I like the idea of a single cap as I can roll between various types and season to taste
The Foster amps are 80w into 8ohms which is what the Beta 15's are. Then I'm gonna start with a Fostex FT17h as its pretty much the same efficiency as the two Eminence drivers (98db/w/m ish)
I just need to figure out the size of the sub cabinets. I might try 10 or 11 cft as this matches the vas of the Beta15's. I'm going IB (sealed not ports) as I like this sound with big efficient drivers.
WOW
Just received the fostex ft17h and wired them up with a single Jantzen Standard Z-cap 1 uF 400V cap.
Well I was getting used to the 'mid' sound of the 12LT but now its like a light has switched on. They integrate so well I can't believe it.
I bought a selection of caps up to a Jantzen Silver Z-cap +/- 2% so I'll be rollin' for a while
Definitely worth a try Godzilla
Just received the fostex ft17h and wired them up with a single Jantzen Standard Z-cap 1 uF 400V cap.
Well I was getting used to the 'mid' sound of the 12LT but now its like a light has switched on. They integrate so well I can't believe it.
I bought a selection of caps up to a Jantzen Silver Z-cap +/- 2% so I'll be rollin' for a while
Definitely worth a try Godzilla
>>> as I like this sound with big efficient drivers.
Me too! You will have some really big boxes when you are done but i expect your setup to sound incredible! I think what we are doing is basically taking pro drivers and (hopefully) using them smartly in a home setup. We are using a wide range driver and supporting the low and high extremes. There is no crossover in the critical band of music. All we need to do is tame the 12lta a bit to make it sound more like a home hi-fi speaker. Honestly, i have really been enjoying mine for weeks and find that little bit of roughness appealing on many/most recordings because it adds a sense of real life to the presentation. Female vocals can sound a bit chesty (still using driver stock), but the presentation 'feels' natural on all vocals regardless of this coloration. I've heard much worse with other drivers. But the 12lta does SO MUCH right in terms of dynamics, efficiency, ease of presentation (unless pushed then it could sound congested... but all full rangers tend to do this, even the most expensive and best). They present a large image that projects into the room with ease. Background instruments pop (sometimes they seem to pop off different parts of the large cone) and sound natural. They may not resolve every last drop of detail like the more expensive Tangband's i have on hand (approx $200 each) but they do things the TBs can't. The Beta 12lta generates an exciting, big sound only larger drivers can. Even unmodified, i can enjoy them for hours at a time. I really am curious how other wide range 12 inch drivers sound.
I like them so much i've decided to build new cabinets. One is finished as of this weekend... a pine cabinet lightly braced that's approx 1.75 cubic foot. This way i can get rid of my larger 2.5cf boxes (anyone want them?) and get down to about 80hz with ease. Sealed and appropriately sized, it will sit on top of the H-frames like they were made for each other. Only DIY offers this freedom of flexibility!
Me too! You will have some really big boxes when you are done but i expect your setup to sound incredible! I think what we are doing is basically taking pro drivers and (hopefully) using them smartly in a home setup. We are using a wide range driver and supporting the low and high extremes. There is no crossover in the critical band of music. All we need to do is tame the 12lta a bit to make it sound more like a home hi-fi speaker. Honestly, i have really been enjoying mine for weeks and find that little bit of roughness appealing on many/most recordings because it adds a sense of real life to the presentation. Female vocals can sound a bit chesty (still using driver stock), but the presentation 'feels' natural on all vocals regardless of this coloration. I've heard much worse with other drivers. But the 12lta does SO MUCH right in terms of dynamics, efficiency, ease of presentation (unless pushed then it could sound congested... but all full rangers tend to do this, even the most expensive and best). They present a large image that projects into the room with ease. Background instruments pop (sometimes they seem to pop off different parts of the large cone) and sound natural. They may not resolve every last drop of detail like the more expensive Tangband's i have on hand (approx $200 each) but they do things the TBs can't. The Beta 12lta generates an exciting, big sound only larger drivers can. Even unmodified, i can enjoy them for hours at a time. I really am curious how other wide range 12 inch drivers sound.
