JE Labs PP2A3

Between '92-'93 I built a few PP2A3s based on the schematic below. Having been impressed with the performance of the Eico HF87 and HF60 amplifier, I thought the driver circuit would do justice to 2A3s.

8 watts Class A

!!!WARNING!!! 

The voltages found in this circuit can be lethal, build at your own risk!!!

I built these amps on a pair of Heath W4 chassis with intact chokes, power transformers from Scott 99 integrated and Peerless 16309 output transformers from Heath W5 amps. This was my reference amp driving Spendor LS3/5As until I started R&D on SE amps.

Fisher 500B output transformers and HK500 power transformer 

Same iron as above but different chassis layout

ST70 chassis with outboard 2.5V filament transformers

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Historically significant PP2A3 amplifier

The Feral Eye

 Featured on the cover of Sound Practices Issue 14

While visiting NYC, I heard this pair of amps in Ding's listening room. 

The 90s, Angela Instruments - Audio Note Kits

I took the photos in the above ad with my trusty Pentax K1000 ;)

Audio Note Kit 1 Schematic

Audio Note Kit 1 Power Supply

I probably built at least 2 dozen Kit 1s... 

...and repaired a good number of botched up Kit 1s.

Just delivered a Kit 1 and hooked it up to the in-house system for break in

Not too many Kit 3s (PSE300B - note the HUGE OPT) were brought in by Steve. But I remember assembling at least two pairs. I delivered a pair of Kit 3s to an avid BBC LS3/5A fan in New Jersey. The combination sounded pretty good.

There was a Kit 4 but I never assembled one. I vaguely remember repairing one unit.

The innards of an Audio Note Kit Preamp

Ad in Sound Practices

The 90s, Angela Instruments - Classic Audio

Servicing, restoring and listening to classic audio gear 

Test Bench late '92-early '93

I was living in my aunt's basement and repaired classic audio equipment for Angela Instruments there.

JE's classic tube preamp picks

Marantz 7C

Looks and build quality aside, the following three preamps sound better to my ears than the Marantz 7C.

Pilot SP215 - full function with cool VU meters. Big, dark and octal-like sound. The tape head input on this preamp is superb. SP216 is essentially the same but more deluxe faceplate and knobs.

Eico ST84 - limited only by its cheap looks, but very well designed circuit. This sounds fast and detailed without harshness.

Another Stewart Hegeman wide bandwidth design is the Lafayette KT600, but unlike the Citation I, this used only 12AX7s, no 12AT7s to make it sound dark and bland. This is full range and dynamic!

JE's PP EL34 Ultra Linear amps picks

The evergreen Marantz 8B

The SA260 is Pilot's best effort in building a PP EL34 amp. Better than a stock Dyna ST70 but not quite in the same league as the Eicos below or the 8B above. Very sweet and three dimensional midrange, but not quite as fast in the bottom and top end.

This Eico HF87 was my first restoration project for Angela Instruments. Elegant circuit - 1/2 a 12AX7 direct coupled to a long-tailed pair of 6SN7s driving cathode biased EL34s. The HF89 is very similar except the EL34s were run fixed bias. I prefer the HF87!

Eico HF60 monoblocks - similar to the above except this now uses a pentode EF86 direct coupled to a long tail phase inverter 6SN7 driving EL34s in fixed bias. Tube rectified using a 5AR4. The heart and soul of this amp is the Acro TO330 output transformer. To my ears, this is an even better amp than the Marantz 8B. The only tweak I did to this amp was install a choke in the power supply in lieu of a resistor.  

JE's collection of PP EL84 Ultra Linear amps

Dyna ST35

This particular unit was so rusty I decided to repaint it. Very simple circuit, the 7247 is essentially a twin triode wherein the first section is like a 12Ax7 direct coupled to a 12AU7 cathodyne phase inverter. To take advantage of its wide bandwidth ability, I removed the input coupling cap. I used this a lot to drive the BBC LS3/5As and Quad ESLs.

Pilot SA232 - just like its big brother, beautiful midrange but compared to the other three, this sounds a bit soft at the frequency extremes. Tube rectified power supply.

Leak 20 - Mullard style circuit using 3 x 12AX7. A 12AU7 would have worked better in the long tail phase inverter position, but then the amp would not have enough sensitivity for the matching Troughline preamp which essentially has no line stage and just a 2 stage EF86 phono preamp. Tube rectified power supply using a GZ34 just like the SA232. I kept mine in stock form and used a voltage divider to lessen the input sensitivity.

Acrosound 20/20 - the Loftin-White PP amp, no caps in the signal path. If you get lucky enough to own one, make sure all the resistors have not drifted, otherwise the performance deteriorates. This is a design wherein the bandwidth is limited only by the output transformer.

I unloaded all these EL84 amps to finance Tango and Tamura OPT acquisitions.  I should really have kept the *ST35* for posterity because it was the first tube amp I bought and spent the longest listening hours with it. 

