Cabinet modifications

[JacksonRR]

Ok so this took about an hour and a half, but most of that was spent looking for tools and such.

The cabinet in question. One Randall RS125CX. 2 12" WGS speakers, a Veteran 30 and an HM75. Based on a Vin30 and G12T75. The 15" is an Eminence Legend.




Here's what it looks like stock inside.

[JacksonRR]

Tried to find my staple gun, but could not find it. I ran across a box of roofing caps and it gave me an idea. I should use those roofing caps. Could not find my hammer so I used Tony's Kahler to hammer them in. It worked great. The nail portion wasn't long enough to go through, but I still left about a 1/4" gap between the orange washer thing and the plywood.



Here it is with the back done. I went to the craft/sewing store and the batting there was pretty expensive and seemed like a waste of time as it was really light and airy. Lot's of hot grandma ass at Jo-ann fabrics at 7 pm on a Friday night though. Went to Wal-mart and bought a convoluted foam mattress topper for $10 instead.

[JacksonRR]

At this point I put it back together and tried it out with just the back covered in this foam. First impressions: Much more controlled bottom end. I slammed this cab with lots of bass and it just took it like a whore. Much tighter, but it was still all there and the general tone was a bit warmer, but nearly all of the mids and highs were unaffected.

Time to try the bracing.

There was already a brace from the front to the back so I just legged off of that. Here is what I did. 2x4 pine ripped down the middle and cut to size.



Put it back together again and HOLY shite! The top end is much crisper and palm mutes were felt in the chest at much lower volume. Getting past noon on the master volume was even better. Wholly recommend doing this at the moment. I may open it up again and do the side panels with the remaining foam, but then again I may not. It sounds a lot better as it is. It's more refined, but has much more immediacy to the notes without losing the 3D nature of a ported cab.

[DoomBuggi]

I slammed this cab with lots of bass and it just took it like a whore.

 :good:

[Toe-Knee]

Could not find my hammer so I used Tony's Kahler to hammer them in. It worked great.

 :shock: :shock: :shock:

[Toe-Knee]

At this point I put it back together and tried it out with just the back covered in this foam. First impressions: Much more controlled bottom end. I slammed this cab with lots of bass and it just took it like a whore. Much tighter, but it was still all there and the general tone was a bit warmer, but nearly all of the mids and highs were unaffected.

Time to try the bracing.

There was already a brace from the front to the back so I just legged off of that. Here is what I did. 2x4 pine ripped down the middle and cut to size.



Put it back together again and HOLY shitee! The top end is much crisper and palm mutes were felt in the chest at much lower volume. Getting past noon on the master volume was even better. Wholly recommend doing this at the moment. I may open it up again and do the side panels with the remaining foam, but then again I may not. It sounds a lot better as it is. It's more refined, but has much more immediacy to the notes without losing the 3D nature of a ported cab.

I'm glad your night of experimentation worked out well! I really hope you did some before and after clips even if they are cr@p quality!

[Kiichi]

This is so very interresting to hear, we need more!!!

I think this will at sometime and someplace end up in:
Can I with some modification have a cheap cab (like a Harley Benton) sound as good as a quality cab?
Can I with this knowledge build one myself from scratch and have it sound better than a quality cab?

[Oli]

I suspect that most of the difference you are hearing is because of the extra pressure on the baffle and rear panel-- It doesn't look like you made a hole for the bracing on the back panel, so the foam is being compressed and creates a more secure join and makes the cab more rigid.

I'd be careful of using nails, I think they'll rattle out over time, especially with the vibration of the cab and pressure of the foam pushing outward.

Cab modifications are a nice thing to make improvements to your sound-- I like that cab, i've not seen 2x12+1x15, but I think i'll keep my eye out from now on! :)

[JacksonRR]

Oli, I woke up thinking the same thing about the nails. I was putting away the beers last night for sure.  :oops:
I have some short drywall screws and later today I'll be yanking the roofing caps, ditching the nail part and using the orange pieces plus screws. The original brace has a bit of felt on the end of it, so I think the compression effect you mentioned was already happening but perhaps to a lesser extent. It was a bit loose where it met the front baffle, and I forgot to mention that I stuck one of those 2" screws through the face to tighten that up as well. That rear panel has always been a real pain to remove, too. It's sized perfectly. Always have to wiggle a butterknife around it for about 3 mins to pry it out.

Tony- No, didn't do sound clips even with the phone. Didn't even think that would have proved/disproved anything. Still have to fix my popping sound card and even with that up again it would have been so hard to try and keep that microphone still! I was thinking I have some neoprene foam sheeting in the basement and should try sealing the ports with two squares of ply with the neoprene between those and the baffle. That would be easy enough to make a good comparison. I mean, move that mic 1" or that cab 12" in the room and it pretty much goes down the drain.....

[Alex]

Err... what impedance is that cab now? Isn't that a problem if you use an uneven number of speakers (or speakers with different impedances)? I know it doesn't matter with solid state amps, but it would still worry me abit on a tube amp.

[SabreStrike]

Man, I can't find any of those cabinets in the US anywhere in the big name stores, even Guitar Center's used area. Are they like a model that they didn't make/bring to the US or something?

I want one so bad. Especially if I can toss in a pair of Celestion V30s and keep the 15" Eminence. Mini-Warhead! :U

[JacksonRR]

I'm in the U.S.!
I think they are discontinued now. The XL model is the EXACT same as this construction wise but it uses two Vin30s instead of the Eminence Legend 12s that came in this one. It has some mic simulation circuit too...

The impedance is 8 ohms. 2 8ohm 12s in series=16ohms and that is in parallel with the 16 ohm 15" to make 8 ohms. Now I bought this cab used for less than I should have, but they did originally have two 16ohm speakers in there making it a 5.33 ohm cab and I e-mailed Randall, which had just been bought up, and they sent me new speakers as I had embellished that exact claim about my tube amp... but that's a different story entirely. All I can say is stick to your guns and if a company promises you two Vin30s and sends two pairs of 70/80s to your house.... keep asking about the Vin30s and where to take the 70/80s for return. hint:it costs them more to ship 70/80s than the speakers themselves so trade them for NOS valves.

[dave_mc]

very nice

can you run the speakers separately?

how's the eminence?

[gwEm]

this looks like it should sound huge  :D nice work!

[JacksonRR]

very nice

can you run the speakers separately?

how's the eminence?

I can't run the speakers separately right now, but I have given thought to allowing myself the ability to cut off the 15" if I wanted to, say I'm playing with a bass player that needs his own sonic space. I just haven't done it yet. It'd be the easiest thing, too. Just a spst for one of the speaker leads if I'm not mistaken.

The Eminence is great! I notice often that it has a smaller excursion than the 12s. The limitations on how thick of a signal it can take are all governed by the 12s, the 15 is just this thing that rounds out the sound and it ends up with tons of authority. It is a cheaper model though and it does cross my mind to keep on the lookout for a 15 with a bit more snap. Hell... maybe I might try doping it further.... after I try a sealed config which will limit cone movement on all of them. Actually, I think I might have space in there to seal the 12" section and keep the 15 ported...  :lol: