How much damage could i do....

dsazz · Post by **dsazz** » Thu Feb 15, 2007 1:06 am

if i run my Rockerverb 50H through an 8 ohm cabinet using the 16 ohm output on my amp ?

aurian4parker · Post by **aurian4parker** » Thu Feb 15, 2007 1:43 am

idk. but that stratocaster is probably one of the nicest ive ever seen(to the left)

LeonC · Post by **LeonC** » Thu Feb 15, 2007 1:44 am

Probably none. Probably. The rule of thumb I've been told is doubling or halving the impedence is not usually going to harm an amp. So using a 4 ohm cab in a 16 ohm slot, for example would be a very bad idea.

retrotone · Post by **retrotone** » Thu Feb 15, 2007 2:15 am

yeah just never go down (16 ohm head into a 8 ohm cab) that would kill your amp pretty quick..;.

by the way leon I have a V-2 the head version of your Vt-40... have you checked out Jeff beck live on the bbc playing your amp with what looks to be a champ and only a wah and an overdriver on the floor? it's very cool stuff

a.hun · Post by **a.hun** » Thu Feb 15, 2007 3:20 pm

http://aga.rru.com/FAQs/general.html#imp-1

Phate · Post by **Phate** » Thu Feb 15, 2007 4:05 pm

You shouldn't do it. Although I think tube amps in this case are not too sensitive compared with solidstate amps.

Match the impedances and you're be good.

TheOrangeJuicer · Post by **TheOrangeJuicer** » Thu Feb 15, 2007 4:18 pm

You shouldn't do it. It probably won't hurt anything on that amp as long as it wasn't cranked and you didn't use it but for an hour or so. It is never a good idea to mismatch the impedances. Plug it into one of the 8 ohm tap sockets next time.

Simon Wicks · Post by **Simon Wicks** » Thu Feb 15, 2007 4:52 pm

Its generally ok to run low amp imdedances into high speaker loads, not the other way around. Think of it like this: You can drive a small train through a large tunnel but you cant drive a large train through a small tunnel without disaster. Dont risk it.

Phate, tube amps are extremely sensitive to loads. Changing from 8 to 16 ohms can affect the tone of the amp. Solid state doest care too much so long as a load is present.

a.hun · Post by **a.hun** » Thu Feb 15, 2007 7:00 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Simon Wicks
 Its generally ok to run low amp imdedances into high speaker loads, not the other way around. Think of it like this: You can drive a small train through a large tunnel but you cant drive a large train through a small tunnel without disaster. Dont risk it.

Phate, tube amps are extremely sensitive to loads. Changing from 8 to 16 ohms can affect the tone of the amp. Solid state doest care too much so long as a load is present.
<hr height="1" noshade id="quote"></blockquote id="quote">
-1

(For valve amps it is the other way around...)
+1 For s.s. amps though. Just keep 'em above their rated minimum 'Z' load.
http://aga.rru.com/FAQs/general.html#imp-1

LeonC · Post by **LeonC** » Thu Feb 15, 2007 7:04 pm

[ot]Hey Retrotone - yes - I've had V2s!! They are killer amps indeed. Love that Ampeg "grunt". Yes, someone posted that BBC clip over on the Gear Page a couple years ago. I was totally amazed to see JB playing through a VT-40!![/ot]

Simon Wicks · Post by **Simon Wicks** » Thu Feb 15, 2007 10:22 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by a.hun
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Simon Wicks
 Its generally ok to run low amp imdedances into high speaker loads, not the other way around. Think of it like this: You can drive a small train through a large tunnel but you cant drive a large train through a small tunnel without disaster. Dont risk it.

Phate, tube amps are extremely sensitive to loads. Changing from 8 to 16 ohms can affect the tone of the amp. Solid state doest care too much so long as a load is present.
<hr height="1" noshade id="quote"></blockquote id="quote">
-1

(For valve amps it is the other way around...)
+1 For s.s. amps though. Just keep 'em above their rated minimum 'Z' load.
http://aga.rru.com/FAQs/general.html#imp-1

<hr height="1" noshade id="quote"></blockquote id="quote">
So explain to me why i can run my little solid state amp into practically anything from 2 ohms to 32 without so much as heating the amp up while i burnt out the bias supply in my OR120 running a 16 ohm amp into a 4 ohm cabinet. What you say flies in the face of what i have been taught by many esteemed techs and engineers.

