Mesa D-800+ clean power?

[eli]

So I just bought a D-800+ on Reverb, all good there.

Right after I pulled the trigger, I looked at the manual online... and it gives the 400W and 800W power into 4 ohms and 8 ohms respectively at 10%THD!

Kinda feeling like I may have been sold a bill of goods here. Does anyone have any idea what the output power is at a much lower THD (like .5% or .1% like most manufacturers rate amps)?

 

[Wild_Bill_57]

You need to ask @agedhorse if you have specific questions. He actually designed that amp.

 

[agedhorse]

Because of the tube emulation present, much of the distortion harmonics are not generated by the power amp but are generated by the emulation circuitry within the preamp and dynamcs management circuitry.

That said, the power amp by itself (divorced from the signal processing) is a little more than 375 watts RMS into 8 ohms at 1% THD and about 750 watts RMS at 1%THD, and at 1/2-rated power the power amp THD is around 0.01%.

Also, most musical instrument amps (bass & guitar) are rated using between 1% and 20% THD depending on the application. This is because in musical instrument applications, there are a lot of things going on with most preamps regarding the intentional generation of musically related harmonics. Since the preamp is part of the signal path, it's contribution is included it the measurements.

As a couple of examples, The Ampeg SVT uses 5% as the threshold, The Fender Bassman 100T uses 5%, the Darkglass Mictrotubes 900V2 and other models use 20%, GK typically uses 1%, but most manufacturers don't even specify the THD so it's an unknown. In general, amps that are designed to be overdriven and where the overdriven tone is part of the product's performance, the numbers will be higher than for an amp that's intended to be more clean oriented.

I can't think of any MI amps that are specified at .1% or even .5% at rated power.

I hope this clears up your concern and confusion.

 

[eli]

@agedhorse thank you for the explanation! I definitely feel better. Nice to have the actual designer in the group!

 

[4Mal]

@eli FWIW I put miles and miles on a D-800+ never felt the need for more headroom and I like it clean and clear. D-800+ is the sweet spot in the Subway line for me.

 

[Sparky Mark]

This raises an interesting point. Vintage Trace Elliot amplifier owners regularly comment how TE amp watts seem to be more powerful than their other amp manufacturers watts. Indeed, the old TE 150 watt 410 combo (spec below) is incredibly loud even at 90 watts without an extension cab and no other 150 watt rated combo I've tried gets close to being as loud.
However, TE used to rate their power amps output at 0.05% or even lower THD.
So the AH150 probably had a fair amount of additional headroom beyond its "clean" 150 watts.
In my experience, my 250 watt TE heads are the equal of my other 500 watt heads.

 

[agedhorse]

This raises an interesting point. Vintage Trace Elliot amplifier owners regularly comment how TE amp watts seem to be more powerful than their other amp manufacturers watts. Indeed, the old TE 150 watt 410 combo (spec below) is incredibly loud even at 90 watts without an extension cab and no other 150 watt rated combo I've tried gets close to being as loud.
However, TE used to rate their power amps output at 0.05% or even lower THD.
So the AH150 probably had a fair amount of additional headroom beyond its "clean" 150 watts.
In my experience, my 250 watt TE heads are the equal of my other 500 watt heads.
View attachment 5060176

This could be part of the explanation, but the voicing choices and how the power amp behaved under overdriven conditions also plays a big part.

 

[Maxi Funkl]

Correct me if I am wrong @agehorse but most amp are approx. 1/2 full wattage with 1 cab & are approx. full wattage with 2 cabs due to lesser ohm load. unless your single cab is 4 or 2 ohm cab.

 

[Ulf Buck]

The D800+ has glorious loud clean tone but turn up the input gain to make the light flicker and it roars, truly magical

 

[agedhorse]

Correct me if I am wrong @agehorse but most amp are approx. 1/2 full wattage with 1 cab & are approx. full wattage with 2 cabs due to lesser ohm load. unless your single cab is 4 or 2 ohm cab.

Correct, a solid state amp (99.99% do not use an impedance matching transformer), acts as an almost ideal voltage source, so the current (and thus power) is inversely proportional to the load impedance.

 

[MultiScaleMale]

Picked up a TE 15" combo for $100 and it was very loud. Was for a gig where I could just leave it on the truck and didn't have to move anything back and forth. I gave it away because it was easier than moving it. Stupid.

 

[Maxi Funkl]

So I just bought a D-800+ on Reverb, all good there.

