16 ohm internal speaker and a 16Ohm cab, which combine to give 8Ohms, and you set the amp to 8 Ohms.

If you use a 16 and an 8, apart from getting a non-matched impedance which stresses the transformer, most of the sound will come from the 8 Ohm cab

In my case, I took out two drivers from my valvestate 812 4x12, making it a detuned 16Ohm cab with huge low end. Sounds absolutely great with a 16Ohm V30 in the open-backed combo. I blanked off the spare cab holes with plywood panels to avoid bass being cancelled.

For you, I can see four solutions to use your cab:

1. Change your two 16Ohm cab speakers for two 8ohm speakers, wire them in series to give 16Ohms, and use that with the internal 16Ohm speaker and the amp set to 8 Ohms. While you are about it, you might change the stock internal speaker to something better, such as one of the 16Ohm ones just taken from the cab, or a V30

2. Take one cab speaker out and blank off the hole. You now have a 16Ohm 1x12 cab. Combine with internal speaker and set at 8 Ohm.

3. Just use the cab without the internal speaker

4. This ones a cheat, but it just about works. Add a high power resistor of 3.3Ohms in series with the 8Ohm cab, making it 11.3 ohms. The combination with the internal speaker is now 6.6Ohms, which is close enough to use the 8Ohm setting, plus, it equalises the power output between cab and combo speaker. I've done this, and it works but I much prefer my current set up.

good luck

John

[HKSblade1]

John 1,2 and 3 are good. Suggest no 4??

hmm not sure if the DSL401 ( easy bake oven )
will like it. Those EL84's are da hottttz

[JohnH]

John 1,2 and 3 are good. Suggest no 4?? hmm not sure if the DSL401 ( easy bake oven ) will like it. Those EL84's are da hottttz

I have tried idea 4, it does work and sounds good but I admit I was slightly uneasy about it. But at 6.6Ohms total load on th eamp, it is within 20% of the 8 Ohm setting, and I dont believe anything in enigineering is that critical, particularly when others talk of ratios of 2 being a safe mis-match.

John

[tlbonehead]

I'll work..... unless it blows your tranny. That's about as safe of a statement as you can make. You have a better chance of damaging it if you are mismatching...... in either direction.