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Jackboot 9th November 2005 07:33 AM

Driver suggestions for a Sonic Impact T-Amp
Hey all...first post!

First off I'm amazed at the diversity of membership (by Country) and comradery on this forum! I've been reading and searching for a week and I finally feel justified in posting a question:) There is a chance that I missed a similar thread because it isn't possible to search for terms like "SI t amp" due to the search character limitations etc so go easy on me!

My goal is to build a speaker setup for use with a Sonic Impact T-Amp. From what I've read, the best drivers for the T-Amp are full range since apparently the T-Amp doesn't like to deal with crossovers. That's why I've posted in the full range forum. If this is incorrect then stop me now and redirect me elsewhere:D

FWIW, I listen to:
Classic rock (on vinyl)
Acoustic artists (Damien Rice, Elliot Smith, Iron & Wine)
Alternative rock (Radiohead, Modest Mouse, Metallica...)

Additionally, this will be my only speaker setup in the house at this time.

My main design goals are:

1. <$250 USD for entire speaker construction
2. Bookshelf / computer desk size
3. No external subwoofer required. In other words, I'd like the speakers to play down to 50Hz or so. I'm not sure if it is possible to go lower than this while using only full range drivers
4. Hopefully a unique, eye-catching and "professional" design but still easy enough for a first project (ie: not liable to screw up the SQ due to a botched enclosure)

I'm a n00b to DIY speaker design but I understand basic audio principles. However, much of the terminology and accronyms on the board are new to me, so I appreciate your patience;)

I'd like some recommendations on driver selection as well as enclosure type/design. Again, I'm new to this, so the more complete the details the better!

Thanks so much for your replies! Cheers

Scottmoose 9th November 2005 10:11 AM

Hi Nic

Enclosures as a general rule are designed for a specific driver (there are exceptions), so we should be suggesting drivers as well as cabinets!

This is not going to be easy however. 50Hz out of a full-ranger -no problem. 50Hz out of a full-ranger in a bookshelf design for less than $250 all in with a T-amp? Well, nothing's impossible, but this is not at all easy as the requirements are moving towards being incompatable. You can get bass from small enclosures, but it kills efficiency, and that little T-amp, lovely though it is, doesn't like difficult loads -distortion rockets with increasing power-output, and it will quickly start to sound vile if its pushed too hard.

We can get close to 50Hz[ish] with a large standmount of around 45L capacity. Shove a pair of Fostex FE206E 8" drivers into it, and watch the fireworks. This will stop and start faster than you'd ever believe possible, and go LOUD. It won't be particularly refined, but it will be great fun. A smaller alternative is to use the FE207E in a 35L enclosure. Have a look at the reccommended Fostex Factory enclosures at for these drivers -the main picture deals with horns or big double-bass-reflex cabinets, but down to the bottom right they have normal BR enclosure ideas. The shape won't matter much with these -build to taste, so long as it isn't a cube.
Hope some of this helps & I'll let you know if I think of anything else


bwbass 9th November 2005 01:12 PM

I use a couple of Tang Band 1052SA's as desktop computer speakers in 7L BR boxes, and I think they're a great match for my T-amp. Anechoic they only go down to around 65Hz, but in a smallish room 50Hz is no problem. I also did MarkMck's #2 mod on these, which involves a cone modification and pre-filter and smooths out the response quite nicely. Easily under $250 for everything..

Scottmoose 9th November 2005 01:52 PM

Sounds like a good option

bwbass 9th November 2005 03:24 PM

2 Attachment(s)
Oh, and I forgot to mention, these speakers are pretty efficient and are 4 ohm, so you get lots of output from the T-amp. And in a SBB4 alignment, the speakers start to run out of Xmax right where the bass rolloff of an un-modded T-amp starts, so you've got a built-in over-excursion filter.

Here's a picture of one of mine, still a little rough around the edges. If you've got room on your desk to space them away from the wall it's probably better to put the port in the back so you don't get HF's from the back of the driver out of the port.

usa_satriani 9th November 2005 06:12 PM

I would suggest a couple of FE167 or 207 with a recommendend Fostex Enclosure.

Jackboot 10th November 2005 12:49 AM

Thanks for the thoughtful replies:)

My biggest concern is building the correct enclosure. In order to keep things fairly simple for my first project I think I should stick to a Bass Reflex design. While not the best for getting the most out of the drivers, it suits my needs for being a simple design that I will be hard pressed to knacker up as well as small enough to be a desktop speaker. Does this logic sound solid to you too?

I have a couple of questions upon comparing 2 of the suggested drivers that seem most appropriate for me (Fostex 167E vs. Tang Band 1052SA). First, here is a quick comparison purely by the specs:

Fostex 167E vs. Tang Band 1052SA
Category Winner
------------ ---------
Lower resistance TB (4 ohm vs. 8 ohm)
Cheaper TB ($23.07 vs. 63.25)
Sensitivity FE167E (94dB vs 87dB)
Lower frequency response FE167E (51.5Hz vs. 60Hz)
Higher frequency response FE167E (22KHz vs. 15KHz)

I realise that I want to push the T-Amp as little as possible to keep distortion down, so which factor will help more: the Fostex's are cleary much more sensitive at 94dB but the Tang Band's are a 4 Ohm driver instead of an 8 Ohm driver. Which will have more of an impact on keeping the T-Amp happy?

Next, the Tang Band's are rated from 60Hz-15KHz. Is this really a "full range" speaker, or is it meant to have a tweeter and crossover also? In other words, will I realistically feel like I am missing something above 15KHz? I'm 26 years old, so I figure my ears are still good for it. On the other hand the Fostex's are rated all the way up to 22KHz...

Please offer your opinion!

I really like the fact that the Tang Bands are so inexpensive (and they are also available from Partsexpress where I would prefer to buy from) and bwbass' endorsement of them, specifically with the T-Amp is encouraging. I won't be able to make my mind up until I know a bit more about the above questions though:)

usa_satriani 10th November 2005 05:12 AM

I have a T-amp on FE168EZ and I really think this amp is done for efficient speakers. I listen quite loud and I often put the T-amp at the maximum. Then what about the sound quality ?

The recommended enclosures for FE167 and FE207 are bass reflex an quite easy to build.

bwbass 10th November 2005 06:07 AM

When you're right you're right, the Fostex's do look better on paper...

Just a few points, then I'll go. ;)

- The FE167 recommended enclosure is 15L, my TB boxes are only 7L.

- With MarkMck's mod #2 (alluded to in this thread: the midrange hump gets flattened out and they wind up being +/- 3dB out to 17kHz. I paid around $40 for a mod kit from Mark which included instructions, mod tool, and a pair of prewired filters.

- With only 0.6 mm of Xmax, it seems like the FE167 would run out of steam at less than a watt around 70Hz or so. Granted, they're very efficient so this is still quite loud for a desktop speaker.

IMO, the Fostex boxes would probably sound a little cleaner (easier load on the T-amp), but be bigger and more expensive. The TB boxes probably have more real-world bass output by virtue of having greater Xmax, but at the expense of some high-end extension.

To each his own - either way you'll have a great first project! :)

blip1882 10th November 2005 06:32 AM

Have you thought about the FE127? I've been thinking about a pretty similar project and the WinISD models look pretty encouraging. Though they bottom out around 60 Hz, if the model is any suggestion they would work well in a small enclosure.

Anyway, I've been thinking about a bass reflex in a 13 liter enclosure.

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