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Old 6th February 2010, 12:09 PM   #91
wahab is offline wahab  Algeria
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Quote:
Originally Posted by irishpatrick33 View Post
Thanks for the diagram! Very easy to understand.

Would you like one of my TDA1558Q's? A gift for your kindness.
thank you, kind proposition..
but perhaps that rather to costly ship this IC from the us
to france, it would wonderfully fit for a kid, as a guitar
amplifier, who knows, you surely know one...
as pointed by daniel, it has a high gain, as 50 mV rms
are enough to reach full output, so it fill perfectly this
purpose..
surely that it was done for automotive radio k7, as the
magnetic head has trouble giving 1 mV output, a hard
task for the following premaplifier, usually a dual opamp,
so a part of the necessary gain was reported on the power
amplifier, not counting that the FM circuits has also low
ouput level, no more than 100 mV...
well, next time, i ll stick to the choice of the majority,
(among 3 !!) , and go for the 8561Q...
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Old 6th February 2010, 01:12 PM   #92
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Quote:
Originally Posted by wahab View Post
thank you, kind proposition..
but perhaps that rather to costly ship this IC from the us
to france, it would wonderfully fit for a kid, as a guitar
amplifier, who knows, you surely know one...
as pointed by daniel, it has a high gain, as 50 mV rms
are enough to reach full output, so it fill perfectly this
purpose..
surely that it was done for automotive radio k7, as the
magnetic head has trouble giving 1 mV output, a hard
task for the following preamplifier, usually a dual opamp,
so a part of the necessary gain was reported on the power
amplifier, not counting that the FM circuits has also low
ouput level, no more than 100 mV...
well, next time, i ll stick to the choice of the majority,
(among 3 !!) , and go for the 8561Q...
Well, the TDA8561Q was your idea, and I think its a good idea. We'll find out more about it soon. Still awaiting the mailbox. . .

If that doesn't work, then a good "Plan C" could be TDA1554Q, because those probably have a good tone, low heat, and reasonable gain. Also, pin 15 on that chip is supposedly n/c like pin 9, and non-connected pins can be joined with the ground very, very conveniently. For the bridge mode amp, this could shield the input pins nicely.
Okay, this was such a cool idea that I bought one of these too. Now a have a wealth of little amplifiers and less real money.

Maybe irishpatrick33 can give me a lesson on how to turn audio back into cash.
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Old 6th February 2010, 11:25 PM   #93
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Quote:
Originally Posted by irishpatrick33 View Post
Understood. I do this type of stuff all the time. I either try stuff and sell it. Or buy something/change my mind and sell it. I guess that's how you get 1,000 Ebay ratings. I can't count how many speakers and amps I have been through in the last few years. Fortunately, the used electronics market is a good one - so I get a good chunk of change back when sell. . . .
Hey man, do you have a link to your ebay store? I'll surely want to read your advertisements, and I might go shopping too.
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Old 7th February 2010, 12:01 AM   #94
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Quote:
Originally Posted by danielwritesbac View Post
Hey man, do you have a link to your ebay store? I'll surely want to read your advertisements, and I might go shopping too.
I don't have a store per say. Just an ordinary person who buys/sells a lot of stuff. You can look for me on Ebay though. Go to Advanced Search and select Find Items By Member in the left hand column eBay Search: Advanced Search

Right now I only have two things for sale: RCA connectors and speaker input plate cups.
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Old 7th February 2010, 12:13 AM   #95
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Quote:
Originally Posted by danielwritesbac View Post
Maybe irishpatrick33 can give me a lesson on how to turn audio back into cash.
There's no trick to it. People will buy any kind of electronics. I have sold things which I couldn't imagine somebody would want. But they usually do.

I just take whatever I don't want and throw it on Ebay. Though I've also used Audiogon to sell a pair of Manley Mahi monoblocks and some tubes. I just start an Ebay auction for a penny and that seems to drum up interest. Any time you use a fixed price, interest is minimal and slow to sell unless cheaply priced.
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Old 15th February 2010, 06:19 AM   #96
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In the mailbox, there were TDA1554Q amplifiers. The newer model TDA8561Q has not yet arrived.

I'll be building them up when both models arrive, and will report back with some observations.

Its "highly likely" that there is sufficient gain this way:
12vdc
MP3 player

However, I'll be checking to see if this combination has sufficient gain to reach full potential (of the more powerful amplifier).
15vdc
MP3 player
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Old 15th February 2010, 01:43 PM   #97
speaker is offline speaker  United States
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Quote:
Originally Posted by paulb View Post
LM4752
LM4752 - Stereo 11W Audio Power Amplifier
Not in the same distortion class as the LM3886 and similar, but I'd still call it a gainclone. Sounds good.
Available at Mouser or Digikey?
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Old 15th February 2010, 05:19 PM   #98
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Probably Mouser, Digikey, Ebay, Allied. . . will have some availability.

11W could be rather under-whelming in comparison to the ongoing experiments with the Philips chips.

Distortion becomes important in direct proportion to the amount of amplification. Proportionately, 1% of almost nothing is really almost nothing; however, 1% of 70w is a bit too much distortion.
For this project, the distortion relates to the gain setting, actually. If the gain is set needlessly high, then the noise floor (distortion) is also needlessly high. That's exactly why the upcoming redo is for a lower gain amplifier, with a "sufficient" amount of gain, but not more.
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Old 19th February 2010, 05:47 AM   #99
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Default Tda1554q

TDA1554Q works appropriately, and is recommendable for a fun little project.

It runs surprisingly cool (hyper-efficient) and gives a nice size presentation. There's not audible noise while its running.

It appears to use a 20k pot (dual gang potentiometer for volume control).

This amp doesn't exceed the quality of a T-amp, and it is exactly as sensitive to power circuit and power cap quality.

The amount of gain is just about perfect for MP3 player and PC. This amp isn't as powerful as TDA1558Q, but the difference is minor, and was expected. I had to use that 15v econo replacement laptop cord to get as much power with TDA1554Q as TDA1558Q can do with 12v; however, there's a good reason for it. . .

Oddly enough, TDA1554Q has MUCH more bass, and the power difference could probably be corrected by choosing smaller size input caps. On these small scale amplifiers, there's no need to pass deeper bass than your speakers can reproduce--12" woofers, corresponding to 0.47uF input caps at the amp's input, with smaller woofers using smaller capacitance for efficiency.

Excellent news: The "uncompress" effect is present, similar to TDA1558Q; however, TDA1554Q plays more cleanly.

Soon, we'll see what TDA8561Q will do.

Last edited by danielwritesbac; 19th February 2010 at 05:50 AM.
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Old 19th February 2010, 09:33 AM   #100
wahab is offline wahab  Algeria
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Quote:
Originally Posted by danielwritesbac View Post
Oddly enough, TDA1554Q has MUCH more bass, and the power difference could probably be corrected by choosing smaller size input caps. On these small scale amplifiers, there's no need to pass deeper bass than your speakers can reproduce--12" woofers, corresponding to 0.47uF input caps at the amp's input, with smaller woofers using smaller capacitance for efficiency.

Excellent news: The "uncompress" effect is present, similar to TDA1558Q; however, TDA1554Q plays more cleanly.

Soon, we'll see what TDA8561Q will do.
surely, the difference in basses is due to input capacitance
being too low in the 1558Q schematic from phillips.

personally, i did double the value, although, as you mention it,
it s somewhat useless considering the kind of speakers that are
used with it..
just waiting for your 8561Q investigations, i m dead curious
about it. Hope it will be successful, as this chip seems to be
a good replacement of its helder brother...
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