TC Electronics RH450 Quasi-Wattage Ratings Discussion Thread

[BurningSkies]

Apparently I am "ignoring half" of the equation (not really). I acknowledged that 236W is not equal to 450W and that TCE misrepresented the specs. So I do recognize that part of the story and accept the validity of that argument (and did from the beginning of this thread).

What I have a problem with is the notion that you can separate "bench test" performance and real world "operational" performance. In my view they are intrisically linked.

If the amp was rated high but consistantly underperformed, then both the equipment and the specs would be bogus.

If the amp performance is equivalent to the specs stated, and the amp performed properly, the specs given would be bogus, but the amp performance would not be bogus.

In my view the information provided by TCE was bogus (I said that from the beginning - check my previous posts). Their actions are not acceptable - (I also stated this from the start.) But, the gear itself is not necessarily subpar simply because of the misrepresented data.

The performance that TC stated was 'this amp provides 450w RMS and 800w peak'. It has been proven that this amp performs at an actual rate of 236w RMS and 236w peak. With a whole bunch of compression in both cases.

 

[JHAz]

drpepper; i am just trying to be fair, and pending the owner's reply tomorrow. i am leaning toward that they lied, but let's see.

all: i was right. see the excerpt from wikipedia below:

"A change in power ratio by a factor of 10 is a 10 dB change. A change in power ratio by a factor of two is approximately a 3 dB change"

so, while a 3 db difference might not seem like much on paper, it is actually that if you have a 3 db increase, you can be twice as loud... i think that is significant.

/s/ Dave

what I've read is 3 dB is what most folks would call "one notch" louder or quieter. Double power all other things remaining equal gives 3 dB increase. Generally, 10 dB is considered subjectively twice as loud. Our hearing is roughly logarithmic too.

If the TC can only make 240 watts, then if the playing field were leveled (hundred dollar compressor/limiter to pull off the peaks and apply compression) then a 450 watt amp will feel twice as powerful as the TC. As others have pointed out, the TC uses more sophisticated compression so the EQ would seem different, but I beileve total loudness would be essentially 3 dB higher if a 450 watt amp were run at the edge of its clean envelope with a similarly compressed (same RMS power) signal.

Two things have occurred to me. First, after chewing on some of VinTone's comments longer, I suppose it is possible the output stage of the amp has the ability to output 450 watts but the compressor/limiter is keeping it from doing so. Maybe there is a signal shape that you could feed the amp to actually get 450 watts out of it.

Second, we don't' really know how much the TC compresses the signal. At the lower iinput levels, there appears to be over 3 dB of compression being released (I know that's clumsy) at the end of the .2 second test signal. But we don't know if the signal would grow another 1 dB or 10 dB before settling into equilibrium, because the test ends after .2 seconds.

Makes me wonder how the 2 amps would compare if you set them both to have the same output at equilibrium. Because I am sure my ears and hands are not fast enough to set my volume level based on .2 seconds of tone. I'm listening to several seconds to hear how loud I seem. So if I were using both heads, I'd set them to be equal after the release of the TC compressor was complete. That is to say, if my signal has 10 dB or more of attack transient, I'm turning the TC down a bit from the levels used in the test, to make the 2 amps sound equal. Which means the TC is compressing both the transient and the beginning of the sustain more than shown in the BGM tests.

I think. But i REALLY don't know what it means sonically. I believe based on my own experience that you can limit the transients a fair bit and still have the note (or drum hit) sound essentially the same (except you can make it louder overall if you want to). But I am clueless where the TC is on the compressor-as-tone-control versus transparent compression line. All the more complicated since the TC's compression is multiband, and the delay, release, threshold and ratio will be different for each band. may be different for each band . . . .

 

[vin*tone]

I'll post again since I didn't get any takers first time around, obviously..

Dismiss it as a fallacy if it makes you feel better, but I doubt anyone who defends it as "sounds like 450watts to me!" will dare to take this up because deep down they know that its not as loud as 450 real watts


I have a very, very nice RTA/SPL meter. The classic AudioControl SA-3050A. If someone near central PA wants to put their RH450 against a SVP/Powerbase2 combo through the same cab to put this "sounds as loud" BS to bed, I'm all for it. I really regret not doing just this before I sold my RH450.

