Fender CS Rumble 300 watt head

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Fender CS Rumble 300 watt head

Postby CoryT on Tue Feb 16, 2010 12:10 am

Does anyone have any pics of this amp or the cabs that came with it (I think they were 410 and 115).
Thanks
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Re: Fender CS Rumble 300 watt head

Postby The Golden Boy on Tue May 25, 2010 3:02 am

I think if you find pix of Glen Matlock on the Sex Pistols' Filthy Luchre tour from 97 or whenever that was- he was playing those amps. From anything I've read- he's about the only person to use them.
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Re: Fender CS Rumble 300 watt head

Postby thornybank on Fri Jun 11, 2010 9:59 pm

Got one for a pal.
Tweed/oxblood.
4x10 top cab, 4x10 sub cab.
Pics on my other compy....
...how do I post 'em?
Shut that thing off and get to bed!
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Re: Fender CS Rumble 300 watt head

Postby Nostromo on Wed Aug 11, 2010 6:25 pm

Here are some pics of my example . . . . still in good condition.
:)
Attachments
Fender Rumble Bass 02.jpg
Fender Rumble Bass 03.jpg
Fender Rumble Bass 01.jpg
Nostromo

Vox AC30TB Sept 1964
Vox AC30HW Limited Hand Wired Edition 2003
Fender Dual Professional Custom Shop 100w Combo 1995
Fender Rumble Bass Custom Shop 300W All Valve Head 1997
Hiwatt DR405 Bass Head 2009
Nostromo
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Re: Fender CS Rumble 300 watt head

Postby Nostromo on Wed Aug 11, 2010 7:29 pm

Niel Young's bass player uses one still.

He used it at the pyramid stage Glastonbury Festival . . . . and it looked for all the world like it was plugged in and running !

:D
Nostromo

Vox AC30TB Sept 1964
Vox AC30HW Limited Hand Wired Edition 2003
Fender Dual Professional Custom Shop 100w Combo 1995
Fender Rumble Bass Custom Shop 300W All Valve Head 1997
Hiwatt DR405 Bass Head 2009
Nostromo
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Re: Fender CS Rumble 300 watt head

Postby Psycho Bass Guy on Fri Aug 20, 2010 8:10 am

If you have one of these that has seen much use and still runs, consider yourself extremely fortunate. Like all the Fender "Custom Shop" amps, the Rumblebass has serious ventilation issues, and once heat damage starts showing up, you'll be chasing it through lots of different components in the amp.
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Re: Fender CS Rumble 300 watt head

Postby Nostromo on Mon Aug 30, 2010 6:25 pm

Here here ! ! . . I agree with that,

Mine is in very very good condition to look at, has never been dropped or damaged, worked perfectly for years - and sounds absolutely amazing when it is working - the best sounding bass amp I have ever heard in my life - nothing can touch it for amazing tone.

But . . . . over the last couple of years it has started to become more and more unrelable.

In fact its just had a couple of months repair time with one of the very best Valve Amp techs in the UK . . . sounded perfect whan I got it back, but only lasted a couple of hours before it started playing up again ? ?

It never feels particularly overheated . . . the fan blowing air onto the transformer works fine . . so, on the face of it, my example is not in any way displaying any obvious signs of overheating . . the valves dont overheat and it doesn't feel like its cooking when you are close around it ? . . . . but it intermittently pops, crackles and motorboats to the extent that you could never trust it for a gig or recording session.

Generally . . . when it starts to play up, a firm slap on the side will silence it for maybe five minutes (just like the old days when you used to slap the TV to get it to work ! !) . . . but after some time, maybe five minutes, maybe an hour, the various noises start to come back again . . . . . . . . . really frustrating !

Real shame . . . . I would desperatly like to get it sorted out properly ! ! . . . . . have tried three different UK valve amp techs and none of them have been able to nail the problem so far ?

Any thoughts or experiences out there ? ? ?

:?:
Nostromo

Vox AC30TB Sept 1964
Vox AC30HW Limited Hand Wired Edition 2003
Fender Dual Professional Custom Shop 100w Combo 1995
Fender Rumble Bass Custom Shop 300W All Valve Head 1997
Hiwatt DR405 Bass Head 2009
Nostromo
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Re: Fender CS Rumble 300 watt head

Postby Psycho Bass Guy on Mon Aug 30, 2010 11:25 pm

The chassis ventillation is the problem, not the tubes or transformers. The fan doesn't do squat for that. ALL the passive components, mostly the caps, suffer from the heat. However, unlike most vintage instrument amps where high capacitance wasn't common and resistor values not so crtical, the drift in tolerance causes serious problems in the Rumblebass. The amp needs a complete recap, including the small coupling caps, and probably could do to have all the critical resistors changed, too. After that's fixed, the chassis needs to be cut for ventillation, including making some ducts through the outside headcase, preferably with their own fan. I'm not a fan of the 'shotgun' approach in most cases, but in this one, it's the only way. It sucks to have to take such drastic steps and make irreversible changes to an extremely rare and valuable amp, but it's the only way it will ever be reliable.
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Re: Fender CS Rumble 300 watt head

Postby Nostromo on Tue Aug 31, 2010 6:59 pm

Thanks for that valuable insight !

I have a simple appreciation of how Valve Amps work but am in any way an amp tech who could do this work myself - my soldering isnt tidy enough for a start ! !

As you know, the Rumble Bass has two chassis units . . One appears to me to be a pre amp chassis and that is screwed to the front top surface of the amp cabinet and incorporates the user controls. The other box must be the power stage chassis as its got the six 6550 power valves seated on it and it is positioned at the bottom rear of the amp cabinet. The two appear to be connected by a multi core umbilical cable. There is about a 1 inch gap between the top of the row of power valves and the back edge of the pre amp chassis with its row of pre amp valves (well I think they are pre amp valves ?)

Which of these two chassis units is it that overheats its components ? . . or is it both ? . . . seems to me like heat rises, and Im guessing its the power valves that generate the heat . . so that would make the overhead pre amp chassis the prime contender for overheating ? . . . but like I say Im no amp tech ! . . so I bet I'm probably totally wrong ? . . . and that its not the power valves that generate the heat . . . and maybe its not heat rising that cooks one of the chassis units ? ? . . . ha !

Also, I read some time ago that the power chassis part of this amp is based on the classic Ampeg design, which is really highly regarded . . . and very reliable . . so its really weird to imagine that such a well tried and tested power stage design could go so badly wrong in this amp . . . I've never heard of the Ampegs cooking ? . . . really weird ?

Best wishes all from the UK.

:?
Nostromo

Vox AC30TB Sept 1964
Vox AC30HW Limited Hand Wired Edition 2003
Fender Dual Professional Custom Shop 100w Combo 1995
Fender Rumble Bass Custom Shop 300W All Valve Head 1997
Hiwatt DR405 Bass Head 2009
Nostromo
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Re: Fender CS Rumble 300 watt head

Postby Psycho Bass Guy on Wed Sep 01, 2010 6:41 am

Nostromo wrote:Which of these two chassis units is it that overheats its components ? . . or is it both ?


It is both. The problem stems from a combination of shoddy flow-soldering, cheap capacitors and heat build-up. The heat is attacking the solder connections and devaluing the caps, causing the oscillations you're hearing, which are doing some SERIOUS damage to your power tubes.

Also, I read some time ago that the power chassis part of this amp is based on the classic Ampeg design, which is really highly regarded . . . and very reliable . . so its really weird to imagine that such a well tried and tested power stage design could go so badly wrong in this amp . . . I've never heard of the Ampegs cooking ? . . . really weird ?


Old SVT's are laid out in similar fashion, but have front and rear vents and a semi-open maintanence cutout on the lower chassis that gives all the major resistors a tunnel-airflow. Their upper chassis is also not fully enclosed and is set forward of the vent fan. Plus the caps they used were of much higher inital quality and the amps were all hand-soldered. I have six vintage SVT's, along with a host of other big tube bass rarities, some of which, a few internet "experts" have said don't even exist! It's been over ten years since I've played through a Rumblebass in a store, but I'd still like to have one some day. Good luck fixing yours, because they are truly tone monsters.
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Re: Fender CS Rumble 300 watt head

Postby Nostromo on Wed Sep 01, 2010 9:23 am

Thanks again for your info.

Priceless information - many thanks.

Must confess it sounds like Im going to have to embark on some serious surgery to sort this rumble bass head out. I'd read they could be tempermental, but mine had always been fine for years, up until it started develpoing the recent faults, so until then, I'd just thought it was a quality control thing rather than fundemantal design flaw, and that I had a "good one" !

Anyway, my problem is finding someone knowledgable enough to take on such a project ? . . . . to diagnose exactly what needs replacing and to undertake the required work ? like I said above, I'm no amp tech . . I definitely cant do the work myself . . . and the people who have looked at it so far clearly had nowhere near the knowledge that you have on this particular amp, so none of them have been able to fix it or even offer any advice on possible ways ahead ?

Can anyone recommend a top quality amp tech guru in the south of the UK who could sort this rumble bass out for me ? ?

Thanks

:?:
Nostromo

Vox AC30TB Sept 1964
Vox AC30HW Limited Hand Wired Edition 2003
Fender Dual Professional Custom Shop 100w Combo 1995
Fender Rumble Bass Custom Shop 300W All Valve Head 1997
Hiwatt DR405 Bass Head 2009
Nostromo
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Re: Fender CS Rumble 300 watt head

Postby Psycho Bass Guy on Wed Sep 01, 2010 8:06 pm

Any decent tech should be able to fix your amp. The reason the ones you have taken the amp to before haven't been successful is that they've probably focused their efforts on a single area of the circuit. The WHOLE amp needs to be repaired/rebuilt with some new thermal management added. This guy should be able to help you: http://www.chambonino.com/index.html
I only know him by his website, but the stuff he has posted shows he is very knowledgable and has great attention to detail.
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Re: Fender CS Rumble 300 watt head

Postby Nostromo on Wed Sep 01, 2010 10:27 pm

Yea Psycho, you are very right, everyone who has looked at it so far has focused on valves and biasing (I dont exactly know what biasing is) but I had a hunch it couldn't all be down to the valves ? . . . . one tech changed some pre valves, one the power valves (ouch expensive !), and one both ! ! ! . . thats what all the tech's I've taken it to have homed in on . . . so, lots of new valves, and expence, and then further replacements of valves that were almost new anyway ! . . and I didn't think could have possibly needed changing yet again ? . . . . . . but it didnt make any difference, the repairs only lasted hours at most ?

That site you pointed to looks good . . . . many thanks for that, but ! ! ! . . . . even they are giving out bad vibes about the difficulty of repairing SVT circuits ! . . . . (I was looking at their repair diary on the Ampeg bass amps they've had through, GENERAL SERVICING WORK CARRIED OUT ON EIGHT AMPEG AMPS ! . . . and I quote "when it comes down to the SVT bass-amp range, my views on [how much they like the Ampeg equipment] change! Yes, I am well-aware that most bass players really like the SVT, and to a point, rightly so. When in good working order they are great, really doing the business and providing the power…..and they are generally a good & powerful bass amp! . . . But, when it comes down to working on them, they can be a tech-guy's absolute nightmare!!" . . . . bad reading ! ! ) . . . but thanks again so much for your invaluable info . . .

it all looks a bit daunting !

:cry:
Nostromo

Vox AC30TB Sept 1964
Vox AC30HW Limited Hand Wired Edition 2003
Fender Dual Professional Custom Shop 100w Combo 1995
Fender Rumble Bass Custom Shop 300W All Valve Head 1997
Hiwatt DR405 Bass Head 2009
Nostromo
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Re: Fender CS Rumble 300 watt head

Postby Psycho Bass Guy on Thu Sep 02, 2010 12:01 am

The biggest nightmare on repairing a vintage SVT is that often they've had more than one "tech" in them over the years that didn't know what he was doing, so in addition to troubleshooting the amp, you're also back-tracking some idiot's half-assed "repair." There are also several modern variations of Ampeg amps that are absolute nightmares, because they use lots of s/s circuitry that is running on the edge of tolerance and when things get out of whack, it's a huge headache to trace and you end up having to replace a whole lot of transistors.

Ampeg was formerly owned by St. Louis Music since 1986, and they produced several s/s and hybrid amps that are hard to get parts for and difficult to service. Since they were bought out by Loud Technologies in 2006, the amps themselves have changed manufacturing sources several times, first Vietnam, then China, and now Korea, all from different factories in each country. Parts for those are all but nonexistent, and the overall quality is drastically lower. So don't let the 'Ampeg' comments scare you off. I used to do repairs myself, and there are lots of amps out there (modern Marshalls and Fenders) that I absolutely HATED working on, but I still did.

That guy built a 1000 watt tube amp from scratch. He can handle your Rumblebass.
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Re: Fender CS Rumble 300 watt head

Postby Psycho Bass Guy on Thu Sep 02, 2010 12:07 am

Please take note that he said:
However, when it comes down to some of the later Ampeg amps...


Those are what I was referring to in my previous post.
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