Chapter 2: The Organ Donor
I now faced a dilemma. Each Sonotube contained 2 subs. My other nearfield sub had 4 drivers. I was going to have trouble level matching my rear subs. Deciding to use 4 drivers, I now needed a new design for this back sub. But it needed to be the "right" design first time around.
Putting 2 Sonotubes behind my recliner was out of the question. Building a dual opposed box presented layout problems, and resulted in very low WAF. A downward firing fake "hope chest" would be too long for the space. Dual opposed Up/Down also had no WAF. Front/Back dual opposed would likely shake my surrounds and any pictures off the wall. I could go with 2 front firing, 2 downfiring, but that meant really tall legs, which likely wouldn't work. I was stuck.
I looked at any sub build I could find, hoping for inspiration. I lost myself in Infinite Baffle, Push/Pull, and all manner of unique layouts. I saw a guitar speaker with 4 front firing 10's. It was ugly as sin, but it wasn't that big. Light shone down from heaven. This was it
. 4 drivers front firing, stacked in 2 rows of 2 each
, butted up against the wall. It was basically a compact version of my nearfield sub.
Whatever I did, it needed high WAF. I don’t have woodworking skills, and good quality wood can get pricey. So I started looking for a pretty "shell" to build my sub inside.
I decided to commit a AUDIOPHILE SIN
and take a vintage piece of audio equipment and convert it into a sub. With much shame, I looked at antique radios, consoles and all manner of things. Then it happened.
I saw an ad for something the seller called a "Reverb" box. I had no idea what it was but it looked pretty, and had 4 10" drivers inside of it and a make/model number of Hammond PR
something. Down the Google rabbit hole I went. I finally locked in on "The One". A Hammond PR
-40 Tone cabinet.
The Hammond PR
-40 is meant to connect to a Hammond Organ. It has 2 15's and 2 12's in a 37 ½” high, 31 ½” wide, and 18” deep form factor. Its "just right". Tall enough to put stuff on, and more a rectangle than square. It also isn't much deeper than a Sonotube would have been.
I scoured the web for the "right" PR
-40. Finding units in Chicago, and Peoria IL, I messaged a local friend to see if he would want to buy any of the parts out of these for the shop he runs. They are tube amp powered after all, and use "ok" vintage drivers. He said he'd be willing to pay about 50 bucks for the parts if they were all there. That put both units at a very good cost, but there would be travel time and gas involved. Do-able, but would require a harder sell than I wanted to do at that time.
Life got in the way, and time passed. Being a horrible person
(see backstory), I had contacted both sellers for more pictures, so I had their email addresses, however I never actually bought either unit.
Finally ready to revisit and move on a unit, I messaged my friend to see if he still would buy the parts out of them, and he surprises me.
"Sorry Dan, not interested…..
" My heart sank
. "Because I picked one up last week. You interested in the cabinet?
My breath caught in my chest, I messaged back "When can I see it?
"I'm eating a (local Mexican place). How about after?
I meet him at his storage unit, and there she is. A PRISTINE PR
-40 in gorgeous walnut, the finish I needed to match our existing darker mahogany/espresso furniture. It was all still in one piece, tube amps and all.
Forgive me Father for I have sinned....
For 25 bucks, I took the cabinet, and he took the internals. It came home with me yesterday. It cleaned it up very well, and I'm now starting to move onto the build I've dubbed the "ORGAN DONOR
I will be posting a TON of pictures later tonight (after I go to confessional
), but suffice it to say, this unit is put together REMARKABLY WELL, and it's all Modular
. The top came off with 4 screws, the front grill is attached with screws, making my job cutting pieces out extremely easy.
One thing I didn't know but is ICING on the cake, is that the grill fabric uses individual strands of wire in it. You cant see it, but its there. Why do I care? Well I've got 3 dogs, a cat, and 2 kids. So it should significantly help deter them from poking drivers, and the grill fabric can handle some poking without needing replaced.
The "only" flaw is that the top grill fabric has a tear, however my friend has a tub of similar older grill fabric that I can use, and he thinks he's got a perfect match for the front grill fabric.
Here is the Hammon PR
When I first laid eyes on her.
After some cleanup
Some other pictures of the unit.
Even the top had a driver in it.
The grill came off with 4 screws and cleaned up beautiful
Need to do some thinking here.
The area I need to think about from the front.
Top needs a small amount of work.
Just look at that detail in the grill cloth!
Here are some rough ideas of what I’m planning (subject to change and updating at all times)
**Note** I've updated this post with "most" of the data from the subsequent build posts so its "close" to a start to finish. Clicking on the DATE section will take you directly to that post which may have additional pictures (I ran into a hard limit of 30 pictures for this post which required me to cut some out.
Baring any crazy stuff coming up between now and tomorrow, I will be making MDF dust and hope to have these built minus finishes tomorrow...
The finishes should go fast once I order fabric and use some rattle can black paint lol..
“The best laid plans of mice and me are opt to go awry”.......
So today I spent most of it in transit to my buddy’s (2.5 hours one way), and then laying out my concept and tweaking it, then building what we could. We intended to get everything done, but it didn’t work out that way...........
That left looking at the Hammond PR40 cabinet and putting together a plan for how to build things.
We ripped out what was there and again were unable to take out the front baffle as the tools we needed were elsewhere....
