Fast, fun, Inexpensive OB project

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#3,402
Good afternoon

This is my first post on this great forum.

My intention is to start in the open baffle with this project

I see that the 20mh inductor is out of stock at parts express.
Would you be so kind as to tell me an alternative to buy that ships to Spain (Europe)?

Thank you very much for your time, and excuse my google translated english

Greetings
 
#3,406
I just found this thread and have been thinking about speaker projects. I love the OB sound when it's done right, and thought this might be a reasonable intro. But...the Peerless driver seems to be unavailable (unless you want to buy 100+ from Parts Express). That's for the 830669 version. Maybe there is another? The thread is quite long and I'll eventually read through it, but it would be helpful to know what the current versions are. Is the GRS version (GRS 15PF-8) the only current one? Thanks!
 
#3,408
Gtm86 said:
Good afternoon

This is my first post on this great forum.

My intention is to start in the open baffle with this project

I see that the 20mh inductor is out of stock at parts express.
Would you be so kind as to tell me an alternative to buy that ships to Spain (Europe)?

Thank you very much for your time, and excuse my google translated english

Greetings
Click to expand...
If the 20mH is very hard to get you can start with the coil from this pre built Parts express crossover.
https://www.parts-express.com/80-Hz-Low-Pass-8-Ohm-Crossover-266-442?quantity=1

If you intend to build this speaker I would suggest t hat you use the woofers that JB selected. John did extensive testing and crossover tweaking. If you pick a different woofer then you are starting from scratch with the crossover and driver "blending."

Jeremy
 
#3,410
jgaupel said:
If you intend to build this speaker I would suggest t hat you use the woofers that JB selected. John did extensive testing and crossover tweaking. If you pick a different woofer then you are starting from scratch with the crossover and driver "blending."

Jeremy
Click to expand...
I'm with Jeremy, use the parts John recommended. He worried about the natural frequency roll off of drivers, how the sound of each driver might (or might not) blend with the sonics of another, etc. It was a lot more than just a couple of specifications.

Maybe the 15" woofer might work? Is that available where you live?
 
#3,411
I was hoping to at least start with the original design (the update one around post 2500 or so) but the Peerless isn't available here. The GRS is, and is pretty affordable so I'll probably start with it. But the Peerless sounds like the better driver, so I was hoping to use it. All that said, I have another project ahead of this one, repair of a dump find speaker (Wharfedale Opus 2-3), so I'm not in a great hurry on this one. Thanks.
 
#3,412
 
#3,414
Hi, I'm new here so I apologize if somebody has already discussed this.
I have purchased the speaker drivers and crossover components for the 12" "Peerless" version as per post #2500.
I have also found another version of a John Busch OB design called the "ULTRA" OB ( https://www.audiocircle.com/index.php?topic=99369.0 ) which admittedly uses the 15" GRS woofer, but the baffle is floor-standing with a height of 48" (unlike the 15" GRS Manzanita height of 29").
My questions are:
1. Why is the ULTRA design floor-standing yet the Manzanita is not?
2. Are there any advantages/disadvantages by going floor-standing with a full-height baffle versus having the baffle open at the bottom (as in the Manzanita version?
3. In respect of the my 12" Peerless woofer version, if I went with a floor standing design would I have to tweak the crossovers much? Or am I best just building the Manzanita version and sticking to the crossover as per post #2500?
Any help very much appreciated.
 
#3,415
Hi Ozrocket,
The following are my guesses.

"1. Why is the ULTRA design floor-standing yet the Manzanita is not?"

John was looking for a new low cost build as the price of the 12" woofer kept going up. That's were the 15" woofer came from.

He seemed to lean towards the 2' x 4' baffles because they would be easy to find for a casual builder. There are big box hardware stores that sell wood panels pre cut to that size making it easier for a 1st time builder.

"2. Are there any advantages/disadvantages by going floor-standing with a full-height baffle versus having the baffle open at the bottom (as in the Manzanita version? "

The Ultra seems to have more bass and is a tad easier to position correctly compared to the stand mount Manzi. But the Manzi isn't hurting for bass. The Ultras have a LOT of bass. Know that going in.

The Ultra is a BIG speaker. You have to have the right room for them and they will take up a great deal of visual space. They don't blend into the background and will likely be the visual focal point of the room. The stand mounted Manzi isn't quite so massive.

"3. In respect of the my 12" Peerless woofer version, if I went with a floor standing design would I have to tweak the crossovers much? Or am I best just building the Manzanita version and sticking to the crossover as per post #2500?"

No Idea, to my knowledge there's never been an Ultra version using the 12" woofer on this thread. There are several stand mounted versions that use either the 12" or the 15" but nothing similar for a 12" Ultra.

Normally it would be easy to make a case for either the 12" Manzi or the 15" Ultra but you've said you already have the parts for the 12" Manzi. It'd make the most sense to build that version. If you still have the itch for the Ultra when your Manzis are done you can always pull some of the parts for the Ultra.

Again, all of this is speculation on my part. Maybe Pano has more ideas.
 
#3,416
John always thought the tonal balance worked best with the 12" Manzie up on a stand. It has to do with baffle peaks and floor bounce.
I asked him many times about a full length version, he finally built a few. I made an Ultra+ with big baffle and 2X GRS 15s per side. Good bass, but the bass outran the little Vifa, so I had to go with a bigger fullrange driver.

My suggestion to @Ozrocket would be to build a pair of prototypes with cheap lumber. You don't need much, just cheap ply, MDF or OSB will do. Whatever is available to you. Make the wings into legs instead of using a stand, it's easy to do and some folks here have done it and posted phtots. Once that is up and running with the stock crossover, add a lower baffle to close off that open space between the legs. With that approach you can try both versions and easily go back and forth.

Room placement makes a big difference to the mid-bass, how far you are from the wall will be audible. Find a good placement with the bottom part open (stock 12" version) then add the lower baffle and have a listen. Take notes! You will easily hear the difference, and room placement might have to change. Refer to your notes and ask questions here. That's a cheap and easy way to test and hear it all before you do a definitive build.
 
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#3,417
Thank you both for your very quick and detailed replies, very much appreciated.
I think I will take Pano's suggestion and build the Manzie version with wing-legs and then play around with the lower baffle to assess.
I went for the 12" Peerless as it was much cheaper and easier to obtain here in Australia than the 15" GRS.
This is my very first ever speaker build so I'm excited to get started on it.
Thanks again for the answers and guidance!
Cheers from down-under!
 
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#3,418
Oh wow! First speaker build - that’s cool.
You have chosen a very good, but unconventional project as your first build. Congratulations.

Don’t forget that speaker placement and usually some crossover tweaking will be needed to get optimum results in your room. Good luck, have fun and be sure to ask for help if you need it.
 
#3,420
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