Brook Model 7 Preamplifier Glory

The units I am proud to own. Click pics to enlarge.

Glory: Brook Model 7 Mono Preamplifier, Part I

Note: Part II has been published. Substitution of the 6SJ7 results in major improvement. Also, in the short Part III, finally a brief test of the Phono Section! 

The Long and Winding Road
More than 10 years ago, when I was addicted to Ebay, I purchased a pair of the legendary Brook 12A's (2A3 PP) from a gentleman in Germany. I also simultaneously from the same seller purchased a pair of the little known mono Brook 7 preamps. I could find no info on the Brook 7, and I wondered whether I paid too much.

I still remember the day they arrived at my door. The packaging was not sturdy and a hole was punctured in the carton, with an edge of one of the amps showing. Luckily, no great harm was done. Talking about in the nick of time!

I hooked up the 12As to my Klipsch La Scala (Paul Klipsch himself used them with the mighty Klipschorn, and I could understand why), and they worked but both had a pronounced hum, likely in need of capacitor replacement. But even though the listening was necessarily brief I could tell these were great amplifiers. So lively, so direct, so much presence! They impressed in an instance and left an indelible memory. It is my fault that I never found time to restore them, but that is due to change soon, I promise.

Shamefully, I had to wait till January 2012 to hook up the Brook 7 preamps (here). Sacrilege indeed! But, very similar to my reaction to the 12A, the fleshy sound immediately appealed to me. One of the preamps was faulty, and I only found time recently, two years later, to rectify the situation by having a dear friend restore them, and they are now treasured possessions that I doubt I should ever part with.

Brook 7: Basic Info
There is still very little information on the internet, and I hope my article adds a little to the database. First, I quote a comment on Audio Asylum:

"...All of the Brook stuff is very fine. Their first preamp was mounted side-saddle on their super rare first version 30W PP2A3 amp. Then, the four knobbed type 3 preamp arrived, which umbilically powered up from the 10C (30W) or 12A (10W) PP2A3 amps. The model 4 preamp came, soon after, with 5 knobs and very versatile, switchable/variable phono EQ. It also stole voltages from either amp, or, a very, very rare external power supply. All of these preamps, so far, used triode connected 6J7 and 6SJ7 tubes...The model 7 preamp is a very desireable, self-powered preamp, with the same versatile EQ switching and very useable tone controls. Utilizing some miniature triode tubes, it's topography is similar to the preamp section found on their final amp offering, the model 22 integrated amp. Into the mid-'50s, designer/engineer Lincoln Walsh was the last, stubborn hold-out for all triode circuitry, while everyone else was racing to the higher power pentodes. He knew the triodes had the "natural sound."..."

Next, my comments on the features of the Brook Model 7:

• For detailed info, please read the 2-page brochure attached at the end of this article. The detailed specifications put many modern preamps to shame.
• The tone controls are among the most unusual I have seen. Tone controls are frowned upon by purists these days but they were ubiquitous back in the 40's and 50's. They are in the circuit and unless bypassed might as well be used. Please note that, unlike most cheaper designs utilizing a carbon pot, no expense was spared, as both treble and bass controls utilize a 10-position stepped resistor-capacitor ladder (click on top right pic). While the Treble Control clearly indicates position 8 as flat, and so mostly attenuates (click on top left pic), the Bass Control does not have such an indication on the front panel. However, if you look at the middle of the 3 tables at the bottom of the brochure, position 4 is flat and so boosts more than attenuates.. Also, unlike the treble control, the bass control is not independent of volume: note the first line in the brochure (under frequency range), the measured spec's were understandably conducted with the volume control at 7 (if you look at the left pic, this is at 1 O'clock, which is usually nominally in the flatest range of a carbon potentiometer used for the volume control). The bass boost is in addition to the defeatable "automatic bass compensation", which is what we usually know as "loudness control".
• Like many preamps of the time, there are provisions for many phono equalization curves. This would be very useful for mono vinyl fanatics (also, only one mono preamp would do! :-))
• As with designs of its time, it uses tube rectification. Like most others, a 6X4.
• As noted above, all preamp tubes are triode or triode-strapped. The tubes used, 6J7 (octal pentode, 1935), 6SJ7 (octal pentode, 1938) and 6C4 (miniature 7-pin single-triode, 1942) are common for that early time, which overlaps with Western Electric era, and long before the advent of smaller noval double-triode tubes like the 12AX7. Note also the 6C4 is electrically half a 12AU7.
• The phono section uses 1 x 6J7 (V1) and 1 x 6SJ7 (V2). The line section uses 1 x 6SJ7 (V3) and 2 x 6C4 (V4, V5) and seems to be an anode follower (hence better to avoid long interconnects) . I was told the circuit is rather unusual. I would love to learn more about the design and so if you have more to say on this subject, please post a comment or email me. Thank you in advance.

