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Open Baffle Epiphany!

opnly bafld said:
FWIW the UFO models have 2 output taps for high and low speaker impedance, therefore it doesn't matter as much what the load impedance is.
The older models were designed to operate "better" with 6 ohm and lower loads, there was an optional X model with OPTs that worked "better" with 8 to 16 ohm loads.

From the UFO owner's manual regarding speaker connections:
"This amplifier can operate speakers as low as 2 ohms, and as high as 16 ohms and everything in-between. No harm can come to the amplifier if the speaker jacks are shorted together.
There is a HI / LO switch next to each pair of speaker jacks on the amplifier. This is used to match the amplifier to a given loudspeaker load. It is operated while music is playing and selected by ear for the best sound. The amplifier will work fine with the HI / LO switch in either position regardless of speaker load, however each setting will make your speaker sound different or perform differently. Choose the setting that you like the best and revisit the setting often to make sure you didn’t just choose one position over the other because it sounded better with the particular recording you were listening to when you made the choice."

No different that most other tube amps.
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I have no experience with the Decware SE84UFO but I'm reporting what owners say when they wire the Fast 8 and F-15 in parallel for a 4 ohm load. With Bottlehead kits you have to make a decision to wire for either 4 ohm or 8 ohms.
 
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Poultrygeist said:
I have no experience with the Decware SE84UFO but I'm reporting what owners say when they wire the Fast 8 and F-15 in parallel for a 4 ohm load. With Bottlehead kits you have to make a decision to wire for either 4 ohm or 8 ohms.
Click to expand...

Their system is now louder = sounds better.

I assume a knowledgable Bottlehead builder could wire the amp both ways?
 
The more I listen the more I like the combination of the Lowther DX3, Lii Audio F-15 and Eminence Alpha 15. Using the SMSL DA-9 amp allows for some useful EQ settings. The DA-9's sub-out is a nice feature for the plate amp powered Alpha woofers.

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Update on my workshop sound system. Photos show a donated pair of Betsy's, back mounted to ¾" pine panel OBs, and the previously decapitated Sonys which have been restored and mounted overhead, 15 feet away. These two speaker sets are powered by separate amps and EQs (15 band and 9 band) for volume/tone control, and also to serve as power and low band filter for a future subwoofer. To my marginal ears, with EQ help, the Betsy's and the 3-way Sony's can be matched closely mid range, but the sealed box Sony's reach about 1KHz higher and 20Hz lower than the OB Betsys, using CD test tone tracks. I'm suspicious of my 2'x3' OB dimensions for the Betsy's, and am next going to try some card- board wings added to the bottoms. I'm also tempted to reduce their overall size, but that would just be flailing around at this stage. Suggestions welcome.DSCN4261.jpeg DSCN4262.jpeg
Restored pair of Sony SS-MB300H overhead. They hold their own, and more, against the OB Betsy's. My OB's are highly suspect.

Also in the works: a 10" Dayton Audio DVC Sub, possibly bucket mounted but more likely a box. What fun! Love this forum.
 
I'm hoping a single subwoofer will also make a big difference for mine, although the environments are very different. I'm going to try my 9 band Behringer Mini EQ as a low band pass for it, but in case, can you share the specs for that crossover shown in your photo? This is all new territory for me after decades with just a boombox.
 
bingow said:
I'm hoping a single subwoofer will also make a big difference for mine, although the environments are very different. I'm going to try my 9 band Behringer Mini EQ as a low band pass for it, but in case, can you share the specs for that crossover shown in your photo? This is all new territory for me after decades with just a boombox.
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I think it was this low pass which I only used for the woofers. The Betsy's are designed to run full range without a crossover. You could also use a Harbison Labs F-mod ( maybe 50 Hz? ) as a low pass filter. It's similar to an active crossover as it changes the frequency upstream of the amp. I always use two amps with open baffles, one for the full range drivers and one for the woofers.

https://www.parts-express.com/80-Hz-Low-Pass-8-Ohm-Crossover-266-442
 
Poultrygeist said:
I think it was this low pass which I only used for the woofers. The Betsy's are designed to run full range without a crossover.
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OK I see that separate Betsy wiring now; thanks. For the new subwoofer, I'll have to see how good a job the Behringer EQ does, using a 12db cut above 125 Hz. It will feed what's left into a second amp (old Sherwood receiver), which has its own bass/treble control to add/cut another 6db. Then it feeds the sub.
The Dayton DVC 10" subwoofer I just got, thanks to @Genov and Parts Express, lists its range as 26-2000Hz. For grins I'm going to play with the Behringer to see how the Dayton interacts with the Betsy, whether the lowest cut to the sub is best, or allow something higher. Each have separate amps, so it should be easy to tweak their volumes. This will all be done with the Sony's off of course. Maybe the current OB design won't need changing.
 
This may be a tough row to hoe. The Betsy's benefit some from a closer proximity to the floor also. Even with bass assist (which is definitely a must for the Betsy's), them being way up in the air like that, will prove challenging to get a good overall sound.

100% agreement with Poultry on the amp setup. Two separate amps will help. No power robbing crossover.

Good luck, and keep us posted on your progress!
 
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opnly bafld said:
How are you planning to use the Dayton DVC? With a box or open baffle?
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Box, sealed vs ported. I have an ugly 6.5 gallon bucket (.89 ft3) that I'll hook up this afternoon for a "baseline" sound. Next I'll try a ready made but not as ugly box of about the same volume. Both are smaller than the 1.2 ft3 recommended by Dayton, but a couple of online calculators (which aren't clear at all) gave smaller numbers. Don't yet know the sub's final location.

Genov said:
This may be a tough row to hoe. They Betsy's benefit some from a closer proximity to the floor also. Even with bass assist (which is definitely a must for the Betsy's), them being way up in the air like that, will prove challenging to get a good overall sound.
Click to expand...

I agree it's a long shot, and next I'm going to add ~6" cardboard wings to the bottom of the pine panels, angled back toward the wall, to see if that helps. The Betsy's really don't sound bad, it's that the Sony's were more attention getters between the two. Meanwhile, it's great fun.
 
bingow said:
I'm hoping a single subwoofer will also make a big difference for mine, although the environments are very different. I'm going to try my 9 band Behringer Mini EQ as a low band pass for it, but in case, can you share the specs for that crossover shown in your photo? This is all new territory for me after decades with just a boombox.
Click to expand...

With that nice shop and tools you're in for some DIY fun.
 
I just kicked that ugly bucket. It failed the Saint-Saens (Organ Symphony)-Chuck Berry (choose any) test. Too boomy, because it's undersized? Tomorrow I'll go ahead with the box test, because it's not an ordinary box (photo promised, later).
Unfortunately there's more. The Behringer's 12 db cut still allows a lot of the higher frequencies into the sub, which is distracting. So I ordered one of those low pass filters suggested by Poultry. I'll keep the Behringer because its indicators show how close its coming to clipping. I also ordered a 100 Watt stereo L-Pad to bring the Sony speakers volume more in line with the Betsys. Haven't tried the OB modification with the added wings yet. Tomorrow.

Drug addicts are amateurs; they should go pro with audio.
 
With the heavy F-15's added to these baffles I was seeing a bit of flex so I braced them with 1 x 2's. I also bolted the L bracket feet through the braced baffle rather than screwing them in. Now everything is quite solid and tight. I also replaced the big clunkey box terminals with female bananas that I bought on closeout at Lowes. They were used in HT wall plates. I see I need to do some touch up on the paint.

P1010020 2.jpeg
 
I use foam pipe insulation as an acoustic barrier between the bottom of the baffle and the floor.

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