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PostPosted: 07 Dec 2010, 12:03 
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Joined: 30 Nov 2010, 09:54
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Location: Oak Creek, Wisconsin USA
dtsup1 wrote:
Very nice!! They definitely need some Baffle Step compensation. If you have some extra parts lying around, try a 1.5mH choke in parallel with a 4.7 Ohm resistor. Then connected in series with the speaker.

OK I get it. I found the BSC calculator on this site. I ran my numbers in the calculator and the results closely resemble yours. A nice schematic also explained how to hook it up. THANKS!!!

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PostPosted: 07 Dec 2010, 13:10 
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Location: Christchurch, NZ
Hi Jim,

I had an 8'' Hemp Acoustic fullrange driver and that was the max BSC I could use. Any more than that and it would suck the life out of the music.

Can you write up a little on enclosure resonances? Are they audible?
Did you add any bracing ? What unique characteristics do the speakers have ?

I believe in allowing "controlled resonances" to let the speakers sing. That would include not overdamping the enclosure, but to allow just a little bit of resonances through for a unique tone.
After all, that is the point of a SET amp + fullrange speaker ! :mrgreen:

Thanks for recommending those drivers. I will build a fullrange speaker soon. Sadly I haven't got a SET amp yet !! :bawling:

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PostPosted: 07 Dec 2010, 13:26 
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Location: Winnipeg, CANADA
Great work Jim. :up: Countersinking the driver does help with the high frequency response.
JimOfOakCreek wrote:
Imaging is so good it’s eerie. The sound stage is suspended in thin air between the speakers.

The treble is strong and needs some attenuation.

Imaging is great with full range. ;)

As for the highs, a BSC will help that. In the meantime you can also experiment with the placement. Try putting the speakers right up against a back wall. It should help somewhat.
Cheers

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PostPosted: 07 Dec 2010, 13:56 
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dtsup1 wrote:
I had an 8'' Hemp Acoustic fullrange driver and that was the max BSC I could use. Any more than that and it would suck the life out of the music.

Can you write up a little on enclosure resonances? Are they audible?
Did you add any bracing ? What unique characteristics do the speakers have ?

The enclosure is braced. I don't know how to recognize resonances. I can’t hear anything that I would recognize as a resonance. The speakers go deep, below 45hz with no port tube installed. At the same time they are too bright, voices have some sibilance, cymbals bite hard and bright, etc. Imaging is excellent. Presence is ‘in the room‘.

I agree with you about over compensating. I intend to use a light hand with the BSC.

I’m going to try a 1.3mH inductor with a 3.3ohm R. I’ll have a 4.7ohm in hand if I want to reign in the highs a little more.

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PostPosted: 21 Dec 2010, 14:52 
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Here’s my last review on the Tang Band W8-1772 project. Now that I've spent some time listening to these I thought I'd post my impressions of sound characteristics. All measurements were made with my ears. The crude & temporary setup (shown in the image) puts the speakers about 6“ from the concrete block wall.

I drive these with a PS Audio 100w/ch C-100 class-d int-amp. With that amp the response is on the bright side but not grating. Eventually I plan to build a 300B S.E.T. amp. There is no BSC circuitry at the moment. I will wait for that step when I get my S.E.T. tube amp.

The enclosures are made from 3/4" thick Aspen. The interior dimensions are 9.75"w x 11.25"d x 22.5" high. The net volume, minus bracing, port tube and speaker displacement, is about 39.5L. A 3” x 6" port tube is installed. There are no resonances that I can hear. I've been reassured that solid-wood resonates no more or less than plywood if braced.

The TB 8-1772 has an extremely impressive response range. The bass begins to roll off at about 47hz in my enclosures. There's good response at 40hz, with audible response down to 27hz! The high-end extends to at least 13K which is the limit of my hearing. No tweeter augmentation is needed for my ears.

I have another DIY speaker to compare the TB 8-1772 project, a two-way that was designed by Jay Kim. It features an SEAS 27TDFC tweeter and a RS180 woofer. Comparing those two totally different speakers I find the SEAS tweeter is sweeter and more refined but not as detailed as the TB. The difference is quite noticeable. Both tweeters are equally extended to my ears. Bass response is roughly equal down to 35hz where the RS180 cuts off.

The mid-range is very smooth on the TB. I've been told that Fostex drivers can sound 'shouty'. There is none of that with the TB. All vocals sound perfectly balanced, both male and female. Brass instruments have convincing bite. Percussions sounds like it is in the room with me. Imaging is coherent.

The 1772 doesn't sound like a FR driver. There are no gaps in the response. Good bass response can be achieved in a reasonably sized ported cabinet for high WAF. Treble is extended further than I can hear. The mid-range is natural. Imaging and detail are impressive.

I don’t listen to these speakers directly on axis due to brightness. The treble is not quite as smooth as a dedicated tweeter like the fine SEAS 27TDFC. I have not design circuitry to tame the high end as of now. Bass response is astounding for an 8” driver.

The quality of construction is very good. The surrounds are cloth and extremely pliable. The gold plated phase plug keeps the paper cone aligned. The heavy magnets are neodymium.

This is a great driver, but expensive. Fortunately you only need one per box. If you can catch a sale at Parts Express I recommend you jump on them.


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PostPosted: 21 Dec 2010, 22:55 
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Awesome. You don't mess around. That looks like a 1.5L bottle! :redwine:

The speakers turned out very nice. That is descent bass extension considering the smallish enclosure. It sounds like that driver is a real winner as I have read a bunch of positive reviews now. The cost may seem high for just one driver, but there is no need for a tweeter or crossover. I bet these will really shine with a SET amp.

Thanks for sharing your experiences and enjoy your build.

Cheers :wine:

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PostPosted: 22 Dec 2010, 02:00 
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Joined: 24 Jun 2010, 00:48
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A marvelous review !
One day I really want to try either this driver or a Fostex F200A (8'') which costs a bomb.

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PostPosted: 28 Dec 2010, 12:33 
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Location: Houston
Nice looking speakers! :up:

I agree the W8-1772 is one of the better full range drivers to come along. It might not have quite the treble resolution of a Lowther, but it does nothing wrong, which is a lot to say for full range single drivers. I prefer the Tang Band to the Fostex and Audio Nirvana drivers I've used in other projects. In my experience the sound was enhanced by a baffle step correction filter, especialy when using a solid state amp. The need would be less with a SET tube amp. I used a Bob Brines design MLTL enclosure with his recommended correction circuit, a 1.5mH inductor paralleled with a 4 ohm resistor.

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PostPosted: 28 Dec 2010, 13:36 
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Hi Fred,

In your experience, what are the sonic differences between a fullrange driver in a standard bass reflex vs MLTL enclosure?

I am betting those 18W midwoofers and scanspeak soft dome are your current reference speakers. :mrgreen:

Sorry OT.

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PostPosted: 28 Dec 2010, 14:48 
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Fred

I calculated the BSC as a 1.1mH and an 3 ohm resistor for a correction of 3db. It appears Bob B. was going for a correction of 4db. I'm going to stay with a 3db correction. If you listen to them off-axis with the speakers close to the wall the treble is not bad without a BSC correction.

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