You need at least the same or higher impedance on the secondary side otherwise the tubes dissipate way too much heat. Solid state amps run at such low voltages they dont care what load they see. Lord Valve is of course right that you shouldnt really mismatch your impedances but i think he's being a little conservative for the sake of not having newbies e-mailing him complaining the advice on his site has killed an amp.

A mismatch either way is usually ok so long as you dont go too far. Some amps actually sound better for it! But in general, dont mismatch impedances

a.hun · Post by **a.hun** » Fri Feb 16, 2007 12:15 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Simon Wicks
 [quote]Originally posted by a.hun
 So explain to me why i can run my little solid state amp into practically anything from 2 ohms to 32 without so much as heating the amp up while i burnt out the bias supply in my OR120 running a 16 ohm amp into a 4 ohm cabinet.

A mismatch either way is usually ok so long as you dont go too far. Some amps actually sound better for it! But in general, dont mismatch impedances

<hr height="1" noshade id="quote"></blockquote id="quote">Sure, I'll explain. What you say about your own amps makes good sense to me because valve amps and solid state amps work differently. Your OR120 is a valve amp. Valve amps have output transformers, but ss. amps usually have output transistors instead. The two different types of amp aren't the same at all and some people who just use modern solid state amps still think they are. This tricks many people.

Into a higher Z speaker (I call impedance 'Z', okay?) ss. amps put out less power. This is safe for them because less current means less heating up of the output transistors. Into too low a Z they will try to put out too much current and the output transistors can just burn out - so you need to stay at or above the amps minimum Z rating. And if 2 ohms is okay for a ss amp then so is 32, or 20,000 or even more. You won't get much sound going into 20,000 ohms but the amp is still very safe.

Oh I don't know about your tunnels and trains - sorry. Electrons don't work like trains. I think about solid state amps differently, more like this:

A big ohmage like 20,000 ohms is a high Z load, yes, but it is not a 'hard load' for a solid state amp. It is a very easy load and the amp does less work, it makes less power and it gets less hot. If you take the speaker away you have very high impedance and NO load at all, so no power at all, yes?

Other way round, if you run below a ss. amps 2 ohms (or whatever it is for that amp) safe low Z limit you give it too difficult or hard a load - it tries to supply more current and power than it can safely and it overheats and burns out. Low Z loads are more difficult for ss amps to drive than high Z loads. Electrons aren't like trains. Maybe that helps with remembering?

Valve amps don't work the same way at all anyway. The output transformer matches the high Z power valves (Kohms range) to much lower Z speaker loads (ohms range). That is its job. You want to match the amp and the load right, or at least be close. Usually (as in mostly, not always) going from an 'X ohm' output into a speaker between '1/2X' and '2X' is okay. But 1/4X which you did isn't and so you had a problem with your Orange. It isn't designed to handle that. 4X would have been a problem too though, and probably a worse one. It might have damaged the output transformer instead of something which was cheaper to replace. With valve amps whichever way you go, either too high or too low Z, you will always get less power output from the amp then at the correct Z. (Not like ss amps at all which give less power in one direction and more power in the other.) So the problem with valve amps if going out of the safe range of Z is not burn out because the amp tries to make too much power. And with valve amps the problems of going into too high and low Z are also different from each other.

I think that a slight mismatch either way is usually alright for a valve amp, but best not to. Some amps seem to have less problems than other amps but best to stay close to the right Z with valve amps. If you go too far either way then things can easily burn out on any valve amp.

Did this help? That 'Alt Guitar amps' site FAQ is very good and I agree with what they say about what happens and why if you do not match Z properly. I find it hard to explain much better than they do.

dsazz I think that if you do what you asked about (run 16 ohm amp into 8 ohm speaker, so 1/2 X) your amp will probably be okay, but you will wear out your valves faster and other problems may happen. Why not use the 8 ohm output of the amp instead? I would.

Simon Wicks · Post by **Simon Wicks** » Fri Feb 16, 2007 12:28 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by a.hun
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Simon Wicks
 [quote]Originally posted by a.hun
 So explain to me why i can run my little solid state amp into practically anything from 2 ohms to 32 without so much as heating the amp up while i burnt out the bias supply in my OR120 running a 16 ohm amp into a 4 ohm cabinet.

