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Discussion in 'Amp Central Station' started by Straydogger, Jan 29, 2019.
Here we go...
With a tube amp, you are safer running a lower load on the amp than a higher load. Running a higher load can cause "flyback" issues. There is so much misinformation about this on the forums, people are confusing SS and tube amps.
This has been hashed and re-hashed a hundred thousand times on TDPRI. Listen to @Wally - but since that's just my opinion, YMMV. But Wally is right. In my opinion.
Also - personally, I'd just seek some 8 ohm speakers to make the correct match for the amp to sound best.
I did that for years with a SF Bassman ... now the amp is in the shop for the third time this quarter. Did that mismatch hurt the amp? I don't know, but it didn't help the amp, that's for sure. The sound didn't suffer, but I suspect the amp did in the long run.
Since a tube amp is at its safest and most efficient when working with matched loads, that is the way I run an amp. I have never burned down an OT, and I don’t burn down power tubes. My amps always have good bandwidth production.
I have replaced quite a few OT’s.
Start a various, what is the problem with that amp and what is the power output? I have a friend who bought a SF Deluxe Reverb with a JBL in it a couple of years ago and dropped by to show it off. He thought it sounded great. It sounded noting like a BF/SF Reverb amp should. I ran it through other speakers....same trashy sonics. Then he told me that another friend, who is a very experienced tech, had measured the output at 15 watts. I asked the amp owner of that tech had suggested a new OT. Nope.....just run it like it is. It wasn’t worth turning on. I told him that the OT was shot and needed to be replaced. I don’t know what he did with it, but I didn’t want to hear a guitar played through it. No lows, harsh highs...bad, sour harmonics...just trash.
But. As Winwood sang.....
To the folks suggesting that mismatches on the high side are harmless....stop handing out advice.
I'm bringing it to Lubbock with me as soon as I get a week off.
Perhaps it should be said that this is a complex matter. What is "safe" depends on lots of variables. Even impedance in itself is not as simple as one number. It varies with frequency, for one. The impedance rating is more like an estimate, based around transformer specs and the output stage configuration and what could be seen as an average, close-as-possible to optimal load.
Ohm's law enters the equation if you want to know what happens in terms of voltage and current.
It's a fact that many amp companies consider 100% up and 50% down to be within safe limits. Some, like Dr Z, consider a higher speaker load to be safer than the opposite.
We might be uncertain about some variables. Like what can the transformer in a particular amp, like the Twin in question, take? And would anyone in their right mind run a 135W Twin at output levels where harm would actually be done?
Some people run mismatched loads for years, others report smoking transformers within five minutes.
As these questions are not easily answered, and the amp maker recommends a particular speaker impedance for a reason, the only reasonable advice is:
Don't do it.
You nailed it, Walley thats what the links I posted as well stated !
That's exactly my conclusion! Thanks to all for the knowledge and advice.
Hah! I'm no young strong person (anymore). I'm 67 and don't worry...I don't lug it around. It's a man cave amp. It's on wheels if I want to move it around there. Thanks for the reply.
That is what dollies are for, right? I found a couple of light, collapsible rigs at estate/garage sales tha5 will haul such an amp. It makes life easier.
68 in two weeks...