Does anyone here have a Yamaha RBX 774 or 775?

[The Marlin]

I was in my local guitar store (BBZ, a tiny place hidden away in an industrial estate in High Wycombe - it doesn't attract time wasters, only a loyal client base - all kit perfectly set up before it hits the racks) when I spotted an identical bass to mine - a Yamaha RBX 774 (I also have the 775).

It's a great bass, we got chatting about it, and I moaned about the active circuit - as enguaging it made little differece to the tone. That when I found out that every Yamaha RBX 774 and 775 ever shipped was faulty! The active circuit has a serious design problem, and it can never work as it was intended. My guitar tech got this Yamaha in as part of a trade in. As usual, with all guitars that pass through his hands, he cleaned it up, took the stings off, gave it a proper set up, and put on the new strings, then played it in. Bemused by the active circuity, he pulled it all apart, whipped out the electronics and discovered the design flaw. He called Yamaha to discuss it, they basically told him to 'go forth and multiply'. So, he managed to get hold of the original circuit diagram, and set about repairing it himself.

With the repair (a cheap minor repair), the circuitry now works properly, this it make a huge difference to the sound. Enormous! Having heard the difference, I've since taken my own 775 in to be modified, and will bring in the 774 for the same treatment once I get it out of storage (moving house).

I just thought that any other Yamaha RBX owners should look into this, as you're really missing out with the current faulty setup. As i said, the repair is cheap - and well worth it.

All the best

Marlin

[SimBass]

[quote name='The Marlin' post='679859' date='Dec 10 2009, 06:34 AM']I moaned about the active circuit - as enguaging it made little differece to the tone.[/quote]
That's interesting I had a 775 for quite a few years...Really liked it.
What do you mean by engaging the active circitry? As far as I was away it was an active only instrument (ie. active circuitry could not be disengaged). There was a "boost" switch...which admitedly didn't make much of a difference but as far as I was aware it was never meant to "engage" the active circuitry, it was just a subtle boost?
[url="http://www.yamaha.ca/content/guitar/products/electricbasses/RBX775/specifications.jsp"]Yamaha Canada Spec (only country with spec still online)[/url]

So does the mod turn this into an active/passive switch?

[The Marlin]

[quote name='SimBass' post='680319' date='Dec 10 2009, 02:57 PM']That's interesting I had a 775 for quite a few years...Really liked it.
What do you mean by engaging the active circitry? As far as I was away it was an active only instrument (ie. active circuitry could not be disengaged). There was a "boost" switch...which admitedly didn't make much of a difference but as far as I was aware it was never meant to "engage" the active circuitry, it was just a subtle boost?
[url="http://www.yamaha.ca/content/guitar/products/electricbasses/RBX775/specifications.jsp"]Yamaha Canada Spec (only country with spec still online)[/url]

So does the mod turn this into an active/passive switch?[/quote]


Hmmmm...... I thought it was passive to active, but picked up mine used, and no info was provided on bass features. So, was most likely an assumption. Regardless, the mod fixes the isses and makes a heck of a difference.

Cheers

Marlin

[BanditSid]

[quote name='The Marlin' post='682626' date='Dec 12 2009, 11:03 PM']Hmmmm...... I thought it was passive to active, but picked up mine used, and no info was provided on bass features. So, was most likely an assumption. Regardless, the mod fixes the isses and makes a heck of a difference.

Cheers

Marlin[/quote]

What was the mod he did?

[The Marlin]

Yamaha put the wring connector in there. Instead of being 'W' shaped, it's like two 'U's, one in front of the other - so it doesn't engage the boost properly, and has little impact on sound.
By re-wiring the connector, you can get it to function in the desired way. It does make a very big difference to the tones produced.

Cheers

Mr Marlin

[he man812]

hey 'the marlin'

I'm quite intrested on getting this modification my self

do you have to take it to this shop or can you do it your self with a pcb diagram and some wires/components?

thanks

[Machines]

Mine seemed to function fine, the boost wasn't overpowering but I never for once thought there was a fault with it.

Just checked the circuit diagram ([url="http://www.yamaha.com/yamahavgn/Documents/Guitars/RBX774_775_E.pdf"][b]here[/b][/url]) and it states the circuit is a +3dB switch which sounds about right.

Mine is currently in bits but i'll mention it to the tech when it gets rebuilt.

[geoffbyrne]

Not the ones you mention, but I did have an RBX375 & in doing reading/research about it, I read one guy found that the pups were wired out-of-phase. I checked & sure enough, so were mine. I reversed one pup & the tone blossomed, so inaccuracies seem to be 'not unusual' in this line.

G.

[he man812]

[quote name='geoffbyrne' post='1223930' date='May 8 2011, 09:54 AM']Not the ones you mention, but I did have an RBX375 & in doing reading/research about it, I read one guy found that the pups were wired out-of-phase. I checked & sure enough, so were mine. I reversed one pup & the tone blossomed, so inaccuracies seem to be 'not unusual' in this line.

G.[/quote]

hey G

I don't wanna be a noob but can you explain to me how to do this maybe with some pictures if you have the time
and what is a pup?

cheers

[geoffbyrne]

'Pup' = pickup - it's faster to type!

I can't do pics of this as I don't have that bass anymore, but in its greatest simplicity, it's just a case of reversing to positions of the 'Hot' & 'Ground' connections of one (1) of the 2 pickups, in the RBX375's case, where they connected to the rotary selector.

When pickups are out-of-phase, usually there is 'phase cancellation' of many of the bass & lower mids frequencies which leaves the tone sounding rather thing & nasally. Putting them back in phase allows the full bass end to come forth & prosper!!!

Helps if you can solder.

G.

Edited May 8, 2011 by geoffbyrne

[he man812]

thanks for the reply!

could this possibly work with the 774 since it has a switch selector instead of a rotary one? or does the problem not exist on that

sorry that this is a bit of a struggle for me to understand since i only do novice electronics at school but I'm good at soldering

I have read about a battery problem with the the 37* series and was wondering if this applied to the 77* series as well.
[url="http://www.talkbass.com/forum/f38/yamaha-rbx374-battery-life-wtf-209227/"]http://www.talkbass.com/forum/f38/yamaha-r...ife-wtf-209227/[/url]

I am asking too many questions as I have recently acquired a 774 off ebay since I tried a 374 and loved the feel of it

many thanks

[geoffbyrne]

[quote name='he man812' post='1224577' date='May 8 2011, 09:58 PM']thanks for the reply!

could this possibly work with the 774 since it has a switch selector instead of a rotary one? or does the problem not exist on that

sorry that this is a bit of a struggle for me to understand since i only do novice electronics at school but I'm good at soldering

I have read about a battery problem with the the 37* series and was wondering if this applied to the 77* series as well.
[url="http://www.talkbass.com/forum/f38/yamaha-rbx374-battery-life-wtf-209227/"]http://www.talkbass.com/forum/f38/yamaha-r...ife-wtf-209227/[/url]

I am asking too many questions as I have recently acquired a 774 off ebay since I tried a 374 and loved the feel of it

many thanks [/quote]

I believe many of these were made with incorrect wiring at the jack socket which allowed the battery to drain, although I might stand corrected, as I seem to remember a possibility the pre had a manufacturing fault which required replacement.

As for swapping the phase, if it sounds thin & nasally (everything set flat including amp), then try it - it can always be put back.

G.

[he man812]

[quote name='geoffbyrne' post='1224651' date='May 8 2011, 11:23 PM']I believe many of these were made with incorrect wiring at the jack socket which allowed the battery to drain, although I might stand corrected, as I seem to remember a possibility the pre had a manufacturing fault which required replacement.

As for swapping the phase, if it sounds thin & nasally (everything set flat including amp), then try it - it can always be put back.

G.[/quote]

cool, much appreciated

will post back when i recive my bass

[geoffbyrne]

I think an abject apology to Marlin for hijacking the thread is overdue.

Sorry, Mate.

G.

[Dropzone]

I have one of these as my reserve bass. Who did you get to do it (and where) as I have never been quite as happy with the sound as I believe others have been.

Ta

Mike

[he man812]

got my new 774 in blue it looks fantastic, amazingly it was the last of a batch that this shop got years ago so it brand new! (but still quite old obviously)

i need to adjust the truss rod as i get fret buzz on some frets cause the strings are too close to the board.
However the question is do i loosen or tighten the truss rod to make the neck more curved?

as for boost switch it dosen't seem to make much difference just makes it a tad louder

and i don't know if i have the battery problem because i haven't had it long enough to tell

cheers

[LYNCHMAN]

On 12/10/2009 at 01:34, The Marlin said:

I was in my local guitar store (BBZ, a tiny place hidden away in an industrial estate in High Wycombe - it doesn't attract time wasters, only a loyal client base - all kit perfectly set up before it hits the racks) when I spotted an identical bass to mine - a Yamaha RBX 774 (I also have the 775).

It's a great bass, we got chatting about it, and I moaned about the active circuit - as enguaging it made little differece to the tone. That when I found out that every Yamaha RBX 774 and 775 ever shipped was faulty! The active circuit has a serious design problem, and it can never work as it was intended. My guitar tech got this Yamaha in as part of a trade in. As usual, with all guitars that pass through his hands, he cleaned it up, took the stings off, gave it a proper set up, and put on the new strings, then played it in. Bemused by the active circuity, he pulled it all apart, whipped out the electronics and discovered the design flaw. He called Yamaha to discuss it, they basically told him to 'go forth and multiply'. So, he managed to get hold of the original circuit diagram, and set about repairing it himself.

With the repair (a cheap minor repair), the circuitry now works properly, this it make a huge difference to the sound. Enormous! Having heard the difference, I've since taken my own 775 in to be modified, and will bring in the 774 for the same treatment once I get it out of storage (moving house).

I just thought that any other Yamaha RBX owners should look into this, as you're really missing out with the current faulty setup. As i said, the repair is cheap - and well worth it.

All the best

Marlin

can someone please spell out just what the fix is?....i can do it myself if i can find out what needs to be modded or replaced....

 

thanx