Bring it! Put up or shut up time.

I'll also loan my SA-3050A to BGM if they want to put together that microamp shootout with some SPL figures. Only request I have would be to try to include 3 classic 'old-iron' amps. The tube SVT, the SVT 4 Pro, and the Hartke 3500.

but isn't that exactly what BGM did?

 

[JHAz]

The simple fact remains that "perceived" loudness at 1 to 3 feet will have very little to do with the "perceived" loudness at 10 to 20 feet, that requires "power" not "magic" distortion of the signal.
HI, a simple concept given your background yes?

Actually it will. Air being subject to the laws of physics, and given the way sound tends to spread from a sound source the rule of thumb is 6 dB quieter for every doubling of distance. The air does not care what shook it hard enough to register 100 dB a 1 meter. It can only do what air does from there.

But that's without reinforcement from walls, ceiling and floor, so in noncavernous rooms the actual loss is less than that.

 

[B-string]

What Munjibunga said was "less than 3db.
It is apparent to this reader there is no "headroom" above 236 watts. I for one want to control my own dynamics, not have my gear do that?

 

[B-string]

"all: i was right. see the excerpt from wikipedia below:

"A change in power ratio by a factor of 10 is a 10 dB change. A change in power ratio by a factor of two is approximately a 3 dB change"

Ah yes Wikipedia......
Into the same speaker you need a factor of about 10 to double the sound from an amp. 100 watt amp is twice as "loud" as a 10 watt, a 1000 watt is twice as "loud" as a 100 watt.

 

[JHAz]

What Munjibunga said was "less than 3db.
It is apparent to this reader there is no "headroom" above 236 watts. I for one want to control my own dynamics, not have my gear do that?

Yep. But not one of the test tones BGM used requires 240 watts for the sustain portion of the note. The louderst sustain is the 2.5 dB peak test tone, on which the 450 watt amp pu tout 214.2 watts according to BGM (after the very brief 450 watt burst). So the question is how much of that extra power we need for the meat, if you wil, of our sound. Like I said above in my too effin long post, IDK. Be fun to set up in a big hall with test equipment, identical cabs, etc. and see.

 

[B-string]

Yep. But not one of the test tones BGM used requires 240 watts for the sustain portion of the note. The louderst sustain is the 2.5 dB peak test tone, on which the 450 watt amp pu tout 214.2 watts according to BGM (after the very brief 450 watt burst). So the question is how much of that extra power we need for the meat, if you wil, of our sound. Like I said above in my too effin long post, IDK. Be fun to set up in a big hall with test equipment, identical cabs, etc. and see.

Yes it would!

 

[JackANSI]

but isn't that exactly what BGM did?

As far as I know they didn't do an accurately measured SPL comparison between the RH450 and another amp through the same cab.

That would give a much more definitive answer to "as loud as any other 450w amp", IMO.

 

[steve_rolfeca]

...all: i was right. see the excerpt from wikipedia below:

"A change in power ratio by a factor of 10 is a 10 dB change. A change in power ratio by a factor of two is approximately a 3 dB change"

so, while a 3 db difference might not seem like much on paper, it is actually that if you have a 3 db increase, you can be twice as loud... i think that is significant.

/s/ Dave

No. No. No.

3dB IS twice the power. But it's NOT twice as loud. That would be a linear relationship, and we hear "loudness" in a non-linear way.

It takes TEN times as much power to sound twice as loud. That means replacing your 236 watt amp with a really big one, that puts out 2,360 watts (!!!).

3dB is a fairly insignificant, "one click on the dial" increase in loudness, even though it represents a doubling in electrical power output.

To further complicate matters, that's only if your speakers are still operating in their linear range. Once you get over a few hundred watts, a lot of cabs won't even give you a full 3dB increase when you double the power, because the drivers run into their mechanical limits, and start to compress.

