Impedance question - external speaker in parallel with internal

A

Asylum

Feb 20, 2022
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#1
Hi. Another impedance question (sorry!).

I have a Traynor Bass Mate YBA-2B amp and speaker combo (early 70s). My goal is to take a direct signal out in to my computer/DAW (for use with an impulse response) for recording. The Traynor internal speaker is 8ohms. I have one output on the back of the Traynor labelled “External Speaker”.

I am trying to determine the safest way (i.e. won’t damage the amp) to take the direct signal out.

I have a 16ohm load box, which I understand should not damage an amp expecting 8ohms (but I may get a loss in power or change in tone, which I’m OK with). But as the internal 8ohm speaker is still operational when I plug in the 16ohm load box, I believe I will be running the 8ohm internal speaker and the 16ohm external load in parallel, so I am not sure what impedance the amp will be seeing and how safe that is.

I welcome any advice on the safest way to take a signal directly out of the “external speaker” output of this amp.

Thanks.
 
#2
If the amp can handle a 4-Ohm load, then you should be fine. But....those two speakers are going to behave differently. The external speaker is likely to be louder, for example.
 
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#3
Thank you. I found some old documentation online that suggested that 4-Ohm was the minimum the amp can handle, so I think I should be OK. Thanks for your advice about the speakers behaving differently. I will experiment with that. I only intend to record what comes from the external speaker output (DI via a load box) so I think it will be manageable.
 
#4
From the OM that can be found here: Traynor-Bassmate-YBA2B-Manual-Schematic.pdf (thetubestore.com)
upload_2022-2-20_16-28-27.png


8 ohms and 16 ohms in parallel work out to 5.33333 ohms.
 
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#7
hbarcat said:
Just for reference, the formula for calculating impedance (r) for speakers in parallel:

1/r = 1/speakerA + 1/speakerB


So:

1/r = 1/8 + 1/16

1/r = 3/16

r = 16/3

r = 5.3 ohms
Click to expand...
hbarcat said:
Just for reference, the formula for calculating impedance (r) for speakers in parallel:

1/r = 1/speakerA + 1/speakerB


So:

1/r = 1/8 + 1/16

1/r = 3/16

r = 16/3

r = 5.3 ohms
Click to expand...

This is great to know. Thank you!
 
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