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Using 2 First Watt SIT3


Jim Gregory
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I have a bi-amped system in which I use the First Watt SIT3 to amplify the HF  K 402 with Radian 760 Br Pb drivers. My thought is to get a 2nd First Watt SIT3 to separate the L and Right HF channels so that each HF channel is separately amplified by its on SIT3. The advantage would be the isolation of the single transformer in the SIT3 only running one channel each. 
Sounds reasonable to me, what do you think ?

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Hey, don't go buying up all the sit-3's now. Leave some for us poor slobs trying to get one.. haha.

 

I don't have any advice on the separate amp deal but i just wanted to know how your'e liking the sit-3 with your speakers. I have a pair of 396's that I love and currently have a Pass Aleph J that is great but I have been intrigued by Nelson's other offerings and have read nothing but high praise for the sit-3. I can send a pm if that works better.

 

-Tom 

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I find that horizontal bi-amping works just as well--and costs a lot less (typically) in terms of separate amplifiers to drive the HF and LF sections.

 

But if you want to be able to say that you're using two SIT-3s on only two K-402-based loudspeakers (and of which you haven't identified the bass bin type/configuration--so I'm currently assuming that you're using direct radiators of some sort), you can certainly do it. 

 

However, if my assumption on the bass bin types are correct (i.e., direct radiators), unless we're talking four 15" woofers in a box, I'd recommend a bit more power than just 18 w/channel (into 8 ohms) or 30 w/channel (into 4 ohms) in order to provide a bit more control and damping of the moving mass in the direct radiating woofers.

 

If however you're running fully horn-loaded bass bins (with all the advantages therein of higher efficiency and full-range controlled directivity), then the second SIT-3 would most probably work very well--either horizontally bi-amped or vertically.

 

Chris

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13 hours ago, Chris A said:

 

I find that horizontal bi-amping works just as well--and costs a lot less (typically) in terms of separate amplifiers to drive the HF and LF sections.

 

The bass bins are klipsch 904. I use a pair of Pass Lab Aleph 2 as amplifiers. 
 

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Thanks for the recommendations and advice. 
Looks like I will be staying with the single SIT3 for the HF. It really does a great job by itself, just enjoy contemplating different ideas. I would love to try a pair of SIT1 but they don’t come up for sell very often. 

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  • 1 year later...
On 12/14/2019 at 9:49 PM, Jim Gregory said:

Thanks for the recommendations and advice. 
Looks like I will be staying with the single SIT3 for the HF. It really does a great job by itself, just enjoy contemplating different ideas. I would love to try a pair of SIT1 but they don’t come up for sell very often. 

Any perspective on the SIT 3 sound? I have 402’s with HF powered by F3, wondering about the sound signature of other First Watts.

thanks, Ted

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My experience with the SIT3 as amp duty on HF with 402’s was very satisfying. A little veiled but natural sounding with a nice sound stage. I have gone in a different direction (tri-amping). I use tube amps to cover MH with the 402’s and tube amps to cover the HF horns. In my system tube amps are better sounding for the vocal and give more of a 3D presentation. A lot more invested to create this additional difference. I could have lived happily with the SIT 3. 

762E9119-2CC1-4315-A763-A0324BB45749.jpeg

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8 hours ago, VDS said:

Any perspective on the SIT 3 sound? I have 402’s with HF powered by F3, wondering about the sound signature of other First Watts.

thanks, Ted

I haven’t any personal experience with the F3 other than great reviews, so I can not objectively compare it with the SIT 3. 

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I have the F3 and it is a fine sounding amplifier using a small power J-fet (LU1014). Never heard an F8 but it uses a larger SemiSouth R100 power J-fets which has become the best selling Firstwatt amplifier. The SIT amplifiers use a different type of transistor which Nelson had built of which only he has or rather had. He had one production run done by SemiSouth before they went out of business. SIT's are fast. The reason they were built was for military purposes, radar etc. Generally not available for the general public. 

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