Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Cabinets-Speakers => Topic started by: Khristophorous on December 06, 2025, 12:47:51 pm
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I really liked the ideas of using T nuts as that would give me the ability to swap the speaker out easily if I ever wanted to but once I got the speaker (Celestion V) and did a dry fit it looks like the distance from center to edge is about 8mm. That would be fine if I just use wood screws - but I am afraid the flange of the T nut, and therefor the spike would be setting right on the edge. I am really wanting to move on from this project and just play my damn guitar so I am real close to just using plain wood screws but I thought I would come make a post and see if anything came of it before I made a decision. Also, would white polyethylene foam be a good candidate for a DIY gasket? Thanks
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Hard for me to visualize (pics would be helpful), but it sounds like you're installing the speaker on the outside surface of your baffle ?
There are a number of fasteners that should work. Probably the most reliable would be to use speaker installation screws "inside out" so to speak. These are available at Amplified Parts: https://www.amplifiedparts.com/products/screw-8-32-12-reverse-thread-speaker-baffle-mount (https://www.amplifiedparts.com/products/screw-8-32-12-reverse-thread-speaker-baffle-mount) . You'd have to cut the excess off, but this would be very reliable and is low profile.
I also use quite a few threaded inserts in this situation. Maybe not as robust as the speaker screws, but would allow a screw head to be seen on the outside instead of a nut/washer. See https://www.mcmaster.com/products/threaded-inserts/threaded-inserts-3~/ (https://www.mcmaster.com/products/threaded-inserts/threaded-inserts-3~/) -- you might have to scroll down the page for inserts intended for wood.
Foam will be messy and won't allow you to change out your speaker easily. And since this is for guitar work, a less than airtight fit won't really matter IMO.
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Yeah it is a sealed box so it is front mount. I went to Home Depot and looked at both T nuts and threaded inserts and just didn't feel comfortable with how close they would sit to the edge. It "could" work and I could probably get it right but I'd have to get it right 8 times all while making sure everything is lined up. This is my first time doing any of this. Ive always been the DYI type but that has also taught me that experience goes a long way. I'd often say to anyone around that if I had do X project over again I could probably do it in half the time and it come out twice as good. I admire that many of you have made all this your craft but my intention was never to take on a new hobby - I just really wanted a tube amp and didn't have the money to buy one outright. So you are suggesting I reach in through baffle hole, drive these screws to where the are facing out then sit the speaker over what would essentially be bolts at this point - and since the wood threads are reversed it would not back the screw out when I fastened a nut on to them. I appreciate you taking the time to leave a reply. Your profile caption fits my experience with all this to a T :laugh:
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Watch this short video to see how easy it is to properly install threaded inserts...
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I think you can do this. And yes, all of what I'm teaching you has been learned through mistakes . . .
For the speaker screw method: First, take some scrap baffle material and drill pilot holes until you find the right size where the screw goes in with little effort until the reverse part of the screw comes into play.
Drill your pilot holes from the outside, then thread in the screws with your hand from the inside, and finally finish them off with a Philips head screwdriver from the inside. This should be doable if you're using a 10 or 12" speaker.
BUT, I think you should check out the threaded inserts. Forget Home Despot. Get your fasteners from McMaster. They ship very fast and you get quality. Buy several different types. Practice with scrap wood. They work great, and your speaker will look better in the end.
Either way this is doable.
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I use tee-nuts myself. M4 is plenty strong enough for a speaker and is dainty enough not to go over the edge of the speaker cutout. Even M3 is strong enough. Also, while you need the teenut to be firmly clamped in, you should achieve this by tapping it down from the front side before you tighten any bolt through it. The speaker nut/bolt doesn’t need to be wrenched down onto the baffle - you only need enough torque for a snug fit. Too much pressure will result in the basket being dented and twisted out of shape, permanently ruining the alignment of the cone.
With any guitar amp speaker (no matter what the speaker diameter is), the cutout should be exactly 1 inch less in diameter than the speaker for it to fit perfectly - whether it’s being mounted in front of, or behind, the baffle.
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Do you guys ever put polyfil into a sealed cab?
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For Hi-Fi yes.
I normally don't build sealed cabinets for guitar amps -- just my preference. But I probably would try without first, and add it only if I didn't like the tone.