I like them so much i've decided to build new cabinets. One is finished as of this weekend... a pine cabinet lightly braced that's approx 1.75 cubic foot. This way i can get rid of my larger 2.5cf boxes (anyone want them?) and get down to about 80hz with ease. Sealed and appropriately sized, it will sit on top of the H-frames like they were made for each other. Only DIY offers this freedom of flexibility!
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>>> Just received the fostex ft17h and wired them up with a single Jantzen Standard Z-cap 1 uF
This is the beauty of full range/wide range drivers. Btw, i can see how you might get used to the speakers even without a tweeter. I listened to them that way for a few days. Of course the tweeter makes a big difference. I use a compression driver that's about 103db with a 1uf cap. I bet we are getting a similar sound... maybe my treble is a bit louder... yours probably a bit more refined and sweet. I know the tweeter you have. Wait until you connect the woofers... it will be an even bigger WOW moment!
The way i see it, who cares if things aren't perfect. But there is a rightness to the sound along with a scale and size most can't compare. Enjoy! I am curious about your bass boxes!
This is the beauty of full range/wide range drivers. Btw, i can see how you might get used to the speakers even without a tweeter. I listened to them that way for a few days. Of course the tweeter makes a big difference. I use a compression driver that's about 103db with a 1uf cap. I bet we are getting a similar sound... maybe my treble is a bit louder... yours probably a bit more refined and sweet. I know the tweeter you have. Wait until you connect the woofers... it will be an even bigger WOW moment!
The way i see it, who cares if things aren't perfect. But there is a rightness to the sound along with a scale and size most can't compare. Enjoy! I am curious about your bass boxes!
I'm with you all the way on that. I cant wait to hear your listening impressions with the new cabinets and H-frames.
I think damping the basket will be my first DIY touch on the 12LTA. Something mouldable on the outside and some felt wadding zip tied to the inside of the legs. Then maybe some damping of the whizzer followed by a phase plug.
I'm gonna have some big old boxes but, on current listening impressions, it is going to be really worth it!
I just need to see what will be the best cabinet sizes. I was thinking about rolling off the 12LTA by using a quite small cabinet like yours and then running the Beta 15's in a whopper.
Godzilla, are you at ur PC at work? Can you ISD me a couple of cabinet sizes up to the 11.8cft vas (all sealed) for me? Amps are enroute
One reason I've gone so big is because of this idea I've had floating around for a couple of years. It all started after I ran my Tannoy Berkerley 15" DC's in a village hall. DAMN did they sound good in that big room
A few of my friends really love music (some of just one genre - others like what they like of it all) and after discussing it with them I formed the idea of hiring a hall for listening evenings.
I would inviting, say 20 people to bring one or two of their favourite tracks on whatever format (No mp3 or otherwise compressed files) and then blast em out as the gods of music intended.
It will soon be a reality
A few of my friends really love music (some of just one genre - others like what they like of it all) and after discussing it with them I formed the idea of hiring a hall for listening evenings.
I would inviting, say 20 people to bring one or two of their favourite tracks on whatever format (No mp3 or otherwise compressed files) and then blast em out as the gods of music intended.
It will soon be a reality
http://www.parts-express.com/pdf/290-410c.pdf
http://www.parts-express.com/pdf/290-410s.pdf
>>> Can you ISD me a couple of cabinet sizes up to the 11.8cft vas (all sealed) for me?
My pleasure. I will do it later today. After looking at the specs and projects by Eminence i am curious to see how this driver will work in a larger sealed box. The specs suggest it should perform really well. Looks like a nice woofer. My H-frames (with Alpha 15s) work great in my room but one day i may need to move. With this in mind i liked the idea of smaller 'main' speakers and subs (whether it be H-frames, a single sub or two subs). Either way, i always like the flexibility of going powered.
http://www.parts-express.com/pdf/290-410s.pdf
>>> Can you ISD me a couple of cabinet sizes up to the 11.8cft vas (all sealed) for me?