Epiphany (Listening)
First, associated equipment are as described in a recent article (System A in this link):

CD Transport: Sony BDP-S190
DAC: Arcam rDAC (also CAS through dongle)
Preamp: Kondo M7, Brook Model 7
Amp: Western Electric 124B (original)
Speakers: Yamaha NS-1000

As I have said above, even when faulty the sound appealed to me, and I was stunned after the restoration. Allow me to expand:

• First, This kind of sound is impossible to describe, so different it is to almost all other vintage and all modern preamplifiers. Although not without its faults (see below), it is on the same footing as Western Electric, and for me that is the highest accolade.
• I have only auditioned CD's through Input A. The sound is completely different from the Kondo M7. Every CD I played is a rediscovery, so different is the musical presentation. Our reactions to the WE133 amplifier can be equally applied to the Brook Model 7. To quote myself a little: "...the real WE sound is quite neutral, possessing transient speed, refinement and detail of the utmost order, fully up to par with modern gears. The WE has superior PRaT and conveys like nothing else the leading edge, phrasing and articulation of music. And all of this in a balanced whole..."
• The Kondo M7 (which also employs the 6X4 rectifier) is imho one of the very best modern preamps. It reveals more rhythmic subtleties and microdynamics than most rivals, but the Brook Model 7 trumps it in rhythmic finesse (though the Kondo is better with large-scaled music - see below).
• The Brook Model 7 is not without its Achilles' heel: with large-scaled symphonic music, it tends to loosen its control - no iron-grip of heavily regulated modern preamps here. This is no surprise to me, as this is a universal trait of vintage preamps (WE is the only exception). As my main diet is usually symphonic music, you can understand why I have always used modern preamps. I do own many famous vintage preamps (like Marantz 1 and 7, McIntosh C22 and C20, Harmon Kardon Citation I etc), have used others (like Eico HF-85) in the past, and have heard numerous others, but the Brook Model 7 is the only one that is able to make me forget its shortcomings. Again, a passage from my article on the WE133, a comment by my friend icefox, can be equally applied here: "...the WE just illustrates what is wrong with hifi...usually we spend all our energy listening very hard trying to identify what is good or bad about the system, fixating on one or two particular qualities...not so the WE experience; with WE we just listen to the music as an organic whole, relaxing and enjoying the experience...the WE goes straight to the essence of every type of music played and draws you in...it may not casually seem the most detailed at first listen, yet you find everything is there... " Note: Part II has been published. Substitution of the 6SJ7 results in major improvement.
• In my setting, the loudness control is defeated. With the Treble Control set at "Flat", there is plenty of air and space around the instruments. Simply Superb! When it comes to the Bass Control, I actually find it useful and prefer it at position 2/3 - this is likely because my Yamaha NS-1000, placed upon a wood platform (see pic above), suffers from a just little too much bass. However, even at the "flat" position 4 music is still eminently listenable. Of course, it should not be a huge effort to have the controls bypassed altogether, but personally I'd prefer to keep these rare vintage items as near original as possible.
• I wish I could evaluate the phono section and the efficacy of the various phono equalization curves, but that will have to wait.
• Tubes are what came with the unit, rather generic: metal 6J7's, metal 6SJ7's and GE 6C4's. I plan to roll in some tubes (for the line section) in the near future. I am sure performance can be taken to a even higher level. The amazing thing is, given my dislike of metal tubes, the unit still performs as miraculously as it does.

Conclusion A miracle! Please read also Parts II and III, linked above.

