What Amplifier Specifications Do You Feel Is Beneficial?

[4stringsjack]

Btw, I'm one of those weirdos who reads the manual cover to cover (after skipping the safety precaution section, of course. )

 

[agedhorse]

in amps, a graph detailing the frequency response with all knobs at noon, and showing where all knobs must be for "frequency flat" response.
If a HPF is built into the amp, then specify at what frequency and slope.
All EQ knobs should be marked with their hinge frequency (and maybe Q. maybe not)

In cabs, we need a standard testing frequency to determine power handling and frequency response.
For guitar cabs, maybe 1kHz.
For bass, try 200Hz.
And ideally, a graph detailing the frequency response of the cab.

I'm seeing that the basic response graphs are wanted, will look into this more. The HPF and eq info is already provided in the owner's manual so we are good on this.

For bass cabinets, take a look at the data presented on the Subway cabinets as we go way beyond this (other than the graph)

Nothing wrong with knowing +/- 12 db at 80 hz shelving or peak and dip at 2k and another shelving at 6k. Even if you add the Q to the mid bumper/cutter, it'll mean nothing to most people and it tells you nothing with how they interact until you do what most people should do anyway which is:

all eq knobs all the way up. It may be the same plot as at 0 db or not; it doesn't matter; the idea is to generate the most "cut" possible. Now take the lowest eq knob and pull it all the way out, max cut and listen to what happens/disappears on the music/instrument. Put it back and to the same to what ever mid knobs you may have. LISTEN to what happens when you pull all those mids out. Of course do the same thing with any hi-freq bands. Now reverse the process, max cut everything and put them up to full one at a time. In this process you're tuning your ear to what's actually happening to this sound with this eq and these speakers. I do this almost everytime I sit in front of a new amp or desk. I started when I was mixing in clubs 30 years ago and the only way to "tune" the PA was to find the feedback and notch it out with a 15 or 31 band EQ so we had to train our ears to intuitively know about where on the eq any given squeal or squawk could be found or what the frequency was to add or cut a little "smack" to the skins of a floor tom or a little "shimmer" to an acoustic guitar. Until you you have the experience to connect 320 hz to a certain sound characteristic, listing the center frequency of the tone knobs is just window dressing.

From one PA guy to another, there's no need to go to anywhere that kind of extreme on eq to hear clearly what's going on. Especially true on consoles with more than +/-12dB of cut/boost. If you do this, you are almost certain to overdrive the eq and makeup gain amps on an analog console and cause DBZ errors or truncate the data stream on a digital console. with all the eq bands flat, 6-9dB of boost/cut on one band will be clearly audible. Don't want folks to unintentionally damage something trying this.

The meltdown point or how long a amp can operate at max volume before going into distress.

This is a good question, and one with a terribly difficult answer. There are many variables outside the amp designer's control, things like the actual (as opposed to nominal) impedance that the speakers present, the ambient temperature, direct/indirect sun, and the signal profile being played (ie. peak to average ratio, average crest factor, duty cycle, definition of "max" volume, etc.) The manuals for the Subway include helpful information in t his regard however, including a discussion about how much time the amp is run into output limiting is save (by design). This covers most player's real world needs.

Specs I look for are RMS-watts; peak-watts (so I know what the headroom is); minimum ohms load; THD rating (so I know what kind of clarity of sound I can expect); Frequency Response at +/-3db; and S/N ratio if available, although the gain will have a big influence on that (55db was considered hi-fidelity in the age of vinyl). S/N ratio is probably not such a big deal anymore especially if you are striving for an overdriven sound. Still, I like to know what it will do "clean". Also, like one of the first responses said, a frequency response curve with controls set flat would be nice so you know where you are actually starting from.

