Patricide and his MAG

Doctor J

Saw this on FS and just wanted to answer your question

Patricide wrote:

Ive got an ashdown mag 300 h that says minimum inpedance 8 ohms, its 300 watts, what i need to figure out is will it drive both my 2 x 10 (ashdown mag 200 deep cab, 8 ohms) and the avatar, jesus this cab situation is so confsing.

Any idea if itl work?

It will, but not in a good way. By adding another cab to your setup you can only either halve or double your impedance, so your cabs combined would provide either 4 or 16 ohms of resistance. 4 will be louder but there's a very good chance your amp will overheat and burn out, 16 ohms means your amp will only put out about 240W tops to both cabs in total, given that the resistance to the signal it is trying to send out will have increased.

You really either need two 4 ohm or two 16 ohm cabs for that head.

Patricide

Doctor j once again you are my saviour, A sticky on oghms and resistance is long needed i say.A lot of people i know are still confused greatly by it.

Doctor J

****e, Paladin actually mailed me a good doc on this stuff... haven't checked my gmail in yonks.

Here it is, I'll add it to the resources thread too.

Patricide

just had a quick flick through it there, Thanks again doc, the amount of times youve steared me clear of instument related stuff.Thanks dude.

Doctor J

No problem. I try to help where Fey doesn't

feylya

Moi? Help? Ah, that's a good one Doc!

Karl Hungus

Doctor J wrote:

No problem. I try to help where Fey doesn't

Help where Fey doesn't? That's a lot of helping you got to do so.

Parsley

I've got an Ashdown MAG300 300watt Combo with a 15" speaker. The manual says the amp's min load is 4 ohms. I'm fairly sure the speaker is 8 ohms. If I want to add another speaker in parallel, it should be an 8 ohm speaker cab to get, right?

Doctor J

Yep. Actually an 8ohm speaker output does sound a little unusual.

According to the ashdown website the minimum rating is 4ohms

Speaker Outputs Minimum impedance 4 Ohms

So Patricide you shold be able to run that 15 with your 2x10 safely and get the full 300W out of your amp.

Patricide

Really, score. dunno if i have the cash anymore though, still i shall look into it.

Parsley

Doctor J wrote:

Yep. Actually an 8ohm speaker output does sound a little unusual.

According to the ashdown website the minimum rating is 4ohms



So Patricide you shold be able to run that 15 with your 2x10 safely and get the full 300W out of your amp.

I'm confused, as is always the case when it comes to impedences. If the amp says the minimum load is 4Ohms, and there's a 4Ohm cab attached (as is the case in my combo, I was mislead about the 8Ohm cab thing) then you can't attach another cab in parallel?

What would I have to do to get the full 307 watts out of my amp?

Doctor J

If your minimum output resistance is 4 ohms it means it'll be running at full output capaicty with a 4 ohm cab attached. That's as much as the amp is designed to deal with. It means the amp needs at least 4 ohms of resistance to the signal it is trying to put out. If you add a lower resistance to the speaker output, the amp will send out more signal, probably overheat and burn out. If you add a higher resistance the amp will not put out it's full capacity, the resistance to it's signal being greater, but it should operate safely.

Combos are generally designed with matching impedances, they're a self contained package. You can use other cabs, generally, but you'll need to stop using the onboard speaker to do so. Your amp is already running at full output.

Parsley

Doctor J wrote:

If your minimum output resistance is 4 ohms it means it'll be running at full output capaicty with a 4 ohm cab attached. That's as much as the amp is designed to deal with. It means the amp needs at least 4 ohms of resistance to the signal it is trying to put out. If you add a lower resistance to the speaker output, the amp will send out more signal, probably overheat and burn out. If you add a higher resistance the amp will not put out it's full capacity, the resistance to it's signal being greater, but it should operate safely.

Combos are generally designed with matching impedances, they're a self contained package. You can use other cabs, generally, but you'll need to stop using the onboard speaker to do so. Your amp is already running at full output.

Well thanks for that. I heard somewhere (probably TalkBass) that Ashdown combos didn't run at the full 300 watts unless you had another extension cab...

Then why the hell does the combo have an extra speaker out???

Doctor J

Are you sure your speaker is 4 ohms?

Edit -> http://www.ashdownmusic.co.uk/contact/index.asp

Never be scared to ask the people who made your gear exactly what the specs are.

If you have an 8ohm speaker, you can safely hook up another 8ohm speaker to the speakon connecter on the back of the amp (assuming the onboard speaker is using the 1/4" out put. If your onboard speaker is 4ohms you need to not use the onboard speaker if you're adding a cab. First though, you need to know what your amp consists of. Ask the manufacturer ;D