Any Other Option for an Amplifier for These Speakers?

Discussion in 'Analog & Mixed-Signal Design' started by Zohar, Oct 12, 2016.

  1. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    Hi

    I have these 2x3W Speakers:



    [​IMG]


    They are not connected to anything, and I want to buy them an amplifier,
    so I can connect some Line Out of it, and thus use the speakers.


    I saw this amplifier, and it seems nice:

    [​IMG]

    http://www.banggood.com/BlitzWolf-B...r-Digital-Car-Amplifier-FM-MP3-p-1053566.html


    This amplifier is based on a TDA7297 amplifier chip.

    My question:
    Is it a good amplifier for these speakers?

    And,
    is there any better option for them, in addition to this one?


    The important parameter for me is not high volume, but sound quality.


    Thank you
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,934
    383
    It will drive your speakers just fine providing you are very careful with the volume control.
    RMS Power is 20W *2 Channels, and the actual output power is 10-15W.
    It will destroy the speakers with ease if you turn it up.

    The biggest determinant for sound quality isn't the amplifier, it's the speakers and the enclosure they are mounted in. They don't look particularly hi-fi to me.
     
  3. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    Hi AlbertHall

    Thank you evry much for your reply.

    So from what you say, because the amplifier is 2x15W, and my speakers are 2x3W,
    it means I should really be careful when rotating the volume potentiometer?

    Thank you for this, I will be sure to be careful.


    BTW, I have a small idea..
    Maybe I can modify the amplifier (whichever one that I buy) so the volume potentiometer will not reach above a certain level?

    Is the potentiometer in amplifiers connected in such a way, that more volume = more resistance from the pot?
    Or the opposite way, more volume = less resistance from the pot?


    If more volume = more resistance, then I can modify the amplifier by replacing the pot to be one that is a 1/5th resistance of the current pot that they use.
    (1/5 because 15W to 3W)


    If more volume = less resistance, then I can modify the amplifier by adding a resistor in series with the pot.
    The resistor's value will need to be 4/5 of the resistance of the current pot that they use..

    Are these solutions good?
     
  4. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,934
    383
    No, that isn't going to work because the volume doesn't only depend on that pot. The input level also changes the volume. So wherever you set the pot, a big input can still produce the maximum output power and I don't know how long it would take to damage them. It is unlikely they would be damaged immediately so, with care, it should be OK.
     
  5. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    I understand.

    OK thank you very much.

    BTW, might there be a smaller amplifier that will be good here?
    (smaller in size)

    And also, are there 5v amplifiers, that give a good sound quality?
    I ask about 5v because then it can be powered by a USB Power Bank..
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    Those look like inexpensive, small speakers so your sound Fi is not going to be very Hi. ;)

    Typically a pot doesn't vary the resistance to control voltage, it varies the position of the wiper on the pot to give a voltage divider effect and vary the voltage out.
    To reduce the maximum volume you would need to add a resistor in series with the top end of the pot that has the signal coming in (not the wiper).
    You'd have to experimentally determine the value, but I'd start with a value equal to at least the pot resistance.
    Note that for stereo there may be two ganged pots and you would need to add resistors to both.'

    Edit: A 5V bridge amplifier would give you a maximum output power of about 3W into a 4 ohm speaker, so that would be the maximum power you want.
    The quality of the sound depends upon the quality of the amp.
     
    Sinus23 likes this.
  7. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    The speakers' diameter is 11cm..
    They are not small.. :)
    (medium, I would say)
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,753
    760
    Why not get a bluetooth speaker
     
  9. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    Well,
    good queestion actually.
    BT Speakers are so wide spread today, and quite cheap.

    The story of the current speakers, is that I took them apart from a synthesizer I had used a lot in childhood.
    I remember their quality, it was very good (despite what people might think from their picture)

    As can be seen their mfrr is Yamaha..
    They are from the good days where things were mfrred in Japan..

    So I thought to use them..

    Also they are 11cm in diameter, what you will not get from a BT speaker..
    (at least not from most of them)
     
  10. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,753
    760
    If you desire quality..3 things to keep in mind.
    1. Quality Source, not crappy MP3's. I use Original CD's
    2. Quality Amp. Not BTL's. Single class A or AB, low distortion Amps. I built the ones from Elliot.
    3. Quality Speakers. 2 way or 3 way.

    Sound is unbeatable
     
  11. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    Thank you for the tips..

    What amplifiers are under "BTL"s?
    Is the TDA7297 that I mentioned here a BTL?
     
  12. tcmtech

    Well-Known Member

    Nov 4, 2013
    2,034
    1,653
    I wouldn't worry about burning them out too easily with a 20 watt rated amplifier. Most of those small lower wattage speakers take a substantial amount of overloading surprisingly well.

    Typically you will hear the voice coil bottoming out on hard base notes well before you reach the instant burn down wattage point. ;)
     
  13. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    Yes, the TDA7297 is a bridge tied load (BTL) amplifier.

    Here's a relativly low distortion BTL amp that will operate from a 5V supply.
     
  14. Zohar

    Thread Starter Member

    Nov 19, 2015
    34
    0
    Oh.. nice to know..
    So this is a warning sign, thank you


    Is the TDA7297 a Class D amplifier also?

    Thank you
    I am looking for a ready made module tho..
    And not to buy a single chip..
     
  15. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    No.
     
Loading...