Links and Acknowledgements:

• There are some great pics at Radiomuseum.
• I thank Tom Bravis at Audiophool for the schematic.
• In addition to the PWK link for 12A above, the precious pics below of the Brook Model 7 brochure are from Iain at itishifi:

Spendor BCIII BC3 All Roads Lead to Rome

Spendor BCIII, BC3
Home Visit: limage, the CAS heretic
Talk CAS: All Roads Lead to Rome?

After covering the HiFi Show, let me return to the weekend before last. I reported my Saturday, which started with a visit to Wo Sir Sir before yumcha, and my time with feikeung after. The following day I found a little time and paid a long-overdue visit to old friend limage. But first, background on the BCIII:

Click pics to enlarge. R: pic of a recent pair from HiFiDo. I suspect this is now limage's pair; L: crossover pic from audioplanet-classical BBC coils, but wires not original.

Spendor BCIII BC3
Compared to its famous predecessor, the venerable 3-way BCI, the larger 4-way BCIII is relatively little known and reviewed. Both were designed by Spendor's founder, the legendary Spencer Hughes (this letter written by him is hugely informative), certainly one of the most important figures behind all the BBC loudspeakers of his time.

The Spendor BCIII loudspeaker was introduced in 1979. It is a 4-way design based on the classic BCI. It also used an additional 12" driver for bass reinforcement. For spec's of the BCIII, consult the informative owner's manual or the Japanese BCIII Page (computer-translated). For great pics, including internals, read the Spanish audioplanet thread (computer-translated).

BCIII begets Spendor S100/SP100??

My particular interest in hearing the BCIII centers on my long-time allegiance to Spendor, in particular the later SP100 (see my overview; originally S100; now in R2 incarnation). Although the SP100 is a 3-way, its size, driver and port arrangement bear more than a passing resemblance to the BCIII.

Spendor's website claims: "...the Spendor SP100R²...is an evolution of the Spendor BC3, S100, S100P, SP100 and SP100R loudspeaker systems...". Indeed, this is not just talk: as quoted in Art Dudley's Stereophile review of the SP100R2, "Spendor remains among the few high-end speaker manufacturers that design and make their own drive-units; indeed, as company owner and design director Philip Swift mentioned in a recent conversation, some of the tooling used to make the drivers in my Classic SP100R² review samples was used in the early 1970s, to make their classic BC3 monitor. That distinction, according to Swift, is more than just marketing fluff: "One of the things that sets Spendor apart is that we understand how our drivers work.""

Another loudspeaker that looks more than similar to the SP100 is the Harbeth M40, and many like to compare the two. But the M40, as with most of Harbeth's products, is more difficult to drive and imho has less of the "traditional BBC sound". In passing and if I may digress, I came across this revisionist history thread which should be of interest to BBC loudspeaker fans.

Home Visit: limage's den, click pics to enlarge.

limage Redux
It has been more than 3 years since I last saw limage. You must read or re-read my previous visit, which remains relevant to this article. This fastidious, stubborn and self-confident man has not changed one whit during all this time, which is to the good. limage does not change equipment frequently; he believes more in executing details (like cleaning pins and contacts).

When I last visited him at his glorious old house, he was using Maggies, so the change to the completely different BCIII came as a surprise. Another major difference is that limage has fully embraced CAS. The layout of the new house, in particular the audio room, bears more than a passing resemblance to that of old. The rest of his system:

Analogue: Technics SP10-(forgot what arm)-Ortofon A-90
Step-Up Transformer: Kiseki
Phonostage: EAR 834
CD Playback: Ensemble Dichrono combo (last generation; not auditioned)
CAS: Windows 7/J River/J Play/USB/DAC (HK DIY)
Preamp: Gnostic Technology 27D (HK DIY)
Amp: Conrad Johnson Premiere 1
Loudspeakers: Spendor BCIII

Some General Thoughts on the Setup and Sound

• If you know limage at all, you'd know whatever he chooses to play with will sound more similar than different (no better proof of his skills; and of course he is experienced enough not to choose equipment that will ill-suit him). What you see in the pics here is typical of his approach, in particular his "room-coupling" approach, yet another attempt at minimizing the room effect. Typically, the speakers are placed rather close to the side walls, in mid-room, closer to the seat than the front wall. In the old house, the Maggies were so close to the seat that the term "near-field" should perhaps be used, and everyone knows near-field more easily avoids room problems but is not for everyone. This round, the BCIIIs are relatively further away, more comfortable imho.

