Sound Improvement with better Speakers on a Sharp GF 9191

Discussion in 'Tech talk' started by DX7boy, Oct 16, 2024.

  1. DX7boy

    DX7boy New Member

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    I'm going to get a good looking Sharp GF 9191 from a friend this weekend.

    I once had a 9292 and I know that it sounds really bad and I also know the 9191 seems to be a bit better but still crappy compared to a JVC RC M70 for example. It hurts in my ears at higher volumes and always sounds muffled.

    So I'd like to replace the speakers. I thought about buying a Universum Super Sound 1600 aka Telefunken CR 8200 for example, which has the same speakers like the M70 but with 3.2 Ohms which would fit perfect into the sharp. If I paint them white and change the Dustcaps it would look original. Would that work or is the Pre Amp Section optimized for that speakers so I'd make it more bad with a different pair?

    As an alternative I also tried to find new speakers in the same size but the highest SNL i found is around 94 dB which shouldn't reach the high volumes it reaches with the original speakers and of course I don't want to pay hundreds of bucks.

    Maybe there are some old original car speakers which would fit? I know that the door speakers of the Golf III for example sounded quite good and they are relatively cheap to get on ebay, they have 4 Ohms and have 165 mm. Idk the SNL of them…

    I know that the components of the GF 9191 are quite good, so I guess it could sound better. With the original speakers it's useless for me because even my Philips D8434 sounds much better than the Sharp but I like the Sharp because of the design.
     
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  2. Hyperscope

    Hyperscope Well-Known Member

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    Interesting possibilities and some potential there. I don't know how much, or if at all, the speakers were carefully matched to the amp in these boxes like the Sharp's.

    Considering how some of these Blue Tooth speakers seem to be able to put out amazing "loud noise" I often wonder what upgrade possibilities exit with that... BlueTooth amp and speaker core transplant into some ugly undesirable old boombox. To create some kind of monster / sleeper that looks like garbage but can somehow rattle the windows :devil: Just some musings... I bet someone out there has done it though.
     
  3. Reli

    Reli Well-Known Member S2G Supporter

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    Something has to be wrong with your Sharp if it doesn't sound as good as a Philips D8434. It's not going to sound as good as a JVC M70, but it was still one of the best sounding boxes of 1978.
     
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  4. Cassette2go

    Cassette2go Well-Known Member

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    Well here I have a sharp GF-9696 and then I have a GF-305st
    17292047061397223038273227045178.jpg
    I don't remember if the g f- 305 is the same as a 9191. I'd have to go to the web to figure that out, but it's the only model that I have that's close to the 9190 or 929 0 or whatever lol
    17292048885117464955678394818088.jpg
    Yes, in the middle is a JVC RC m71 with no handle and a cassette stuck in the deck. 17292051190292863486755957858747.jpg
    Sharp JVC and sharp again
     
  5. DX7boy

    DX7boy New Member

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    that would be an interesting comparison!
     
  6. Cassette2go

    Cassette2go Well-Known Member

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    Compare them using what? There's all kinds of ways of comparing things. Don't have any direction here so don't know what you're interested in.
     
  7. soluna

    soluna Active Member

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    Could it really be, that the sound of GF 9191 is so bad ? We had a GF 9090 with a very good sound, and the bass-middle speakers have the same diameter, may be, they could fit. But bad sound also could come from the high speakers.
    And may be- the reason isn`t to find in the speakers - i guess there`s someting wrong with electronics.
     
  8. Silverera

    Silverera Active Member

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    I have a refurbished GF9191 which sounds OK for a 1978 BB. The bass wasn't as I expected when it arrived but it was in near mint condition and I don't think this generation of portable gear had much of a bass response. The emphasis seemed to be on loudness rather than the EQ. So as I have done with other boxes I generally use a line out into a small Bluetooth speaker like a Bose. Sound is greatly improved without tampering with the original build of your GF9191 and looks pretty much like a soundbar addition to your favourite boombox.
     
  9. Silver965

    Silver965 Well-Known Member

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    There are few differences between the two
    They have the same amplifier that mounts a power amp per channel
    Sharp calls it RH-IX1020AFZZ but in fact it is an old
    TBA810s... the net is full of amplifier diagrams with this chip
    If yours is not feeling well...I would check the power supply and the capacitors of the motherboard...first of all

    gf 9090-91.jpg GfAmp.jpg
     
  10. DX7boy

    DX7boy New Member

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    Well, i didn’t have it. A mate called me a few days ago he have some stuff for me and the GF was one Piece of that. I Visited him yesterday. Have to wait for the replacement Parts for the Cassette Deck, i am glad that the Motor is Working After cleaning it. I Hope W&F will be ok. Can Not Check it before the Parts arrive.

