19 November, 2017

Brook 7

Click pics to enlarge: L: JBL system; R: Electronics.

Brook 7, Part III
Letter from NYC (74) 2017 (13): A Fine JBL Horn System

Article finished in HK.

For detailed info on the Brook 7, see Part I and Part II.

Time to catch up with some loose ends, though these shall evolve into the most significant of events, I predict.

Our team leader and friend Andy has such generosity in heart that he always tries to do best by his friends and cater to their whims of the moment. In order to let his friend R decide what horns to go for, with help from fellow JBL guru Simon he actually revamped his old dining room JBL system so R can compare Altec with JBL. But I got there way before R. System:

Loudspeaker System: JBL 2440 with 2390 horn and lenses with no baffle, JBL D130 in C34 enclosure with the 175DLH compression horn removed, a DIY crossover at 900Hz in place of the 1200Hz crossover that comes with the C34.
Amplification: Audio Research SP-8 and Canary 300B
Front End: modified Bogen B61 turntable with stacked platters in Baltic birch plinth, Rabco SL8 tonearm, Ortofon SL15T cartridge.
Cables: garden variety.

According to Andy, and Simon, who built the crossover, the JBL system is a close extrapolation to the one JBL loudspeaker that I like the most, the L300. Anecdote: Many years ago, I heard many JBL systems in close succession, but the one that impressed me the most, by far, was the L300, which was able to sail effortlessly between all musical genres, playing classical music with the utmost distinction, all in a compact enclosure.

Over lunch we heard the JBL system to great effect. A richer, more forgiving, yet detailed sound. I'd not elaborate, but Andy did express the interest to move the JBL system to where the Altec system now is. I'd help any time if I could. Similarly, I had not visited Simon in a long time, who now has a quasi-L300B system as I understand. Shall catch up next time.

Brook 7, Phono Resounding
This time, I actually tried the Phono section of the Brook 7. Unfortunately, one channel had a noise that I could not get rid of. But, although my loudspeakers are >100db, the noise was not intrusive enough that I was able to evaluate it. Suffice to say, the phono section was just as exemplary as the line section. I felt nothing wanting and was truly impressed. Due to the space constraint, I could not really change tubes to make it even better, but I am convinced by its greatness. I took it to Andy's and my opinion remains the same. There would be more.

One interesting thing is that, with the quicksilver horns, the preamp did not feel "slow" at all! Marvelous!


  1. Hi Doctor John,

    Following up on our discussion on the phono stage I have now moved to a Lehmann Black Cube and I'm also planning to buy the Denon DL-103, so thanks for all the good advice. I'm currently looking for speakers and I wanted to ask your opinion. To remind you that my amplifier is a Leben CS300XS (15 watts). I currently have a set of B&W which sound good but would like to move to something better. I have auditioned Harbeth who sound good but I feel generally lack bass (I did like the 7ES though), Stirling who I felt sounded really natural but again shy on the bass and Proac who I wasn't very excited about. I'm planning to audition Audio Note and I would like to include Tannoys. I was wondering what else I should be looking at, what you would recommend for my Leben? From your writings I understand you're very fond of horns and Klipsch, I have listened to Klipsch with the Audio Note Otto amplifier in the past and didn't like it but it might not have been properly setup. Generally what would you recommend to listen to? Thanks again, Peter K.

    1. Basically you are limited by the low power of your amp, and so higher efficiency loudspeakers are what you should go for. Harbeth and Proac don't belong in this category. Upgrading the phonoamp and cartridge shall bring you better quality playback (hopefully), but the power situation remains unchanged.

      AN is expensive for what it is, but perhaps older models are cheaper in the UK. They favor close to wall placement. If I were you, I'd take my time and broaden my investigation into vintage models. EMI loudspeakers are cheap in the UK and of great quality. So are older Tannoys (but they tend to be big, though the 10" old Tannoys concentric are not that big). I'd also think hard about old Spendor SP1 and BC1 - they are quite tube friendly. It's a vast world out there, but one has to be a little patient.

      Another thought: subwoofers are cheap. The Andrew Jones designed Pioneer subs are great and cheap. Add one and you may look at your B&W's with new wonder.