My pleasure. I will do it later today. After looking at the specs and projects by Eminence i am curious to see how this driver will work in a larger sealed box. The specs suggest it should perform really well. Looks like a nice woofer. My H-frames (with Alpha 15s) work great in my room but one day i may need to move. With this in mind i liked the idea of smaller 'main' speakers and subs (whether it be H-frames, a single sub or two subs). Either way, i always like the flexibility of going powered.
You sir, are a gentleman
I'm trying to work out a system, with my limited technical ability, whereby the midrange enclosure could house a TA2020 amp, a Mini A and a small valve amp of some sort so I can swap them about to power the tweets & mids together.
With the size difference between the Sub and the mid cabs there should be room
btw, i returned the Lapai amps... did not look good at all. never turned them on tho. Arrived with scratches and the knobs did not turn smoothly. the dayton t-amps look much better and sound very good to me. i love tubes as you already know. the beta 12lta does not need much power to get loud. my 30 watt cary amp sounds way too powerful with them connected.
Here you go, Beta 15 in closed cabinets. Looks like 7 - 9 cubic feet closed is the sweet spot. I simmed an 11cf vented box and it goes deeper but it's bigger, it's vented and it may sound boomy in a home environment. If you look at Eminence's suggested projects you will see they modeled a 6cf vented cabinet that's -3 @ 45hz. The slightly larger closed boxes also reach 45hz but measure flatter. Closed appears to be a good idea. Choose your size and dimensions and build away. They should provide visceral bass you will feel as well as hear.
Do the foster amps allow you to roll off the hi frequencies or will you be using a coil to do that?
Zilla
Do the foster amps allow you to roll off the hi frequencies or will you be using a coil to do that?
Zilla
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Thanks for that Godzilla - Bigger looks flatter so 
let the build commence!
The Foster amp has a "4th order (24dB/octave) low pass adjustable from 50-200Hz. 0-180 degree phase switch, RCA and speaker level inputs, volume control. Unit has a 3rd order (18dB/octave) high pass filter at 29Hz with a Q of 0.707 built into the subwoofer section. Can easily be modified for any Q and cutoff frequency that you want by changing R615, R617, R618, C607, C608 and C609. The amplifier also has a spectral tilt control that is adjusted to give about 10dB of shelving. It can be manually adjusted with a pot on the PCB" according to the blurb
One thing I'm not sure on though is where to put the sub amps. I may build them into the mid cabinet and have that as a sort of control unit for the entire system. What do you think?
let the build commence! The Foster amp has a "4th order (24dB/octave) low pass adjustable from 50-200Hz. 0-180 degree phase switch, RCA and speaker level inputs, volume control. Unit has a 3rd order (18dB/octave) high pass filter at 29Hz with a Q of 0.707 built into the subwoofer section. Can easily be modified for any Q and cutoff frequency that you want by changing R615, R617, R618, C607, C608 and C609. The amplifier also has a spectral tilt control that is adjusted to give about 10dB of shelving. It can be manually adjusted with a pot on the PCB" according to the blurb
One thing I'm not sure on though is where to put the sub amps. I may build them into the mid cabinet and have that as a sort of control unit for the entire system. What do you think?
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OOF
I just received this http://cgi.ebay.co.uk/MINI-DAC-DIR9...Amplifiers&hash=item41555c8ede#ht_6357wt_1141 Previously I was just using an iPod headphone to phono cable (I know, I know thats rubbish!). The dac must have a pretty big output because I only need to turn the volume a few degrees from 0 to get a real blast
I just received this http://cgi.ebay.co.uk/MINI-DAC-DIR9...Amplifiers&hash=item41555c8ede#ht_6357wt_1141 Previously I was just using an iPod headphone to phono cable (I know, I know thats rubbish!). The dac must have a pretty big output because I only need to turn the volume a few degrees from 0 to get a real blast
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Greets!
