Just a thought...how about some Single Ended Gain modules

I nwas sitting here thinking and an idea came to me...how about some Single Ended Gain modules, that work off a single rail which could also provide the power for the phantom supply. In general my taste leans towars the SE designs both in tubes and semiconductors. The design can be quite simple 4 pins, (In, Out, V+, and Ground) something along the lines of the Hamptone JFP (FETboy) or something like the Neve BA283 or B100 or maybe even this thread http://www.groupdiy.com/index.php?topic=7793 The point would be to stadardize on an overall package layout and make variations from there. It might be nice to standardize on 48V for the B+ and regulate down on the module as needed. In theory a beefy 48V supply would be the only thing needed for many channels....or maybe I should go back to daydreaming

see layout attached

This would be the "standard" module size and pinout

I think the first circuit to consider would be the TNT Preamble
http://www.tnt-audio.com/clinica/preamble.html
The following may make it easier to build the circuit
1. Sub BC109 with BC550, much more availible
http://www.futurlec.com/Transistors/BC109.shtml
http://www.futurlec.com/Transistors/BC550.shtml
Replace 2N3819 with 2SK170
http://www.futurlec.com/Transistors/2N3819.shtml
http://www.futurlec.com/Transistors/2SK170.shtml
use a capacitor on the input so the biasing is not as effected by the impeadence of the input source.

Have been toying with the idea for SE-quickies as well and so far was inclined to give them the same footprint & pinning as the various DOA's out there (2520, 990 etc).

I realize that it's then still not fully compatible or a valid replacement (nor will it make tube-stages easy - to say the least), but a small change like a few resistors will usually do. The mechanic side it usually much harder to mod, so when it's already identical...

Just my 2cts,

Peter

[quote author="triodemike"]The point would be to stadardize on an overall package layout and make variations from there.[/quote]
In that respect maybe an added gain-config pin could come in handy ?

(I'm thinking along the lines here of the Altec plugins - like for instance the 1588B-circuit.)

By adding an addional pin this leave the option to use the pins now maked N/C for various options to be explored later, next I will look at the JFP and the Preamble to try to come up with a circuit that has the best of both.

[quote author="triodemike"]see layout attached

This would be the "standard" module size and pinout[/quote]

I think that the V+ pin would be better at the bottom right position. This allows easy access to the middle pin for both V+ and ground... I can envision the middle pin as a bypass for a 1/2V+ reference and this would make layout easier on the tiny board.

regards, Jack

New Module Layout

next lets look at the circuit

The 2 transistor Preamble circuit doesn't interest me at all. There are so many Ring of Three circuits that would work much better. Some of the old designs out of the Wireless World from the 70's would be good, as well as some of Neve's designs. Half of an Altec 4975 or some of the old McCurdy or Langevin would be good too. They all are single ended and proven designs with enough gain to actually do some good.

Jim Zuehsow

This looks like a great idea. Different blocks in a common form factor.

If I may make a suggestion that comes from past experience, make the pin layout assymetrical, or have some form of keying so I cant plug it in backwards.

Peter

Hope it can all fit, I may have to expand the footprint if it doesn't. This is based on the Hamptone JFP circuit modified to work at 48 V with some different transistors.

[quote author="Jim Zuehsow"]The 2 transistor Preamble circuit doesn't interest me at all. There are so many Ring of Three circuits that would work much better. Some of the old designs out of the Wireless World from the 70's would be good, as well as some of Neve's designs. Half of an Altec 4975 or some of the old McCurdy or Langevin would be good too. They all are single ended and proven designs with enough gain to actually do some good.

Jim Zuehsow[/quote]
Nice indeed, so gain can be configured by means of an external resistor. The Neve-stage you said, or Altec 1578, 1588B are examples.

How about clipping a corner to designate pin 1:



-Jack

In case someone wants to draw a 1588Bish module in EAGLE, here is my try (with euro transistors) from some time ago (the layout is for use with a DIP24 IC adapter, though and it is untested (eagle is more fun than sokoban :roll: )). Maybe this at least saves someone some work with the schematic entry.

HTH
;Matthias

For a ring of three I would recomend 2N5210 and 2N5087 both can take 50V and are very low noise. By the way these butes are 4 cents each at Mouser. At that rate a ring of three should run under $5.00 each all parts included. Thaats cheeper than some of the better OP-AMPS.

IMHO, the modules should be more generic:



This allow the external components to set some of the operating characteristics of the circuit. Also, the big electrolytics are moved off the module to make more room for essentials.

Couple the 48v dc into pin 6, using whatever external RC or LC components that you desire.

Set the input impedance by the external resistor to ground on the pin3 input.

Let it run open loop by leaving pin2 open, OR increase gain by putting a large capacitor from pin2 to ground, OR connect a resistor from pin2 to pin1 to provide feedback to limit gain to a set value.

This is essentially a simple discrete opamp, and allows the same module to be used to make a variety of circuits.

regards, Jack

Here is the TL071 (dip8) mapped to our module footprint to illustrate the concept:



Just for demonstration purposes. Don't build this as it will not work without some extra on-board components - the TL071 won't like 48v, for example...

regards, Jack

[quote author="AMZ-FX"]IMHO, the modules should be more generic:



This allow the external components to set some of the operating characteristics of the circuit. Also, the big electrolytics are moved off the module to make more room for essentials.

Couple the 48v dc into pin 6, using whatever external RC or LC components that you desire.

Set the input impedance by the external resistor to ground on the pin3 input.

Let it run open loop by leaving pin2 open, OR increase gain by putting a large capacitor from pin2 to ground, OR connect a resistor from pin2 to pin1 to provide feedback to limit gain to a set value.

This is essentially a simple discrete opamp, and allows the same module to be used to make a variety of circuits.

regards, Jack[/quote]


The problem with that generic design is limited input capability on Pin 3
this tweak increases input and output swing. The output is now capable of something like +20/-20V.

analag

parts is parts

http://www.passdiy.com/pdf/ZV9.pdf

WholeNote is a place where all the some-time, full-time, part-time, and not-enough-time guitarists

just thought the "not enuff" angle was amusing
sorry!

[quote author="analag"]this tweak[/quote]
Targets might be needed - what is wanted here, an universal building block or the Hamptone JFP in a modular form ?

If the latter then there are reasons to keep the circuit unmodified, including the various details that scream loud to be improved upon... but these are just from a technical point of view.
W.r.t. 'reasons', I recall a posting from PRR were he nicely summarized why it'd be good to refrain from modding right away - the original circuit was the result of long hours testing & listening, why not try it like that first ?

Please skip if it's about the former (universal block) of course.

Regards,

Peter