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Discussion in 'DIY Amp Forum' started by sumran, Oct 30, 2015.
Ill try to get some pictures of my two DIYs
Before the weather sets in tomorrow.
According to the plans (If I'm not misinterpreting things), that's missing the "port cover" over the center opening.
Edit: I zoomed in on the plans so I could read all the text, and I see the port cover is an optional thing that changes the low end response, and can be put on or taken off, depending on the application. That's a pretty neat cabinet.
Its curious that in high end hi-fi speakers the interior is most usually stuffed to the max with damping material to prevent this beaming effect stated. I guess others effects must go on, but guitar & pa cabs are usually devoid of anything like that. Somewhere a trade off is going on with regard to the 'loss' happening due to such amping in ratio to the gain in clarity coming out. Is that along the lines of whatever sound might get itself involved in beaming is best locked in & prevented thru a relative expenditure of amplification wattage sacrificed to inertia in damping - well at least in hi-fi?. If so the resultant sound can emerge better it just costs wattage basically - the cubic volume of a properly measured hifi speaker ( like KEF who get that right ) versus speaker characteristics seem not hindered by full stuffing of interior. The desired emission goes on regardless & surely is it just a literal usage of power which is lost here i.e the damping needs to use power to prevent beaming before a clean signal can rush by a busy inert vortex kind of thing ?.
No idea if thats just some nonsense or not but personally i have never put two & two together for guitar cabs in relation to why the hifi guys do this stuffing so much - i must try it in my 4x12's and prove if i'm talking bs or not but i'd expect people already know and can explain something better in this sense.
Yes, quite a bit of nonsense.
Beamwidth and resonance damping are two separate unrelated characteristics.
The only "power" that is involved is the reduction of efficiency at the standing wave frequencies.
Here's a peek inside a '60s Fender cabinet.
Ok - i'll assume that a 50 watt head is putting out the same 50 watts at the front even after standing waves have been absorbed by damping.
You probably know already, but the actual power going out of a speaker isn't very much, since the conversion to pressure waves is not very efficient. The writeup on that Electrovoice cabinet in post 31 talks about 6% acoustic efficiency, so a 50 watt amplifier would put out about 3 watts of sound energy.
I will post pics once I am satisfied with its performance. First incantation was helpful but not satisfactory. Rework is in process. Currently hampered because I can’t find my pop rivet tool. Found the rivets and drilled the holes. I am using the rivets to hold the lid rim in position where the two buckets join together. It will surface soon I hope. If not, I will have to get another.
Regarding the joints on the cabinets: I have decided to use an interlocking miter joint instead of a box joint. Once you have the tool and setup it is faster than a box joint. The are no layout concerns as to where the fingers fall on the cut lines. It is a stronger joint. And I prefer the appearance of the miter, especially on woodgrain cabinets. They both look good and work well.
All my projects take way longer (and many more trips to the hardware store) than I at first thought.
The locking miter is a clean look and once the set up is dialed in it goes pretty quick. Also, once the two parts are assembled it naturally squares the cabinet.
Good stuff, keep us posted.
I think there is something to using lighter materials in cab construction, especially with baffle thickness. The older Fender and Music Man cabinets I've been into used 3/8" pine plywood for baffle material.
Great job on the cab!
Thanks, and that was my thought as well.
That is a great looking cab. The combination of the Baltic ply and the box joints make a nice graphic element.
Thanks! Wish the picture was better, I really am liking the oxblood grill cloth these days.
Hoping to have jigs and equipment ready to go by the weekend. Have been searching for a good set of dimensioned plans for a Deluxe Reverb cabinet but have had no luck. Feel free to share a link if you know where to look. There are inconsistencies and variations from year to year anyway. Seems that there are variations on the faceplate angle from chassis to chassis.
It isn’t rocket science. I am going to make some design changes on the construction methods. Fire up the tape measure and make some sawdust. What’s the worst that could happen? If I get it wrong I”ll cut it down to a Princeton!