 

[steve_rolfeca]

...companies do tend to measure in watts, but like to fudge the info around that measurement, you know, things like THD. In practice a good company should give you their information coached in terms of the other measurement aspects that play in. Some do, some don't.

Really? Name two MI amp companies that do, aside from Eden and Epifani.

 

[sawzalot]

The only way we are going to get an accurate picture of what the rh450 can do is to tear it down and see what power modules are in there. If they've got the B&O 125ASX2 in there, well, it's a 450 watt power section. If it's something less than that, TC has some explaining to do. Anyone up for it?

 

[BurningSkies]

Really? Name two MI amp companies that do, aside from Eden and Epifani.

Here's the spec from my Peavey amp:

Rated Power (1 x 2 ohms) - 1,640 watts @ 1 kHz at <0.1% T.H.D.
Rated Power (1 x 4 ohms) - 930 watts @ 1 kHz at <0.1% T.H.D.
Rated Power (1 x 8 ohms) - 470 watts @ 1 kHz at <0.1% T.H.D.

 

[BurningSkies]

Really? Name two MI amp companies that do, aside from Eden and Epifani.

The manual for the Hartke VX3500 lists:

Rated output Power: 350 watts @ 4ohms
Total Harmonic Distortion: less than .5%

 

[Gizmot]

This issue continues to surprise me - TC (and its associated companies Lab Gruppen, Tannoy, Linn) are all legitimate brands. Whomever decided to put published specs on a product based on "apparent output" must be either dishonest or crazy.
Although I've never played a TC, I've heard them several times and I thought they sounded okay. However, based on these false claims about the product, I wouldn't consider buying one

 

[fdeck]

As far as I know they didn't do an accurately measured SPL comparison between the RH450 and another amp through the same cab.

That wouldn't help, because SPL isn't a measure of loudness either.

If somebody wanted to research this, you could build an A/B box with a panning knob, and then put two amps behind a curtain. The person can play their bass while adjusting the knob until the two amps have equal loudness. While they are doing this, the output signals of both amps are being recorded for analysis. This would tell you which amp requires more power to reach the same loudness. In both cases it's a real bassist playing a real bass, or you could use a recorded bass signal.

Going further into research, you could do this to test the efficacy of different amp design parameters, i.e., to learn how to build the loudest amp for a given watt rating.

 

[BurningSkies]

The manual for the Hartke VX3500 lists:

Rated output Power: 350 watts @ 4ohms
Total Harmonic Distortion: less than .5%

Fender Bassman 300: 300W R.M.S. into 2, 4, or 8&#937; @ <3% T.H.D.

Carvin R600/R1000:
Output Power 8&#937; 4&#937; 2&#937;
8&#937; Bridged 4&#937; Bridged
THD < 1% THD < 1% THD < 1% THD < 1% THD < 1%
R600 R1000 175/175w 225/225w
250/250w 350/350w 300/300w 500/500w 500w 700w 600w 1000w

Carvin BX500:
Output Power
8ohms, 4ohms, 2ohms,
THD <1.0% THD <1.0% THD <1.0%
300w
500w 500w (2 ohm switch engaged)

Peavey Headliner 600:
Power Output:
All measurements with no more than 1% THD + N
8 ohms 200 watts (40.0 VRMS) 4 ohms 300 watts (34.6 VRMS)

 

[BurningSkies]

...but not to get away from the real topic and not the 'ratings game as the rest of the amp world plays it besides TC'...

 

[vin*tone]

As far as I know they didn't do an accurately measured SPL comparison between the RH450 and another amp through the same cab.

That would give a much more definitive answer to "as loud as any other 450w amp", IMO.

I imagine a speaker would be more forgiving than a pure measured signal as it's not going to have perfect reproduction of the transient peaks which according to the BGM test last 0.02s. The rest of the note is as loud or louder than the test amp.

 

[vin*tone]

The only way we are going to get an accurate picture of what the rh450 can do is to tear it down and see what power modules are in there. If they've got the B&O 125ASX2 in there, well, it's a 450 watt power section. If it's something less than that, TC has some explaining to do. Anyone up for it?

lol. Sure. I might get a chance tomorrow night.