Help me design my home music system amplifier with loudness controls.

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After listening to a few different systems, I have some idea of what I want my home audio system to be.

First, I have read this thread.

req help in choosing audio amplifier IC for DIY home speaker system

The thread covers a lot of ground, but does not have all the info I am looking for.

None of the existing systems are adequate, for reasons I will explain later. But for now, here is how I plan to proceed:

1. List existing systems and analyse their sound, using pink noise as well as listening tests to standard sample tracks.

2. Swap a few components and try to arrive at a combination that works for me.

Existing systems have good clarity, but bass is lacking, or vice versa. Basically I will be using a low power chip amp with tonal controls, an equalizer or a loudness circuit.

For starters can anyone tell me what the difference between the loudness switch and bass controls are? The loudness switch makes everything better.

Here is some background.

Systems tested - AmeresearchAudio

More accurate:

I post pictures of my current systems
 
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First, some testing.

I played my standard test CD on the Sony STR-333S receiver that is set up in the living room. This receiver sounds capable but is in need of a service, and sounds somewhat ragged on vocals at medium volumes. Overall, it sounds too boomy through its standard speakers, which are all over 20 years old and sometime in storage.

I usually use the loudness switch with a little bass and treble added. As seen in the picture, I hooked up my bookshelf speaker incorporating a 4 inch full range from a PC speaker to the receiver, being careful not to use high volumes.

SmallSpkrTest.jpg


Curiously, the little speaker vibrated when the receiver was switched on. Why, and is this damaging to speakers?

Testing results:

Without Loudness and without Bass or Treble :
Barely acceptable

With : Listen-able
 
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What it the point of all of this?

The speakers I have built so far have had barely adequate bass levels. These same speakers have been so far connected to amplifiers that have either a basic bass/treble control or inadequate controls.

Listening to the Sony receiver without loudness controls, (remember this is at low volume levels, about 70 dB at 1 meter from the speaker) gives the same clear but unsatisfying sound. I read that speakers and recordings are optimized for around 85 dB, so the assumption all round is that this is the listening level that is going to be set by the listener at home.

So it is not really a problem with the accuracy of the speaker, which in any case would be difficult to build with a loudness control unless it was powered. That means that loudness compensation is best done at the amplifier end.

Which leads me to my amplifier search : I am can listen all day to the PC amplifiers such as my 8002A and the TEA 2025, but for the lack of bass. What I am looking for is an amp with loudness and tone controls, and any speaker I have will do, but of course I will continue to build better and better speakers, aiming at neutrality and compensating for loudness with the amplifier.

Now, what amplifier board should I get? I am looking at a external power supply, USB charger type or brick type with 5 V to 12 V output.

Do I get a 'preamplifier with loudness controls' and hook it up to an existing amp? I don't want it to sound too terrible, because the amps I have tried so far are all fine as far as clarity of sound is concerned. The bass is another matter.

Looks like I have been looking for bass in all the wrong places :)

So head on to Ebay and I find these:

New LM4610 + NE5532 preamp LM4610 tone control Board with loudness switchable | eBay

Low noise tone control preamplifier with loudness control stereo assembled ! | eBay

[FONT=Bookman Old Style, Book Antiqua, Garamond]"Besides bass, treble and volume control, this board also features a loudness control which give a full body sound during low volume application."

Exactly. Full body of sound is what we want.
[/FONT]
 
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From the rather dodgy looking construction of the speaker in the posted photo, I think you'd want to ensure the enclosures are not only structurally sound and don't leak, before attempting to assess what the amp tone control's / loudness / EQ might need to , or be able to correct.
 
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Patchy speakers

From the rather dodgy looking construction of the speaker in the posted photo, I think you'd want to ensure the enclosures are not only structurally sound and don't leak, before attempting to assess what the amp tone control's / loudness / EQ might need to , or be able to correct.

Yes, Chris, I have practically sealed the speaker opening with tape and cardboard - the result of a speaker cut out going horribly wrong. The left side speaker looks much better. Both need sealing, I understand that the trapped volume of air damps the cone reducing its natural frequency, meaning more bass.

None of the speakers I have built ever had any airtight sealing, I understand the concept now. My first speakers were built in 1990.

Next step would be sealing up the enclosure, also, I need to add damping material to the inside as well, and re-test.

Thanks for the reminder.
 
I could use an EQ, but I do not want to spend too much, it will cost much more than the amplifier board.

There are software EQs did you mean that? Some streaming music services do not have the EQ facility, and anyway have to be adjusted on the device, nice to have some physical tone controls.

If you are using Windows, you might find "equalizer apo" useful. It installs at the operating system level and can be used for anything you play. And its free.

Equalizer APO download | SourceForge.net

Peace Equalizer, UI for Equalizer APO download | SourceForge.net
 
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