I appreciate everything about this thread. However my role here might be to ask questions that some less experienced folks may not know how to frame or phrase. I have lost access to my friend's large shop which was a great chance to try an OB; it ain't gonna work here at my small house unless The Wife goes away for a couple of weeks and I can destroy her interior scheme. NO possibility of sizable speakers 3 - 4 feet from the walls. Or 1 meter, even. So thank you Pano and John B for this project. I look forward to fresh posts here.
The GRS is produced in China, GRS seems to be an american company. A little investigative digging could unearth the chinese manufacturers name. Otherwise the job is to find a woofer with matching specifications: GRS 15PF-8 - 15" Woofer
As far as I understand it, sensitivity, qts and xmax are defining characteristics, and obviously freq response.
Woofers meant for guitar/bass amps seem to be the ticket.
yes peerless available local forum reviews are not good as they said it is not tympohny. many woofers avaible at 6 to 10 inch but too costly as this project is inexpensive.
Crossover decisions
Hi all, I'm new to this thread but hope to get building the Ultras soon. I'd appreciate your thoughts and suggestions on the following three questions...
1) Given that the Jantzen 2.7 mH air core 15 AWG is out of stock at PE until the end of March and I'm impatient, what would be an reasonable alternative:
a 2.5 mH 14AWG inductor (PE 257-332),
a 2.7 mH 18 AWG (PE 255-272) or
a 3.0 mH 15 AWG (PE 255-436)?
2) When it comes to resistors, is there a significant difference between fancy Mills no-inductance resistors and generic low-inductance wire-wound ceramic resistors?
3) Pano provided PE 266-446 as a possible alternative to the expensive ERSE superQ 20mH inductor. Has anyone tried it?
Hi all, I'm new to this thread but hope to get building the Ultras soon. I'd appreciate your thoughts and suggestions on the following three questions...
1) Given that the Jantzen 2.7 mH air core 15 AWG is out of stock at PE until the end of March and I'm impatient, what would be an reasonable alternative:
a 2.5 mH 14AWG inductor (PE 257-332),
a 2.7 mH 18 AWG (PE 255-272) or
a 3.0 mH 15 AWG (PE 255-436)?
2) When it comes to resistors, is there a significant difference between fancy Mills no-inductance resistors and generic low-inductance wire-wound ceramic resistors?
3) Pano provided PE 266-446 as a possible alternative to the expensive ERSE superQ 20mH inductor. Has anyone tried it?
Harold....
Question #1 I would choose PE 257-332
Question #2 I would stick with the Mils on the tweeter (high pass pad) circuit and trap bypass resistor.
For Zobel circuits the low inductance wire wounds are fine
Question #3 The inductor portion only of the PE 266-466 works ok... a slight loss of efficiency and slight gain in final woofer Q which is OK. So, depending on your taste, the Vifa pad resistor may require a bit of adjustment to retain balance.
Question #1 I would choose PE 257-332
Question #2 I would stick with the Mils on the tweeter (high pass pad) circuit and trap bypass resistor.
For Zobel circuits the low inductance wire wounds are fine
Question #3 The inductor portion only of the PE 266-466 works ok... a slight loss of efficiency and slight gain in final woofer Q which is OK. So, depending on your taste, the Vifa pad resistor may require a bit of adjustment to retain balance.
Thanks for the guidance, John. I remember reading that you'd said that inductors were often the weak link in crossovers. Accordingly, I'll look to invest in those with higher gauge wire.
I'm in Canada and it turns out that Solen stocks identical or comparable components to those I saw on the PE site. It'll save me a bit of money and nothing is out-of-stock. Only the ERSE 20mH inductor and the GRS woofer will have to come from the states.
I'm in Canada and it turns out that Solen stocks identical or comparable components to those I saw on the PE site. It'll save me a bit of money and nothing is out-of-stock. Only the ERSE 20mH inductor and the GRS woofer will have to come from the states.
John and Pano, I'm trying to keep my Ultra build as "stock" as possible, keeping things tried-and-tested using the build guide in post #1602 (aside from adding the bass trap). With that in mind, should the faceplate of the tweeter be inset into the baffle front? (I plan on bevelling out the space behind the tweeters). And is the woofer mounted to the back or front face of the baffle? Thanks!
