GKP4 - $350! Is this a record?

Started by highlandsrock, April 23, 2013, 12:23:22 PM

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highlandsrock

I was watching a GKP4 unit on the eBayUK today. I thought I might bid but it went way out of my league. Final price including postage £230 = $350. Is this a record?  :o
Ibanez RG870 with GT3 internal kit +
GR-33, VG-99, GR-55, GP-10, SY-1000, Strymon Big Sky

Elantric

#1
And idiotic IMHO

DIY for $40


Now_And_Then

#2
Quote from: highlandsrock on April 23, 2013, 12:23:22 PM
I was watching a GKP4 unit on the eBayUK today. I thought I might bid but it went way out of my league. Final price including postage £230 = $350. Is this a record?  :o

I've seen it go for that price before; it made me consider selling mine.

I can not really figure out how to use it in the sense of not knowing where to put it while in use, or how to put it somewhere that it will not be damaged. Unless you have actually seen one in real life, you don't realize how small it is. There is not only no mounting hardware, there are no provisions for mounting it or attaching it to anything at all. And with up to 5 GK cables coming out of it - 1 input and up to four output cables, that's kind of a problem.

Put it on a table, and it will fall off when you move around and thereby move the input cable attached to your guitar. Put it on the floor, and while it won't fall off of the table, it will get underfoot as it moves around (again because you are moving) and that will put a large amount of stress on whatever cables are attached to it. One could, I suppose, use C-clamps to secure it, but that might risk damages its internals.

Each of the  4 GK outputs has a "GK Vol" and "GK SW" switch, and while that might sound like a handy feature, their physical size is "miniscule" (as inconvenient, for example, as the dip switch on the face of a SansAmp Classic) and using them while playing or performing is not in any way practical.

Although it is the only device with which I am familiar that will let you use up to 4 GK devices, it's problematical for the reasons I have outlined here. I don't believe that there is any other way to run 4 GK devices simultaneously; if I correctly recall, you can not cascade US-20's or CHD SGUS-3's, which allow connecting 2 and 3 GK devices simultaneously. (Edit: this is incorrect at least in regards to the US-20, as pointed out by Elantric in the following posts where he points out that one *can* cascade US-20's and that people on this forum have done so successfully.)

Elantric

#3
Actually you can cascade two or more US-20s

QuoteI can not really figure out how to use it in the sense of not knowing where to put it while in use,


90% simply add velcro to the bottom of GKP4 and install on a pedalboard.

Then one guitar can feed VG-8, VG-88, VG-99, GR-55 all at once.


Roland discontinued the GKP4 in 2005, because it sold very low numbers, and since it required a redesign due to its  "Lead (solder) & Cadmium (13pin DIN Jacks) components ) it was dropped in 2005  due  to the Global Weee/RoHS standards that became law that year.
http://export.gov/europeanunion/weeerohs/

(And who (besides Vernon Reid) actually needs one guitar to feed VG-8, VG-88, VG-99, GR-55 all at once!)

Lucky for us, Roland decided to "respin" a lead free US-20 instead.

All the GKP4 parts are still available,  and as I said, $40 will get you all the parts at Mouser, Digikey, Jameco, Amazon, Ebay.
If you really need one - print out this thread, and find a local electronic geek, or learn to build one of your own.

Here is one type build strategy for a DIY GKP4

https://www.vguitarforums.com/smf/index.php?topic=8391.0

 
 

Now_And_Then

 Actually, the idea of Velcro did occur to me, but then again, the surface area of the unit is so small that I would still worry about it. And as I don't use a pedalboard, I would still need a mounting board of some sort to which to attach the second piece of velcro.

Are you absolutely sure that you can successfully cascade US-20's? Have you done it? I seem to recall looking into it and am pretty sure that I have read that you can't, due to power considerations.

The problem with DIY hardware is that not everyone does DIY. I once tried. I have no aptitude with a soldering iron at all. I mean, none whatsoever.

Also, I see that a US-20, new, sells for $215-$249 (($107-$125 per GK output), so I suppose that that makes $350 ($87 per GK output) look more reasonable. Although used US-20's go for about $150 (as a ballpark figure, giving a cost of $75 per GK output), you'd need, I believe, three of them to use 4 GK devices simultaneously - and that would cost $112 per GK output. So as "standard" factory-made things go, the $350 GKP-4 can appear to be not terribly unreasonable.

Elantric

#5
QuoteAre you absolutely sure that you can successfully cascade US-20's? Have you done it? I

Yes - I have and it works

On ALL US-20's you intend to use, You must connect output labeled "UNIT A" directly to a 13 pin processor (VG-99 / GR-55, etc) ,


Cascade additional US-20's via the output labeled "UNIT B" to the "GK IN " jack of the next US-20. 