Right after I pulled the trigger, I looked at the manual online... and it gives the 400W and 800W power into 4 ohms and 8 ohms respectively at 10%THD!

Kinda feeling like I may have been sold a bill of goods here. Does anyone have any idea what the output power is at a much lower THD (like .5% or .1% like most manufacturers rate amps)?

Honestly you can not go wrong with MESA Enjoy your amp.

 

[Keyser Soze]

…. I gave it away because it was easier than moving it….

You’re a man after my my own heart and, obviously, competing for my “World’s Laziest Man” title.

 

[eli]

... I can't think of any MI amps that are specified at .1% or even .5% at rated power...

I guess I was thinking about PA power amps, most of which show rated power somewhere below 1% THD (Crown rates at .5% and QSC rates at .1%). I suppose I can understand MI amps being rated differently.

 

[juancaminos]

Picked up a TE 15" combo for $100 and it was very loud. Was for a gig where I could just leave it on the truck and didn't have to move anything back and forth. I gave it away because it was easier than moving it. Stupid.

I did something similar with an old Ampeg piggy back. It was way heavy, ugly and terrible sounding so I gave it away!

 

[Geri O]

So I just bought a D-800+ on Reverb, all good there.

Right after I pulled the trigger, I looked at the manual online... and it gives the 400W and 800W power into 4 ohms and 8 ohms respectively at 10%THD!

Kinda feeling like I may have been sold a bill of goods here. Does anyone have any idea what the output power is at a much lower THD (like .5% or .1% like most manufacturers rate amps)?

All the various ways of rating output power of various amps led me to just say, screw the numbers, screw all that, is the amp and speaker in question loud enough for my needs. If it is, I’ll take it. If it ain’t, I won’t.
After you bought the D800+, did you even try the rig to see if it met your needs? Or did that even matter and you didn’t like what you read in the spec sheet?

 

[eli]

All the various ways of rating output power of various amps led me to just say, screw the numbers, screw all that, is the amp and speaker in question loud enough for my needs. If it is, I’ll take it. If it ain’t, I won’t.
After you bought the D800+, did you even try the rig to see if it met your needs? Or did that even matter and you didn’t like what you read in the spec sheet?

Well, see, ya can't try out a rig with the band on a gig before you buy it, now can you? So how do you know if it is or if it ain't loud enough for your needs?

You read what you can about equipment to determine whether it will suit your needs, relative to other equipment you have used before in similar situations. This is why manufacturers publish specs on their stuff, to allow consumers to compare as best they can. So no, I don't "screw all that". It was a non-returnable purchase, so I needed to be reasonably sure in advance that it was gonna do what I needed. (Lucky for me, turns out it will.)

 

[agedhorse]

I guess I was thinking about PA power amps, most of which show rated power somewhere below 1% THD (Crown rates at .5% and QSC rates at .1%). I suppose I can understand MI amps being rated differently.

These products are intended to be used primarily for reproduction and are not used in the creation or generation of additional tonal or textural elements.

This is no different than comparing the frequency response of a pro audio preamp to a guitar or bass amp. Pro audio fundamentally values flat response while guitar/bass amps are voiced (anything but flat).

 

[eli]

These products are intended to be used primarily for reproduction and are not used in the creation or generation of additional tonal or textural elements.

This is no different than comparing the frequency response of a pro audio preamp to a guitar or bass amp. Pro audio fundamentally values flat response while guitar/bass amps are voiced (anything but flat).

Totally understand. Thanks for clarifying.

 

[agedhorse]

Well, see, ya can't try out a rig with the band on a gig before you buy it, now can you? So how do you know if it is or if it ain't loud enough for your needs?

You read what you can about equipment to determine whether it will suit your needs, relative to other equipment you have used before in similar situations. This is why manufacturers publish specs on their stuff, to allow consumers to compare as best they can. So no, I don't "screw all that". It was a non-returnable purchase, so I needed to be reasonably sure in advance that it was gonna do what I needed. (Lucky for me, turns out it will.)

My suggestion is to read through comprehensive real world reviews by players. In the case of the Subway amps, there is a large thread with tons of input by those actually playing the amps.

One challenge with providing comprehensive specs is that it's more common for somebody to misunderstand what the specs actually mean (like you did) than to gain real world value from them. If you had understood how the power rating was specified in the published specs, you wouldn't have come to the conclusion that you did. Re-read [note 1] and you will see why.