Adding a 1/4" input to a MAGNASYNC/MOVIOLA URS

Jeff White · Post by **Jeff White** » Fri Jul 21, 2006 10:05 am

I've been watching this all week and finally won it:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... %3AIT&rd=1

Now I need to add a 1/4" input jack to the thing. Should I do this myself or take it to someone? I have no experience working on tube gear.

Jeff

I'm Painting Again · Post by **I'm Painting Again** » Fri Jul 21, 2006 10:13 am

shouldn't be too hard..you sure it doesn't have one already?..either way those things are awesome..

Marc Alan Goodman · Post by **Marc Alan Goodman** » Fri Jul 21, 2006 12:44 pm

I wired one up myself recently and it wasn't that bad. Josh DiJoseph (jDj on here) did one recently as well and I bet he did a much more professional job than I did so you should ask him about it.

-marc

JdJ · Post by **JdJ** » Sat Jul 22, 2006 12:06 pm

Howdy-

I ended up going the Marc route which involved removing the weirdo single-pin power jack to use for the 1/4" in jack.

First thing is to carefully remove the 4 feet so you can pull chassis from the case.

BE CAREFUL WHERE YOU PUT YOUR FINGERS!! Despite both of my Moviolas having discharge resistors across the caps, you can easily zap yourself into a coffin- no joke... So follow the typical tube precautions. Keep one hand behind your back etc and make sure those caps are discharged!

First I snipped the resistor lead (or weird spring thing in the older one) that connects the single pin power supply where it connects to the tube/cap (I can't remeber which off hand). This will allow you to remove the jack so you can install a 1/4".

Alright, now you need to find the lead coming off of the 4 pin input that goes straight to the input tube's grid. In mine I think it is a solid lead coming off of the bottom tab (when looking into the open bottom of the chassis). Just tack a lead onto this tab. This will connect to the tip of your 1/4".

If you are using a open Switchcraft jack, the ring grounding to the chassis is all you'll need ground wise. If it is a rean/insulated type, you'll need to solder a ground wire from the sleeve to any one of the grounding tabs on the chassis.

Reassemble and you should be done!

Go easy on the volume, I think that the normal input level for these things is tiny!

Hope it helps.

Cheers,

Josh

inverseroom · Post by **inverseroom** » Sat Jul 22, 2006 12:59 pm

Mine already had a 1/4" input...but I had these guys mod it for me a bit, replacing the pot and changing the input impedance...

www.voodooamps.com

It sounds so amazing I can barely stand it.

JdJ · Post by **JdJ** » Sat Jul 22, 2006 1:43 pm

Mine already had a 1/4" input...but I had these guys mod it for me a bit, replacing the pot and changing the input impedance...

I haven't checked the input impedence of mine, but I think it would be pretty easy to mod. I'm sure the stock impedence is probably waaaaay off. Did you notice a big difference in tone?

-J

inverseroom · Post by **inverseroom** » Sat Jul 22, 2006 4:35 pm

Well, I wasn't getting much out of it at all when I bought it (on eBay, for $25) except shitty-pot noise. So I couldn't really tell. It definitely distorted really hard, really soon. But now there's a bit of clean gain up to about 3 or 4 before the sound gets really furry. I've been using it right on the borderline, mic'ed super close.

T-rex · Post by **T-rex** » Sat Jul 22, 2006 8:49 pm

Congrats on winning the Moviola.

Man I have been looking for one of these forever and I am not sure how I missed that one.! If anyone sees one or has a lead on one, please hook a brother up!

Jeff White · Post by **Jeff White** » Wed Jul 26, 2006 9:16 pm

Thanks to everyone on here for the feedback. JdJ, I appreciate the step by step instructions.

Here's an update on the recently received Moviola.

It powers up and I am getting the sound of an amp on 11 (without a guitar connected); noise is passing through the speaker. The light does not work, though I imagine this easy to fix.

Is the weird little jack next to the fuse & power cord the one that I want to replace with a 1/4" input jack? Can the headphone jack be used for this?

I opened up the back of the chasis and discovered that all of the tubes that I can see are RCA. Sweet.

I am going to have someone mod this for me. I want the following:

* 1/4" input jack for guitar & reamping.
* recap if needed
* replace old AC cable with grounded modern 3-pin
* Adjust input impedance
* Test all tubes, speaker, and gain pot, etc. Replace if neccessary
* Install a 1/4" speaker output (mod the headphone out jack?) if possible to try it through 10", 12", etc.
* replace burnt out light/LED with new one, possibly blue.

Is there anything else that I should be looking to do to this thing? I'm dying to hear it!!!

inverseroom... How much did www.voodooamps.com charge you for the work that they did?

Jeff

inverseroom · Post by **inverseroom** » Thu Jul 27, 2006 6:15 am

They did most of the stuff you want done (my pilot light was working, though, and it already had a 1/4" jack) and charged me around a hundred bucks. It did need a recap, for sure, but the tubes were in great shape...they put on the new cord...adjusted the input impedance...fixed the pot...etc.

Next time I do something like this I'm going to try to do it myself. But I'm really satisfied with what they did...and now that they've done mine they won't wonder WTF you're talking about when you ask them about yours.

Jeff White · Post by **Jeff White** » Thu Jul 27, 2006 10:05 am

inverseroom wrote:They did most of the stuff you want done (my pilot light was working, though, and it already had a 1/4" jack) and charged me around a hundred bucks. It did need a recap, for sure, but the tubes were in great shape...they put on the new cord...adjusted the input impedance...fixed the pot...etc.

Next time I do something like this I'm going to try to do it myself. But I'm really satisfied with what they did...and now that they've done mine they won't wonder WTF you're talking about when you ask them about yours.

thanks so much for the information!

Jeff

Dubious · Post by **Dubious** » Thu Jul 27, 2006 1:51 pm

Songbird music in toronto usually has a couple of those modded and on sale in the shop.. not o ntheir website but maybe you could call the sote and inquire.

i jusat bought a bogen challenger im going to mod out with 1/4"s and a 3prong this weekend.

for the record the "strange jack on the back" is an old stlye speaker jack.

JdJ · Post by **JdJ** » Thu Jul 27, 2006 4:36 pm

jdub wrote:

Is the weird little jack next to the fuse & power cord the one that I want to replace with a 1/4" input jack? Can the headphone jack be used for this?

Yup that's the one that I removed, I was thinking about using the headphone jack, but then I was considering using it for a ext speaker jack so I didn't. I guess you could put a speaker jack where the old weird speaker jack is, and rewire the headphone jack as the input. Keep in mind that the headphone jack is switching, so I beleive you'll have to connect the two leads which go to it to keep signal going to the internal speaker.

Good luck,

J

enduringboredom · Post by **enduringboredom** » Thu Aug 03, 2006 1:43 pm

Here is a pdf of a scan of the schematic.

We have a bunch of theses at here at the Evergreen State College. I made an 1/4" adaptor for the 4 pin input and tested 3 of them today. They sounded pretty good.

Aaron

runrunrun · Post by **runrunrun** » Fri Jul 13, 2007 1:48 pm

does anyone know exactly what to change/swap to adjust the impedence?

is R1 removed and R2 is changed to 1 meg, kinda like blackface fender style?

would anybody who has had theirs modded care to send a pic of the insides? thank you.

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Adding a 1/4" input to a MAGNASYNC/MOVIOLA URS

Adding a 1/4" input to a MAGNASYNC/MOVIOLA URS

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