Help Needed re Speakers Upgrade

Several years ago, I bought this: Hitachi Mini Hi-Fi Component System AX-M137

It works nicely. However, I want to know if it is worth upgrading the speakers, and what sort I should buy.

The amplifier output power is 50W x2, and the frequency response is 20HZ-20kHZ.

The existing speakers have an impedence of 4 Ohms and an input power of 50W

All advice gratefully received.

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14 responses to “Help Needed re Speakers Upgrade

  1. Well, you want some 4 ohm speakers that are rated to at least 50W RMS :)

    Depends if you’re unhappy with the current sound. What ones to buy would depend on listening to a bunch of different ones and hear what you like.

    I got my Soundcraft Absolute 2’s out the other day. Beautiful things, but too loud for this tiny flat with elderly neighbours, so I listened in the middle of the day to a few good quality things, then put them away again and went back to making do with these little computer speakers by the monitor. My dream is to have enough money one day to live somewhere detached. Or which at least has a kitchen I can’t touch opposite walls of simultaneously.

    Anyway, point is, depends what you like. I love my Soundcrafts, but some people think they’re a bit “toppy”. But then, I’m deaf in one ear and the other ear is a bit lacking at the top end. So it’s down to what sounds good for you, is what I’m saying.

    My though, but they’ve got some welly. Glorious thundering things.

  2. Thanks. Am I limited to 4 Ohms? Or can I buy more or less than that?

  3. That’s the impedance (resistance to the flow of current) through the speaker, and it’s a nominal figure. So a higher impedance speaker (normally, nominal 8 ohms) will work, but it will be half the volume. If you find something lower than 4 (unlikely) you’ll be in danger of drawing too much current from the amplifier and blowing it up, or at least popping a fuse. You should be looking for 4 ohm speakers to match the amplifier.

  4. For example, how about this:

    120 WATTS 6 OHMS

    But, since the amplifier has an output of 2x50W, is it worth looking for more powerful speakers?

  5. No. Speakers are passive. They can only reproduce the power supplied by the amplifier, in this case 50W RMS per channel. The 6 ohm impedance will also reduce that to less than 50W, and some amplifiers may not like the mismatched impedance [deletes technical stuff] for obscure electronic reasons. If you want more power, you need a different amplifier.

    Also, it is important to check that all your ratings are in “RMS”. This is the correct measure of ouptut power. Some manufacturers cheat by quoting other measures which produce an artificially high figure, such as “PMPO” (Peak Music Power Output) which is the instantaneous absolute maximum power for a fraction of a second and is a deliberately dishonest measure, or “Music Power” which is less dishonest but still overrates the spec for advertising purposes.

    If your amp is rated 50W RMS, you want 4 Ohm speakers rated at (at least) 50W RMS. A higher rated speaker won’t harm anything, but you won’t get any more out of it either.

  6. Chris Morriss

    Given that the existing speakers are 4 Ohms, then obviously the amp is able to drive an impedance down to that value. Any speakers therefore of 4 Ohms or above will be ok. Note however that 8 Ohm speakers will be taking only half of the current from the amp that the existing ones did, so will be approx 3dB quieter at any particular setting of the volume control, although this does depend on the sensitivity of the speakers. Basically you can drive anything, but keep away from speakers with a sensitivity of lower than 84dB per Watt as the amp may not have enough output power to drive them to your intended sound level. DD knows all about this sort of thing, didn’t you bounce the question off him first?

  7. I agree that I should have asked DD forst. However, I’ve been selling books like hot cakes for the past month, and have an overflowing PayPal account. And I want Mahler to sound like an earthquake in my kitchen.

  8. That’ll be a new amplifer and speakers you’re after then, Sean.

  9. Oh, I suppose I could just turn the volume up….

  10. The best speakers, in the past, in the UK, were made by people like Goodmans and Rogers. All speakers, to a first approximation, are now made in China like the rest of the gubbins. Or Japan still for some things. There is nowt wrong with Chinese gear. It is all of very high quality in general.

    If your amplifier channels are rated at 50w at 4 ohms, then you should buy any 4-ohm (impedance) speakers that you like the sound of best, on trying them in the shop. It is quite right that you could plug in 6-ohm or 8-ohm speakers and this will not degreade the sound quality, only the observed power. When Chris (see above) said that 8-ohm ones will be 3dB quieter, he means that they will radtiate about half the sound-pressure for the same amp output, but as the human ear is a logarithmic detector like the eye, they will sound about 65-70% as loud in the same room in the same conditions.
    Really, the speakers you have now are quite adequate for the amp, and it would be hard to notice a large difference in quality in my opinion between those and newer ones. But you should go somewhere knowledgeable and try variations, perhaps taking your amp with you to the showroom place. If they are serious audiophiles (there is such a shop here in a back street in Southport) then they will let you power up different cabinets with your own amp while sitting in the middle of a sound stage, and help you to decide.

  11. Sean, I would be happy to take the cabinets and build you a (probably better) speaker roundup in them than what you have. I expect I’d change at least the largest speaker cones, if not the others too. I would almost certainly throw out the “crossover” that is currently installed in each one (that is the little and fairly simple circuit that decides which frequencies go to which speaker cones.) I’d then produce my better ones for you from scratch. But it’s a bit difficult to get them here from Kent, and the benefit of my ones would be outweighed by the inconvenience and shipping nonsense.

  12. This might help, Sean.

  13. David’s post has reminded me of the four Goodmans 12″ bass drivers I carted around from place to place for years. They were 16 ohm (well actually 15 nominal, close enough) 120W, the intention was to build two 2×12 PA cabs out of them for 240W 8ohm per cab. But my live musical pretensions faded away, and they ended up just sitting in the boxes.

    Gave them to a friend who was helping me move with his van from London to Northampton about 7 years ago, who was a bit of a sound bod himself. I wonder if he ever used them.

    Goodmans don’t really exist any more, not in audio anyway. They seem to just import a bit of digital tat probably from China and brand it these days. They were a great company once though.

  14. I do remember that sketch very well, thank you! Indeed, I saw it on first run.

    I’m being nudged on FaceBook towards making a clean sweep and buying different equipment.

    I sold an astonishing number of my self-published books before Easter, and now have a swollen PayPal acount. If only I knew what I wanted, I’d run straight to E-Bay.