Epiphone Valve Jr Combo - put in a 10 inch Speaker
I picked the speaker because of its physical depth - it does not touch any of the tubes after the install. I used a Jensen 10 inch 16 ohm speaker (P10R - was originally used by Fender in some amplifiers, however this one is Italian made - It is rated at 95 dB SPL)- the 10 inch Eminence I tried to fit would have hit one of the tubes.
The main problem with switching from an 8 inch to 10 inch speaker is that the inside of the cabinet is only 9 1/2 inches tall - you have to make a slot in the lower part to gain the extra 1/2 inch.
Measure on 1/2 inch 5 ply - plywood. New height is 9 1/2 inches.
Pre-mark Speaker - working in the front of the baffle board.
Mark the real opening on the front of the baffle board. Verify that the amplifier part still fits - shave down baffle if needed.
Needed to make notches bigger so I could remove the baffle board as often as required (It was in and out many times while I was fitting things).
You will notice that the lower corners of the baffle board have an angle cut out of them - the cabinet had glue there and needed a bit of wood removed to sit right. This was not a problem for the original 8 since it had lots of room to spare.
Find and mark Center location of Speaker (Note: This is sitting on the hood of my Jeep Cherokee in this picture).
NOTE: The case wood is 5/8 inch thick - so be careful. Its why we only want to drill 1/2 inch deep. I used a shallow depth drill motor - my router would not fit.
These holes should be in the same place as the original baffle board.
You can see how much larger the opening will be - still restricting to the 10 inch woofer. A lot of sound comes out the back of the cabinet, so it still is a great improvement
The card board is a spacer stapled to the front of the cabinet is for clearing the t-nuts (grill cloth). Fender does this in many cabinets. Spray painted the baffle board flat black - don't forget the cut where the speaker opens up to - spray the all of the edges.
I cut the grill cloth off the original baffle with a razor blade - at the folded edge (right where the staples are on the sides) I restapled on the front at the outer edges - you won't ever see that. I used a hammer to set the staples place. Used T-50 (Arrow) 3/8 inch depth staples - Used around 50 staples.
All put together. It now has better bass response, and its a little louder. It still breaks up at the same place on the dial.
The Speaker was pretty harsh sounding when I first started playing, but after a few days of jamming at higher volume (the Valve Jr is only a 5 watt amp, so its not hurting the 25 watt RMS Jensen no matter how hard I crank it), the tonality opened up and it sounds a lot nicer - this is not uncommon for new speakers. It's got a lot of punch for a 5 watt amp, much more than it did with the original 8 inch speaker. I played it with a Gibson SG/P-90's and a highly modified Danelectro U-2 (1999 re-issue) with lipstick pickups. The class A tube breakup sounds smoother than the original 8 inch speaker.
Note:I shaved off approx 1/8 of an inch from the top of the speaker frame since it was actually 10 1/8 inches tall. I did this with a
hand operated grinder.
Questions? Comments? .
(c) 2012 Shavano Music Online