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Advice needed - Putting an amp in a rack case??


GreeneKing
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Now, I've done this before (not with this amp)and I perhaps should know the answers to my own question. Maybe senility is kicking in but can someone help me here?

A have an EBS Fafner. It's a big lump and I need to put it in a rack case (4U to allow adequate ventilation evidently). I don't have the case yet but it'll hopefully be with me soonish. I anticipate that the front amp chrome 'ears' that the Fafner already has will mount on the front plates on either side using captive nuts and screws. That leaves the hefty rear of the amp unsupported (or am I missing something).

I emailed EBS about a fitting kit and they tell me that the case fittings are all I need. There's also no obvious mounting points for 'ears' to the rear of the amp.

I'm looking for some advice, do I need to get any extra bits and pieces before the case arrives?

Thanks in anticipation.

Peter

Edited by GreeneKing
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The chrome ears on the Fafner are very sturdy indeed. Screw the amp into the rack case and that is all you need to do. No need to worry about the rear of amp. No need to buy anything else as you should get all the stuff you need with the rack case. Just have a screwdriver to hand and you are all set. 

My Fafner has been in a rack case for nearly ten years. No issues whatsoever apart from the fact that the little lightbulb needs replacing every few years.

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On 19/10/2019 at 18:20, chris_b said:

Don't worry. Your amp was designed to be supported from the front only. As most rack mount amps are.

I'm sure EBS know, after all this time, how to correctly design their products.

I bought an old valve amp in a rack sleeve, and found it had been dropped at some point.  I guess it had hit the ground at the rear, because the impact had ripped the whole amp chassis from the faceplate.   Some support at the rear to stop the chassis sliding in the sleeve would have helped, but I've never seen one designed like that.

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11 hours ago, converse320 said:

I bought an old valve amp in a rack sleeve, and found it had been dropped at some point.  I guess it had hit the ground at the rear, because the impact had ripped the whole amp chassis from the faceplate.   Some support at the rear to stop the chassis sliding in the sleeve would have helped, but I've never seen one designed like that.

Yes, despite the earlier slightly patronising comment, a heavy amp supported on its faceplate alone, acting cantilever like, isn't ideal from an engineering perspective in terms of loads on components especially if as you say, it's given a shock load. I'll have a think when I get it fitted. It's possible that the feet will rest on the base I guess.

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32 minutes ago, GreeneKing said:

Yes, despite the earlier slightly patronising comment, a heavy amp supported on its faceplate alone, acting cantilever like, isn't ideal from an engineering perspective in terms of loads on components especially if as you say, it's given a shock load. I'll have a think when I get it fitted. It's possible that the feet will rest on the base I guess.

I will take a picture of how my Fafner rests in the EBS rack case I have. I really don't think that you have anything to worry about, but it might help in any event. 

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1 hour ago, GreeneKing said:

Yes, despite the earlier slightly patronising comment,

No patronising intended. . . but take a step back. The guys who design these amps know what they are doing. They understand the tolerances involved and there would have been reports of problems if these amps didn't perform as designed.

20 years ago I used a 45lb Mes 400+ and it supported itself from the front plate with no issues. You really are over thinking this.

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I've had this worry with PA power amps. If your rack case has the provision to mount things either way round - i.e. has drilled strips both front and back - you can get rack shelves, which you can attach at the rear. You can then rest the rear of the amp on the shelf (get a sturdy metal one, obviously), which will take part of its weight. I always do this, even if the amp is supposed to be able to be mounted front only. It may be OK just sitting in a rack, but if dropped or struck (which happens), it might be a different story.

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6 hours ago, chris_b said:

No patronising intended. . . but take a step back. The guys who design these amps know what they are doing. They understand the tolerances involved and there would have been reports of problems if these amps didn't perform as designed.

20 years ago I used a 45lb Mes 400+ and it supported itself from the front plate with no issues. You really are over thinking this.

The amp I had to repair was a Mesa Boogie D-180, cooincidentally.  There's really not very much holding the face plate on the D 180 - 4 small bolts per side, which stripped on mine.  I'm sure 99% of the time supporting only from front will be fine, but a couple of blocks at the back of the sleeve stopping the amp body sliding inside the sleeve would have save me about 12 hours work in this particular instance.  I had to use very small children to get some of the case bolts out.

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Okay, so on checking my own amp the rubber feet on the amp are solidly secured against the bottom of the EBS Proline rack case. There is no need to put anything underneath the amp to secure it further and I don’t think that there is any space to fit a rear sleeve in any event. 

Other rack cases may vary in terms of fit. However I don’t foresee any obvious issues that cause me concern or make me think that the amp needs to secured any further. I have toured with this amp and it has been travelling in vans and cars with dodgy suspension for nearly ten years. I suspect if there was an inherent design flaw of the rack case and how the amp is secured I would have discovered it by now. 

I don’t rule out the possibility that front mounting amps are less likely to survive a drop or fall than a front and rear mounted amp, however I don’t think that is an area of concern here as the amp isn’t floating. The amp is not all valve anyway so the risk is less than a front mounted Ampeg SVT II, Mesa 400+ or such like.

I just try not to drop it in the first place.

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Thank you all. I will check out the feet on the bottom versus the desirability of rear support when I cast my own engineering eye over it. I don't even have the case yet. I was wanting to know if I need to get any other bits in to do the job properly hence my seeking advice. I'm not an engineering numpty. Engineering honours degree followed by a Post Grad Diploma in Nuclear Technology and proceeded by C&G Mechanic & Technician and a B-Tec Diploma.....

Nowadays I just tinker with motorbikes :)

Peter

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22 hours ago, Jack said:

You can either fit a rack shelf to the rear rails or just wedge a block of scrap wood between the bottom of the amp and the rack floor.

Just to add to the above, a thick piece of foam will do the job too without adding any weight.

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It took only a few minutes to put the amp in the case this morning. A £2.36 length of foam insulation from B&Q, cut into lengths and halved means that the amp is firmly sat on a cushioned base of 6 'half segments' with the front screws only holding it in place and not taking the considerable weight.

I'm happier anyway :)

 

 

_DSC3314.jpg

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I'd only support the side edges. Sometimes these amps are built so that the case forms part of the heat sink and they need an airflow on all sides. If you sit the amp on foam it may not be acting the way it was designed.

My 2u Thunderfunk sits in the middle of a 4u rack case and it can get hot underneath.

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On 22/10/2019 at 23:17, Jack said:

You can either fit a rack shelf to the rear rails or just wedge a block of scrap wood between the bottom of the amp and the rack floor.

My tech guy is very much a “belt and braces” fella, and reckoned my GK1001RB needed some support at the rear of the case, so just made a wooden support (painted black) for my SKB Roto rack. High density foam would have worked equally well I’m sure, but he’s very old school. 😄

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