dsl40cr speaker cab question

[jdmarsh]

Hello. New here so forgive me if this has been answered.
JUst picked up a used dsl40cr. I have a spare speaker cab with an 8 ohm speaker in it. Can I use the internal speaker and plug the cab in also? If so, which inputs do i use?

 

[Creach]

Hello jdmarsh,

The internal speaker is 16 ohm, so you must have a 16 ohm external cab.

 

[fitz]

Hello. New here so forgive me if this has been answered.
JUst picked up a used dsl40cr. I have a spare speaker cab with an 8 ohm speaker in it. Can I use the internal speaker and plug the cab in also? If so, which inputs do i use?

to the forum.
The 40CR is a 5 speaker jack amp, so it is possible to mix speaker impedances if done correctly.
Put the internal 16 ohm speaker in one of the 1x8 / 2x16 jacks and the external 8 ohm cab into one of the 1x4 / 2x8 jacks.
This puts two 1/2 loads on the output transformer.

 

[SkyMonkey]

The internal speaker is 16 ohm, so you must have a 16 ohm external cab.

As @fitz said, the Marshall 5 speaker jack amps like the big DSLs, JVMs, Astorias, Studios, etc. can be used with a mismatched load.
But 1x16 ohms and 1x8 ohms is the only mismatch possible.
When you half load each 2x pair, the transformer sees a whole load.
This is on the authority of Santiago, who designed the JVM line-up.
(and I just bet he's sick of confirming it)

 

[Creach]

..

As @fitz said, the Marshall 5 speaker jack amps like the big DSLs, JVMs, Astorias, Studios, etc. can be used with a mismatched load.
But 1x16 ohms and 1x8 ohms is the only mismatch possible.
When you half load each 2x pair, the transformer sees a whole load.
This is on the authority of Santiago, who designed the JVM line-up.
(and I just bet he's sick of confirming it)

8R and 16R parallel : 5.33R, if i had to do it i will go to the 4R output.

But electricity always flow to lower resistance, so most of the sound will go to the 8R speaker, the 16R speaker will probably only receive half of the amp's output.