#1
I've decided to get a Valveking 212. I couldn't settle for a half stack for it was too big, parents thought it was too loud (I don't blame them for thinkin that), and too expensive. I read that open back speakers sounded loose while closed backs and a more tight bottom end to them. I was wondering how I could close the back of the speakers up. Of course, I'm scared of ruining amp for there might be overheating or soemthing. I'm new to this so please be understanding. In addition, I also read that you don't want to restrict air flow to the "valves". I'm not sure what that means but can guess that they might be the tubes of the amp. I thought of closing most of the back off (with something, I don't know what to use and would like to know what's the best) and leave the area where the tubes are open. Anyone know if this could work? Please reply and be understanding for I'm new to this. Thank you for your time!

P.S. Here's a link to an image of the back of the amp. http://www.gbase.com/files/store_images/gear/2314374/p2_u4bx0ktqi_so.jpg
#3
If you want to close the back, get a good piece of plywood and cut it to fit the opening. Cover it with tolex to match your amp. Mount a few metal flanges in the back of the amplifier and drill them for screw holes. Then drill matching holes in the new cover and screw the thing into place. People have done this with a number of combo amps over the years. It might tighten up the sound a bit, but then again you might decide it was a lot of work for nothing. Talk to a good amplifier technician and get his or her input.

One other thing to remember: those tubes are hanging upside down in a combo amp. If you seal the back, you are going to cut off the air flow and greatly increase the heat inside the amplifier (not good). Leave a decent space for ventilation.
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#4
This is how some dude turned his Flextone III Plus into a closed back combo...

It might give you some ideas?

http://riversideguitardave.awardspace.com/flexIII_closed_back_project.htm
Last edited by BurstBucker Pro at Sep 24, 2010,
#5
The big concern would be heat and airflow. In the Flextone project, the housing of the chassis was grilled, plus that handle spot was there to give more flow. If you have to leave enough opening for airflow, it might negate some benefit.

What about just running your output into a closed cab?
Water which is too pure has no fish - Ts'ai Ken T'an
#6
The problem is; in order to really get a 'closed back sound' you need the whole thing to be closed off so the speakers have a sealed enclosure to 'push' against. If you leave an opening for the tubes to vent heat, which you really need to, then its not a closed back and you might as well not waste your time.

If you really want to pull this off, your best bet is to somehow enclose the speakers, but not the chassis... So basically you want a head and a speaker cabinet. Sorry.
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#7
You could source out a cheap amp head cabinet, and convert the combo into a 2x12. Heat is an issue though, your tube amp will never be a combo.
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