Mods for IEC

polrbehr

Per my post in another thread about doing an IEC mod, I started doing the necessary changes to one of my Adcoms today so that I may be able to use/try out different power cords.

I'll post whatever may be of interest as I go along. Stay tuned ...

fbm211

What adcom are you modding.I bought a craftsman rotary tool a few weeks ago for the same purpose.Im planning on adding IECs to my 565s.

Face

I believe I have a nibbler here if you want to borrow it. If you have a dremel, that may work as well.

Tomasito

Guys, kindly post a review, if the mod made an improvement to the sonic quality
thanks

F1nut

Changing to an IEC won't improve the sound quality, it's the ability to use aftermarket power cords that will.

zingo

Face wrote: »

I believe I have a nibbler here if you want to borrow it. If you have a dremel, that may work as well.

I used a Dremel and it cut through a thick chassis no problem.

polrbehr

Thanks for the offer, Face.
I will try it on the next one and see if it's any easier.

I actually only used the Dremel I have for the grinding part of this mod, the cutting blade I had was pathetically worn out, and I didn't feel like going out and getting another one!

polrbehr

OK, this is now pretty much done.
I realize it's taken several days to do, but not because it's that difficult or anything, I just had other things crop up, and to be honest I wasn't in that much of a hurry

IEC mod for Adcom GTP-450

Tools
Safety goggles
Variable speed 1/2" drill and jigsaw ( FYI, I used Ryobi battery powered tools )
3/8" hi-speed drill bit
1/8" hi-speed drill bit
Metal cutting blade for jigsaw
Dremel-type Moto tool with grinding wheel (deburring the cut edges of metal, a file should work as well)
Sharpie (for marking cutouts and mounting holes)
Phillips and flathead screwdrivers
Linesman pliers / wire stripper / crimping tool
Centerpunch or awl (not 100% vital, but makes things easier, IMO)
Microfiber cloth, slightly dampened
Work area, I use an old padded card table (saves whatever you work on from getting scratched up )

Parts
IEC power jack chassis mount (from PartsExpress, item # 090-442)
# 6 1/2" sheetmetal screws (x2)
AMP female disconnects 16-14awg, 10 pk. (from HomeD, about 3 bucks)
12 or 14 awg stranded wire for ground, about 8" long with spade terminal crimped on one end

Procedure
Unplug EVERYTHING - power cords, ICs, whatever ( I'm saying it anyway )
Remove 6 screws holding top cover ( 2 on top near front, 4 on back - this obviously applies to the unit I did)
Remove cover.
Go ahead and cut the power cord, leave 3-4" from the unit, separate two wires to existing connector.
Carefully remove connector (this may require those pliers, but it should come out fairly easily)
Push the separated wires into the unit and out of the way.
Using the hole where the power cord holder was as a guide, mark the location for the new IEC with a Sharpie (I used blue against the black of the unit). It is easily done if you hold the connector backwards and trace around the perimeter. The marking will be rectangular, with rounded edges, approx 1 1/4"w X 3/4"h.
The existing cutout from the old plug holder should ideally be one corner of the new cutout pattern.

* This is the point at which I used the damp cloth behind where I planned on drilling/cutting the metal - simply push it gently into the space behind the back plate covering whatever you DON'T want metal pieces falling into. It's also about the time to find those safety goggles - take my word, there's a reason they're # 1 on the tools list ! *

