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**MWJB** · 03-08-2011, 09:34 AM

These nice tidy charts & scales are very interesting but ultimately of limited value. Let's take your "50W amp" it is likely to be fixed bias, 500vdc B+, a pair of 6L6/EL34/6550 power tubes and a substantial & efficient speaker array (100dB+ & 300"sq.?). So now we compare to a typical 5W amp - 1x6V6 or EL84, 300-400vdc B+, cathode bias, single ended, tiny transformers...because 5W amps are typically made to be cheap, entry level amps, it may have no tone stack, or just a simple tone pot, small single speaker (<90dB & 50"sq.?). The "wattage" is the least of your differences...if you built a 5W amp with 50W transformers, made it fixed bias, high B+, substantial speaker array, push pull you will find that it sounds considerably louder than the SE, cathode-biased, single speaker version with little transformers & a little speaker. It's not uncommon to hear two similar designs of amp & percieve a vast difference in volume...20-30vdc on the power tube plates can have a considerable effect...it's not unusual to see 50-60v differences in many production amps of 50W, more if that amp has had a long production run with many voltage changes, speaker efficiency & particularly voicing will also play a big part in perceived volume. Clean W RMS is measured with a constant signal level in to a resistive load, musicians play instruments, with dynamics, into speakers.

For home use, less than 1W is probably more like it for apartment use, I use a 12AT7 push-pull amp, that I can play at 0.125W output...my 2W amp annoys everyone in the block, not just my immediate neighbours.

**guitarmike2107** · 03-09-2011, 09:01 AM

The only reason to work out these figures is to predict the power output so you can put dial markings on your faceplate. Thats why I did it, at the end of the day if its too loud, it's too loud,
When the police arrive at your door because your neighbours complained, telling them that you have turned the amp down to 2watt of power output, and thats only 38% as loud as full volume isnt going to help you.

I am sure my neighbours wished I had a 2 watt amp :}

**kldguitar** · 04-22-2011, 05:00 AM

this chart has relation ship with how to select right attenuation

we know a power attenuator reduces dynamic depth to some degree. The more attenuation is , the more the sound loss is .There is some debate about how significantly an attenuator flattens the dynamic depth. Guitar speakers sound best when pushed hard. Below about 1 watt, guitar speakers sound especially thin and fizzy.
when we reference the chart, there are no attenuator which no effcet sound. only more or less. So I think the right idea is we need look for right attenuation not exensive attenuator. If you found right attenuation rat, the cheaper attenuator still have good result.Tube Guitar amplifier,effect pedal and studio gear manufacturer kldguitar

**mooreamps** · 04-22-2011, 06:24 AM

This is why I have a P/P to S.E. switch on the back of my amp....

-g

**Chuck H** · 04-22-2011, 08:36 AM

Steve Conner has noted the Fletcher Munson curve on several threads. It's very relevant. And there's a point where the ear begins to compress too. No way to emulate that affect without volume unfortunately. So... The amp power, speaker response and human ear perception all come into play. Top that off with a nice dose of amp, power tube, guitar particulars and there's just no way to emulate all the harmonic nuances with an attenuated amp. Harmonics and resonances drop off dramatically as volume is decreased. Balance that against the EQ perception and take all the variables into account and you should be quick to realize that whatever you do to reduce volume is a compromise. If your really lucky you can manage one great tone attenuated. But any others will seem somehow elusive. That's just MHE.

**kldguitar** · 04-22-2011, 09:22 AM

Very good ideas

I agree with chuck. Harmonics and resonances drop off dramatically as volume is decreased. It is rule. Some expensive attenuator told people they don't change sound , I think it is only want people buy so expensive gears.
we research many kinds of attenuator, and develop many attenuator.I think" Apprapriate attenuation rat you found is more important than expensive attenuator". ,

**cminor9** · 04-23-2011, 03:48 PM

Does everyone here have neighbors that hate the sound of a guitar? I have never had a problem with that. My current neighbors come out and listen when my band rehearses.

**Wilder Amplification** · 04-30-2011, 08:00 PM

Perceived volume vs output power relationship...simple answer...there is none.

They say that perceived volume increases by +3dB everytime you double the output power and it takes 10x the power to perceive double the volume. However, this discounts lots of variables that come into play such as speaker sensitivity, the voicing of the amp, etc etc.

The human ear doesn't hear flat by any means just as guitar amplifiers are not voiced flat either. A 50 watt amp that accentuates the frequencies that your ears are the most sensitive to will be perceived as "louder" than a 100 watt amp that amplifies everything flat. Moreover, the frequency response of the human ear changes with volume (Fletcher/Munson curve) and these things along with numerous listening environment variables trump the perceived volume vs power debate.

Treat power as a "headroom thing". The more power, the more clean output signal swing you get and the louder the amp has to be for the power section to clip. For high gain, power amp headroom is a necessity and as such I won't build anything high gain that's less than 100 watts. But if power amp overdrive is what you seek, 25 watts and lower is an avenue to explore as they don't have to be turned up as much to clip the output section.

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