BillFitzmaurice.info

Built a pair of Simplex 12's over this past weekend for use as Bass Guitar backline.

Used the 3012LF and the BGH25 for drivers.

Finished Cabinets weigh in at about 32 pounds each.
These things are light and SOLID!

Using an online cut sheet program, I was able to fit everything for two cabinets (except the baffles) in one sheet of 5x5 Baltic Birch (2 space rack for the Bass head not included) but it got tough/time consuming towards the end of the cuts, being careful cutting all the ports and braces and remembering not to just rip through each crosscut piece. It would be faster to not be so careful with the wood waste, but are about an hour fifteen from the closest lumber yard that carries actual Baltic Birch (and all the Lowe's in the region stopped carrying Arauco some years back.

I did not low-pass the woofer since the 3012 seems to play out toward the 2k range and that is where the BGH25 picks up. The BGH25 is HOT. I built a 6db fixed pad for them and it's still pretty loud, but a little fine-tuning with the on-board EQ on the little Bass head seems to bring everything in line. The BGH25 is also deeper and heavier than I realized.

I tried to take my time so the finish looked very presentable. Ended up with about 36 hours invested over three days. Lots of sanding, and I had to repair some tearout from routing and some places where I left the jigs on too long in the early steps and the PL dried.

A Bass playing friend stopped by last night and played on it for a little while (short video clip in the link.) He LOVED it and stayed playing for about 2 hours. He has me totaling up the cost of materials so I can build him one (He's been breaking his back for years moving a 3/4" 4x10 cabinet back and forth between gigs and rehearsals.) With this rig, you could literally carry your Bass over your shoulder, the head in one hand, and a single cabinet in the other and make 1 trip from the car for rehearsals and probably most gigs.

I am VERY pleased with it so far.
I'm going live with it this weekend for two Blues gigs. I'm curious to see how they like it. (I will have the additional house PA support of some 15" Jacks and 2 20" T39's - so we should be good, given that we will be in smaller school auditoriums for both shows.)

I am considering adding the APT80 on a flip-switch so they could do double-duty maybe as small PA tops. If anyone has a suggestion of the switch to use, or a better high frequency horn in a similar form-factor/size - please chime in.

Great design! I like it so much that I think I'm going to build the Tilt-Back next for use as a keyboard amp.

Here is a link to some pics and the short phone video clip of my friend playing through it last night:
https://photos.app.goo.gl/HbZG6RTy6pt2GFPt8

Congrats

Looks great! Except for your inductor placement. Having your inductors that close together in that orientation effectively makes them a transformer, meaning some of the energy in one coil gets transferred to the other coil through magnetic fields.

Here is a link to explain inductor placement :
http://greenboy.us/fEARful/crossovers.htm#inductor

Essentially, if they are close together, orientate them so that you can't put a hula-hoop through the middles otherwise their magnetic fields will induce a current in each other otherwise known as cross-talk. If you can't do that then separate them by a good 6".

Looking at the plans, those coils are just shunts to ground so not very much current is going through them so that induced current effect probably isn't that big a deal. It's still good practice to orientate them as that link shows.

Good point CoronaOperator, I should have known better. I wasn't thinking about the actual magnetic fields crossing one another.

Of all the speakers and crossovers I've built in my day, this was actually the first time I had inductors that were just raw coils of wire ( as opposed to having some sort of core or top/bottom plastic mount or something you could drive a screw through) so I guess I got carried away in trying to make them have as small of a footprint as possible for flexible placement inside the cabinet. I literally used one zip-tie to hold the two together and to the plywood base in their middle. It saved me from drilling two more holes per crossover LOL

Thanks again. I'll address this when I tear back into them to wire up the flip-switch and full-range tweeters to make them dual-duty PA tops.

CoronaOperator wrote: ↑Thu Sep 27, 2018 7:31 pm Looking at the plans, those coils are just shunts to ground so not very much current is going through them so that induced current effect probably isn't that big a deal. It's still good practice to orientate them as that link shows.

+1. Also, the primary reason for keeping coils not only separated but also mounted on different planes is to prevent possible cross talk between coils when high pass, band pass and low pass sections of a full crossover are all on the same board. Preventing that is one reason why I specify that HP/BP/LP filters be mounted on separate boards. As for not using a low pass on the woofer, that can cause peaks and valleys in response where the woofer and tweeter outputs overlap, so I don't recommend it.

Good job.

I am considering adding the APT80 on a flip-switch so they could do double-duty maybe as small PA tops. If anyone has a suggestion of the switch to use, or a better high frequency horn in a similar form-factor/size - please chime in.

Perhaps a single pole/double throw SPDT switch will work for you. It would be positioned before the filters for the tweets since each tweet has a different filter demand (filters as per the plans).

Tom Smit wrote: ↑Fri Sep 28, 2018 12:10 am
Perhaps a single pole/double throw SPDT switch will work for you. It would be positioned before the filters for the tweets since each tweet has a different filter demand (filters as per the plans).

That is exactly what I was thinking Tom.
I have my eye on this one at the moment:
https://www.parts-express.com/spdt-heav ... h--060-088
I'll have to do some measuring, but hoping I can place it between the Speakon Jacks. Not an emergency, just something I'd like to do to get maximum value out of the cabs.

Thanks for the suggestion.

Just an update.

We set the rig up for Bass Guitar duty tonight for a full-on tech rehearsal.
Everybody in the band LOVED it and could not believe how light it was. I haven't let the secret out that I built it myself yet.

Even though I had the pair of T39's and Jack15's for mains, it was actually not necessary to put the Bass guitar in the house (although I did for a little while just for fun

The pair of Simplex's with the little 250 bass amp head was able to keep up with the drummer, the keyboard player, AND the guitar player (who could get obscenely loud if left unchecked) plus 4 vocalists. All playing mostly Blues, since Blues History is the focus of the program. At no time did the Bass Guitar sound overbearing either. Just greatly present.

Again - great design. Thanks!

Bill Fitzmaurice wrote: ↑Thu Sep 27, 2018 9:17 pm Preventing that is one reason why I specify that HP/BP/LP filters be mounted on separate boards. As for not using a low pass on the woofer, that can cause peaks and valleys in response where the woofer and tweeter outputs overlap, so I don't recommend it.

Another reason to separate the different filter boards is for simplicity. It makes it so much easier to follow if you do it that way.
I built several Wedgehorns a few years back and threw everything on one board. It was very confusing and difficult to think through (and by that time of the build I was pretty brain-dead to boot. I always had 1 pair of the Wedgehorns that just did NOT sound right. I'd check the piezos, swap the entire piezo cross-melded array out with other known good ones, but no improvement. Ended up discovering that I had wired up the resistors exactly backwards in those two. It was complicated because the crossover components were ordered at different times so on the 1 pair, the 4 Ohm resistor was smaller than the 30 Ohm resistor (but the opposite on the other 6 monitors - big mess.
Placing them on separate boards, you can duplicate the layout from the plans perfectly and all is well with the cosmos.

Thanks!

Just thought I'd chime back in after going through a setup, rehearsal, show, teardown/load-out, travel, load-in/setup, and another show in less than 24 hours.

This thing is just awesome. Even with the house PA and subs, I was just fine without adding the Bass in the mix - and the Bass player was very well reserved.
It easily kept up with the mic'd drum kit beside it, the super-loud guitar player, and the keyboard player with the giant Roland 5000-pound keyboard amp. All that while being gentle enough, when necessary, to allow a narrator and 4 vocalists perform their program.

After the end of the first event, the guy I had hired to help me break down and load out actually reached down and grabbed the lower handles and carried out BOTH cabinets and the amp rack. I told him, "You're doing it wrong" and he didn't seem to care (he's much younger... LOL) I figured it was about 75 pounds all told.

This thing just sounds great and looks cool too. I highly recommend it.

Great review! Glad that you enjoy it.