Drill three 3/8" holes in the other corners of the pattern - I used such a large bit to save on the amount of cutting that would need to be done. The awl is useful here, it prevents the bit from "walking" on the metal.
Once the holes are drilled, the final cuts can be made. I used the battery powered jigsaw, as I find it's easier to control. Take your time and follow the lines as best you can - there is some room for error, it's not necessary to be perfect.
Once the shape is roughly cut out, you can either file the edges with a metal file, or use a mototool with a grinder to smooth out the edges. Be careful, as the edges can be sharp.
Test fit the IEC connector. If need be, make any alterations as necessary.
Once it will fit, hold it in place and mark the holes where it will be screwed into the back plate, drill them out with the 1/8" drill bit, and test fit the screws.
Now the cloth can be carefully removed and shaken out (or thrown away, they're cheap enough), and you can either blow out or vacuum out the inside of the unit. If you used the cloth, there should not be too much debris in there.
Strip about 1/2" of insulation from the existing separated wires, same for the ground wire you made up, and crimp them to the female disconnects (they can also be soldered to the IEC if you want to go that route, but I prefer the crimp-on style for removal down the road if need be). Following the markings on the IEC connector, push the connectors onto the terminals, making sure to follow the polarity marks on the IEC.
At this point, I attached the spaded end of the ground wire to a spot on the metal chassis of the unit; I was fortunate it was close enough as well as pre-tapped for a screw. I am still not certain it's even necessary, but I did it anyway.
Push the IEC connector into place, and screw it in, snug but not too tight.
Check for any loose metal pieces (again), and connect an IEC plug to the unit, then into an outlet of your choice ( I prefer a GFCI on the initial test plug-in ! )
Now unplug the unit, and replace the cover.
Get started testing out all those different PCs available !!

I did take some pictures of the work in progress, I will try to upload them later on.

FTGV

polrbehr wrote: »

At this point, I attached the spaded end of the ground wire to a spot on the metal chassis of the unit....I am still not certain it's even necessary, but I did it anyway.

From a safety standpoint it's always good to have a chassis ground.However adding it could potentially create a ground loop issue in your system if the circuit is also connected to the chassis at some point and there are other units with 3 prong power cords(ie the amp).You will know if you have a GL when you connect back into your system.Should that be the case there is an easy fix.

polrbehr

For those people who are thinking about doing this, I say go for it. It was not that difficult to do, really, and it's certainly cheap enough from a parts-cost
standpoint. The connectors were $1.97 each, and the rest of the items can probably be found in anyones junk/parts box, or at Home Depot.
I suppose if you have two left hands, or a workbench that looks like a new sheet of plywood, maybe it's not worth buying the tools I used and recommend.
As for differences or sonic improvements, I honestly can't comment on this particular units' mod, as I don't have nearly enough prior listening time with this pre to make a judgement. And so far, seems to be no ground loop issues that I am aware of.

And now that one of my GFA535lls is completed, I can comment on that as well. Doing this one was almost the same as the GTP450, only I used a nibbler tool (props to Face for letting me borrow that) to even out the corners. I would also caution that one of the circuit boards is right behind where you'll be cutting out for the new connector; take your time. I would also advise using flag-type crimp terminals rather than straight, as these would make for a better fit given the proximity of the board.

The PQ of my cell camera is not worth writing home about, sorry.

Face

Good job and you're welcome bud!

Tomasito

Good work polrbehr,
Did you hear a sonic improvement?

polrbehr

Well, that's a tough question because of several changes that were made within a week or so. I understand the importance of not making too many wholesale changes at once, but that's how it worked out this time .
FYI, I am using a Signal Cable Magic Power (6') on the amp, and a SC DigitalReference on the preamp, both modded as described above.

Overall, I think the biggest difference is that the sound seemed to have more "force"; not necessarily louder, but there was definitely a presence that was absent before. It really seemed that the speakers got closer to the listening position, if that makes any sense, but without losing any of the soundstage width I was accustomed to.
At the same time, I noticed that during quiet periods, whether between songs or just at idle, there was almost no hissing or background noise at all, even with the volume up to about 11 o'clock.
And even though I did connect the ground wire to the chassis on both the amp and the pre, I hear no evidence of any groundloop issues (which is to say I don't even know if they are present, as I never heard them before).

Overall, I would not say this is a must-do upgrade; however, it is both an easy and fairly cheap mod to do, and there is definitely an improvement to be heard, even with these mid-grade power cords.

zingo

Good to hear, and it yes, it is a cheap and easy mod.