Amp is too powerful for daily use

Discussion in 'Hi-Fi Stereo Systems & Separates' started by MikeyDread, Aug 12, 2019.

  1. MikeyDread

    MikeyDread
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    I recently bought a 1980s Toshiba SA-R1L receiver/amp, along with Toshiba turntable + cassette deck.
    It is proving to be too powerful for daily use in my living room. I am forever adjusting the amp volume sliders, right at the bottom of their limit.
    * Radio: for low-volume background music and talk stations I have one channel on 0 and the other on 0.5 (out of 10)!
    * Cassette deck: 0.5 on both channels is loud enough. The tape deck does not have a volume control.
    * Turntable: not quite so bad, I can go up to 1 on both channels. The turntable does not have a volume control.

    My speakers are 10W, 4 ohms. They are easily loud enough for the room.
    The amp is rated at 20W x 2, 4 ohms.

    Anything I can do to alleviate this problem? For example:
    * Get 20W speakers
    * Use an in-line attenuator
    * Get a 10W (or even a 5W) amp
     
  2. DT79

    DT79
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    The problem is not wattage, it’s gain. Of your suggestions, the one that will make a difference is the in-line attenuators.

    Less sensitive speakers would also help (expressed as loudness measured at 1m away per 1watt of input power - ##db @1m/watt). This is different from the power handling expressed in Watts.
     
  3. noiseboy72

    noiseboy72
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    I would suggest there is a fault somewhere if you are setting the gains that low!

    You could use some in line attenuators. I would start with 12DB from the levels you are suggesting.
     
  4. MikeyDread

    MikeyDread
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    @noiseboy72: Could you suggest an online retailer that sells audio attenuators?
    TIA
     
  5. Ugg10

    Ugg10
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  6. MikeyDread

    MikeyDread
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    The tape deck is a Toshiba PC-G2T. Output spec is LINE: 0.4V
    The turntable is a Toshiba SR-B2 with C-62M cartridge. Output voltage spec is 0.6 mV/cm/sec
    The amp is a Toshiba SA-R1L. Input sensitivity spec is:
    PHONO: 2.5 mV
    AUX: 150 mV
    TAPE: 150 mV
    Speakers are Samsung PS 6700 10W 4 ohms, from 1990s midi system.

    If you want more specs, I have Owner's manuals for the Toshiba components. I could possibly upload photos/scans.
     
  7. noiseboy72

    noiseboy72
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    I don't know of anyone who sells them ready made these days, but they are easy to make using some resistors. Depends what your soldering skills are like!!

    This does sound like more of an issue than just dropping the level, as the phono and radio inputs should be correct. I remember an old unit Dixons in the UK used to sell where the minimum volume was deafening but it only went up slightly when you turned the volume control. That was just poor design and not a fault and they withdrew the product, but in your case, it sounds like the volume control might be faulty - probably a missing earth, so the effectiveness of the controls is diminished. They could also have been replaced incorrectly in the past?
     
  8. Mark.Yudkin

    Mark.Yudkin
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    The Rothwell attenuators (Attenuators) are well known.

    That said, I rather feel that your Toshiba SA_R1L needs servicing. The symptoms you describe are not normal and the published specifications of the Toshiba do not give cause to suspect issues of the sort you describe.
     
  9. Paul7777x

    Paul7777x
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    I would normally suggest attenuators too.

    But as the problem occurs with the inbuilt tuner as well, it sounds like the problem is with the receiver itself.

    Or the speakers.

    Hate to be rude, but they are truly horrid speakers; wouldn’t take much to damage them I’d say.

    Have you got any other speakers, or can you borrow some, to test with it? Any kind will do.
     
    Last edited: Aug 12, 2019
  10. Paul7777x

    Paul7777x
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    ...also, it’s possible that the sliders need a damn good cleaning.

    Especially if there’s momentary crackling when moving the sliders?