• I heard both CAS and analog, but not CD playback. Needless to say, I prefer vinyls. But, overall, the sound was definitely better than my last visit. Smoother, with less of that old Maggie ribbon sound.

• limage is proud that he has clean bass without any treatment. Indeed he, as usual, has done a great job. But I do think while the midrange and treble are cleaner than before, the bass of BCIII is a just a tad slower than ideal. You just cannot have everything!

• Again, the bass is leaner than my own preference. limage says it goes down to the mid-30's, but my subjective feeling is less so. Note here that the official spec's of the BCIII states a lower frequency response than the SP100, but my own listening tells me it is the opposite. I'd love to hear the SP100 is his room!

Some Info and Thoughts on limage the CAS Heretic
limage has totally immersed himself in CAS. He claims that his rips/perfect copies are mostly better than the CDs they derive from. He also played some Hi-Res files. He also claims in some instances the digital copies better the vinyl counterparts. In the brief visit, I did not challenge him, or asked him to make a CD/CAS or LP/CAS comparison. In many ways, I am completely different from him, but I love what he does and respect his preferences, even if they are different from mine. Whether in a hypothetical given instance or two I may dispute his claims is really not important, and perhaps I do not want to know (maybe same for him).

Concerning CAS, limage has tried everything. Given my disinterest in CAS (despite this excellent demo) I shall report briefly limage's delightful preferences and views:

• limage prefers Windows to Apple, purely on sonic reasons.
• limage not only uses the popular J River, but he also uses the controversial J Play.
• limage believes there is a sweet spot for music server digital buffer, not the larger the better.
• the DAC sounds much better without the lid. How about that (I believe him)!

My thoughts on the CAS:

• Excellent as it is, it still has not convinced me of CAS' superiority. Chief among my concerns regards a certain sameness of playback, regardless of genre, performer or recording. A certain synthetic quality, if you may, even if appealing. But then, to me, limage has always been after the broad strokes, not subtleties.

• Whatever my preference, it is clear that this CAS sound is a lot better than most of the CAS sounds I have heard, including those from so-called experts (that includes HK dealers of high-end Weiss etc). This is a relatively simple setup, yet it effectively shows that all roads lead to Rome. It also shows, as with all aspects of hifi, the human ear is the most important when it comes to CAS, not numbers and specifications. You shall note that many of limage's preferences are highly controversial, but if you believe me, if I were into CAS I'd rather follow him than all those numbers given out at various forums.

• I'd think a good 44.1 through the Ensemble DAC may sound even better, but that is just a guess...

• To throw a gauntlet: if limage truly believes CAS sounds better, then please sell me the Ensemble CD combo to me! I'd have better use for it! :-)

Candid Talk
Suffice to say limage and I, who have gone way back, talked a lot about various matters. I sincerely appreciate his candid nature, rare in HK's narrow hifi circle. These conversations are what I treasure, and hifi differences fade into nothingness.

Hong Kong High End Audio visual Show 2014 Part II

Hong Kong High End Audio visual Show 2014 Part II

See Part I (previous post below) for a lot more coverage (pics and brief comments)

I attended Saturday mid-afternoon and there was no line. It seems to me the show is getting a little smaller. But I was able to spend a little more time than last year. Overall, there were more new things and it was not too bad. This report is brief and I shall reference only what is rare and interesting in my opinion.

Click pics to enlarge. Notice due to editing limitations, the pics are stacked somewhat unconventionally. Watch the legends.

Some Good Efforts


Audio Extreme has always done reasonable demonstrations, but this year was substantially improved. Electronics were similar to last year, Mod Wright, JMR, Acoustic Solid, Northstar etc.

So, what makes the difference? Simple, cunning use of an all-Ortofon front. Ortofon arm, SPU cartridge and phonoamp, lending it badly needed texture (as my friend icefox would say, "normal stuff", "正路口野"). By no means the most expensive arm/cartridge/phonoamp in the show, but equal to all in performance. On the other hand, I regret they did not demo their Phasemation and Aurorasound products (the latter especially interests me).

