Octal EAR 834P phono preamp

During my visit to NYC earlier this summer, my buddy Ding loaned me his home-brewed octal version of the EAR 834P phono preamp using 3 x 6SL7 octal tubes. Powering the preamp is a General Radio 1201-B tube regulated power supply.

Ding is not into boutique parts. Instead, he used carbon film resistors, mylar coupling capacitors and electrolytic caps gathered from Hamfests and surplus stores. Proper grounding and parts placement ensured a very quiet phono stage.

Traditional tube phono stages like the classic Dyna PAS 3 and Marantz 7 employed active RIAA EQ networks inserted in the negative feedback loop from the final stage to the input stage. In the 834P, Tim de Paravicini used active RIAA EQ with a clever twist - the EQ network is fed from the cathode follower output back to the second stage only. IMO, the benefits of this topology are: a 1st stage unimpeded by negative feedback, low noise and low output impedance.

I've been enjoying this phono stage so much that I'm inspired to build my own version. Good job, Ding!

Shippensburg Music Festival 2016

From 1999-2008, I spent three weeks of July making music with these wonderful musicians at the Luhrs Center. It was great to be back!

Vidcaps of rehearsals 

1st week

R. Strauss - Metamorphosen

2nd week

Schubert Symphony No. 9 - Finale

3rd week

Verdi - La Traviata

Capital Audiofest 2016

 Here's my Vintage/DIY centric point of view of the July 8-10, 2016 event at the Hilton Hotel in Rockville, MD.

EMIA

Custom turntable and tonearm

2 x 300B amps per channel 

using high nickel content iron 

wound and designed by Dave Slagle

Bi-amped stacked QUAD ESLs

DejaVu Audio

Mint Garrard 301 + Ortofon tonearm + Koetsu Rosewood 

in a custom plinth

Custom tube preamp and amp by Aldo D'Urso using vintage Western Electric tubes, iron, paper in oil caps and carbon composition resistors.

Speaker system by Aldo D'Urso 

Altec 803A woofers, 60s vintage Japanese horns + Jensen RP302 super tweeters.

Aldo D'Urso and Vu Hoang

DC Audio DIY

Joe Roberts' Garrard 301 + Schick 12" tonearm

in a custom plinth

Joe Roberts' Altec 756B in 2.5 cubic foot sealed cabinets on retro mid-century modern hairpin legged stands. Highs are augmented by Fountek ribbon tweeters through paper in oil caps and transformer attenuators. Hey Joe, you need Altec 3000s tweets there instead ;)

Custom GM70 monoblock amplifiers with hefty Tamura output transformers by David McGown

David McGown (center)

DCAudioDIY set up

Roscoe Primrose 

Head honcho of DCAudioDIY Forum

Lots of LPs!

Yours truly with Herb Reichert and Joe Roberts ;)

more pics

Leica Store SoHo NYC

While strolling around SoHo NYC,  we stumbled upon this Leica store. This guy looked so familiar, I had an inkling he was the one who sold me my Leica M6 at Tamarkin waaay back in '96! I was right! Nice seeing you again, Craig!

PNoy 2010-2016

PNoy at the November 2012 Hi-Fi Show 

I am glad the bulk of time I spent in Manila was during your term. I know you tried your very best. I just wish more Filipinos cooperated with your vision of a better Philippines. 

Thank you very much, Mr. President!!! 

(Re)building a Hi-Fi Room

ca. 2006

Eight years ago I vacated this space, not knowing that I would be back someday...

Late Spring 2016

Altec 861 cabinet

Among those that didn't make it into the 20 foot container in 2008 was a pair of Altec 861 cabinets loaded with generic 15" drivers. I used one temporarily to get some sounds going in the room while I figured out how to repurpose the other cabinet.

Amplification

Grommes LJ2

 This sweet "Little Jewel" PP6V6 integrated mono amp fired up with no problems after almost 8 years of silence.

Rek O Kut B12GH + Velvet Touch

My hand-carried Velvet Touch tonearm "blu-tacked" on a ROK B12GH and mounted on a state-of-the-art crate plinth. 

After a thorough cleaning and re-lubrication of the main bearing, Papst motor and replacement of motor mounts, the dreaded motor vibration is still felt on the tonearm finger lift. I have to send the idler wheel to Terry Witt for a rebuild and plan on building a heavy plinth.

