M90 Speaker replacement.

[mark]

Where can I find a modern replacement speaker for a M90?

 

[floyd]

Where can I find a modern replacement speaker for a M90?

What's wrong with the original speakers ?.

 

[mark]

they are in need of a restoration. I’d like to put some new speakers in it while I have the originals fixed.

 

[floyd]

they are in need of a restoration. I’d like to put some new speakers in it while I have the originals fixed.

If I remember right the m90 speakers are 6 ohm but I have used 4 ohm woofers with no problems. The 8 ohm speakers would work just as well . the m90 has enough power where it shouldn't make that big a difference .

 

[Superduper]

If I remember right the m90 speakers are 6 ohm but I have used 4 ohm woofers with no problems. The 8 ohm speakers would work just as well . the m90 has enough power where it shouldn't make that big a difference .

It’s important to remember that there is a difference between SE amps (single ended) and BTL (bridged) topologies. On SE amps, 4 or even lower impedance drivers (3.2 on the Sanyo m9994) are often used but BTL amps almost always recommend near 8 ohm drivers (jvc m70). That’s because with the BTL amps, an 8 ohm impedance will appear almost like how a SE amp perceives a 4 ohm load due to how a bridged amp pair operates in unison.

BTL Amplifiers and Impedance:

• BTL amps drive the load differentially, with two amplifiers pushing and pulling the signal across the speaker. This doubles the voltage swing, which can result in up to four times the power output compared to a single-ended amp for a given supply voltage.

• Because of this, BTL amps effectively “see” the load impedance as lower than it actually is. For example, a 4-ohm speaker in a BTL configuration might behave like a 2-ohm load from the perspective of each amplifier in the bridge. To avoid overloading the amplifiers, higher impedance drivers (e.g., 8 ohms or higher) are often preferred to keep the effective load manageable and prevent excessive current draw.

SE Amplifiers and Impedance:

• Single-ended amplifiers drive the load with one amplifier output referenced to ground. They typically handle a wider range of impedances but are less efficient than BTL amps. SE amps, are often paired with lower impedance drivers (e.g., 4 vs 8 ohms) because they don’t face the same effective impedance reduction as BTL configs.

I highly recommend you do not install drivers lower impedance than the factory 6 ohm ones, as the M90 employs a bridged amp system and 6 ohms is already on the low side for these types of amps. Consequences of installing lower than recommended impedance drivers include blown amps or drivers. In my experience, the Sanyo M9994 has a higher than average blown amp record as I’ve replaced those several times.

 

[floyd]

It’s important to remember that there is a difference between SE amps (single ended) and BTL (bridged) topologies. On SE amps, 4 or even lower impedance drivers (3.2 on the Sanyo m9994) are often used but BTL amps almost always recommend near 8 ohm drivers (jvc m70). That’s because with the BTL amps, an 8 ohm impedance will appear almost like how a SE amp perceives a 4 ohm load due to how a bridged amp pair operates in unison.

BTL Amplifiers and Impedance:

• BTL amps drive the load differentially, with two amplifiers pushing and pulling the signal across the speaker. This doubles the voltage swing, which can result in up to four times the power output compared to a single-ended amp for a given supply voltage.

• Because of this, BTL amps effectively “see” the load impedance as lower than it actually is. For example, a 4-ohm speaker in a BTL configuration might behave like a 2-ohm load from the perspective of each amplifier in the bridge. To avoid overloading the amplifiers, higher impedance drivers (e.g., 8 ohms or higher) are often preferred to keep the effective load manageable and prevent excessive current draw.

SE Amplifiers and Impedance:

• Single-ended amplifiers drive the load with one amplifier output referenced to ground. They typically handle a wider range of impedances but are less efficient than BTL amps. SE amps, are often paired with lower impedance drivers (e.g., 4 vs 8 ohms) because they don’t face the same effective impedance reduction as BTL configs.

I highly recommend you do not install drivers lower impedance than the factory 6 ohm ones, as the M90 employs a bridged amp system and 6 ohms is already on the low side for these types of amps. Consequences of installing lower than recommended impedance drivers include blown amps or drivers. In my experience, the Sanyo M9994 has a higher than average blown amp record as I’ve replaced those several times.

I understand now. Basically the btl amps are already pushing the maximum load and can't be taxed any further to drive a lower impedance load than it already has . so the 4 ohm speakers are a bad idea lol.

 

[BoomboxLover48]

Recently I learned about using the right impedance speakers for Speaker pairs A and B. I have several receivers and Carver HR772 is one of them. I remember Marantz warning on not to use different impedance speakers on speaker pairs A and B continuously.

The Schematics of Carver HR772 gave some valuable information on Simultaneous speaker operation.