AW12 and AW15 dual field speaker info

[Corby Dawson]

Hi,

I've been going over the info several members have helped provide and I think I'm finally on track in my understanding.

Please let me know if I've made any wrong conclusions here!

 

1- There are two different dual field speakers for the AW12 and AW15 and they are not interchangable.

2- The AW12 has a 900 Ohm coil for biasing the 45 tubes and a 2500 Ohm coil in the B+ line.

3- The AW15 has a 790 Ohm coil for biasing the 2A3 tubes and a 2175 Ohm coil in the B+ line.

The speaker I have looks to be the one for the AW15.

To use it in my AW12 would adding a 120 Ohm 5 watt and a 330 Ohm 10 Watt in series with the respective coils work OK?

 

Thanks,

 

Corby

[Kent King]

Corby -

Those values are about right..I'd have to calculate the voltage drops to be sure of the wattage, but 5W and 10W should be about right.

Kent

[David C. Poland]

But what about the output transformers?  The  P-P 45's and P-P 2A3's have rather different requirements (compare data in a tube manual).    I would think the design and specs of the output transformers would be significantly different, in order to present the proper load to the output tubes, and that the AW-15 transformer has a higher wattage rating.   I would be uncomfortable using an AW-15 speaker on an AW-12 (and vice-versa) even if it seemed to play. My fear is mismatch would affect tube life  and cause other problems besides distortion.

My shelf AW-15 speaker (unrestored) has a part # 3573 stamp on the pedestal and also on the output transformer. My AW-12 pedestal speaker reads # 3569 (in the cabinet so I can't see if the same number is on the output transformer). I suspect both use the same voice coil but I have never checked. The AW-12 and AW-15 speakers have different basket castings. 

[Corby Dawson]

My guess is that the AW15 speaker with the rating for the 2A3 tubes would be a higher wattage speaker and would be OK to use in the lower wattage 45 tube amp.

 

Corby

David C. Poland said:

But what about the output transformers?  The  P-P 45's and P-P 2A3's have rather different requirements (compare data in a tube manual).    I would think the design and specs of the output transformers would be significantly different, in order to present the proper load to the output tubes, and that the AW-15 transformer has a higher wattage rating.   I would be uncomfortable using an AW-15 speaker on an AW-12 (and vice-versa) even if it seemed to play. My fear is mismatch would affect tube life  and cause other problems besides distortion.

My shelf AW-15 speaker (unrestored) has a part # 3573 stamp on the pedestal and also on the output transformer. My AW-12 pedestal speaker reads # 3569 (in the cabinet so I can't see if the same number is on the output transformer). I suspect both use the same voice coil but I have never checked. The AW-12 and AW-15 speakers have different basket castings. 

[Corby Dawson]

Dave, You are correct about the output TX not being compatible but since mine is bad I can replace it with one that matches the 45 tubes!

Corby