I'm curious which specs did you use, published or some measured ones posted recently or........?
FWIW, for a 0.707 Qtc max flat alignment using the decades old, well proven Margolis/Small HP calculator program:
published specs:
~464.36 L/16.4 ft^3 lightly damped with fiberglass insulation.
~274.56 L/9.7 ft^3 stuffed at 1.5 lbs/ft^3 fiberglass insulation, so would theoretically need somewhat more for polyfil.
average measured:
~347.21 L/12.26 ft^3
~218.9 L/7.73 ft^3
Pretty big difference, though at least going in the right direction, a rarity.........
WinISD Pro:
~763.4 L/26.96 ft^3 lightly damped with ?
Couldn't find any Ql, Qa adjustment to come close to the fiberglass calc'd Vb WRT F3, Fb.
average measured:
~470.00 L/16.6 ft^3
Sealed is very tolerant of Vb errors, but this disparity between programs for a basic max flat alignment is a bit much!
GM
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![Beta-15A measured specs - avg. [2].gif](/community/data/attachments/183/183579-13a41cc34c0bf8ff6c65d205791562db.jpg)
Thanks for checking GM!
I used the specs from Parts Express here:
Eminence Beta-15A 15" Driver | Parts-Express.com
I used WinISD and noticed they had parameters for the Beta 15 already in their database that did not match the ones on the PE website so i input them again and generated the sim that way.
Zilla
I used the specs from Parts Express here:
Eminence Beta-15A 15" Driver | Parts-Express.com
I used WinISD and noticed they had parameters for the Beta 15 already in their database that did not match the ones on the PE website so i input them again and generated the sim that way.
Zilla
Snow day today so I thought I'd try some things and take a few measurements. First the disclaimers:
I don't know much nor have much experience. This is the first time I've used ARTA, but I used a tutorial I read on the PE board.
Measurements taken in my cluttered basement with 12lts in a 1.9 cu. ft. sealed box. Box stuffed with dacron pillow stuffing. Center of 12lta about 3" off the floor and mic about 30" from speaker.
First, the stock 12lta:
Then I removed the dust cap:
Next I made a quick and dirty phase plug. I used a deep well socket wrapped with foam and covered in electrical tape. It's about 3" long.
Left the phase plug in, but cut off about 0.5" of the whizzer:
Cut off another 0.5"
Cut off all of the whizzer:
I see some inconsistency below 1K that I attribute to my difficulty in deciding where to put the cut off point before the first reflection, but maybe some of you can gleam something useful from this - or tell me how to improve it. From listening I do know that I don't like the cupped sound and removing the whizzer did get rid of it. Most likely I'll build an econowave with my 12ltas.
I don't know much nor have much experience. This is the first time I've used ARTA, but I used a tutorial I read on the PE board.
Measurements taken in my cluttered basement with 12lts in a 1.9 cu. ft. sealed box. Box stuffed with dacron pillow stuffing. Center of 12lta about 3" off the floor and mic about 30" from speaker.
First, the stock 12lta:
Then I removed the dust cap:
Next I made a quick and dirty phase plug. I used a deep well socket wrapped with foam and covered in electrical tape. It's about 3" long.
Left the phase plug in, but cut off about 0.5" of the whizzer:
Cut off another 0.5"
Cut off all of the whizzer:
I see some inconsistency below 1K that I attribute to my difficulty in deciding where to put the cut off point before the first reflection, but maybe some of you can gleam something useful from this - or tell me how to improve it. From listening I do know that I don't like the cupped sound and removing the whizzer did get rid of it. Most likely I'll build an econowave with my 12ltas.
Thanks for doing that. With an untrained eye I would say that the greatest 'improvement' (smoothing it out) to the measurement line thingy came when you used a phase plug.
I'm definitely gonna get one made up to Planet10's measurements I noted a few posts back.
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