When explaining EQ controls, it's helpful to know if they are shelving controls (bass and treble almost always are) or semi-parametric controls. On semi-parametric controls that do NOT have an adjustable sweep, really need to know where they are centered. Also, if there is a specific way to get "the best sound" out of the amp using the gain control, would like that explained. For example, Eden used to go into detail on how to get the best sound out of their amps. Even with that you'd find people asking on the Eden forum how to set it up. Now that Marshall owns Eden, they have super simplified the owners manual so they could include 7 languages in the one manual. Take a look at any of the new Eden manuals for a good example of what not to do.

I've discussed the whole peak watts thing before, but I think it bears repeating. Once you know the "RMS" power of a sine wave, you automatically know the peak power of a sine wave, which is 2x the "RMS" power. It's just a math conversion and has nothing at all to do with headroom. So, for example, the peak power of the Subway is 2 x 800 watts (RMS) = 1600 watts peak. (technically it's not quite 1600 watts due to specific processing elements, but close enough for this discussion). Do you think we should include the peak power number in light of all the accusations being tossed about over "honest watts", and such? We are clear that we are using volts RMS to determine power in our specs. currently.

Signal to noise ratio specs are already included, once they are quiet enough (below the noise floor of the other system components), I don't know if that adds value or is just another number.

I doubt if tonal personality is a trade secret. It's too easy to measure the frequencies to expect it to be secret. "There's a app for that!"

Well, yes and no... frequency response can vary with signal level (dynamic eq), with gain (dynamic response) compensation. Yes it can be measured, but to be accurate, it's a lot more time consuming, and some of this contributes to the "secret sauce" of some amps. Perhaps a simplified graph using nominal gain and level would do?

For me I really want to see-
* wattages at perspective ohms (@8 @ 4 etc....) preferably continuous VS peak
*weight
* physical dimensions
* EQ centering per control (lows- 60, mids 250 etc)

So, I've discussed the whole issue with continuous, and the math conversion from "RMS" to peak already. The other stuff is already included.

Honest RMS watts @ 8-4-2, peak w, THD, you guys proved you don't need dozens of knobs and sliders, loving my D800, thanks.

And you already have this info in your manual.

 

[HolmeBass]

For me, there is a distinction between "Amplifier", "Pre-amp", "Head"
Which I think this thread could be titled:
What Head Specifications Do You Feel Is Beneficial?

The "Head" *is* the amplifier. The speaker cabinet is *not* the amplifier. An amplifier is an electrical component that takes low-power electronic signals and boosts them in power (I suppose technically voltage, but the result for audio is increasing the power).

 

[Old Garage-Bander]

Hopefully, I understood the question for which I am about to answer.

IMO, specifications all by themselves are more or less meaningless without knowing the methodology used to derive them.
An amp's spec sheet says: 500 watts at 4 Ohms. But under what conditions was that measured? Continuous tone? What Frequency? How much distortion do you get?

I always got a chuckle out of FM receiver specs. This receiver has blah blah insanely low audio distortion specs. An FM station doesn't even come close to meeting those numbers not even by a factor of 10 or even more. If everyone knew that, they wouldn't shell out big bucks to get an extra 0.05 percent better distortion figure on one receiver vs another. And no one knows how those numbers came to be, or if sales just said, brand B's brochure says yadda yadda, so ours better say yadda yadda -0.01.

Specifications are only helpful if everyone is on the same page. That would require a standards committee. But a start would be to publish how the specifications are derived. That way if you wanted to compare one amp vs another and Mesa has this handy brochure that tells how they came up with 500 watts at 4 Ohms, and the equipment used to measure it, you could take that on over to Aguilar and say, HEY! Lets put your gear through the "Mesa Ringer" and see how it compares. Then if others followed suit, you could run amp B through the amp A ringer to see how they both compare.

Or maybe a pre/post D.I. with a level adjustment. Just in case I misunderstood.

 

[agedhorse]

Also, include drop testing videos shot with a high speed camera in the digital version of the owner’s manual.

(Just as an aside, in one of my roles as a product design engineer I used to conduct and film drop tests to a very specific regimen: drop height and product orientation when dropped. The bigger and heavier the product, the more fun the high speed videos were to watch. It’s amazing to see how rubbery steel structural members would become on impact.)

Fortunately too, for those of us living in seismic zone 4. Displacement beats rupture every time.

 

[Old Garage-Bander]

The meltdown point or how long a amp can operate at max volume before going into distress.

In other words... What's the best meltdown point for metal?

 

[agedhorse]

Hopefully, I understood the question for which I am about to answer.

IMO, specifications all by themselves are more or less meaningless without knowing the methodology used to derive them.
An amp's spec sheet says: 500 watts at 4 Ohms. But under what conditions was that measured? Continuous tone? What Frequency? How much distortion do you get?

I always got a chuckle out of FM receiver specs. This receiver has blah blah insanely low audio distortion specs. An FM station doesn't even come close to meeting those numbers not even by a factor or 10 or even more. If everyone knew that, they wouldn't shell out big bucks to get an extra 0.05 percent better distortion figure on one receiver vs another. And no one knows how those numbers came to be, or if sales just said, brand B's brochure says yadda yadda, so ours better say yadda yadda -0.01.

Specifications are only helpful if everyone is on the same page. That would require a standards committee. But a start would be to publish how the specifications are derived. That way if you wanted to compare one amp vs another and Mesa has this handy brochure that tells how they came up with 500 watts at 4 Ohms, and the equipment used to measure it, you could take that on over to Aguilar and say, HEY! Lets put your gear through the "Mesa Ringer" and see how it compares. Then if others followed suit, you could run amp B through the amp A ringer to see how they both compare.

Or maybe a pre/post D.I. with a level adjustment. Just in case I misunderstood.

I have in fact already included some of the details in how the spec's were derived (certainly a lot more than most provide).

When we compare amps, we generally don't worry about specs., we listen and listen and listen to how the features work, how it feels, how player friendly it is, and how it measures up to out collective tastes.

We include a mic/line level switch which covers all bases without the typical problems associated with another level control (including breakage)

 

[ThisBass]

The THD spec isn't very useful when it's tightly integrated into the entire amp. This is the problem, how to extract the important specs from the unimportant ones. In play-tests, where I can add and monitor harmonic percentages, most players, given their choice, preferred THD (made up of a series of harmonics) levels far higher than I would have expected, feeling that the amp sounded richer and more full, more organic.

This is a complex topic, and frankly the details really get into the proprietary aspects of a particular product's design. Just note that most players would find .1% THD (and even 1% and more) sterile and lifeless, not very finger-friendly either.

So true.

As bass players (at least lots of them like me) like it to have this "livelike" feel that comes with Harmonics of an overloaded power stage so I think it makes no sense to provide 0.1% or 1% THD or 10%THD numbers derived with steady sine waves.

If the power specs would relate to Peakt To RMS numbers of a more "realistc" signal (may be a Pink Noise) personally I would get a better imagine of sound goals of the engineer who designed tha amplifier.

Let me tell it this way. The spec might tell that an amplifier was designed to generate musical Harmonic content at overload range and as well can savely amplify the bass guitar signal with a "smallish" 6dB crest and even can amplify this strong compressed signal over time within "generic" room environment conditions (delta T), so I could know how much loudness I can get and also I would know how much of dirt I can get out of the amp over time.

Of course 6dB crest for a bass guitar signal means much of dirt all along the line and even a tube head like svt already would probably sound a little bit muddy pushed onto similar tiny crest number condition

Either way even a tube head like svt can't push the full power with 3dB crest (audible) clean if the signal feed to the amp is a bass guitar signal.


What's reasonable to me as bass player was

#1
"standard" rated output power derived with a steady sine 100Hz (or 1kHz) at just slightly clipping (or 1%THD for more "linear" amplifiers like PA amplifiers). I think some "deviation" is nothing to talk home about just to compare with other products.

#2
Output power in relation to crest number which represents the sound design goals, just to state the amount of (design goals) Harmonics at overload range, respectively "musical" sounding compression ratio for the "real" signal which is commonly a bass guitar.