Unlike the fussy Rek O Kut, this Pioneer PL6U is running quietly on its original lightweight plinth after I replaced the 3 perished rubber motor mounts with rubber grommets + light cleaning and re-lubrication. It sounds great with a $40 Stanton 500 cartridge!  

Pioneer PL6U

Line-level sources

KLH Model Twenty One

Classic Hi-Fi FM table radio found in a bicycle shop. 

Western Electric 111C
+
UTC A20

Stereo > Mono transformer mixer for the iPod Nano

Hi Eff Speaker

Since the Altec 861 (aka Madrid) share a similar internal volume with the Altec 614, I went to Lowe's to get 3/4" plywood cut to the size of the front panel. Using a Harbor Freight Router + Jasper Jig 200, I cut a hole for a rear mounted Altec 414A and a rectangular 2" x 7" port to mimic an Altec 614.

Altec 2-way

Altec 861 loaded with an Altec 414A running full range augmented on top by an Emilar EH800 horn or Altec 32A horn with an Emilar EA175-16 compression driver.

Work in progress...

Altec 605B experiments

Hot on the trail from the 1" compression driver survey, I set forth to re-evaluate my open baffle mounted Altec 605B. This Duplex system is essentially an Altec 416A woofer + Altec 806A compression driver with an integral short horn. I wanted to address a mild honk and try to squeeze out more "air" in the top end from the horn/driver combo.

605B as a 416A woofer

Since my modus operandi has always been to listen carefully to each component as a separate entity, I disconnected the compression driver from the N1600C crossover and listened to the woofer rolling off at about 1100 hz as well as bypassing the crossover, in full range mode. 

After several days of listening with and without the crossover, I realized that the "honk" actually emanated from the woofer. Perhaps this was due to the typical midrange impedance rise in a woofer exacerbated in an open baffle by the lack of a true enclosure? So I winged and auditioned a few Zobel EQ values and ended up with 10 ohms + 11uf in parallel with the woofer terminals as the "best compromise." This circuit cost a couple of dB in efficiency but did not significantly affect dynamics while minimizing the honk. 

Towel damping

Not scientific, but hanging a towel behind the driver focused the sound a bit further ;)

+ Altec 32C horn

For kicks, I did another round of listening with the 605B acting as a woofer coupled to the Altec 32C horn using the same drivers (except the Beyma) and crossover options discussed in the previous survey. But unlike the 12" Altec 414A which has a smooth roll off characteristic, the 605B woofer had to be configured as outlined above. In this configuration, the woofer blended nicely with all four drivers. In fact the 605B woofer section + 32C/802D horn combo had a similar midrange tonal balance to the Altec 2-way. Could that be a 32C horn coloration? ;)

Altec 16 ohm diaphragms

The Altec 605B was factory fitted with the aluminum voice coil 20275 diaphragm. By the time I acquired it, the diaphragm has been replaced with the newer 34852 with a copper voice coil. I've swapped the 34852 and the 20275 (from my 802D) in and out of the 605B and always preferred the midrange oriented 20275 over the more extended high frequencies from the 34852. Thus, to my ears the 34852 and 20275 cannot be used as a stereo pair. Alas, NOS 20275s are very scarce but fortunately GPA is reproducing original 34852 diaphragms. Just to make sure my 34852 is an original Altec item I posted a query at the Altec Users' Board.

34852 vs. 20275

Having confirmed that my 34852 was genuine, I compared the JEL/N1600C XO to the stock N1600C in search of more sparkle and air from the 806A. The JEL/N1600C with EQ circuit did augment the top end a bit, but not to the same degree achieved by the other drivers with more powerful magnets used in the 32B horn experiment above. With or without the Zobel network, I found too much depression in the midrange of the 605B. This was most notable in the vocal range but not as audible with instrumental music. Switching to the 20275 diaphragm improved the midrange a smidgen but I was still not fully convinced that using the JEL/N1600C XO was the proper course.

Coda

Altec N1600C + Zobel EQ

For now I'll continue using the Altec 605B with the N1600C crossover with Zobel EQ + a sparkler...

Sparkler = Altec 3000H