    What i did yesterday was fixing the Treble and Bass sliders, they did Nothing anymore. They don‘t Turn Smooth after fixing but it works now.

    But i noticed that the Left VU Meter don’t shows the Values Like the Right. Even if i turn the Poti for the Adjustment on Full. It’s the Same if i press Record. I Hope there is no Bad Cap. Maybe i destroyed something when i desoldered the sliders.

    I cleaned also the rec Switch yesterday.

    Well my Memory about the Sound was a Lot worse than it is, but i miss some highs at the top. It‘s the warmer mid highs that gets boosted. M70 Sounds much crisper. Also it has no real Punch in the Bass. And it is as i Said: If i Place my philips D8434 in the right Position it Sounds a lot better than the Sharp at lower Volumes, i replaced the the Piezo tweeters with cheap permadyns and now the highs Are much crisper. It can produce a Lot of punch and comes surprisingly Deep But If You Turn it higher than Mid Volume the Magic is gone fast. Also the Cassette Deck circuit is budget is it produces no flat frequency response under 150 Hz while Radio Sounds very Full and Deep. I replaced the Head against a better one i had laying Around, so the Bass response is a Bit better now but Not the Same Like Radio.

    On higher Volumes the Sharp Wins clearly against the Philips.

    The sounding of the Sharp makes Sense. It comes out of a Time where Most Cassette Recorders Hardly reached the 12 kHz on Type I. Boost the treble over 10 kHz will just cause more Hiss then. Also Deep Bass was practically Not required for the Most Music. Rock and Punk at that time didn’t have that much Punch in Most cases.

    Tuning the tweeters will Not work Like i would prefer. I guess if i remove the resistor it will be louder but it will Boost the Mid highs so it will still Not Sound crisp, Maybe it Even hurts then because it’s no more balanced.

    i Need to find out First how the Pre Amp is Tuned and what the Bass and treble sliders/loudness do on external Speakers or headphones. If it just boosts the Bass Around 150 Hz and the highs Around 8 kHz it will Sound midsy/hummy if i Change the Speakers to ones Like in the M70 i guess.

    Adding an external BT Speaker to the pre amp out doesn’t make Sense to me. I want to use it as it was made. It loses it‘s mobility if i Need to add some other stuff to it.

    The amp is Absolutely ok. No distortion, only on high Volumes, Both Channels reach the Same volume.
     
  11. Cassette2go

    Cassette2go Well-Known Member

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    ? cheap ? ( permadyns - is this the correct spelling) ? Can you share a link to these tweeters and a better spelling?
     
  12. DX7boy

    DX7boy New Member

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    I don’t have the link anymore. I bought them on Ali express. 10 for 2,50 or so. They have 8 Ohms but they fitted in the holes of the Piezos and the Are Thin. They Are the Kinda you find in old handheld Video Games or watchmans or so. Of course it‘s not a real tweeter but with a capacitor it does the Job on the Philips without that hissy Dirty Sound of the Piezos.

    I Tested a few tweeters yesterday i had laying Around. 2 from an M70, 2 from an old LOEWE TV and 2 from a Senator Boombox. I First desoldered one of the Original tweeters of the GF 9191 and then connected one of each to an amplifier. Then i played a 10 kHz sind Wave and measuered which one is the loudest, i tried them all separately. The LOEWE and the M70 won. The Sharp was weakest although it had 4 Ohms while the others had 8 Ohm.

    Then i tried Both the M70 and the LOEWE on the Sharp. I just added one First to compare it with the original Tweeter on the other Side. Also desoldered resistor and tried it with and without and i also changed the polarity. Didn‘t notice a difference in Change of polarity so i changed it back to normal. The resistor makes a difference of maybe 2-3 dB so there is only the capacitor between the Woofer and the tweeter now.

    i needed to Cut out the edges on the tweeters, they didn’t fit First but the wholes were in the Right Position and now Everything was in Place.

    Then i put the Mains Plug in the Wall socket and the Moment of truth Came. Both M70 Tweeters were now connected to the GF…

    The curtains fell. It’s a difference Like day and Night. The muffled midsy Sound of the GF9191 is gone now. It Sounds brilliant and open and has crisp highs now. Much much better than before and it changes Nothing an the original Look.
     
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  13. Hyperscope

    Hyperscope Well-Known Member

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    Nice update report :thumbsup: Lucky you had the old M70 tweeters just sat there to use. But what if you didn't have them? What new off the shelf ones could a person buy that would be or could be as good? Ah... that is the question.
     