The 90s - Angela Instruments

I was initially an Angela Instruments customer but when I returned to the USA in '92, Steve hired me as a part-time audio technician while I was working on a DMA degree at University of Maryland. 

I worked in the shop during catalog making season or when orders piled up.

If memory serves me right 1996 was the last year of the cool newsprint catalog. In 1997, Angela Instruments went on-line.

Steve, taking an order...

...in between orders, he tests tubes or repairs guitars and/or amps.

Susan also takes phone orders but most of the time she looks after the books.

Lots and lots of vintage gear

Those Scott FM mono tuners were difficult to sell in those days without an outboard MPX adapter.

Dyna ST70s galore

Heath W5s and WAP1 mono preamps

Heath A9 integrated amps

Top: 2 x Bogen PP 6L6G mono integrated amps

Bottom: Lafayette KT550 stereo amp designed by Stewart Hegeman. Just like the Citation II, the KT550 is designed for high power and wide bandwidth using lots of feedback loops.

Top: REL Precedent - state of the art tube FM mono tuner. Hooked to a Scott MPX adapter, this would give a Marantz 10B a run for the money. But why? Mono FM sounds great too!

Below: Fairchild Mono preamp, Rauland tuner and integrated amp 

From the other side of the pond, Leak

80s Nostalgia

This is the first installment of my audio journey triggered by my unearthing a box full of negatives and prints.

NYC ca. '81 

While doing undergrad studies in violin at The Juilliard School,  I assembled a system comprised of a Dual CS 505-1, NAD 3020 integrated amplifier, Sennheiser HD40 headphones and a pair of DIY mini-monitors inspired by BBC LS3/5As using Radio Shack drivers. Eventually, I removed the jumpers on the 3020 to use it as a preamp after acquiring a Dyna ST35 tube amp from Morel Electronics along West Broadway in what was left of NYC's Radio Row in the World Trade Center district.

The Dual was quickly displaced by a thrift store found ARXA which I eventually upgraded using a Merrill acrylic sub-chassis bored for a Grace 707 tonearm while retaining the same $15 Grado GTE+1 cartridge from Leonard Radio which started its career on the Dual.  

My brief foray into high end audio was inspired by reading The Absolute Sound (TAS) and Stereophile. I traded the NAD 3020 (plus cash) for a conrad-johnson PV2Ar preamp - touted for its soundstage and imaging abilities ;). To drive the pair of Magnepan SMGas from Lyric Hi-Fi, I found a used Berning EA230 at Stereo Exchange. The whole ensemble was connected by Straightwire, MIT and Kimber cables.

Being a tinkerer at heart - justification for limited funds ;) - another thrift store bargain ARXB chassis was prepared for a full blown Merrill modification program. I sent the inner and outer platter for an upgraded bearing, balancing and lead lining. Merrill also supplied a new Hurst motor in a proprietary mount and another acrylic subchassis was ordered predrilled for a Sumiko FT3 on a VTA-16 base fitted with a Grado 8MR Signature cartridge. The whole assembly was mounted on a custom Narra base. A SOTA mat and reflex clamp completed the front end package.

NYC ca. '85-'87

Frustrated by the frequent trips the cj PV2Ar was making to McLean, VA due to blown regulators in the PS, I posted an ad on the NY Sunday Times and quickly unloaded the Berning EA230, cj preamp and SMGas - a pair of bridged ST70s could not make it sing ;(. I was gaining confidence in DIY/repair and was afraid I could not maintain the Berning and c-j with the same ease as Dynaco tube stuff.

By early '87 (see top left picture) I was listening through a stock PAS 3 preamp + ST35 (note: VPI bricks! ;)) with a Scott 350B tuner providing FM. Top right picture - barely visible off my shoulder is the right channel black Rogers LS3//5A. Soon I would add a PAS 2 (below), an ST70 and a pair of MKIV mono blocks.

Although it was an honor and pleasure to meet J. Gordon Holt during the 1987 Stereophile Show at the New York Hilton, I had just started subscribing to Audio Amateur and Audiomart because of the great articles written by the late Walt Bender on Olden-Golden Components Part I and Part II in The Absolute Sound. 

This was my first project - a modified Dyna PAS preamp using 80s philosophy on how to achieve good sound - high capacitance photoflash caps or computer grade electrolytics with solid state regulation in the B+ rail, polypropylene capacitors for coupling and bypassing.  I also modified my Dyna ST70 and pair of MKIVs using Andy Fuchs' GSI driver boards - cross coupled cascoded 6DJ8/6922 running constant current.

The late Tom Cadawas, mentor and friend. I never had formal training in electronics and in the early days when a project did not go right, I went to him and he always sorted the problem quickly and explained step by step where I went wrong.

Thanks Tom, you made a lot of audio hobbyists happy!