Just remember the Roland US-20's "UNIT A" jack must ALWAYS be directly connected to a 13 pin processor (VG-99 / GR-55, etc),

because the UNIT A jack is where the US-20 (and the connected GK-3 Guitar ) obtains all its power!



Other members  here have also reported success

Now_And_Then

Quote from: Elantric on April 23, 2013, 05:51:08 PM
Yes - I have and it works. On the first US-20, You must connect output labeled "UNIT A" directly to a 13 pin processor (VG-99 / GR-55, etc). Cascade additional US-20's via the output labeled "UNIT B" to the "GK IN " jack of the next US-20. 

When cascading, is it the case that the last US-20 in the chain gives you 2 outputs to run GK processors while each of the others in the chain net you one additional output to run a GK processor? So would you need three US-20's to run 4 GK devices? That's expensive; three US-20's would almost certainly cost more (and with the extra cables required, possibly more fragile and less reliable) than a single GKP-4 for $350.

That's far more expensive than DIY hardware, but some people are not going to run DIY hardware under any circumstance; they feel much more assured by a factory-made, name-brand item.

Elantric

#7
QuoteWhen cascading, is it the case that the last US-20 in the chain gives you 2 outputs to run GK processors while each of the others in the chain net you one additional output to run a GK processor? So would you need three US-20's to run 4 GK devices?

Correct!

But I advise this warning ;

Just because it can be done , does not mean it should be done! ;)

Thats why I prefer to buy used or broken at severe discount ( because I used to earn my living repairing this stuff!) or build a DIY solution.

here is the schematic


QuoteThat's far more expensive than DIY hardware, but some people are not going to run DIY hardware under any circumstance; they feel much more assured by a factory-made, name-brand item.

Their loss

The rest of us will happily be using bleeding edge devices that "the major manufacturers" deem too arcane

- like this soon to be completed system for wireless control by Gumtown:

https://www.vguitarforums.com/smf/index.php?topic=7984.0 

and companion 13 pin router
https://www.vguitarforums.com/smf/index.php?topic=7852.0

that all get configured by the user using a nice GUI

highlandsrock

Thanks for all the circuit diagrams. Think I'll have a go at making one myself. The 13 pin sockets are available in the UK, just need to find a good way of making a pcb to mount them on. Don't really want to get involved with baths of Ferric Chloride like I did many years ago
Ibanez RG870 with GT3 internal kit +
GR-33, VG-99, GR-55, GP-10, SY-1000, Strymon Big Sky

Elantric

#9
QuoteThanks for all the circuit diagrams. Think I'll have a go at making one myself. The 13 pin sockets are available in the UK, just need to find a good way of making a pcb to mount them on. Don't really want to get involved with baths of Ferric Chloride like I did many years ago

Since you are only building one for yourself - Just use Panel mount 13 pin Female DIN jacks mounted in a box, and hand wire / solder - no PCB required.

http://www.packetradio.com/catalog/index.php?main_page=product_info&products_id=706

billbax

Silly me, only now spotted this topic.  $350 is an obscene amount of money.

By my component calculations a DIY GKP4 should cost no more than $30 max.

Bill   

Toby Krebs

Guitar Center had one used for 100 dollars. I looked a couple times but decided to bring less to my cover gigs rather than two or 3 GK devices. Now if I could just hack my VG8-EX!

Elantric

#12
QuoteGuitar Center had one used for 100 dollars.

Next time you see one that cheap buy it - sell it on ebay and double or  triple your money.
Tell them on the Yahoo MIDI Guitar Group
http://groups.yahoo.com/neo/groups/midiguitar/info

Here in the USA the GKP4 has been hard to locate for 10 years now, and there are many many 13 pin users (without time or soldering skills to make a DIY version) who still dream of owning one because someone told them it was the Only way to use multiple 13 pin units at same time. (which isnt true BTW)
https://www.vguitarforums.com/smf/index.php?board=127.0

Toby Krebs

Yeah I should have pulled the trigger on that one. It's gone now. I never see used US 20s. Going to grab one of those when I do!
I did find a second used mint black GR55 for 450 dollars a couple months ago in a box. It only goes to the church I work at. Never to a club gig. It's still stock too!

aliensporebomb

Wasn't the only reason it was discontinued was due to the lead solder/environmental kerfuffle from some years ago?
My music projects online at http://www.aliensporebomb.com/

GK Devices:  Roland VG-99, Boss GP-10, Boss SY-1000.