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Yamaha 8" speaker replacement

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Yamaha 8" speaker replacement

Postby shufflebeat » Tue May 18, 2021 7:15 pm

I have a couple of old Yamaha msr100 powered speakers, one of which has developed a nasty growl. A new replacement driver looks uneconomic and could take months for parts, a recone may or may not be possible.

There is a version of the Stagepas (300) which uses what looks like a similar 8" low driver.

Anybody got any insight as to whether parts are interchangeable or whether there's another 8" that'll do the job?
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Re: Yamaha 8" speaker replacement

Postby Wonks » Tue May 18, 2021 10:22 pm

They share the same HF driver, but the woofers look different.

Yamaha AAX4222R for the MSR100

Yamaha AAX6165R for the Stagepas 300

MSR100 driver here, but as you say, it's expensive, about £109 with VAT.

https://www.proaudioservice.co.uk/produ ... -aax4222r/

The performance of the enclosure will be heavily reliant o the T/S parameters of the driver, and without knowing those, I wouldn't really like to speculate what may be suitable.

Probably cheaper to look for some used Alto TS308s or TS310s, which you can get for around £200-250 a pair if you look around and get lucky. They are often well overpriced (often more than available new) .
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Re: Yamaha 8" speaker replacement

Postby shufflebeat » Wed May 19, 2021 6:42 am

Thanks for that. I've been in touch with PAS and got the same numbers but parts aren't immediately available, est. 3 months delivery time.

At the minute I'd be prepared to compromise sound character on both soeakers for something useful that won't pull itself to pieces.

It may be unrealistic but otherwise I have one elegant doorstop.

Alto has already had some of my money and won't be getting any more.
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Re: Yamaha 8" speaker replacement

Postby Wonks » Wed May 19, 2021 7:29 am

Have you tried turning the speaker round by 180°?
Sometimes gravity will cause the cone to sag downwards, and the voice coil can then start to catch. Rotating the driver can sometimes offset this.

Otherwise, do you know what the speaker ohmage is? I’d assume 8 but you never know. Can’t see any obvious values printed on the chassis in the pictures.
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Re: Yamaha 8" speaker replacement

Postby Wonks » Wed May 19, 2021 7:51 am

The other consideration is the space available within the speaker enclosure. There’s this £45 Celestion 8” driver, https://www.lean-business.co.uk/eshop/c ... 9qgt52msq5 but its magnet looks a lot wider (but flatter) than that of the Yamaha’s. Depth can also be an issue as the amp PCBs can often be mounted directly behind the speaker.
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Re: Yamaha 8" speaker replacement

Postby shufflebeat » Wed May 19, 2021 8:19 am

Thanks W, I know it's irrational but I have a soft spot for the name Celestion.

At first glance I think there's enough space to accommodate that but will get the divining rod out and check.

Should I expect to see any kind of false reading on the meter if the coil is damaged but intact?
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Re: Yamaha 8" speaker replacement

Postby Wonks » Wed May 19, 2021 8:28 am

It’s obviously working, so you should measure the normal DCR reading. if there was a short between two adjoining coil windings, then you’d hardly see any difference in the readings. A short to ground would probably cause any short circuit protection in the amp to kick in and the speaker not work at all.

An open circuit is the most likely other sort of reading, but as the speaker makes a sound, that’s very unlikely.
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Re: Yamaha 8" speaker replacement

Postby shufflebeat » Wed May 19, 2021 6:05 pm

Speaker is reading 5.7 ohms, not a number I was expecting but it's consistent pre/post a good jiggling shake so I'm thinking there's no temporary situation going on.

I'm reading this as an 8ohm speaker unless advised otherwise as it seems relatively safe to err on the higher side if I must. The original was advertised as a "custom" driver but I'm not sure if that extends to a custom impedance.

Another thought comes to me. As the original is a foam surround with apparently quite a long travel is it worth considering something similar rather than a paper surround which I would think has a much stiffer response and shorter travel.

As you might guess I'm way out of my comfort zone here.
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Re: Yamaha 8" speaker replacement

Postby Wonks » Wed May 19, 2021 7:04 pm

That's about normal for an 8 ohm speaker. Its impedance varies with frequency and any audio frequency signal will see a higher value than the DC reading.

'Custom' drivers are often only marginally different to standard range drivers, often only 'custom' because it's got a different sticker on the back or the assembler's own part number on it. I wouldn't worry too much about it.

No idea about the foam. Without knowing the T/S parameters of the original driver and comparing them with the Celestion's, then you'd be guessing as to what the differences may be. The overall efficiency of the MSR100 should have been 92dB for 1W input (based on 112dB for 100W). The Celestion is quoted at 94dB for 1W, so it may in fact have more travel than the original speaker, as its got to shift more air to be that bit louder. The speaker diameter is the same so the overall movement of the Celestion must be greater.

You'll end up with the speakers sounding a bit different anyway and 92dB vs 94dB isn't enough of a difference to worry about.
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Re: Yamaha 8" speaker replacement

Postby Murray B » Wed May 19, 2021 8:51 pm

As a MSR100 fanboy (despite their limitations) , I am wondering if it's worth you buying another second hand MSR100 - there are a couple on eBay for the same price as a new driver. Your problem speaker could then act as a future pars donor?

If you decide to get some new speakers instead I might be interested in taking the old ones off your hands. They make very nice monitors - just wish they had an XLR through / link :headbang: to save me using splitters.
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Re: Yamaha 8" speaker replacement

Postby shufflebeat » Thu May 20, 2021 6:41 am

Food for thought.

I shalll peruse my options, cheers Guys.

@Wonks, thanks for the guidance. Very helpful.
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