Sunday, August 12, 2012

JE Labs SRPP 45/2A3




SRPP 45 and 2A3

In general I prefer the simplicity and purity of a plate loaded voltage amplifier [R-C couple], however i found SRPP [shunt regulated push pull] sonically satisfying using low-gm, hi-mu tube like the 6SL7/5691. if you find the Simple 45/2A3 a bit slow or lacking in definition, then this may be your solution.

I do not have the technical background to fully explain how SRPP works however through pure logic, the top half of the triode acts like a constant current load to the plate of the bottom triode and the drive signal is basically a combination of the low impedance nature of the top half's cathode and voltage amplification ability of the lower half, Giving this input/driver circuit greater potential drive signal to the grid of the output power tube.






This is a simple and straightforward design and the only thing I need to point out is the voltage divider network in the power supply that lifts the cathode potential of the 6SL7/5691 around 70-90 volts above ground. Thus, the +/- 90V heater [filament] heater to cathode rating is not exceeded as per the RCA manual's recommendation.


Thursday, August 9, 2012

SETUP





SETUP

These guys are pioneer users of idler driven turntables and flea power amps driving high efficiency speakers.



Joel


It is a small room and I forgot to bring a wide angle lens, so here's a cropped view from the listening position. Those monoblocks at the bottom of the shelf are SE2A3 [monoplate] amps with Tamura F7001 permalloy OPTs. Barely visible towards the top left is his Garrard 301 [oil bearing] with an Ikeda 12" arm. Depending on his mood, you may find him alternating between an Ortofon SPU-GME, Koetsu Black or Denon 103R through Tango MCT999 MC-step ups.


Altec 414Z on hardwood OB, Altec 511 horn mounted on top, 902 ceramic magnet compression drivers with original aluminum diaphragms and tangerine phase plugs. Alnico is nice but execution is more important and Altec did not skimp on this underrated model. This is really a nice sounding system. He built/tweaked his own crossover and L-pad to match the levels between the horn and woofer. 


He also has a pair of Altec 755Cs in OBs. EV T35Bs supplement the top end on both speaker systems.

Joel's got really good ears and gifted with a nice singing voice, aside from the fact that when he is "in the right mood" he can really build very nice projects like this PAS chassis based preamplifier. This is an RCA phono preamp circuit with battery bias using 12SL7 tubes and 12SN7 for the linestage driving Tango NP216 line output transformers mounted horizontally at the back.


Aside from being the JE Labs master builder/technician in Manila, Joel is known as the analog meister and sets up and restores anything from TD124s, 301s to suspended TD150s/160s and etc.


Nonong

These open baffle loaded Altec 755As are probably the only existing ones in Manila as far as we know. Someday he dreams of owning a pair of WE/Altec 756s [10"] with 3000A tweeters.


Prior to idler drive he had a VPI TNT Jr. with an Air Tangent 10B airbearing linear tracker. He sold the TNT Jr. and fitted the A-T10B on a TD 124 as an interim front end. Finally he settled on a Garrard 301 with an Ikeda 12" arm wherein an SPU Meister takes duty to the grooves. This is hooked to a pair of Tango MCT999 step-up devices which is routed into an RCA based phono preamp using 5691s and a linestage with 76s driving the NP216Ns built by Joel.


His amps include a pair of SE 300B amps with Tamura F7002 permalloy OPTs exclusively tuned for the OB755As that replaced a pair of SE2A3 amps with NY15S OPTs.


SE WE205D amp with F7004 OPTs and an SRPP 45 with Tamura F475.


equipment rack




William


When I visited William in the mid 90s, he had equipment that would turn a reviewer for any of the high-end rags green with envy - Wilson Grand SLAMM, VPI TNT, Air Tangent, CAT-SL1, Kondo's PSE300B Kegon, TAS/HPs cartridge of the month, connected with cables using "controlled substances" or "classified materials". 


However his taste and listening habits quickly evolved to a system centered on Tannoy Westminsters [now sitting sadly behind] and subsequently, RCA LC1s [early version without the cones] housed in walnut veneered "furnace style" cabinets [aged to perfection] that were originally intended as monitors made for executive suites at RCA... 



...driven by an all out stereo SE WE205D amp with Tamura F5004 OPTs, custom wound Tango power transformer, tantalum resistors, silver foil paper in oil coupling caps, Cerafine and Black Gates for decoupling built on a copper chassis by Joel. 


The preamp is either a Kondo M10 or JE Labs preamp [depending on his mood] fed by top of the line Audio Note, Japan MC step-ups.


High-end dealers may think it's a major step down to use a Garrard 301 with an Ikeda 12" arm from his previous front end or tracing grooves with an Ortofon SPU instead of a Lyra since William took his business elsewhere..... purchasing more records! The 301 has since been upgraded with Shindo platter and bearing, now he is hunting for an EMT turntable....

Aside from this system, he has another listening room at a remote location where he hibernates equipped with a TD124, Fidelity Research FR64s, Denon 103R front end into JE Labs preamp/amp electronics driving vintage Altec speakers.