But we got the plan formulated, and at the end of the day, it’s a basic box so he’s good on building it.
But here is where we got.
He’s gonna work on stuff when he’s got a bit more time but we made very good progress.
So that’s my update. More will come as my buddy continues to make progress.
Massive update from yesterday. Had a marathon day to complete the Organ Donor build and it is alive and kicking.
I got up at 4:30 AM on Sunday morning, got in the car and drove to my buddys in Evansville. I arrived around 7:00 and we got to work quick.
First things first we decided to remove MOST of the existing front baffle. We ended up leaving the sides mainly because we were scared of damaging the finish on the visible sides with the cutter. This worked good because it left the mounting screws for the original grill, and also ensured I have MORE than enough space for cone movement before it hits the grill.
We decided the best size box was to leaving some space at the top (there are pieces connecting the existing panel together there we didnt want to screw with), and also leave the bottom (original plan was to remove that as well and drop the box to the floor). After those sizing adjustments we ended up with a box with these dimensions. I was shooting for a 6 cubic foot box but in all liklehood am closer to 5.0 (5.3 prior to drivers and bracing). Since its a sealed box and these JBL's aren't known for digging deep, I wont lose much down low, and I plan to EQ them with a shelf filter anyway.
The box came along nicely as it wasnt as much a PITA as cutting 150 million baffles for the Sonotubes.
Once it was all glued up and the glue set we did a test fit. We discovered our initial plan (the box goes up, rotates in) wouldnt work as the tolerance for the turn was too tight. This was done initially to save the rear horizontal piece that held part of the top grill on, and just looked quite nice. We ending up takign CONSIDERABLE time to remove it as carefully as we could, so it could be reattached later.
The box fit like a glove, so tight in fact I will need to install nylon straps at the back to aid with removing the box if I need to work on it as it wont budge unless you pull it out JUST right lol...
At this point (it was close to 2:30 PM) I left my buddys house and drove the 2 hours 45 min trip back to mine to continue working on the box.
Rather than go with duratex, my buddy had some leftover black speaker box carpet, so in the interest of time I decided to use that instead. It went on fairly easily with spray adhesive and looks great. Plus the front grill isnt easily removed, so I wont be showing that off much if at all.
I ended up installing the fabric on the front and back of the enclosure. I also sanded down the bottom of the Hammond PR
cabinet and attached fabric there as there is a small portion that could be viewable with the grill on, and it also helps slide the box in. The sides and top currently have no fabric. I HAVE debated installing patches on the side of the Hammond cabinet for similar reasons to why I did it on the bottom of the box. I have extra so we will see.
After installing it I did a test fit to ensure it would still fit. Tolerance at the top was tight to begin with so was concerned if I still could get it in. Much easier to man handle a box without 4 drivers weighing it down lol.
Some of you may notice I didn't seal all the sections of the box. My OCD lead me to start, and in the interest of time I stopped. I made a few compromises and this is always something I can go back and do later if its even needed (likely not we used a TON of glue when building the box)
The rear actually looks better than I thought it would. I was originally unsure if I should carpet or paint it (which would have happened at a later date). I'm glad I went with carpet just to get it done. I think it was around 10:30 pm before I had the box fully carpeted.
Wiring the 4 drivers was a lot of "fun". 4 SVC 4 ohm drivers wired to a 4 ohm load. Lots of quick disconnects and fun. I wired and tested them to ensure the were all playing prior to screwing them into the cabinet. Easier to troubleshoot that way.
Here is the final product, completed at around 1:00 am on Monday morning (the next day). Its currently missing the front grill which is mounted using screws from behind, so its a PITA to take off, so for now while I dial in EQ and whatnot I'm leaving it detached. It also needs some cleaning up which will be done in the next day or two.
Whats left for me to do now is all based on some of the compromises I made yesterday just to get this up and running.
I bought a bunch of REALLY nice connectors from David Gage of Deep Sea to use initially, but in order to get it up and running,I just used drywall screws for now. Since I have only a single 3/4" baffle I would have had to install blocking (8 pieces) on the back of the box for each drivers, meaning installing 32 pieces of blocking, then drilling, mounting hardware, etc. I can always do that at a later date.
I also didnt have any speaker gasket, but with the carpet and a really tight fit I think the drivers will be OK for now.
Also made a compromise on the speaker wiring. I bought really nice 14 gauge Furez speaker wire. The quick disconnects I got weren't super tight so I did a lot of extra crimping to make them work. Also since I needed to combine a few wire together and the disconnects were only rated for a single 14 gauge run, I ended up cutting a 1" section out about 2" above the disconnect and stripping that section, and then pairing the connected wire to it, then wrapped the whole portion with lots of electrical tape to keep it safe. At a later date I may go back in and solder those connections, I just didnt have the material for that on me.
I also need to buy some pillows and stuff the box a bit. I'm aware of the data on how a box performs stuff v unstuffed on databass and that I may be giving up a bit of SPL to stuff it, but given that its literally less than 2 feet from my back, I am ok with that.
All in all I'm super happy with how this box came out, and feel the few compromises I made were worth it to get this thing up and running.
Hopefully today I can get it connected (have to pull out my rack and re-organize) and take some measurements and EQ it.
Then I just need to wrap up my two Sonotubes, which we didnt even touch yesterday.
Some cleaned up pics (taken with my iPhone X and apparently with some glare/lighting issues):