This is a review and detailed measurements of the accessory bass module for the JBL CBT J70-1 that I just reviewed. It was kindly sent to me by the same member and costs US $594.
My sample is still sitting on the measurement gear so I thought I just show you the stock picture:
Note that the 70JE-1 mounts on top, not bottom. I am not sure how stable it will be as the 70J-1 did not want to sit by itself all that much. So likely you need to mount these to a wall or something. A bracket is provided to attach the two speakers together.
As you see the 70JE-1 only has the bass drivers and lacks the "J curve" of the 70J-1.
Since this is a bass module, I limited by scan to 8 kHz and used my usual 1000 point measurements. Error rate was well below 1% up to 2 kHz which is way past or frequency of interest. Measurement temperature was 60 degrees F.
JBL CBT 70JE-1 Measurements
Let's look at our usual spin data:
Hmmm. Bass response is quite peaky an uneven and different than what Harman shows in their brochure:
In-room response confirms my measurements to be correct as seen in distortion plots:
Distortion is low:
Here is the 70JE-1 response overlaid on top of the spin for the 70J-1:
As I am speculating on the graph, I wonder if the sum would then fill in the response below the peak resonance and give us something close to what Harman advertises?
Harman only speaks of beam forming in the context of combining the two modules and how it can go lower in frequency now. Here are my directivity plots:
Vertical response is sure narrow but not constant. Maybe it is in a narrow margin of 500 to 700 Hz? I plotted that in at a few points:
Looks like it is working. At 300 Hz and below there is next to no control though as you get an omni response (not shown).
Edit: here is the impedance:
Conclusions
It seems to me that 70JE-1 is more there to increase power delivery at lower frequencies than to provide much of any extension. After all, it uses the same four drivers. As it is, the baseline 70J-1 has excellent power capability. I am imagine with the addition of 70JE-1, you get incredible amount of loudness. I think the company advertises crazy numbers like 120 dBSPL!
No, I have not had time to listen to the stack. I don't want to go through the work of attaching them together. I didn't export the data either as I am not sure how useful that is to have for a bass module.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
My sample is still sitting on the measurement gear so I thought I just show you the stock picture:
Note that the 70JE-1 mounts on top, not bottom. I am not sure how stable it will be as the 70J-1 did not want to sit by itself all that much. So likely you need to mount these to a wall or something. A bracket is provided to attach the two speakers together.
As you see the 70JE-1 only has the bass drivers and lacks the "J curve" of the 70J-1.
Since this is a bass module, I limited by scan to 8 kHz and used my usual 1000 point measurements. Error rate was well below 1% up to 2 kHz which is way past or frequency of interest. Measurement temperature was 60 degrees F.
JBL CBT 70JE-1 Measurements
Let's look at our usual spin data:
Hmmm. Bass response is quite peaky an uneven and different than what Harman shows in their brochure:
In-room response confirms my measurements to be correct as seen in distortion plots:
Distortion is low:
Here is the 70JE-1 response overlaid on top of the spin for the 70J-1:
As I am speculating on the graph, I wonder if the sum would then fill in the response below the peak resonance and give us something close to what Harman advertises?
Harman only speaks of beam forming in the context of combining the two modules and how it can go lower in frequency now. Here are my directivity plots:
Vertical response is sure narrow but not constant. Maybe it is in a narrow margin of 500 to 700 Hz? I plotted that in at a few points:
Looks like it is working. At 300 Hz and below there is next to no control though as you get an omni response (not shown).
Edit: here is the impedance:
Conclusions
It seems to me that 70JE-1 is more there to increase power delivery at lower frequencies than to provide much of any extension. After all, it uses the same four drivers. As it is, the baseline 70J-1 has excellent power capability. I am imagine with the addition of 70JE-1, you get incredible amount of loudness. I think the company advertises crazy numbers like 120 dBSPL!
No, I have not had time to listen to the stack. I don't want to go through the work of attaching them together. I didn't export the data either as I am not sure how useful that is to have for a bass module.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Last edited: