Reverb bag

[dude]

I searched here and on the net, a lot of posts and info but no facts. So, I'll ask opinions here. I have a pine head cab I just finished and need to install the reverb tank. Since it's a head do I need a reverb bag and besides possible vibrations issues from a speaker, why are they used? I was just going to screw the tank to the bottom of the head cab through the four grommets, loose not cranking them tight. Situate the output on the tank opposite the PT. The only reason I can see using a bag would be to keep dirt out. Some say place cardboard under the tank then screw to the bottom loose, some say cardboard then place in bag screw through the bag to base. I guess the tank just sits on the cardboard in the bag, only having the bag screwed down...? This seems off to me. Why is the cardboard suggested under the tank? Any other suggestions how to attach the reverb tank to a head cab appreciated.
     

[Latole]

IMO cardboards is useful to keep dust off and to protect springs and transducer from small object.
I alway put cardboard hold on the tank with twist.
I'll put grommets as you say, not loose but not too tight

I build some amps with reverb tank.

I sometimes use simili- leather to make tank bag, small part of cab covering

[acheld]

Reverb bag is used to reduce feedback (spkr-->tank).   I've never used one, and never had a problem. 

But it does happen, and just the other day another forum member reported significant feedback in his new combo, and was in the process of mitigating it.   

Don't worry about dust!  It keeps the sound real.   Honestly, my guess is that few of us here use reverb bags.

[HotBluePlates]

... Since it's a head do I need ...

I didn't wreck my car today, so do I really need a seatbelt?

Almost every day driving for 30 years, I never encountered a situation where the belt did something useful.  But there was that one day I totaled my vehicle, and it was a good thing I had it on...

A lot of Amp Best Practices might not be strictly necessary.  But they're done "just in case" so a bunch of extra effort isn't required later when a Rare Problem impacts the amp.

Ampeg didn't use Tolex bags (that I've seen), and seem to have gotten away with it.  You can use some alternative method to shock-mount the pan to try to avoid feedback problems.  Make sure you copy a good plan that a manufacturer implemented successfully (unless you want to do your own trial & error testing).

I'm sure Fender could have saved $$$$$$$$$$$$$$$$$$$$$$$$$$ if they didn't use tolex bags & tie-down straps for the past 60 years.  I suspect they spend the money for a reason.

[Latole]

... Since it's a head do I need ...

I didn't wreck my car today, so do I really need a seatbelt?

Almost every day driving for 30 years, I never encountered a situation where the belt did something useful.  But there was that one day I totaled my vehicle, and it was a good thing I had it on...

A lot of Amp Best Practices might not be strictly necessary.  But they're done "just in case" so a bunch of extra effort isn't required later when a Rare Problem impacts the amp.

Ampeg didn't use Tolex bags (that I've seen), and seem to have gotten away with it.  You can use some alternative method to shock-mount the pan to try to avoid feedback problems.  Make sure you copy a good plan that a manufacturer implemented successfully (unless you want to do your own trial & error testing).

I'm sure Fender could have saved $$$$$$$$$$$$$$$$$$$$$$$$$$ if they didn't use tolex bags & tie-down straps for the past 60 years.  I suspect they spend the money for a reason.

I agree
And bag are so cheap $10 or very easy and cheaper to make one

[mresistor]

I agree
And bag are so cheap $10 or very easy and cheaper to make one

I'd like to know where you find one for sale for $10.

[Latole]

https://www.amplifiedparts.com/search/node/reverb%20bags