I so confused reading this!
Your Hot Rod D is made for a 8ohm speaker and you put a 16ohm in there, right? Increasing the impedance like that is going to make the speaker sound bad because you are restricting the current rate that the amp is capable of. Your actually lowing the current rate through out going with 16ohm. And if you went with a 4ohm you will be increasing the current rate higher then amp is capable of in turn causing things to heat up.

For a 8 ohm designed amp going Higher is to cold (weak) sound bad and lower to hot (burn it)!
or think of it this way Lower impedance cause amp to work to hard and too high requires more then amp capability for good sound!.

Man I fix these things all the time but still have hard time trying to explain

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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

Well when I put it in there I didn't think it would make a difference. I thought it would work the same way as pots like going from a 250k to a 500k pot brightens up the tone kind of thing. I thought of the impedance more as max output rather than impedance. Haha I don't really know. I'll working on switching it out. Do you think I should replace the output transformers before they blow?

How long have you been playing it this way?

If not long, replace the speaker with an 8 ohm and cross fingers.

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-T

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

About 6 months

Do you think I should replace the output transformers before they blow?[/quote]

No, you should use the proper speaker configuration. Replace the speaker with one of the proper impedance before you damage the amp. That's pretty much what everyone's telling you to do. You can find the amp manual on Fender's site.

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

Why would something blow? Having to high impedance is just not getting the speaker the needed current flow to sound correct! Not able to reach potential from lowering current! Now if it was a 4ohm speaker the current would be to high and cause heat problems to the amp drawing more then designed for.

Look at it this way higher impedance causes lower current flow and lower impedance means more current flow. Its important to match the speaker to the amp design for max performance and sound quality. Your amp cant sound good and if you think it does you are sadly mistaking.

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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

Some people are thicker than cement.

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'65 Strat,65 Mustang,65 Jaguar,4 more Strats,3 vintage Vox guitars,5 Vox amps,'69 Bassman with a '68 2-15 Bassman cab,36 guitars total-15asst'd amps total,2 vintage '60s Hammond organs & a myriad of effects-with a few rare vintage ones.

Put a 16ohm speaker in your extension cab and the wire it in parallel with the 16ohm speaker in the HRD. That'll give you 8ohm impedance with two 12" speakers.

http://www.jumbosunshade.com/swd01.htm

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In my opinion Leo Fender had essentially perfected the guitar amplifier by 1964.

Arjay/63supro,

You guys are always saying that Fender OTs can tolerate a 2:1 amp/speaker mismatch, i.e: 8 ohm amp/16 ohm speaker or 8 ohm amp/4 ohm speaker. Now you and everyone else are telling the OP it is a bad thing and he risks damaging his OT. Why the change in opinion? Is it because the OP's amp is is a Hot Rod Deluxe? I know you guys don't like anything from the Hot Rod family because of past experience, but are you now saying that the HRD OT is inferior to other Fender OTs and can't handle the mismatch?

Also, enough with the water and pipe analogies. The OT is an impedance matching device designed to transfer maximum power from the output tubes to the speakers. Ideally, the OT output impedance needs to match the speaker impedance for that to happen.Using a higher ohm speaker than the amp calls for results in less current flowing through the speaker/OT secondary, but more current flowing through the OT primary. Conversely, a lower ohm speaker than the amp calls for results in more current flowing through the speaker/OT secondary and less current flowing through the OT primary. That is why the OT can be quickly wiped out when there is no speaker connected to the amp, but the OT can reasonably be expected to survive a short circuit of the speaker/OT secondary.

For the record, I have been running an 8 ohm cab with my 4 ohm output 5F1 configured Champion 600 for several months now with no ill effects. In fact, the amp sounds better and plays louder with an 8 ohm cab then it did when I tried a 4 ohm speaker in the cab. The OT on the Champion 600 is just a little bitty thing compared to the one on the HRD.

Not trying to start an argument, just trying to understand the change in view.

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Bill

You don't understand how OTs work either.

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Bill

Well I would replace the OTs as well as the speaker. I don't know if I should trust the OT's because I've been running it like this for a while and I don't have a back up amp because I can't afford it.



My amp sounds great at most levels actually, that's why I never thought anything of it. The only problem was that when I turned it up around 6 or 7 for the first time (never needed to/was too loud), it sounded like it was falling apart. That's what raised the red flag.

I unequivocally am.

And the re-issue iron wins no prizes either. Having examined trannies from the DRRI and TRRI then compared them to artifacts from vintage amps I discovered that the contemporary components are approximately ten percent smaller than the original real McCoys and substantially lighter as well. What's been sacrificed? Quite simply, reserve capacity and the ability to tolerate the typical abuse all amps are periodically subjected to. As for the 40-watt OT in the HRD, you need only compare it to a vintage 40-watt tranny from a Pro Reverb, Super Reverb, or Bandmaster. The size differential is dramatic. Welcome to the "Brave New (downsized) World".

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY

That is not necessarily indicative of a failing/damaged OT. More information needs to be provided before any conclusion can be reached.

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Bill

Hi, Arjay.

Thanks for responding.

While I don't necessarily disagree with what you are saying, I don't necessarily agree either.

I think a lot misplaced "mojo" gets applied to certain vintage amps compared to modern equipment. I will admit that I would prefer a hand wired turret/eyelet board or point-to-point wired amp over most PCB based amp any day of the week. But that is not we are talking about. I do believe that modern design and manufacturing techniques have allowed companies to design and build components in a much more efficient and cost effective manner compared to 50 years ago. This has resulted in components that are smaller and lighter then their forebears, but every bit as good in quality. Let's not forget that Leo Fender built his amps using components purchased in bulk from the lowest bidder, just as today's Fender does. Without being able to examine the electrical and magnetic characteristics of a modern OT compared to a vintage OT (or any other component for that matter), I am not willing to arbitrarily declare a modern component to be inferior to a vintage one. Do you have any failure data to back up your contention that an HRD OT is inferior to a vintage OT and more prone to failure? I don't recall any posts from people complaining that their OT failed in their modern amp after using a mismatched speaker.

Given that the OP has apparently used his mismatched speaker for about 6 months with no issues makes me think that no problems will occur. Granted, I don't gig or play professionally like some here, but I do use my amps hard and the 4 ohm OT in my Champion 600 seems to coexist quite nicely with the 8 ohm Celestion in my external cab.

I guess I am more concerned about the misinformation provided here by some posters (not you or 63supro) about why a mismatched OT/speaker might be a bad thing to do.

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Bill

You said the same that I said, He will not burn anything up with the higher impedance but the speaker is not being used to potential. The transformer on the HRD has a 8ohm tap the older Hot Rod Deluxe's had two taps a 4 ohm an 8 ohm.
A fixed output transformer will only deliver max power when the impedance load matches. Thats what impedance matching is. I do know how transformers work. We are talking about Lam Core Transformers where the tap is placed along the winding for impedance adjustment to match the speaker being used. As said some transformers have multiple taps allowing for a user to change the impedance but I do not believe any of the new HRD's have this like the older ones.

They used to teach OHM's Law not sure if they still do.

If you wish to talk about the transformers on the pole outside or on a tower I can do that too since I have installed a whole lot of them in the past

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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