*New* High End FRED Gilmore Power Supply Design
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BoyElroy

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Here's a variation of my "high end" Gilmore power supply that uses FREDs (Fast Recovery Epitaxial Diodes) in place of the Schottky/standard silicon rectifiers.

FREDs are considered by some to sound superior to other rectifying devices and I made the board to fit the IXYS DSEI 8-06A TO-220 form factor FRED. The 8 amp/600V FRED costs about $3.50 each (actually, as Antness has pointed out to me, you can get them at Digikey for $1.41 each--part # DSEI8-06A-ND). You will need 8 of them to complete the 2 full wave bridges. You can find the datasheet for this device at:

IXYS DSEI 8-06A Datasheet

Here's an excerpt from http://www.vacuumtube.com regarding the advantages of FREDs:

Quote:

Compared to silicon diodes, FREDs have a full and airy sound. The bass is tightened up, and the harsh edge in the mids and highs almost disappears. Details in the music start to come out with greater clarity than ever before. FREDs sound as close to a tube rectifier as one can get, while not requiring additional power to run a filament or heater....Even though they are more expensive than ten-cent 1N4007 diodes, installing FREDs in your power supply can improve the sound of your system to a greater degree than exotic cables or most other tweaks. You will hear detail and depth in your music that will astound you!


You can download the FRED Gilmore PSU files by clicking on the links below:

FRED Gilmore Bottom .PSD 520K

FRED Gilmore Bottom .GIF 83K

FRED Gilmore Composite w/ Pads 99K

FRED Gilmore Components 30K

FRED Gilmore Master Composite 125K

FRED Gilmore Pads 18K


Here's a picture of an earlier version of the board without on-board rectifiers (they were placed on another board) but it should give you a rough idea of what a finished PSU board looks like.

Please note that the design is made to fit on a 6" x 9" board (I used the Injectorall 1 sided 6x9 copper clad board-Digikey # PC11-ND). There is enough space for up to six 10,000uF capacitors and/or any combination of values that will fit on the board. There is also enough space for large sized polypropelene capacitors both before the OPA548 and after.

The Bottom artwork MUST be printed out at 6" x 9"!!

I left enough space for anyone who wants to use heat sinks with their TO-220 form factor FREDS. Please note that you will need 8 FREDs to complete the 2 full wave bridges.

Also, it is highly recommended that you heat sink the particular FRED diode leg you are soldering due to the possibility of heat damage to the diode.

I also mounted the LM317/337's on "rails" in order to accomodate a variety of different size heat sinks. You can now move the LM317/337's back and forth about 2 to 2.5 inches to mount much larger heat sinks.

The downside to this approach is that the copper traces are a bit longer than necessary so if you know which heat sinks you're going to use, you may want to shorten the rails using Photoshop or some other editing program to modify the artwork.

Unfortunately, you still have to hard wire the +24 Vdc out to +24Vdc in. Please look at the master composite for more details.

You can use the Bourns vertical 20K Ohm Multi-Turn Pot(Bourns Part# 3299Y-1-203, Mouser Part #652-3299Y-1-203) for the adjustment pots.

Again, feel free to make any changes and/or improvements.
 
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antness

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BoyElroy,

This is great. Thanks for posting the PCBs for this power supply.

I have some suggestions if you'd be interested in creating a modifcation to this board.

1) Pads for small capacitors to bypass each of the FRED diodes.
2) 0.5" spacing pads to use a resistor instead of a pot for setting the output voltage of the regulators...leave the pot pads though, just add ones for the resistor.
3) Pads to bypass the leads mentioned by Kevin Gilmore w/ capacitors to stop oscillation of the opamps
4) resistor pads for LED and VLED pad
5) switch pads on AC voltage input with a capacitor to bypass the switch
6) this one is optional, but might be nice....some jumpers to bypass the opamp stage of regulation in case someone just wants to build the PS with the first stage of regulation
 
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BoyElroy

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Antness:

AAArgghh!!!!! More work!!!! Yes, you are absolutely right about the mods. I'll have to work on them over the weekend, I guess.

Thanks for your input ...and....

when are you going to come out with a balanced bridge Gilmore?

