1. #1

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    I know these old Norlin Lab Series amps have been discussed here before. I believe our very knowledgeable member, Greentone, knows all about them. I have an L3 (single channel, 60W, one 12” speaker). Many years ago, I put a JBL D-120 speaker in my L3 and I ended up letting the original speaker go with another amp. The amp sounds great, but I am wondering if the JBL is really the best choice for this amp. A Google search turned up a number of threads where people said they put 4 ohm speakers in this model. It seems that the original speaker may have been a CTS, but I can’t seem to find out if it would have been 4 ohms or 8 ohms. My JBL is 8 ohms. Does anyone know what the amp was designed to use? And, if I did go for a 4 ohm speaker, how would that affect the performance of the amp?
    Thanks in advance,
    Keith

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  3. #2

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    Quote Originally Posted by floatingpickup
    I know these old Norlin Lab Series amps have been discussed here before. I believe our very knowledgeable member, Greentone, knows all about them. I have an L3 (single channel, 60W, one 12” speaker). Many years ago, I put a JBL D-120 speaker in my L3 and I ended up letting the original speaker go with another amp. The amp sounds great, but I am wondering if the JBL is really the best choice for this amp. A Google search turned up a number of threads where people said they put 4 ohm speakers in this model. It seems that the original speaker may have been a CTS, but I can’t seem to find out if it would have been 4 ohms or 8 ohms. My JBL is 8 ohms. Does anyone know what the amp was designed to use? And, if I did go for a 4 ohm speaker, how would that affect the performance of the amp?
    Thanks in advance,
    Keith
    I’ve got a service manual and even that doesn’t list the expected speaker impedance. I’ve owned an L5 and and L3, and in both cases, the stock CTS speakers sounded really good.

  4. #3

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    Quote Originally Posted by wzpgsr
    I’ve got a service manual and even that doesn’t list the expected speaker impedance. I’ve owned an L5 and and L3, and in both cases, the stock CTS speakers sounded really good.
    A couple of guys on the TDPRI forum have assured me that the original speaker was 4 ohms. They recommended a Celestion G12 Hot 100 4 Ohm speaker as a suitable replacement. A shop right here in town has that speaker in stock so I think I’ll give it a try. Funny thing, I still have the original schematic and it doesn’t indicate the speaker impedance, but one of the guys on the TDPRI forum shared his schematic, which says 4 ohms (image attached) Lab Series L3 speaker question-46a82aea-a5f8-473e-bd8c-dcea11d27df0-png