William is a music lover and Art aficionado. His LP collection include not only LSC "shaded dogs" or Mecury SRs, but also mono LPs acquired purely on musical merits.




Nilo


Analog Sources

Thorens TD124/SME3012/SPU - lit by an uber cool glass art deco lamp

Empire 208/SME3009


Garrard 301/SME3012/Fidelity Research MC202 cartridge and headshell [restored at Joel's shop]
Cartridges- Ortofon SPU, Ortofon MC25fl, Denon DL103, various Fidelity Research MCs and Goldbug Clement
MC Step-up devices- Ortofon STM72, Supex SDT-77 [used with SPU/Goldbug], Altec 15095A [primarily with MC25fl], Denon AU320 [spare] and FRT-3 [on loan from Joel].


Digital - Marantz Tube CDP
Preamp- JE Labs [Telefunken 12AX7s on phono and 6SN7GTBs linestage] and Harman Kardon Citation I
Amplifiers- SE 300B silver which uses 6SN7/6V6 tubes/Tango XE20S and an SE 2A3/45 using 6H30pi/5687/Tango U-808. Both custom made by Khun Kittipol in Thailand.


Main Speakers- 12" Altec 419A on custom furniture grade cabinets internal volume made exactly according to Altec 614 plans, Fostex FT-600 Horn crossed around 1khz and vintage Telefunken alnico super tweets to add a bit of sparkle

Nilo's comments on his system:

Other speakers - Klipsch La Scala, Pioneer PIM8L [on vintage sony portable cabs], 15 ohm 10 inch Goodmans Triaxiom on vintage BR cabs

Future plan - convert the SE 2A3/45 to a JEL Simple 2A3/45.
I have this philosophy that any "upgrade" should be funded by disposing the least utilised inventory of equipment. First to go was my Project RPM-9- used half of the proceeds to buy the klipsch/ pioneer PIM8/various stepups and the other half on software, equipment shelves, and 2 paintings (!). Next to go were my vintage fisher amps [x-100, x-202, 400] which went to fund my turntable restorations, cartridges and as always, more software [LPs].



Rex


Altec 2 way horn - 414 woofers in 614 cabinets, 811B horns with 804 compression drivers and Fostex FT-17H working as super tweets.


DIY Simple 45 with Tango ISO U808s and locally wound power transformer

Garrard 301 grease bearing Neat 10" tonearm/DL103 and an SME 3012 at the back


Another Garrard 301 in a Shindo inspired plinth crafted by Joey with a Neat GA-04 transcription tonearm (Pickering 190 clone). Is that an Audiophile label 78 rpm microgroove record?

He is trying to decide which one of the three 301s he will keep and is contemplating on an octal based RIAA preamp to replace his present 6DJ8 phono preamp.




Rofiel


JEL deluxe preamp [6SL7, 76 & 6SN7] and JEL SE2A3dx amp 56/6SN7 [front end] James 6123HS opts


Garrard 301 and Grace 12" on solid Acacia wood plank taken from an ancient tree that fell in their backyard during a typhoon. Cartridges are vintage Pickering, Stanton and Shure shared between these 2 turntables.

Rek-O-Kut L34H [Papst motor] and Ortofon AS-212, plinth is from the same tree. He is contemplating whether to get a step-up transformer/DL103 combo or a monaural cartridge.


Tannoy 3828 pulled out of Berkeley II enclosures and mounted on an open baffle. Crossover modified to a simple capacitor filter and L-pad for the HF unit by Joel.




Let's fly back to the USA and down to earth, particularly the SETUP branch in NYC.

This is Ding's system, a pair of Altec 604-8Gs on OBs driven either by a pair of SE300B monoblocks with Tamura F2007 opts...

...depending on his mood he might change output transformers on anotherpair of SE300B chassis using alligator clips to either a Tango NY15s or Audio Note UK 3ks.

...or Simple 45 with OPTs scavenge from an old Fisher integrated

JE Labs Preamp with external PS

A long time Linn Sondek LP12 user he eventually discovered the potential of classic idler driven turntable in the form of a Thorens TD124/Rega RB300 +... 

...Dynvector DV505/Denon 103S fed through vintage Thordarson mic input transformers of excellent quality!


His other sources include a Fisher FM200B tuner and a Pioneer DVD/CD player.

One thing I love about this guy is that he is so level headed about audio. Enjoying music is first and foremost. It's not typical to meet people in this hobby who will never engage a conversation on, "what is the best circuit, capacitor, output transformer or anything like that......" Obviously, he has no inclination towards audio neurosis.
He keeps me on the level and many times, has been my worst critic when I come up with a new idea or design.

Here are some of his current projects.....mono system in the making?


Gray 108 to be fitted with a Fairchild mono MC and mounted on the Gates CB77 idler driven turntable sitting on a wooden EMT inspired skeletal base.


Where's the Fisher mono preamp picture bro'?




Now let's visit Abe's system in the west coast


Altec 604-8G in open baffles

Garrard 301 and Schick 12"


Thorens TD 124/SME3012
+
a few modified DL103 cartridges and Cinemag MC step-up 

JE Labs preamp

Simple 2A3/45

Everything was built by Abe!