P.S. Maybe I could just turn <Fred Gilmore> into an open source project and let anyone who wants to make mods do so and post them. I could put up all the necessary .psd layers/files and starting materials...
 
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antness

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I looked up that part # for the diodes on Digikey and it says they are $1.41 each. Is this the diode you had in mind?

There will be a balanced bridge Gilmore, but I can't make any promises just yet about when it will be available.
 
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BoyElroy

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Thanks for the tip--$1.41 is really, really cheap. I priced the DSEI 8-06A at www.vacuumtube.com and the price they had was $3.50. That's a pretty severe price difference. Well, I guess we now know where people should go to buy their Ixys FREDs.

(I'll correct the price on my initial post above)

Re: the balanced bridge Gilmore--Antness, you have to get to work on this. The BB Gilmore will really knock your socks off.
 
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antness

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Well, I can't wait to get to try the balanced bridge amp then...I've heard your comments and am very interested.

Since I gave you some suggestions for that PCB, I'd love suggestions for a balanced bridge Gilmore.
 
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BoyElroy

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Hi Antness,

I think the balanced bridge Gilmore with a high quality power supply (dual mono but not necessarily), stepped ladder attenuator and balanced/single ended active/passive pre outputs would be one of the audio steals of the century. The sound of the balanced headphone output competes with the best headphone amps in the market (incl. the Blockhead) and the preamp section also compares with Stereophile Class A level equipment. The BB Gilmore puts out enough current to deal with just about any impedance load and if you put in a bypass switch for a passive preamp out, jeez, you'd have one of the best darn headamp/preamps available anywhere.

I'm going to put up some photos of my work-in-progress BB Gilmore headamp and PSU sometime next week and try to get some feedback on execution and layout. I have to borrow a digital camera first, though.
 
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goon-heaven

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BoyElroy:
So did you hear FREDs improvements as per the VacuumTube quote.

Antness:
The BB can be implemented with 4 of your amp boards. Not having received the kit yet, I dunno if 4 boards would fit the std enclosure. But I would like to see a power socket per channel on the amp, and two power sockets on the PS. That way, one has the choice whether to Dual mono the supply or not.

Also if you decide to have different amp boards for the BB, I would like to suggest having extra pads for doubling the number of output transistors.

Kevin:
How easy is it to go to full H bridge configuration?

Steve:
(Hey, thats me)
Dream On.
 
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antness

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Steve,

You could build the balanced bridge amp with two of the Gilmores that I build. One power supply box and one amp box per channel. Then, wire the amp boards for balanced bridge configuration. You would have two mono volume controls, and two headphone jacks. To make the two headphone jacks right next to each other, simply turn the front panel on one of the amp boxes 90 degrees clockwise or counter clockwise.
 
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kevin gilmore

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no no no...

You put one on top of the other then use a large rubber
band between each of the volume knobs.
 
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antness

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Here's another alternative if you want to build the balanced bridge amp, but don't want dual power supplies.

Replace the Neutrik locking jack with two standard 1/4" jacks. The amp boards will fit in a single enclosure. Wire the boards for balanced bridge config.
 
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goon-heaven

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I had in mind (eventually) 2 PSs to one amp box with 4 boards ( or 2 boards + piggybacks) & a dual channel switched attentuator. I need the rubber band to drive the genny from the bike, and I've to build the std yet, so I've to walk before I can pedal.
 
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BoyElroy

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Steve,

I've already ordered some bamboo from my supplier in mainland China to start work on my Gilligan generator bike. Apparently the Chinese sourced bamboo results in a noticeably more mellow and "bamboo-like" sound. I guess it just proves the adage that you can never have too much bamboo in your headamp.

I'll keep you guys updated on this.

BTW, to answer your question, I haven't made the Fred Gilmore PSU yet. I'm going to make a new board next week and populate it with hopefully all new parts.
 
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Budgie

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erix

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Didn't he and Ethel live across the hall from Ricky & Lucy?

But seriosly folks..

GOOD WORK on that board Bob, nice to see an original layout in this forum once in a while...

ok,
erix
 
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