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  14. DX7boy

    DX7boy New Member

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    That's the thing! It was just by accident and I don't even know if those are the best tweeters I could have used for it, maybe there are other ones with a much better FR and even more SNL. Maybe there are some new car speakers for cheap out there which would sound better but in my experience everybody says "it won't work well…" allthough they didn't test it.

    if it would be easier to measure speakers everybody could test the ones in the blasters he got and we could make a Data Base for the best replacement speakers for units with good components but bad speakers. In some cases the the ribbings are hardened or broken so the speaker wouldn't sound as they did original anymore. I also had blasters with broken speakers and I didn't find a fitting replacement.

    So may there are some new cheap speakers out there who would fit and sound better, than the original ones, but we never know if we don't try because I don't even know the SNL of the original ones and also the frequency response etc… So the only thing that would help would be buying every cheap set of Car Audio speakers til around 50 or 60 bucks and check how they sound in a Blaster… nobody would do that, so we'll never know. We could may turn the GF 9000 into an M90 soundwise or make the GF777 much better… I know that people used the 3D Super Woofer Woofers from Hitachi for the GF 777 for example and they do a very good job, compared to the often worn out original woofers but do we know if it may even sound better with other speakers? Nobody can ever tell if we don't try.

    What I can say now about the GF 9191 16 cm Speakers: They are quite good and they are very bassy when the unit is placed well in the room. combined with those M70 tweeters it is not far from the M70 but the M70 has less distortion at higher volumes and more power. I guess for 1978 the GF 9191 maybe was the best blaster out there. There are many points which are unusual at this time. Especially the Cassette Deck. It has Full Auto Stop, APSS and a Frequency Response which will beat all other units, especially when you think about that it's just a GF 9090 with bigger Amp and all the 9191 has, the 9090 has also and it's from freakin' 1976. So the 9090 must have been an Alien at its time. As far as I know APSS is an invention by Sharp so nobody else had it at this point.

    Cheers Tobi
     
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  15. Cassette2go

    Cassette2go Well-Known Member

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    Correct me if I'm wrong because I can't remember because well that's another story. The gf9191 does not have a selector switch for line in and that's its downfall present day. Whereas the sharp GF 9090 and 9292 do have a selector switch for line in. Where is the odd 9191 does not.
     
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  16. DX7boy

    DX7boy New Member

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    I only know the european Versions, they all have a DIN socket for in and out, which is only for Recording or playing back through another machine.

    You can only select the Phono Socket, it is easy to Mod as a line in or you can use a Converter Box which converts the Line Signal to a RIAA Phono Signal. Most Boomboxes of that era don’t have a line in.

    Also it is possible to use the MIC Mixing Port as a Line in. It only is Mono and You have to be careful to Set Not the Level of the Source to high but it will work.
     
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  17. Hyperscope

    Hyperscope Well-Known Member

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    I have one of those "3D Super Woofer Woofers from Hitachi" in a 3D5 Hitachi that my was first actual dumpster find. I try to give it away to the right person when they walk into the office here. No interest yet...

    For great sounding modern ere boomboxes (early 90's) those ugly Panasonic Cobra head ones sound incredible. Old member here Reno aka Radio Raheem used to recommend them to those chasing audio quality and bass. So I searched e-bay and found a Panasonic RX DT707 on e-bay locally for $65US with dented in speaker grilles. Easy fix. Sounds fantastic. Can't believe it's a cassette playing. W&F is 0.10 too what a great dual cassette mechanism. Now I am praising these Panasonic's and sincerely recommend them to anyone actually interested in rich powerful bass and detailed layered sound from the dual amps :thumbsup: I should start looking at some of the higher end ones myself...
     
  18. DX7boy

    DX7boy New Member

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    Yeah. Also got a Panasonic RX DT680 which is basically the same but with detachable speakers. The Tape mechanism is great. Sounds very good with relatively deep bass and compared to the JVC Boomblaster the Batteries never get empty. But on mine the CD Player is broken. I g the Laser died. Doesn't read CDs anymore. I also bought mine for cheap. It's built well and not that ugly as the Cobras but not that beautiful than the older Panasonics.

    The Hitachi 3D5 is one of the tinier Models, it has only one Motor and tiny Woofers, works on 8 D Cells. Doesn't sound that good. I also had one, when I was a child. The bigger ones have 16 cm Woofers and more Power, they can sound really good with lots of Bass and they have 2 Motors on the Twin Deck so they reach better W&F although they have All Tanashin Mechanisms.
     

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