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Open Baffle Epiphany!

Poultrygeist said:
The Tekton OB4.5 has outstanding micro detail and imaging but without the H-frames it's lacking in LF. Placement was difficult in my listening room as they had to share space with some larger OB's. I liked them best in near field and would prefer them over the other speakers mentioned.

A friend now has them on stands in his bedroom powered by a wonderful 300B.

I noticed that Eric ( of Tekton ) no longer sells them or any other Fostex based speakers. He once told me that the Fostex 4.5's were his favorite driver.
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Yes, Tekton phased them out sometime ago, maybe a couple+ years ago. As you know, they are the base for the bookshelves I'm building, finally started, have one bare enclosure finished, trying to find time to finish the other. But, instead of the "dipole" configuration of the Tekton, I went the simpler route with a 5" HiVi Woofer in a vented enclosure, and an OB 4" MarkAudio CHR70.3 in an extension of the front baffle (7.5" Wide x 6" High OB), total height of the speaker including enclosure + OB is 16.5". We'll see how they sound, I might add 4" L x 6" H side walls to the OB; but, only if needed, and simulation tells me it will be smoother.

BTW, just a quick hijack, need two pairs of banana speaker terminals, I used to buy some simple but good ones at RS (closed), a simple black plastic plate with two screw holes and a pair of jacks installed, and I haven't been able to find them. Please, advise which ones I can use for 1/2" Thk wood? Going to Bi-Amp, and the bi-amp cup I purchased is almost as big as the back of the enclosure, so I can't use them. PM with ideas, if you don't want to answer here.
 
BHamm said:
Is there an issue with inletting the drivers slightly or mounting them from the rear. I know sometimes there's a time-alignment issue, but will it matter in this case. My reasons are aesthetic only.
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If we were talking about woofers, any detriments would be very minimal. I wouldn't do it with a full range driver, however. Diffraction would be an issue but may not be objectionable enough to be concerned with. For me, I'd avoid.
 
BHamm said:
Is there an issue with inletting the drivers slightly or mounting them from the rear. I know sometimes there's a time-alignment issue, but will it matter in this case. My reasons are aesthetic only.
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The design has them mounted on the front. Look at the SPL and phase curves, they are nice and smmoth through the crossover region.
 
Holy Damn! Not to be deviated in the least. Makes the assembly that much easier.

But really I'm good with that. I received my drivers today, and ordered the 120uf caps.

Again, thank you all.
 
After three days running on the setup with the Eminence 15A, FHT-2 and FHT-4 I put today the 15" Magnavox speaker that I had instead of the Eminence and the character of the speaker changes totally. I know a new speaker needs some time to make them going but the Magnavox are so much stronger that I'm not sure if the Eminence will ever get that. Bass is going lower with the Magnavox and somehow compared to the horns it seems more efficient so that the horns seem to need some boost.
With the Eminence I ran the FHT-2 horn from the crossover and a 5 Ohm resistor in front of the FHT-4 tweeter to have a more even loudness distribution over the range but with the Magnavox I had to pull that in order to have a little bit more HF.
The Magna seem to be a little bit boomy at the end of the crossover frequ of 800Hz while the Eminence seem more flat.

However, both setup have a little bit the issue that the FHT-4 is somehow not having the right sound. The HF sounds a little harsh but does not creat crispness of well defined highs. Hi-hats are missing the last zingggg but also voices sound a little bit muffeled or like behind the curtain. Either the whole horn setup is not giving the right combination or I'm missing something here or the crossover is having bad crosspoints. Maybe 800Hz is to low or too high.
The speaker are not working for TV with a lot of voice cover like my other speakers. Are OB rather for music than for a limited frequency band signals?

Down the road I want to replace the fix upper part with the horns with a front plate which can take other speaker. I want to put both 15 inch speaker in the main baffle and the horns on an extension above. Question is just which in the lower and which in the upper position? How wired?

- Is the Eminence or the Magnavox the better bass speaker?
- Would it make sense to run the both in parallel like they did it in some of the older stereo consoles?
- Should I splitt the bass off in let's say 1Hz to 400Hz for the Eminence but run the Magna also from 1Hz to maybe 800Hz in parallel and than the horns?
- Another combination would be leaving the Eminence in the crossover wired and run the Magnavox of a single low pass to maybe up to 1KHz or even higher since it seemed to be originally run as a full range?

No matter what, the whole setups are very efficient they just need some finetuning or a different mid range and tweeter.
 

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Quick update: Work has really been getting in the way, restricting the time I can devote to my new OB build.

