No
You are fine. Your amp matches your attenuator. Period.
You can use your cab (it will be 8ohms - pair of 16s in parallel. No one has 32 ohm guitar cabs!) out of your current Hotplate without issue.
THD attenuators and Vintage Cabs
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You are fine. Your amp matches your attenuator. Period.
You can use your cab (it will be 8ohms - pair of 16s in parallel. No one has 32 ohm guitar cabs!) out of your current Hotplate without issue.
Douglas Cram
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I've used THD Hotplates for decades on my JMP and JCM Marshalls, as designed and impedance matched - no issues. I have also used the Weber Mass attenuator, which is nice because it has selectable ohm settings. Be aware that just about any attenuator will add some coloration of its own (in my opinion) . I've even tried a chjeap Behringer attenuator and it never hurt anything. I've heard good things about the Rivera Rock Crusher, but at $650, a bit steep in price. I've been pretty happy with the Weber unit mainly because of it's flexibility, and you can get a 100 watt Mass used for about $150 - $200. Nothing wrong with the THD units either. https://musicgoround.com/locations/...Mtwrx9r7CGj6b_NSZw0QwJxekV-bv2qUaAuB8EALw_wcB
JohnH
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My thoughts on the safety of using attenuators:
The whole point is that you'll be turning up the amp, to get to a level where they sound best. That's usually not at max. Amp will be working harder but shouldn't go red-plate except if it's designed or set-up in such a way that it really shouldn't be set that high. Some amps need to be set cooler, or not pushed there. It's more about the amp having issues when running hard, than about problems in a good attenuator.
But I'm totally OCD about attenuator design and read as much as I can about it. I believe the attenuators impedance curve can in some cases contribute to stress on the amp and it certainly affects the tone. But, in terms just of amp stress, a simple resistive design of the right consistent matching value, that stays at that value as you adjust it, should be fine for the amp. Creating a reactive attenuator to get far better tone, should provide a curve that either matches a real speaker, or stays somewhere close to it or at least for safety, stays somewhere between a real cab and resistive of the right value.
But some attenuators deviate, and although I'm not the one to comment on significance of such deviations, I still worry about such issues, and avoid them in my designs:
1. There are resistive designs that wander far away from the nominal ohms, depending how you set them.
2. Many add treble compensation to replace the highs, using a bleed capacitor. This tends to bring the impedance seen by the amp way down low at these frequencies.
3. Some reactive designs have a bath-tub curve that gets very high at all low frequencies, rather than a localised peak. There may be powerful percussive thumps in a guitar signal down there, even below string frequencies.
The whole point is that you'll be turning up the amp, to get to a level where they sound best. That's usually not at max. Amp will be working harder but shouldn't go red-plate except if it's designed or set-up in such a way that it really shouldn't be set that high. Some amps need to be set cooler, or not pushed there. It's more about the amp having issues when running hard, than about problems in a good attenuator.
But I'm totally OCD about attenuator design and read as much as I can about it. I believe the attenuators impedance curve can in some cases contribute to stress on the amp and it certainly affects the tone. But, in terms just of amp stress, a simple resistive design of the right consistent matching value, that stays at that value as you adjust it, should be fine for the amp. Creating a reactive attenuator to get far better tone, should provide a curve that either matches a real speaker, or stays somewhere close to it or at least for safety, stays somewhere between a real cab and resistive of the right value.
But some attenuators deviate, and although I'm not the one to comment on significance of such deviations, I still worry about such issues, and avoid them in my designs:
1. There are resistive designs that wander far away from the nominal ohms, depending how you set them.
2. Many add treble compensation to replace the highs, using a bleed capacitor. This tends to bring the impedance seen by the amp way down low at these frequencies.
3. Some reactive designs have a bath-tub curve that gets very high at all low frequencies, rather than a localised peak. There may be powerful percussive thumps in a guitar signal down there, even below string frequencies.
Okay....many thanks thus far for everyone input (excuse the pun!!) - very informative and useful.
I've checked my speakers and they are 16 Ohm running in parallel which should give me circa 8 Ohms. As @PelliX kindly pointed out this should be circa 8 Ohms. Checked and I'm hitting 7.3 Ohm from the can jack so = 8 Ohms load. JMP switch on back of head is set to 8 Ohm on the back and I have both a 16 Ohm and 8 Ohm Hotplate....so I'll be using the 8 Ohm hotplate so full end to end Ohm is the same.
Again, many, many thanks to everyone who has commented. A wealth of knowledge on this forum and really appreciate the input.
Interestingly I read from THD that you can also use the 16 Ohm Hotplate into an 8 Ohm load but, as I have both, ill save the 16 Ohm for my 4x12 ;-)
I've checked my speakers and they are 16 Ohm running in parallel which should give me circa 8 Ohms. As @PelliX kindly pointed out this should be circa 8 Ohms. Checked and I'm hitting 7.3 Ohm from the can jack so = 8 Ohms load. JMP switch on back of head is set to 8 Ohm on the back and I have both a 16 Ohm and 8 Ohm Hotplate....so I'll be using the 8 Ohm hotplate so full end to end Ohm is the same.
Again, many, many thanks to everyone who has commented. A wealth of knowledge on this forum and really appreciate the input.
Interestingly I read from THD that you can also use the 16 Ohm Hotplate into an 8 Ohm load but, as I have both, ill save the 16 Ohm for my 4x12 ;-)
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