Joe's FVP Page

133 Dalmeny Drive, Prestons NSW 2170, Australia +612-96074650 & 0412-203382

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Four Valve Preamp

HYBRID VALVE/TUBE PRE-AMPLIFIER WITH AN UNUSUAL BACKGROUND AND PEDIGREE!

  Many Happy Users World Wide 

Please Note:

Joe's FVP continues to ongoing revision. Cosmetic differences to photos shown is also to be expected but the over-all theme is the same.

Usually only available subject to order and not as a stock item.

CAN YOU BUY A SECOND HAND FVP? 

CONTACT ME FOR UPDATE COSTS

AND SAVE DOLLARS!


            Introduction

            New Improvements

            Power Supply

            Super Linear Cathode Follower (SLCF)

            Improved Phono Stage

            Specifications

Some of you may have heard of, read and/or bought The Tube Preamp Cookbook, reviewed by Ken Kessler in Hi-Fi News & Record Review and also the review in Hi-Fi World, as well as Sound Practices where Allen's current advertisement was placed under the name of Vacuum State Electronics. His latest effort is The SuperCables


Simplified Circuit Schematic


Introduction

In his book, Allen describes in particular two designs, one not too complex and one a more all-out assault on the S.O.T.A. (You may also find my name mentioned a few times as well). It so happens that the less ambitious design got a lot more ambitious, a lot more. Please read on:

This design, code-named FVP since it is a Four Valve Pre-Amp, was originally made for Tara Labs (yes, the famous cable people) a company run by an ex-patriot Australian living in America, a certain Matthew Bond (no relation to James).

Matthew/Tara Labs imported in from us in Australia the electronics (the guts) of the FVP design and installed it in a box design of their own design and called this the Tara Labs Passage Pre-Amp.

As Allen has pointed out emphatically in his book, this is not the same Line Stage only pre-amp that was reviewed by Stereophile (it didn't do so well, its line stage circuit was a design that had been tried and rejected by us for exactly the sonic reasons set out in Stereophile. And they were not able to use our copyrighted power supply (oh why did you do it Matthew?).


Matthew wanted us to supply a Line Stage only pre-amp, but....

I was asked to cost a Line Stage only FVP and since the costs are basically in the major parts that still has to be there even if the Phono Stage was not, the costing did not turn out to be that significantly lower, less than 20% when he was looking at an unrealistic 30% plus. So Tara Labs dropped ours and designed their own.


If you come across a Tara Labs Passage Pre-Amp, you will be able to determine whether it is the original superior design by one of two ways:

A) The original has a genuine Moving Coil capable Phono Stage.

B) The PCB will have one of two notations on the underside:

FVP2-rev1 (c) 1989 Allen Wright Australia

or

VSE FVP2 (c) 1989 VSE AUSTRALIA

But the FVP design with its Phono Stage in tact is not dead. Over a period of time it has been honed to a degree that it is vastly superior to the original FVP/Passage pre-amp. And it is now available at a very reasonable cost.

Some optional features dictate the final price at the time the order is negotiated and placed. Select the type of Volume Control and one of two versions of the Phono Stage.

This is a lot of pre-amp that can be compared or put into any system of any cost and still surprise.

One friend took his to his friend's place and inserted his FVP into a system replacing a top of the line U.S. made pre-amp costing more than five times as much and came away from that evening with a big smile on his face. He realised that he had saved a bundle!

Another dealer well known around here in Sydney sold his expensive ARC valve pre-amp and got his hand on an up-to-date FVP, pocketed the not insignificant difference and reckons he has a much better sounding system. Nice to be able to upgrade and make money on it at the same time. Doesn't happen too often.

 

NEW IMPROVEMENTS SINCE TARA LABS

Power Supply

State of the Art designs usually use the over-kill cum brute force methods when dealing with power supplies (very expensive), whereas the FVP uses techniques that are in themselves State of the Art (S.O.T.A.) but cost effective and strangely enough... superior.

Such as the SuperReg - the whole pre-amp has a fixed load to the mains supply, the power supply is actually running in Class A as if it was an amplifier driving a load, in this case the pre-amp circuit itself, which also is Class A - virtually killing undesirable interactions and achieving a near perfect interface.

The SuperReg is a two stage regulator, the first part regulates the total current and keeps it constant. This creates huge isolation from the raw supply. The second stage regulates the final voltage required via a shunt. The dynamic impedance of the power supply is not just kept low but also dynamically stable in a way that conventional 'series' regulation does not.

Super Linear Cathode Follower (SLCF)

In his book, Allen is asked by someone whether he uses Cathode Followers. When he answers 'sometimes yes' his questioner turns his nose up. But Cathode Followers do provide the low output impedance that is often needed, especially on the main output of pre-amps. But they have sonic problems: They loose information. If you are using a good Single Ended power amp (I say 'good' as all SE amps are not created equal) or something equally revealing, then the loss is crucial.

Introducing the SLCF: An improved Cathode Follower that leaves many of it brethren behind. It is fed in a Constant Current mode and the follower element (triode) works in Constant Voltage mode due to bootstrap fitted. See Allen's book for further analysis. A 'mu' follower or SRRP could also have be considered. It seems a good idea since it overcomes short-comings in Cathode Followers but has higher output impedance.

Recent experiments show that the SLCF is sonically W*A*Y better than SRPP.

Improved (Optional) Phono Stage

The original FVP/Passage circuit was optimised around the X7 tube. The improved Phono Stage has been optimised to use the T7 tube with significant sonic gains. This Phono Stage is equally well at home with Moving Magnet and Moving Coil cartridges. The total gain including Line Stage is 70dB approx. This is usually enough to cover most Moving Coils. We know of a Van den Hul MC-10 cartridge (0.3mV) user who has no problem at all. I have heard this system many times and never noticed noise to be a problem, being way down on the vinyl noise. I have also tried using a rebuilt Accuphase AC-2 Moving Coil at 0.2mV and am extremely pleased with the results.

So this original Phono Stage has been dubbed FVP-2, it uses Active RIAA EQ.

The newer and optional Phono Stage has been dubbed FVP-5. It uses Passive RIAA EQ which means that it now matches the Line and uses no feedback. It makes use of the 6922 / 6DJ8 / ECC88 / E88CC type tube. It has has some flexibility in varying gain.

SPECIFICATIONS
 

Phono Overload: 200mV RMS @ 1KHz
Phono Sensitivity: 0.3mV @ 1 Volt RMS out
CD Sensitivity: 100mV RMS @ 1 Volt RMS out
Other Line Inputs: 70mV RMS @ 1 Volt RMS out
Frequency Response: 20Hz to 20KHz +/- 0.15dB Phono
  10Hz to 50KHz +/- 0.15dB Line Out
Channel Separation: 80dB  
Max Output: 20V RMS  
Distortion: Typically less than 0.05% @ 1 Volt RMS out
Input Impedances: Phono 47K (-load plugs)
  CD 55K
  Other Line Inputs 88K
Output Impedances: Main Out (SLCF) 200 Ohm typically
  Tape Out (IC) 600 Ohm Max

These are subject to change - but are moslyt conservative.


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Copyright 2003-10 Joe Rasmussen & JLTi
Last modified: Monday June 08, 2015

Just had a terrible thought. If "intelligent design" is unscientific, then who will design our audio equipment?