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Old 21st March 2010, 10:45 AM   #111
wahab is offline wahab  Algeria
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Quote:
Originally Posted by danielwritesbac View Post
Like most of the car amps, its tonality beats most gainclones, quite easily (but that is mostly due to the regulated power supply).



P.S.
This amp wasn't sufficient with the 12vdc wall plug (I'm running 8 ohm speakers). Sorry about that. Will try again later. Perhaps there's another model that will run well under-volted?

Better sound than , say, the LM38xx series .?...
Quite amazing...I thought the NS where superior in all ways..

As you mention it, 12V is not enough to extract the good
juice from these amps.
15V is way better, and i use a 16.4V smps..
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Old 22nd March 2010, 03:01 AM   #112
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Quote:
Originally Posted by wahab View Post
Better sound than , say, the LM38xx series .?...
Quite amazing...I thought the NS where superior in all ways..

As you mention it, 12V is not enough to extract the good
juice from these amps.
15V is way better, and i use a 16.4V smps..
National Semiconductor's LM1875 is superb; and it doesn't contain the noisy spike system. Unfortunately, the larger scale chips, LM3875, LM3886, LM4680 have the spike system whereby if there is clipping there is noise added by the spike system; and, this is not good at low voltage because low voltage amplifiers don't have enough headroom to avoid setting off the Spike system.

We could use LM1875 for this project. Given eight of LM1875, then bridged topology and 4 ohm speaker support is possible. That can also run a 19vdc econo laptop power cord per each channel. Amperage on those power sources is insufficient for stereo amp. Dual mono (individually powered left and right) is workable. At 30 watts per channel, the heatsinks would be rather large.
I doubt that you'd notice a difference in output power between 22~24 watts car amplifier versus 30 watts, because the additional decibels output at the speaker is 1 or less decibel.
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Old 23rd March 2010, 01:50 AM   #113
aditya is offline aditya  India
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Default 12 v chip amps

hmmm how about TDA7385 ( i thin thats the no, )
or probably TDA8561 /62 elecktor has a single side pcb layout for the chip,

plus get 2003's elektor it has a complet single sided board for active filter input and a amp on single board very very neatly done, if interested i will mail the pdf to you,,, let me know

interested in having a peek in it daniel... whats up
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Old 24th March 2010, 04:41 AM   #114
nige838 is offline nige838  United States
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Default ta2020

try the tripath ta2020 class-T amp...Google it. It is relatively simple, produces 22 watt RMS into 4 ohm, and will run off of 12 volt, even batteries.
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Old 25th March 2010, 09:05 AM   #115
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Quote:
Originally Posted by aditya View Post
hmmm how about TDA7385 ( i thin thats the no, )
or probably TDA8561 /62 elecktor has a single side pcb layout for the chip,

plus get 2003's elektor it has a complet single sided board for active filter input and a amp on single board very very neatly done, if interested i will mail the pdf to you,,, let me know

interested in having a peek in it daniel... whats up
What do you think of STA540? Digi-Key - 497-8880-5-ND (Manufacturer - STA540)
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Old 20th May 2010, 03:39 AM   #116
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Any news on the 8561Q?
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Old 27th May 2010, 03:10 PM   #117
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Originally Posted by irishpatrick33 View Post
Any news on the 8561Q?
There is certainly enough gain for use with an MP3 player.

I'd give it a go. Like the rest of its family, its super efficient (on my 8 ohm speakers, the amp runs cool), assembles fast and has a nice range to it. On a spare 15v laptop cord, it will easily keep pace with a bigger amp. It can handle 4 ohm speakers and that (4 ohm speakers) would make it play very, very loud but also require a bit larger heatsink.

With some ordinary 8" speakers, it will play loud enough to crash the heads on your hard drive. My hard drive met an early demise this way. This is sufficient bass. The basic tonality can beat most tripath amps quite easily, and that is mostly because the Philips is so much easier to work with.

Like the rest of the car chip category, the Philips is a bridged amplifier, and this does several things well. You get less blare. Louder bass will come from sealed box speakers (louder lower notes than compared with a non-bridged amplifier). In trade, the bridge amp likes smaller rooms, and its not for outdoor use.

I liked a polyester Wima 330nF input cap on the Philips chips, if when the amp is going to power 6" and smaller speakers. I simply paralleled it with a really small value electrolytic (maybe 0.5uF?) to boost the range for use with the great big speakers.

Differences between model of chip are extremely small in comparison to component variety, power supply and music source. And, every one of the car chip amps gives availability of the really inexpensive super clean power from 15v laptop power packs.