Harold... Flush mounting (counter sinking the tweeter face plate) is preferred... but for those who do not have a router to accomplish this, the speaker will perform well with out that extra step. The large baffle area is a bit more forgiving than what you would find with a typical narrow baffle closed box speaker.
Thanks, John. I'll try to flush mount the tweeter. And am I right to assume that surface mounting the woofer on the front face of the baffle is okay?
I'm investigating a local guy with a CNC machine to see if he can do it. If not, I'll see about renting a router and creating a jig of some sort. (That's what google and youtube are for!)
I'm investigating a local guy with a CNC machine to see if he can do it. If not, I'll see about renting a router and creating a jig of some sort. (That's what google and youtube are for!)
There is a nice step by step on how to create a template that will let you cut the router shape quite easily using a router. I did that for my Manzanita build and it worked a charm.
https://www.diyaudio.com/forums/mul...n-inexpensive-ob-project-185.html#post5455690 - heres an example.
Tip: How To Flush Mount Irregular Shape Driver -
Techtalk Speaker Building, Audio, Video Discussion Forum - and here is the guide for the routing.
Good luck
https://www.diyaudio.com/forums/mul...n-inexpensive-ob-project-185.html#post5455690 - heres an example.
Tip: How To Flush Mount Irregular Shape Driver -
Techtalk Speaker Building, Audio, Video Discussion Forum - and here is the guide for the routing.
Good luck
Thanks, silasmellor! I'd actually seen your post earlier and it helped inspire me to try my own build. I see you also flushed mounted the woofer as well as the tweeter. Was this 1) for aesthetic reasons, 2) for acoustic reasons but specific to the Manzanitas only or 3) intended for both types of builds (Manzanitas and Manzanita Ultras)?
Also, thanks for the link to the how-to guide. It's an ingenious approach to making a jig!
Also, thanks for the link to the how-to guide. It's an ingenious approach to making a jig!
Yes, that approach is pretty neat, and a little bit like magic when you see the final result
I did cut a small rebate for the woofer - 1-2 mm only. I am not sure if it matters much soundwise (Pano or John will know), and looks-wise it is not very noticeable for the peerless woofer as the outer frame slopes down towards the outside so even if you didnt flush-mount, the outer edge would almost be flush anyways. Overall i went by the assumption that flush mounting never hurts so why not
I did cut a small rebate for the woofer - 1-2 mm only. I am not sure if it matters much soundwise (Pano or John will know), and looks-wise it is not very noticeable for the peerless woofer as the outer frame slopes down towards the outside so even if you didnt flush-mount, the outer edge would almost be flush anyways. Overall i went by the assumption that flush mounting never hurts so why not
Woofer mounting options
Harold... the GRS woofer can be mounted several ways. You can just do a standard 14" cutout and mount the driver with the flange remaining above the baffle front surface. Or you can flush mount, or you can rear mount. If you rear mount it is recommended you round (1/4"-1/2" round-over) the front of the cutout.
All work OK. For the Ultra, flush mount is best over all. On the smaller Manzanita, rear mounting with 1/2" round over on the front side of the baffle gains another 3/4" to 1" of path length which does lower the F= slightly. With the smaller Manzanita baffle size you need all the path length you can get. Staying with the Manzanita... when using the Peerless 12" woofer just make the cut out and mount the woofer on the front side of the baffle. The 12" has a built in cosmetic flange which makes for a nice simple installation.
Harold... the GRS woofer can be mounted several ways. You can just do a standard 14" cutout and mount the driver with the flange remaining above the baffle front surface. Or you can flush mount, or you can rear mount. If you rear mount it is recommended you round (1/4"-1/2" round-over) the front of the cutout.
All work OK. For the Ultra, flush mount is best over all. On the smaller Manzanita, rear mounting with 1/2" round over on the front side of the baffle gains another 3/4" to 1" of path length which does lower the F= slightly. With the smaller Manzanita baffle size you need all the path length you can get. Staying with the Manzanita... when using the Peerless 12" woofer just make the cut out and mount the woofer on the front side of the baffle. The 12" has a built in cosmetic flange which makes for a nice simple installation.
I've had these drivers for some while. Guess I should put this together. I assume these are not very efficient, any one have a guess how efficient, err, inefficient they are? I am mainly using 25-40 watt Class A Pass Firstwatt clones, one is a good 50 watts. I do have a JBL pro amp that would do it, but maybe one of my stout class A amps would do?
Russellc
Russellc