Your explanation is seriously lacking. You are talking only about the secondary side. The problem occurs on the primary side as I explained it. When you use a higher impedance speaker on the secondary side, the current flow through the speaker drops. However, the current flow on the primary side of the transformer increases. If you disconnect the speaker entirely, the current flow on the primary side of the OT will increase to the point that it WILL destroy the OT pretty quickly and take the output tubes with it. However, if the speaker is shorted, the current flow on the primary side will decrease. OTs and power tubes have a much greater chance of survival if the speaker is shorted than if it is open. Tubes are voltage sources. Speakers are current sinks. The OT converts the high voltage/low current on the primary side to a low voltage/high current on the speaker side. Increase the current on the speaker side and the tube side current decreases. Decrease the current on the speaker side and the tube side current increases. That is basic tube amp design.

_________________
Bill

- quote Audio-output transformer-coupled amplifiers should not be operated without a load connected because the inductance of the transformer's primary can cause the plate voltage to reach a sufficiently high voltage to break down insulating materials, resulting in amplifier failure and even fire. -quote

As for the amp/speaker being run this way for several months, it's hard to tell what damage may have been done. Only the designer of the amp who considered the possible problems can answer that.

If you have no problems now, consider yourself lucky.
If it were me, I'd have a matched impedance with the amp and speaker.

_________________
-T

"You can't spend what you ain't got, you can't lose what you ain't never had" ~ McKinley Morganfield

Guess I better go change the 4 ohm OT in my Champion 600 to an 8 ohm one to match my external speaker. Its only been working this way for about 5 months now. Funny how no one jumped all over me when I posted about it here.



viewtopic.php?f=13&t=63259

_________________
Bill

I agree with Arjay here. It's not the 2:1 amp/speaker mismatch as much as the quality of the transformer. I trust nothing in the whole HRD series. The old components were hardy beasts. Not just the trannies, but the caps, resistors, tubes and everything else, including the cheesy ribbon connectors. With the mismatch your tone will suffer period. That alone is the reason I personally wouldn't do it. It's the OP's amp, he can do what he wants with it. I always match the load with the tranny. Why make things work harder than they need to?

_________________
Life...... It's sexually transmitted and always fatal

Ok. Well, I'm just trying to get to a technical reason why people feel that modern OTs are inferior than vintage ones. Instead it seems I am just getting personal bias against modern amps and their components in general and bias against Hot Rod amps in particular. Guess its just time to give up.

As far as an amp sounding worse with a mismatched speaker, I will say it again: My 4 ohm Champion 600 sounds better and plays louder with a 12", 8 ohm Celestion than it does with a 12", 4 ohm Eminence. I have no intention of changing it.

_________________
Bill

Bill, no offense meant. My HRDlx was a POS that spent a lot of time in the shop under factory warranty, so I do have a serious bias there. The newer transformers do seem quite a bit smaller and cheaply made. I just look at it as thing are spec'd for a reason. I for one never liked the tone of a 16 ohm speaker run in a 8 ohm amp, but that's purely a personal opinion. I've played around with it a bit with my 5 watt amp that I built. I wound up getting a Weber Z-Matcher because all my extension cabs are 16 ohm and I don't always want or need to bring two 16 ohm cabs out on small gigs. I don't like the way my 76 Champ sounds with an 8 ohm speaker but when I bring it back to where it should be with the Z Matcher, I think it sounds great.

I don't like the way the new Fender amps are built, especially the HRD series perion. But again, that's me.

Sorry if I offended you.

_________________
Life...... It's sexually transmitted and always fatal

No offense taken.

I'm just trying to separate personal opinion from technical facts. That's what happens when you are an engineer.

_________________
Bill

Bill you answer two different ways, one way you say more impedance on the secondary side increased the primary side and then your say no impedance on the secondary side increases the primary. Cant have it both ways.

The ratio of turns in the transformer determines the impedance along with load on the secondary side which is reflected to the current flow on the primary side. More impedance reduces the primary current flow and not having enough impedance increases the flow on the primary side causing heat issues. As secondary impedance decreases the current increases causing more power to be consumed by the transformer primary power source. Thats why a transformer can overload without proper impedance on the secondary side, meaning too low or none.

Your using a speaker with impedance higher then the transformer is spec. for is not letting the speaker get needed current as designed for best sound performance . And your not consuming more primary current doing so. Thats the importance to match speakers, get max sound performance as each individual speaker is designed for.

Done with this post, as Ricky say to hard to splain it Lucy

_________________
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.

Thomas Jefferson

Yes, I am done too as I am tired of trying to explain things.

_________________
Bill