For some reason, one of the Philips chips took quite a while to break in and run decently speedy, but after a few weeks of run time, the slow transistor sound was gone and it sounds awesome now.

Like any "laid back" amp, it exposes its own little flaws (and its power supply too), but this is true regardless of price range. The deal is that shouty amps aren't any fun loud, and laid back amps like the Philips are fun loud (when loud isn't piercing). So, I do like the Philips quite well. All of the power that is has is also useful for music. It doesn't whimp out or screech and there's no mandatory minimum level either. Instead, the behavior is quite good.

Caveat: You must pick a compliant source device, and here's a comparison. Driven from an X-Fi Music/Gamer source the results are horrible indeed; however, a nice cheap Via Tremor (with some approximately 500nF~330nF caps paralleled to the Tremor card's huge output caps to augment the treble clarity) will inspire the Philips to rock down the house with a nice big concert sound.
Likewise if your MP3 player sounds great with some Koss Porta Pro (or the really similar Grado SR80's) then it will sound great with the Philips amp too. That concept is true of most chip amplifiers that don't have preamps.

Well, I just thought I should mention that the source device is super-important if you're going to be amplifying its output a heck of a lot. A buffer circuit, or an input transformer, or a chb, or an optoisolator based volume control, or a mild preamp could possibly increase the entertainment value, and that is true of any chip amplifier.

I think its time for some soldering.
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Old 5th July 2010, 03:08 PM   #118
kroto is offline kroto  Indonesia
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Default preamp for TDA1554Q

I was rebuild my oldy TDA1554Q, and I more like the TDA1554 sound compared to LM1875 whan playing oldies song... smooth performance, not too much detail

I use W200i walkman phone for the input source, what is the best preamp voltage gain for TDA1554Q with W200i?
suggested OpAmp to be used, any idea?

regards,
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Old 9th July 2010, 09:12 PM   #119
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Quote:
Originally Posted by kroto View Post
I was rebuild my oldy TDA1554Q, and I more like the TDA1554 sound compared to LM1875 whan playing oldies song... smooth performance, not too much detail

I use W200i walkman phone for the input source, what is the best preamp voltage gain for TDA1554Q with W200i?
suggested OpAmp to be used, any idea?

regards,
Its a bit unusual to need any voltage gain with an already high gain amplifier. Most MP3 players can push the bridged 1554q most of the way or all of the way into clipping.

A Walkman is designed to drive headphones and the very light load of the TDA1554Q amplifier may be giving the walkman "nothing to do" and thus you might employ a buffer chip at the amplifier input. There is room to use a very slight amount of gain. Nevertheless, the chip is the same--a "Unity Stable" op-amp is what you're looking for.

Some Unity Stable op-amps have voltage tolerances in the 12vdc-15vdc range, which could be convenient. Perhaps you can find a unity stable op-amp with a J-fet input? That could be fun, but a buffer or preamp really isn't necessary with TDA1554Q.
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Old 10th July 2010, 09:43 AM   #120
kroto is offline kroto  Indonesia
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Quote:
Originally Posted by danielwritesbac View Post
Its a bit unusual to need any voltage gain with an already high gain amplifier. Most MP3 players can push the bridged 1554q most of the way or all of the way into clipping.

A Walkman is designed to drive headphones and the very light load of the TDA1554Q amplifier may be giving the walkman "nothing to do" and thus you might employ a buffer chip at the amplifier input. There is room to use a very slight amount of gain. Nevertheless, the chip is the same--a "Unity Stable" op-amp is what you're looking for.

Some Unity Stable op-amps have voltage tolerances in the 12vdc-15vdc range, which could be convenient. Perhaps you can find a unity stable op-amp with a J-fet input? That could be fun, but a buffer or preamp really isn't necessary with TDA1554Q.
hi Dan,
I'm not sure about W200i V_out. from 8 bar of volume control, best sound I get from 4.5 to 6 bar, I've got more noise(@ lesser volume) and lesser dinamic(@ more volume). Thats why I intended to use a PreAmp .
and somehow at maximum volume, the sound isn't quite loud.
it can only drive earphone, driving a headphone wasn't load at all, with the same impedance (32R).

I've built the preamp, the circuit is attached.
C6 and RL(bridged TDA1554Q Z_in) are in TDA1554 kit.

Now I use Ti NE5532, can be operated with VS as low as 10Vdc, low noise, unity-gain stable, good PSRR too.
next week I will use Philips ones, 6Vdc minimum (ALL PHILIPS CHIP).

regards.
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