    My mum had an old cd unit thingy with a slider control and the volume was all over the place.

    Some contact cleaner, a fistful of cigarette papers and some wiggling about sorted it.
     
  11. MikeyDread

    MikeyDread
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    I have tried some contact cleaner on the volume controls. It didn't improve matters -- is it worth taking the top off and having a go from the inside?
    So do I need to use 20W speakers with a 20W amp such as the Tosh SA-R1?
     
  12. Ugg10

    Ugg10
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    The watts rating on the speakers is pretty meaning less unless your amp is significantly above and you play them full volume. The issue may be the sensitivity but the symptoms you are describing do not equate to a difference between the sensitives of range normal speakers (usually max 6dB, 86-92dB/W/m). Unless you can get borrow a set of speakers of know sensitivity that make a difference then it is difficult to answer (and TBH I would not loan you a pair if I know that the amp would send full power to them with almost zero on the volume knob).
     
  13. jimster99

    jimster99
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    Can you ask the national grid to turn down the electricity from 240v to something a bit less powerful, maybe 183v? :)
     
  14. RBZ5416

    RBZ5416
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    I'd say the issue is the speakers. Impedance is too low & probably sensitivity too high.
     
  15. Paul7777x

    Paul7777x
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    Ignore the amps power output, it doesn’t figure in this. You’d need 800 mighty watts to cause what you’re hearing.

    If the slider is a sealed unit, and it likely is, then there’s little you can do about it except remove it from the amp and soak it for a goodly while in contact cleaner, and hope it has some effect.

    However, I’d also expect a bit of crackling on movement if the sliders are rogered. Still worth the effort though.

    When you sprayed it, did you wiggle the slider back and forth like greased buggery?

    Also, if it’s been stored for a while, any gunk on it could easily have turned to corrosion.

    I’d whip the lid off, make sure there aren’t mice setting up home in there, make sure there’s nothing obviously amiss and see if the sliders can be removed for better access.

    Perhaps they’ll have a ref number and can still be found...

    But I still suggest you find different speakers to check out too.
     
    Last edited: Aug 12, 2019
  16. Khazul

    Khazul
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    It would seem to be an excess input level problem to the amp. Those quoted figure seem to be excessively low and way below common modern specs, that said, even for the given specs something else is probably wrong as well - as suggested, sliders maybe.

    There are a bunch of vendors of attenuators on amazon.
    For eg: https://www.amazon.co.uk/s?k=rca+attenuator

    The Rothwell attenuators are good of course (should be at the price), I use a pair myself, however they will probably cost more than you paid for the amp or speakers.

    If you can, I would put amp and speaker on the shortlist for replacement with something modern, decent and appropriately priced for whatever budget you have.

    Vintage gear is often just old and trouble as you are discovering - nothing classic or endearing about it at all. Things that were possibly part of a set of components (matching amp and speakers, but you only get the speaker or amp, or they were designed to work with a specific tape deck, or turntable etc) are just yet more trouble and just exist to trap the unwary and should have been put out of our collective misery at the bottom of a landfill years ago.
     
    Last edited: Aug 13, 2019
  17. Khazul

    Khazul
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    :rotfl:

    My vote would have been large hairy spider :)
     
  18. MikeyDread

    MikeyDread
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    The amp-turntable-tape deck were all bought at the same time. I have the original receipt from 1983 (£250 from Currys)!
    So I would expect the components to be matched OK and no problems with input levels to the amp.

    The volume sliders seem OK to me. No crackling. But I will take the top off and have a look.

    I will investigate some alternative speakers.

    Also attenuators. There is obviously a market for these in the hi-fi world. Maybe others out there have a similar problem?
     
  19. MikeyDread

    MikeyDread
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    The User Manual specs seem to indicate that 4 ohm or 8 ohm speakers can be used. This seems reasonable, for a home system that will not be overdriven.
    Would you recommend that I use 8 ohm?
     