Ernest Audio once again delivered. I had to walk around several times to hear something, because they spent too much time talking. Like last year, the large room was divided into two, and the same Rockport Altair was used, driven by the same top VTL electronics.

While CAS through Blue Smoke (USB to SPDIF converter) and some Korean DAC was respectable, Time Out lacked the ultimate rhythmic finesse and microdynamics. Needless to say, analog playback via the excellent Spiral Groove SG2 turntable (not sure what arm) and Clearaudio cartridge (they are no longer dealer and too bad Tranfiguration was not demo'ed) was way superior and more emotive. I was shocked though to learn that 阿明 had left the company.

Cabasse (right) finally got a good effort from Dah Cheong. I have always loved Cabasse, especially for their high frequency performance. The strangely named satellite system Baltic Evolution + Santorin sub was smartly placed close together for enhanced texture, yet dispersion was pretty good, as one would expect of coaxial designs). I was shocked to find out how much they cost! A more humble floorstander also did well in a smaller room (Part I, pic 1)

Revel loudspeakers delivered the goods in two separate small rooms (Part I, pics 11 + 12). This proves a competent design needs not fear the vagaries of show condition. Too many excuses, too many over-priced bad products, especially expensive multi-driver speakers.

Dynaudio is commonly said to be hard to drive, but I think this is not true. Most of the terrible Dynaudio sound (their own design as well as other brands using their drivers) I have heard (and I have heard a lot!) come from being driven by over-sized, over-priced, over-damped, over-designed and over-praised solid state amps (most of high-end). Let it loose a little and it shall be content with much less. In the show, several rooms, including tube amp manufacturers, used Dynaudio to reasonable effect. But by far the best was in the large room partnered by simple Musical Fidelity CDP fed into Nuvistor 800 integrated amp (Part I, pic 22). This shows yet again a hybrid consisting of tube front and solid state end can sound better.


Most unusual demonstration (left)
This has to be the demonstration of the DS audio Optical Cartridge (6.5 gm, output 500mV). This was used on the TechDAS Air Force Two turntable (TechDAS is descendant of the legendary but imho frequently mechanical and not good sounding Micro-Seiki), curiously fitted with a vintage SME arm! This has to be for a reason, perhaps to warm up the sound? Like all cartridges, this one uses a cantilever (bolon) and stylus (shibata), but employs optical instead of magnetic conversion, said to consist of few parts and all analog. But I have my doubts: few parts is still not like magnetic conversion (no parts) and here you are tied to DS' own phono equalizer (definitely no-no to me).

Through Nagra (preamp and 845 amp) and "small" Wlison Benesch speakers, sound was not exceptional, but not too bad. I'd love to spend some time carefully auditioning this cartridge (if there is such a thing). Credit to Forthwise for demonstrating this novelty but thumbs down to the BS salesman who introduced the system, who said things like Wilson Benesch does not build things based on sonic principles, rather on material science. I am sure WB will disown him soon.


In passing, in the same room (pic to the right) , Forthwise demonstrated the Stenheim Reference loudspeakers with CH Precision electronics. Sound was promising, and that is not only because I like Stenheim's looks and most things Swiss. Note the Stenheim uses my favorite D'Appolito array (least problematic multi-driver array imho).

Power Failures

Avantgarde (Part I, pic 30) has to be one of them. They used to be better, but recently they tend to make the sound smaller, more focused on the few people in front. There is no excuse for big horns like the Trio + Basshorn not to fill the room. Why concentrate on hifi "virtues" like imaging with big loudspeakers? Where is the presence? In a way, the sound is not too different from their much smaller showroom. That said, Kondo (including the Kagura) sounds a whole lot better than last year's Avantgarde amplifier, though not even close to ideal.

JBL Everest DD67000 (Part I, pic 15) Come on Harman International! Get something decent to demonstrate the Everest! Your own humble Revel Salons sound a whole lot better! Why so much power needed from the bank of 6C33 tubes? I'd rather think a cheap and cheerful NAD3020 or Cyrus I/II would do a much better job!


