Fast, fun, Inexpensive OB project

Jump to Latest
#2,083
I'm going to try and fit a pair of KEF coaxial drivers on top of the two GRS 15PF-8. The seas fullrange drivers are way too beamy for me, as you can't really move out of the sweetspot. Otherwise I'm not unhappy at all 😀

Incidentally, if one were to make a no holds barred construction, what would it look like?
Would it be something akin to a curved front that integrate smoothly with the wings?
What would be the maximum thickness of the baffle be?
(I have some solid oak I need to use. )
 
#2,084
Cheap XO parts in The EU????Where

I tried to compile a basket with all the XO parts for the Ultra on Parts Ekspress. And ended up with a bill of 140 USD for tax and shipping!!!!

Anyone who has found a cheap EU source ? Especially the coils are hard to find at a good price
 
#2,088
Martin King has a paper with a comparison of the alpha, beta, and gamma in OB, U, and H frame baffles.
It's more important what the response is after you have applied filters than before(and filters always mess with those pretty graphs that tempt us to try a given driver).
 
#2,089
ewollowe: The tweeter location can be closer. The current location was mainly decided by diffraction effects, as in minimizing same. Un equal distances from tweeter center to baffle edges. This is a simple forgiving design and can work well with small physical modifications.
 
#2,090
Johncy: The 2015 can be made to work, but would not be close to optimal using the standard crossover. Significant differences in operating Q and efficiency would require quite a bit of crossover work to get a usable tonal balance. There would also be some loss in bass extension also to lower Q value and higher free air FS. John
 
#2,095
DOUBLE 15" MANZANITA PLS..

The daul 15" , 8" fullrange, manzanita you announced a "few" post back has since perked my mind in a big way. The look of your prototype, and the promise of the sound it should reproduce would be on top. I can very well understand you not wanting to give this desighn away, very understandable, you've " got to pay the bills", have you or would you entertain the thought of selling this desighn as a "DIY" with a complete parts list and breakdown of mat. including crossover-well every thing needed to complete? :scratch2:



'
 
#2,098
You're welcome! Who knew this thread would still be active 12 years later?
Just goes to show what a fast and fun project this is. With some guidance and John's excellent crossover work the Manzanita has evolved and adapted while remaining true to its roots.
 
#2,099
Pano said:
3: The GFS 15 and the addition of the Ultra

The ever-rising cost of the Peerless 830669 woofer led to a search for an affordable woofer that worked well in the design and not hurt the wallet. The desire of many for a floor standing baffle also drove the choice of a new woofer. Enter the Parts Express GRS-15PF-8 15" woofer and a larger baffle. The GRS 15 is a suitable mate for the Manzanita project with its high Qts, low price and surprisingly good sound quality. Working with the TC9FD as a mid-tweeter, we are back to an excellent and affordable duo.

Baffle dimensions for the Manzanita utilizing the GRS woofer increased to 17” W x 29” H to accommodate the larger woofer frame. See baffle drawing and crossover in the post above.

The floor standing version of the Manzanita, dubbed “Ultra” uses a much larger baffle with the dimensions growing to 25.5” W x 48” H with full length 5.5” deep wings . The larger baffle increases the operating efficiency by around 3 db and extends usable bass response into the upper 20’s.
The low pass crossover remains the same, 20mH iron core inductor, the high pass retains the same number of parts while being adjusted slightly to suit the new woofer and baffle size. See the schematic. As always, we suggest buying a small range of resistors to fine tune the tweeter response to your room and your ears. 7, 8 and 9 ohms for the high pass pad, 10, 15, 20 and 25 ohm for the trap resistor. An optional trap can be added to the woofer, consisting of 15uF in parallel with 0.4 mH.

Going forward.
What’s in store for the next ten years? That’s hard to predict, but coming up soon there will be some baffle and side wing tweaks that will help extend the bottom end response a little, as well as improving overall efficiency. Stay tuned!
Click to expand...



I know this is a older post
I have a question or two
What changes would I need to do if I wanted to use 2 of the GRS 15PF-8 15" woofers ?
How much higher would the baffle need to be and what change is needed for the crossovers ?
Thanks and sorry if this has been covered already
 
#2,100
I've done the 2xGRS 15" on the same baffle size as the single 15 and it was OK on that. However the Vifa can't really keep up with the dual 15s. I ended up using an 8" fullrange above the 15s, but a more efficient 3.5 or 4" could work.
 
You must log in or register to reply here.
Top Bottom