  20. RBZ5416

    RBZ5416
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    Yes, it will immediately halve the power. If the amp is rated at 20W into 8 ohms then if it does indeed support 4 ohms, the power virtually doubles to 40W. It's also likely that your speakers are very sensitive to allow them to produce high volume from a low powered amp. So proper HiFi speakers will also likely be less sensitive (quieter). Any chance you could borrow a pair of HiFi speakers to try? If not you could probably pick up something cheap & cheerful to tide you over from Gumtree or Facebook Marketplace, maybe even Freecycle.
     
    Last edited: Aug 13, 2019
  21. MikeyDread

    MikeyDread
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    I contacted the person who sold me the amp and the other Toshiba stuff. They have a pair of Toshiba speakers for my system, but wanted to keep them. I have offered £20.
    If they are the original speakers, they should match my amp perfectly.
    Will report back in a couple of weeks.
     
  22. dogfonos

    dogfonos
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    If, at the volume settings you describe in post#1, you can't hold a conversation (albeit talking slightly louder than normal) when around 8 feet in front of the speakers, then I think something is broken, probably the amp/receiver. You could effect a (temporary?) solution by adding attenuators on the inputs or buying less sensitive speakers but you'll not solve the real cause of the problem and the amp/receiver could pack up at anytime.

    I understand the logic in getting it serviced but that will likely cost you more than you paid for the thing (did you really part with money for a 35 year old, low-powered receiver?). Personally, I wouldn't spend more money on it. Was it sold to you 'in full working order'? I'd be tempted to ask for a refund then come back onto this forum and ask for advice/suggestions before heading back into the market.
     
  23. Jampot90

    Jampot90
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    Does the receiver have tape out as well as in connectors on the rear and a tape monitor button?

    The principle of attenuators described above is sound but of course the integration of the Toshiba doesn't lend itself to using them in the normal manner. If the tape in / out and monitor button are present you could fit short attenuated cables between them and listen permanently via the monitor button. The cassette deck can then be used via the aux in.

    Flashback Sales will make you a set of phono leads with attenuation built into the the phono plugs. I use their cables extensively (including an attenuated set between pre amp and Leak Stereo 20 valve amp which has very low sensitivity) and find them great to deal with.

    Phone them rather than ordering from the web site so you can ask for short lengths of their basic (i.e. cheap) wire with attenuation to keep the cost to a minimum (it's an experiment after all). The attenuation seems to add about £12 to the cost of the cable so you might get fixed up for a little over £30.

    Attenuated Phono/RCA - Phono/RCA Cables

    Phono/RCA - Phono/RCA Cables

    Jim
     
  24. nigelt

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    My suggestion would be find a tech who can modify the volume control circuit with a couple of resisistors so that you have a better range of movement of the slider. Like many products, most of us only use the botton 1/4 (or less) to give normal volume. This would give you slightly less volume at full, but not an issue in your case.
     
  25. Paul7777x

    Paul7777x
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    There is really no need for attenuators with the sources you are using.

    It is clearly not a source problem as the issue is the same with the inbuilt tuner.

    If the tuner worked properly re the volume then there’d be a case.

    I’d strongly suggest you simply bin it. It’s clearly rogered somehow and it’s very old indeed.

    Giving the same seller more money is perhaps, erm... not wise.
     
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    Last edited: Aug 17, 2019 at 7:29 PM
  26. RBZ5416

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  27. Cliff

    Cliff
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    Not a source issue if the radio and turntable are too loud. Not a speaker issue either. The gain is just too high and cannot be reduced properly by the volume sliders.
    Just as an aside, are the aux inputs all RCA phono sockets? If they were DIN then the sensitivity would be high. The spec was different to RCA.
    Anyway, assuming they are all RCA inputs then you need the unit serviced. Could be something simple like the ground on the volume sliders has gone high. To test this, if both sliders are at minimum, do you hear anything, or is it muted?
    But, don’t waste money on it.
     

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