Thoughts

•  Again, there is no surprise that the best sounds come from analog setups. But, the use of cheap vintage SME on the TechDAS/NS setup and, especially, the success of the Ortofon arm/SPU/phonoamp described above are reasons enough for reflections. These traditional products when used properly sound a lot better than many ridiculously expensive modern analog inventions, be it tonearms, cartridges or phonoamps.

• Again, there is no proof that CAS sounds better than CDs, not to say analog.

• Simple often sounds better. No better proof than the Musical Fidelity Nuvistor 800 amp. Simplest setup in the whole show.

• Aside from the VTLs, where are the big tube amps? No more ARC, CJ etc. For sure, aside from some Chinese brands, fewer tube products are used.

• The CD/SACD is ok, reasonably detailed but dynamically unnatural. At least, no horrible EMI classical cut this year! Best cut musically is the little known Balkan Baroque Band. But the more you listen to this CD, the more unnatural it sounds, result of too much digital manipulation. Sometimes I even think it has some digital "fog".

Hong Kong High End Audio Visual Show 2014 Part I

Hong Kong High End Audio visual Show 2014 Part I

This year my reporting shall take a slightly different path. This Blog you are reading is free, and editing tools are limited. My coverage of the 2014 show is a little more comprehensive than before, and there are more pics. In Part I, I am posting the pics and brief comments.

Selected detailed comments are in Part II

Last revised  August 10, 2014

Click pics to enlarge. In order, comments below on the pics. To save your time, they are color-coded for sonic merit (Excellent, good to ok, bad to dreadful):

1. Mini Esoteric, Cyrus Lyric and Cabasse do a reasonable job.
2. I'd have loved to hear the truly innovative and reasonably priced Townsend Rock 7.
3. Kharma, as driven by Orpheus. Still no karma for me after all these years.
4. Martens Coltrane is dreadful. John is turning in his grave.
5. Harbeth and Sugden are pretty bad.
6. Eclipse setup driven by Luxman are dreadful.
7. Passable Wilson Alexia driven by EMM Labs electronics.
8. Passable rossofiorentino partnered with MSB and PiGreco.
9. Hit and Miss Audio 1 - ATC100 + drumming = disaster.
10. Hit and Miss Audio 2 - Dynaudio slightly better with Line Magnetic.
11. Revel driven by Moon. HK Lumin CAS. Excellent.
12. Revel driven by Mark Levinson. Excellent. 11 + 12 = Revel is the star.
 13. German Physiks underperforms yet again with Plinius. Dreadful.
 14. Tim de Paravicini of EAR is my hero.
 15. As usual, awful demo of JBL Everest DD67000, driven by Chinese electronics that should remain a Secret.
 16. A full system of Electrocompaniet is quite listenable.
17. Audio Note UK system. Nothing bad, nothing of note.
18. McIntosh. The further you get away from the girl, the better the sound.
19. Pedestrian Burmester, as usual. But I like the cyber feel of the Acoustic Signature Novum.
20. Wisdom. Not heard.
21. Audio Extreme did a good job (see Part II).
22. Dynaudio was capably served by simple Musical Fidelity (see Part II).
23. Avalon (Isis) disappoints yet again being driven by Audia.
24. Avalon Tesseract silent but evil (hifi excess). This planet needs to defend against it.
25. As usual, dreadful Eventus as driven by Luxman.
26. In the same room, YG + Soulution is a bit better, but...
27. Steinheim + CH Precision (see Part II).
28. NS Audio optical cartridge (see Part II).
29. Cabasse Baltic Evolution + Santorin represents Dah Cheong's best effort to date. It puts similar satellite system (pic 6) to shame.
30. Avantegarde driven by Kondo, better than last year, but sound is small and not room filling.
31. Highly artificial Siltech and Crystal. Excel excels no more.
32. As usual respectable Vivid Giya.
33. This room is always good. This round, Wilson and T+A.
34. Raidho + Ampzilla was not well controlled.
35. Rockport + VTL + Spiral Groove. Excellent (see Part II).
36. Salesman trys to sell material science, not audio! :-(
37. MBL.  Worst sound in years.