So.....I still have to order the Alphas and get with the cabinet maker who does the wood work for me.

More to follow as I am able to devote some time.....
 
Based on the comments about the narrow beam from the Tang Bands, I would agree.

"With considerable fussing I was able to achieve extraordinarily good focus resulting in excellent soundstaging both in size and placement of instruments."

The speakers look exceptionally nice though, but many of you on this forum have been using the same drivers and building nice speakers for far less $$$$.

Poultrygeist said:
Here's a review of the Pureaudioproject Tang Band/Eminence Alpha OB's.

http://www.enjoythemusic.com/magazine/equipment/0415/PureAudioProject_Trio_15_TB_Review.htm

In this configuration I can't see any advantage with the Tang Band aimed at belt buckle level vs ear level?
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BHamm said:
Based on the comments about the narrow beam from the Tang Bands, I would agree.

"With considerable fussing I was able to achieve extraordinarily good focus resulting in excellent soundstaging both in size and placement of instruments."

The speakers look exceptionally nice though, but many of you on this forum have been using the same drivers and building nice speakers for far less $$$$.
Click to expand...

It's why DIY open baffles make so much sense. They sound better, you don't have to float a loan and building them couldn't be easier.

When I started building OB's there weren't many pictures on the net. Now google OB images and you're overwhelmed.
 
Another weekend and another try on my OBs. Now it's 4 way due to the awful sound the Foster FHT2 has when driven down to 800Hz and I'm rebuilding right now the Xover for my Visaton speaker which freed the old Xovers.

I also substituted the Alpha15A as bass driver since I figured the Magnavox I had is far better at that in this setup. Only thing with the Magnavox is that it doesn't like to go higher than maybe 600Hz or it becomes a little bit too much.
Combination is now 15 inch Magnavox as bass to 300Hz, Alpha15A 300 to 1500 Hz, Foster FHT2 1500 to 7000Hz and the rest for the little Utah FHT4.

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Need to workout a little bit of level correction for the horns but so far the best results that I can get without going MiniDSP AND 4 little amps to tweak until I have the right values together and build than a passive Xover and LPad.
Voices are much better than I had it before with the three way version and bass is nice.

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darg I think you have that baby screwed down anyway might have set a OB record on amount of screws used......Seriously they look great cheers...
 
They look a little bit like Frankenstein's monster but the upper part is exchangeable and I need to keep that from moving :-) don't look at the back side....
 
For those thinking of OB and an augmenting woofer for the lower frequencies of a main broadband driver with an electronic crossover, here is a model that is pretty well suited to the task...the Dahlquist DQ-LP1. I've played with using these and they're very well suited to the task.

The DQ-LP1 range is well suited to the lower freq augmenting task. The EQ function on it can be used to help match up and flatten (or fatten if that's your thing) in the lower range.

One is up on eBay now....not related in anyway...

http://www.ebay.com/itm/Dahlquist-lp1-electronic-crossover-/291445968308?pt=LH_DefaultDomain_0&hash=item43db888db4


And here is a link to a nice batch of information...

https://sites.google.com/site/mpbarney/home/dahlquist-dq-lp1

Other models of crossovers are available of course, this is just one I've played with and do know can do a great job. It tends to go on eBay at about the $300 mark, plus or minus about $25-50 depending on those willing to compliment the desirability with bids at any moment. Sometimes none but pretty often one or more is up at about anytime.

EV3
 
Alright.....!

Ordered four Eminence Alpha 15" woofers today.

Already have the Tang Band W8-1808s.

Time to get the wood lined up so I can get on the cabinet maker's calendar.

Now we are cooking!
 
Do you plan on running the Alphas in parallel and if so how high of a frequency or do you plan on having one as bass driver and the other as a helper up to a certain mid range?
 
darg said:
Do you plan on running the Alphas in parallel and if so how high of a frequency or do you plan on having one as bass driver and the other as a helper up to a certain mid range?
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I would only run the Alphas in parallel as the benefit is their greater LF output and use of a less powerful amp.
 
I figured the Alphas are not very powerful in regard to LF. In my setup the Magnavox is doing a much better job in the basement. I'm toying with the idea of having kind of a 3.5 way setup instead of the actual 4 way setup and have the Alpha also running from bass to 1500Hz instead of cutting it in around 300Hz like it is right now. Just need to run the numbers on the crossover filter and see if that would work out.

As driving amp I'm using my Akai M8 rebuilds and they are making a hell of a noise so the efficiency seems to be good.
 
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