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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 5th Dec 2018, 3:59 pm   #1
Syrinx1
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Default Exley - Bass without big Baffles

Hi,

I came across this interesting wireless world article...

http://www.douglas-self.com/ampins/w...Apr51%20p1.jpg

I'm in the process of designing a small guitar amplifier for low volume practice, and I'm aware that one of the issues with low wattage designs is that the human ear is less sensitive to certain frequencies.

The above circuit is a low volume compensation circuit which looks quite interesting, and I was wandering what members opinions were on its merit in the context of a small guitar amplifier?
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Old 5th Dec 2018, 8:23 pm   #2
terrykc
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Default Re: Exley - Bass without big Baffles

You can see the full article here:

https://www.americanradiohistory.com...ld-1951-04.pdf

It starts on page 8 of the pdf.
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Old 5th Dec 2018, 9:20 pm   #3
Syrinx1
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Default Re: Exley - Bass without big Baffles

Thanks Terry
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Old 6th Dec 2018, 4:28 am   #4
arjoll
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Default Re: Exley - Bass without big Baffles

Is this a forerunner to Aphex's "Optical Big Bottom?"

http://www.aphex.com/products/exciter
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Old 6th Dec 2018, 9:21 am   #5
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Default Re: Exley - Bass without big Baffles

The idea of having a 'harmonic' structure to trick the ear into thinking there is deeper bass there is quite ancient. Plenty of old pie organs have a mutative stop labelled 'Quint'

It adds a rank of pipes sounding at 1.5 times the frequency of the note being played, and the non-linearity in the listener's ears produces the sensation of sound at 0.5 times the frequency of the note being played. The Quint pipes are a lot smaller and cheaper than a real rank pitched an octave lower.

David
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Old 6th Dec 2018, 12:27 pm   #6
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Default Re: Exley - Bass without big Baffles

I believe that there is a fundamental problem in 'synthesising' low bass notes by trying to 'trick the ear' in that we don't just 'hear' these notes but we 'feel' them too.

If you are used to listening to music through 'straight' reproducers like a large speaker on infinte baffle or in a decent sized vented cabinet, and then go on to listen to one of these small speaker systems you should indeed notice the difference. For instance some time ago a friend brought me a small speaker system, I think it was made by Bose, that claimed to reproduce bass down to some very low frequency, he raved about the 'bass performance' but to me it sounded strange, there was something 'thin' about it, something 'missing' from the sound, it just did not 'feel' right. I invited him to come and listen to the same piece of music played on my system and he immediately commented on the 'powerful bass notes'!
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Old 6th Dec 2018, 1:10 pm   #7
John10b
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Default Re: Exley - Bass without big Baffles

I agree you can certainly notice the difference, I bought my wife a Bose radio several years ago and it is a very nice performer, my wife likes Vivaldi, however when I listen via my system, big speakers etc, you can certainly hear the difference.
Cheers
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Old 6th Dec 2018, 2:24 pm   #8
Craig Sawyers
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Default Re: Exley - Bass without big Baffles

The psychoacoustic trick of fooling the ear into thinking low bass is there when it isn't is also used in headphones.
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Old 8th Dec 2018, 9:51 pm   #9
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Default Re: Exley - Bass without big Baffles

There are two methods of faking bass. The more elegant (well, less crude is probably more honest) is the quint trick with added tones at 1.5 times the frequency of the note being played. This at least conveys a sense of pitch and musical sounds can be made.

The crude method is where a speaker doesn't go very low, so an exaggerated bump is planted in its frequency response at its bottom end. This boosts the thump or thud effect, but it is unmusical. This is the notorious 'one note bass' and although it boosts the effect of untuned thump sounds, bass lines disappear into mud.

There's no substitute for a pair of decent speakers, large enough to do the job, or several ranks of pipes really in the 32 foot pitch.

David
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