A mismatch either way is usually ok so long as you dont go too far. Some amps actually sound better for it! But in general, dont mismatch impedances

<hr height="1" noshade id="quote"></blockquote id="quote">Sure, I'll explain. What you say about your own amps makes good sense to me because valve amps and solid state amps work differently. Your OR120 is a valve amp. Valve amps have output transformers, but ss. amps usually have output transistors instead. The two different types of amp aren't the same at all and some people who just use modern solid state amps still think they are. This tricks many people.

Into a higher Z speaker (I call impedance 'Z', okay?) ss. amps put out less power. This is safe for them because less current means less heating up of the output transistors. Into too low a Z they will try to put out too much current and the output transistors can just burn out - so you need to stay at or above the amps minimum Z rating. And if 2 ohms is okay for a ss amp then so is 32, or 20,000 or even more. You won't get much sound going into 20,000 ohms but the amp is still very safe.

Oh I don't know about your tunnels and trains - sorry. Electrons don't work like trains. I think about solid state amps differently, more like this:

A big ohmage like 20,000 ohms is a high Z load, yes, but it is not a 'hard load' for a solid state amp. It is a very easy load and the amp does less work, it makes less power and it gets less hot. If you take the speaker away you have very high impedance and NO load at all, so no power at all, yes?

Other way round, if you run below a ss. amps 2 ohms (or whatever it is for that amp) safe low Z limit you give it too difficult or hard a load - it tries to supply more current and power than it can safely and it overheats and burns out. Low Z loads are more difficult for ss amps to drive than high Z loads. Electrons aren't like trains. Maybe that helps with remembering?

Valve amps don't work the same way at all anyway. The output transformer matches the high Z power valves (Kohms range) to much lower Z speaker loads (ohms range). That is its job. You want to match the amp and the load right, or at least be close. Usually (as in mostly, not always) going from an 'X ohm' output into a speaker between '1/2X' and '2X' is okay. But 1/4X which you did isn't and so you had a problem with your Orange. It isn't designed to handle that. 4X would have been a problem too though, and probably a worse one. It might have damaged the output transformer instead of something which was cheaper to replace. With valve amps whichever way you go, either too high or too low Z, you will always get less power output from the amp then at the correct Z. (Not like ss amps at all which give less power in one direction and more power in the other.) So the problem with valve amps if going out of the safe range of Z is not burn out because the amp tries to make too much power. And with valve amps the problems of going into too high and low Z are also different from each other.

I think that a slight mismatch either way is usually alright for a valve amp, but best not to. Some amps seem to have less problems than other amps but best to stay close to the right Z with valve amps. If you go too far either way then things can easily burn out on any valve amp.

Did this help? That 'Alt Guitar amps' site FAQ is very good and I agree with what they say about what happens and why if you do not match Z properly. I find it hard to explain much better than they do.

dsazz I think that if you do what you asked about (run 16 ohm amp into 8 ohm speaker, so 1/2 X) your amp will probably be okay, but you will wear out your valves faster and other problems may happen. Why not use the 8 ohm output of the amp instead? I would.

<hr height="1" noshade id="quote"></blockquote id="quote">
In my last post i was being a little sarcastic. I have built a few valve amps myself and know a bit. Thats some interesting stuff you posted though. I didnt know the bit about solid state amps. I had always assumed it didnt really matter because the output from the power circuit was such low voltage.

I'd still disagree on a few point regard valve amp imdeance matching based on my own experience and that of others but the bottom line is to match your speakers up properly!

A mate of mine plays in a band and the lead singer uses a Selmer Treble and Bass. She has blown the tranny on it three times because she pluggs into any old speaker cab then wonders why smoke starts out of her amp

It always happens whe the amp is set higher than the speker cab impedance. There is never any problem the other way around.

a.hun · Post by **a.hun** » Fri Feb 16, 2007 1:44 pm

Sorry to miss the sarchasm. I intend no offense, just to help if possible.

Selmer T+B amps are quite good. They can run Z of 8 and 16 ohms (I think), so should be able to handle 4 - 32 ohms if working okay. But all amps are different, and you won't find many cabs higher than 16 ohms Z anyway.

If she keeps blowing transformers she should plug into the right Z. And maybe check the bias supply and valves too? Maybe there is another problem too?

Yes match properly. That is always best!

screamingdaisy · Post by **screamingdaisy** » Fri Feb 16, 2007 11:51 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dsazz
 if i run my Rockerverb 50H through an 8 ohm cabinet using the 16 ohm output on my amp ?
<hr height="1" noshade id="quote"></blockquote id="quote">

You might damage the output transformer.

How much damage could i do....

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