note the significant drop in response even before the Fs, it's down over 15 dB by 40 Hz. Not promising. I don't know what all the factors are that affect a driver's response near it's Fs, but it sure does vary quite a bit from one driver to the next. Presumably things like suspension factor, motor design, etc. all matter, but more to the point, not sure this driver will have real useful bass in an OB arrangement below 50 Hz. At a minimum I'm searching for an arrangement that gets me an F3 of 40 Hz, but I'd really like to see 35, and 30 would be endgame.
How is that any different than the inside of the slot. The slot channels are half rounds so the sidewalls in the back of the slot are closer than the sidewalls on the back of the facade.
Take a look at the RS225-8 or Peerless SLS 8". They appear to be better, but also come with a "better" $$$.
The slot channels would at least load the cone roughly symmetrically, and at ~5" there is a fair amount of room looking straight across the inside of the slot. The problem I see is that he's recessed the front edge of each driver perhaps an inch or more "under" the back of the baffle board, and the clearance is very tight to the back of the cone as well.
Could always put some channels on the back for some symmetry. Front and backwards facing U channels.
The bass MDF stack would get a lot thicker and heavier.
Would have to account for the larger diameter of the bezel versus the seating hole diameter.
The picture was meant to give a visual example of symmetric forward and backward U channels, not necessarily the slot width or driver mounting choices based on @Cavedriver 's concerns about front/back loading symmetry.
Last edited:
Not sure when I will finally get to building my set of speakers but did decide to build 15" subs into the remodel as have enough space for one on each side, either sealed or ported. I have a new pair of ID 15's that are great subs I will be using unless they broke down after nearly 10 years in storage but they are car audio, should be fine.
That said, I have no need to go to the trouble of using the 8" GRS8-8 drivers I bought so going to list them for sale, mentioned here first as others have talked about or even gone this direction. I have either 18 or 2o of them, only opened one to look at it, rest I have to go check out and count them.
If interested let me know so you can have first chance at them.
Soon as sold I will order the 6.5's and the tweeter wave guides.
-------
Just about to miss out on the filter last day deal, might get lucky and get an offer on the GRS drivers and get that on order instead
Rick
That said, I have no need to go to the trouble of using the 8" GRS8-8 drivers I bought so going to list them for sale, mentioned here first as others have talked about or even gone this direction. I have either 18 or 2o of them, only opened one to look at it, rest I have to go check out and count them.
If interested let me know so you can have first chance at them.
Soon as sold I will order the 6.5's and the tweeter wave guides.
-------
Just about to miss out on the filter last day deal, might get lucky and get an offer on the GRS drivers and get that on order instead
Rick
You don’t need all these tables. Just calculate the wavelength using the speed of sound in air. Speed of sound at normal ambient conditions is 342m/sec.
For any frequency in Hz (cycles / sec), divide speed of sound by frequency to get wavelength.
For example, L=(342m/sec) / (50/sec) = 6.84m. The quarter wavelength is usually the important length corresponding to minimum length closed-end to open end TL to sustain that resonance. This is same as a quarter wave trap. Or 6.84m/4=1.71m or 67in. (Matches value of the “trap” in table above). But note that now you don’t need to carry tables around but just remember the speed of sound.
Speed of sound is proportional to sqrt of temperature so a mild sub linear dependence.
For any frequency in Hz (cycles / sec), divide speed of sound by frequency to get wavelength.
For example, L=(342m/sec) / (50/sec) = 6.84m. The quarter wavelength is usually the important length corresponding to minimum length closed-end to open end TL to sustain that resonance. This is same as a quarter wave trap. Or 6.84m/4=1.71m or 67in. (Matches value of the “trap” in table above). But note that now you don’t need to carry tables around but just remember the speed of sound.
Speed of sound is proportional to sqrt of temperature so a mild sub linear dependence.
Last edited:
The TC18 would work I think from acoustic standpoint - but the frame has a curved plastic bezel meant for topside surface mounting. You can’t mount that to have the cone facing in very easily and get a good seal. Also, the passive XO would not be valid anymore and you could use your own or DSP.
How did you find building this amp? I had a look at the thread, it looked like one for more advanced diy-ers to me. Right or wrong?
I’d been considering a Wolverine amp for these, whenever I get round to building them! But always interested in options..
Not really, I found BA3 to be a touch more difficult. If your solder skills are good, give it a whirl. I made about every mistake possible, and made sure
to note them and the solution. Lots of builders, lots of info now on this amp. It is the best amp I've ever had, built or otherwise. This Square Law output stage is making some noise. You will not regret building it. All the tiny bits are already soldered on with the kit. You just add the normal through hole stuff.
Russellc
to note them and the solution. Lots of builders, lots of info now on this amp. It is the best amp I've ever had, built or otherwise. This Square Law output stage is making some noise. You will not regret building it. All the tiny bits are already soldered on with the kit. You just add the normal through hole stuff.
Russellc