#3
Derived with Pink Noise the Peak To RMS ratio the amplifier can withstand at "none clipping" working mode over time without overheating at generic room temperature.


Unfortunatelly I'm afraid that specs number #2 and #3 would be hardly understood by the crowed. Although those specs would be way more meaningfull than number #1 cause there is no more relation to pure (poor) THD numbers

 

[BassmanPaul]

Well, after agedhorse's angry diatribe that resulted from my post... sorry, and good bye...

What angry diatribe? Andy stated his experience in the HiFi/audiophile business. It echoes my own in the service department of a high end stereo store. Talk about bloated specifications and expectations!!

 

[Josh Kneisel]

So I'm sitting at my desk pondering some thoughts for an update of specifications provided, and while there are a ton of possible specs. to include I think many of them are virtually meaningless to the overwhelming majority of players. Of course there are some important ones as well.

Now's your opportunity to state your opinions as to what an "ideal" amplifier spec. sheet should contain. As ideas come up, I may wish to discuss them to be sure we are on the same page.

The one thing I am not going to accept are disrespectful posts however, and this is not (yet another) class D amp debate as the class of amp does not matter for this discussion.

I would want to know how many watts it actually could put out in a real life situation. I would want to know the minimum ohm load. I would want to know the input impedence.

 

[Ross W. Lovell]

So I'm sitting at my desk pondering some thoughts for an update of specifications provided, and while there are a ton of possible specs. to include I think many of them are virtually meaningless to the overwhelming majority of players. Of course there are some important ones as well.

Now's your opportunity to state your opinions as to what an "ideal" amplifier spec. sheet should contain. As ideas come up, I may wish to discuss them to be sure we are on the same page.

The one thing I am not going to accept are disrespectful posts however, and this is not (yet another) class D amp debate as the class of amp does not matter for this discussion.

I've had a lot of amps.

One of the features I liked, was on a LabSeries 100 with 4x10"'s, a guitar amp, a light that came on to tell me how much of the on board compression was being used.

 

[ThisBass]

#2
Output power in relation to crest number which represents the sound design goals, just to state the amount of (design goals) Harmonics at overload range, respectively "musical" sounding compression ratio for the "real" signal which is commonly a bass guitar.

Of course different EQ settings and different lowest tuning relates to different crest numbers as just to "exactly" hit this attempt.
And also different playing style and different notes of playing relates to different numbers for the crest.
If possible the only way was to set the preamp to flat EQ setting and use of (common) standard basses like J- or P-Bass stringed with round wounds and then predict kinda average for notes A1/E1

At the other hand side once measurements are done it's quite easy to state a cross list of different playing styles versus lowest tunings versus sound settings which relates to "predictable" crest numbers at overload range the amplifier still sounds "musically"

#3
Derived with Pink Noise the Peak To RMS ratio the amplifier can withstand at "none clipping" working mode over time without overheating at generic room temperature.

I think every manufaturer should state this number

 

[GIBrat51]

What I look at:

- THD @ a given frequency
- Watts RMS @ a given impedence
- Watts peak
- Impedence, nominal
- EQ: adjustment range
- Voltage (US/Europe)

Aside from that, it's features (like the separate Gain and Volume on the G-B Shuttles.)

You can't even get info on the specs above for some amps, but you can usually get most of it. I KNOW that the numbers are always fudged, but in the real world they always will be. At least you have numbers that might have been fudged in similar ways.

This is what I meant. Those are the specs I'd be looking for. That's what the OP asked. Whether the manufacturer is lying about meeting them, is a totally different matter. And I don't really care about his anecdotal experiences at work (or yours, either, for that matter), or how often he feel the needs to bathe. That's the angry diatribe I'm talking about.

 

[non]

There used to be a tongue in cheek spec, back when esoteric distortions were "popular"T.I.M. and such. This was E.R.D., standing for elastic rebound distortion... how high an amp would bounce when dropped onto a concrete floor from 6 feet. It was used when folks who had no idea what they were talking about were insisting that they knew more than they understood. They would always know about E.R.D, and which amps were the greatest and which amps sucked and how it related to spacial sound field and the other Audiophile BS that was popular at the time. All the while, those who knew what was going on could watch the impending crash and burn when it was explained.

back in the late eighties i had a mesa bass 400. going to my first gig with it i was pushing my skateboard with the cab on it and the head on top of that and a coke i was drinking on top of that (you know where this is going). it was about 4 feet high (cab was on it's side). well i hit a crack in the cement and everything went over. the head hit the ground face down and the coke fell right into the back of the head and drenched the tubes. at that height the mesa has no e.r.d. i later bought a road case for it. i dried everything best i could and the head work with no problems. the gig was good. nice build mesa!!!

 

[eigentone]

I'd like to know which tubes are used.

I'd like to know which speakers are used. If said speaker has no published specification, at least a basic description along the lines of "The speaker is a derivative of a Celestion Vintage 30. It has slightly more low mids and is made in England.".

In the case of tube amps, I'd also like to know the manufacturer of the transformers.

Sorry if these are repeats. I didn't bother to read all 10 pages. Of course, these may not apply to all amps.

 

[ThisBass]

Besides specs it might be beneficial to "train" the customer a little bit by reading the user manual.
Just spend one page (or two at most) of the user manual just to demonstrate
a sine curve RMS versusus "generic" bass guitar traced curve, line the RMS on both curves, show how to chop off the transient content that is inaudible per se but, effects "feel" and compression

If the amplifier design goal is also aimed to "smooth" even the steady swing of string then demonstrate how it works cause it's "musical" enrichin' Harmonics

 

[alaskaleftybass]

Good question @agedhorse . I think there are always up and coming youngsters learning bass. As they aspire to higher levels of gear, they really don't know what they're looking for. A spec sheet that would break down HOW the controls work and what each control does would be good. When the print gets too small the paper just gets tossed in the shipping box. Not by me, but I've seen it done.

I hope what I'm saying makes sense. A spec sheet that would kind of teach the novice a sense of what the amp is about. AND maybe on the flip side of the page, the more technical specs. If you look at Mackie manuals they're really good at breaking down the specs to understandable.

I wish everyone would standardize on RMS watts. Or whatever you think is the most truthful. And then EVERYONE use THAT standard. But that's probably "in a perfect world."

 

[40Hz]

Actually, the single "spec" that would be the most beneficial and desirable for someone like me would be a half dozen or more untweaked but still professionally recorded sound files (in a lossless file format such as FLAC, WAV, ALAC, etc.) of the amp being played in a variety of styles and with a variety of different instruments.

I'll 'fess up. I know enough to be dangerous rather than knowledgeable when it comes to most audio specs. Sure, I understand most of them - but only in broad strokes. So in that regard, numeric specs hold "educated but still layman-level" meanings for me.

What I'd really like is to hear it. Most information on audio product data sheets I only find moderately helpful when I'm making a purchase decision. Ten minutes plugged into something - or a half hour listening to a really good and not fudged series of recorded demos - tells me almost everything I'd want or need to know.

I really don't care about distortion figures. Or impedances, or power ratings. Does it sound good? Will it match my cabs - and does it have sufficient power to drive the cabs I'm planning on using at the volume level I need to run them at? Does it run cool? Is it easy to pick up? Is it reliable? Is quick technical support and repair service available?

Those are the "specs" I'm really interested in.

 

[eigentone]

If it has been mentioned already, I apologize....

I'd like to see the "effects return" and "power amp in" input sensitivity specs.

Me too. This would also be helpful for input.

If there is an input Pad, I want to know what the amount is (unless it's very nonlinear). Some manus do this already, perhaps Mesa does.

 

[seamonkey]

The "Head" *is* the amplifier. The speaker cabinet is *not* the amplifier. An amplifier is an electrical component that takes low-power electronic signals and boosts them in power (I suppose technically voltage, but the result for audio is increasing the power).

In my view, A "Head" includes a "Pre-amp" and an "Amplifier"