FirstWatt SIT-3

Mike

Mike

Audioshark
Staff member
Joined
Apr 2, 2013
Messages
30,488
Location
Sarasota, FL
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They’re starting to arrive...

7 more to go. If you purchased one from me, I will be shipping them in order that they come in. All are spoken for, but I MIGHT have one additional one I can get.


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PeterA said:
How do they sound Mike? Please tell us something about them.
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VERY SET like. Does not sound at all like SS. Needs a high gain preamp. Isn’t the last word in dynamics and slam, but super sweet sounding. No solid state artifacts. Overall, a superb amp on the right speakers. It MIGHT be 10 watts. On 18 ohm speakers m, that’s down to maybe 3-4 watts, so it seems way less powerful than my 300b SET amp.


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Mike said:
VERY SET like. Does not sound at all like SS. Needs a high gain preamp. Isn’t the last word in dynamics and slam, but super sweet sounding. No solid state artifacts. Overall, a superb amp on the right speakers. It MIGHT be 10 watts. On 18 ohm speakers m, that’s down to maybe 3-4 watts, so it seems way less powerful than my 300b SET amp. Sent from my iPhone using Tapatalk
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What is the 300B you are comparing it with - Is the SIT 3 sold out....
 
I just read the review. He seemed to love the sound, and of course believes Nelson is a genius. However half the review, or more, was discussing the difficulty with matching speakers. Impedence was the huge issue, not so much power... some bass concerns. He was also very concerned about only 400 are going to be made. This tells me the amplifier is probably sold out by the time we are reading his review.
 
Randy Myers said:
I just read the review. He seemed to love the sound, and of course believes Nelson is a genius. However half the review, or more, was discussing the difficulty with matching speakers. Impedence was the huge issue, nit so much power... some bass concerns. He was also very concerned about only 400 are going to be made. This tells me the amplifier is probably sold out by the time we are reading his review
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400? In my dreams. Try 65-75. I have 13 on order. Only received 5.

As for speaker matching, you just need some relatively efficient speakers (93 or above I would say). The tricky part for the amp is handling a high impedance speaker like mine. Go figure that one out. Anyway, it’s nothing a couple of resistors can’t fix. (Thanks to Rick who works with me for putting these little resistors together with the banana speaker terminal adaptors).

How’s the amp? Freaking incredible.

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Yea, that is what the reviewer said. One of the speaker companies had him make a resistor sort of like what you have done! It was not so much the efficiency, he had a 101db speaker give him issues, but it worked fantastic with Maggies... said 88db or above but 8 or 4 ohm speakers.

I would love one. I really liked the F6 I had :)...
 
Randy Myers said:
Yea, that is what the reviewer said. One of the speaker companies had him make a resistor sort of like what you have done! It was not so much the efficiency, he had a 101db speaker give him issues, but it worked fantastic with Maggies... said 88db or above but 8 or 4 ohm speakers.

I would love one. I really liked the F6 I had :)...
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If you use the resistor, it works great. The amp sees a 18ohm load as 8ohm. Most amps like higher impedances. Strange. Not this one.


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I'm in the UK and have a SIT-3 driving an older pair of Avantgarde Duo Omegas (17Ω). The SIT-3 has been a bit disappointing compared to my Yamamoto SET because it is less dynamic, an issue I didn't notice with the SIT-2. I was not aware of this impedance issue, I'll search out a copy of Stereophile today.

Mike, it looks like you are using 15Ω resistors in parallel with the speakers. What is the wattage rating and type please? I can obtain locally some 20W Mundorf M-Resist Supreme resistors in 15Ω or 18Ω.

Thanks in anticipation.

John T
 
I do wish they could come up with a way of building more. I understand the main issue is the supplier of the one main part (the SIT something or another) went belly up :(....
 
Montage said:
I'm in the UK and have a SIT-3 driving an older pair of Avantgarde Duo Omegas (17Ω). The SIT-3 has been a bit disappointing compared to my Yamamoto SET because it is less dynamic, an issue I didn't notice with the SIT-2. I was not aware of this impedance issue, I'll search out a copy of Stereophile today.

Mike, it looks like you are using 15Ω resistors in parallel with the speakers. What is the wattage rating and type please? I can obtain locally some 20W Mundorf M-Resist Supreme resistors in 15Ω or 18Ω.

Thanks in anticipation.

John T
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Hi John,

I’m using a 12 ohm resistor across each amp terminal which brings me down to just under 8 ohms.

To me and my taste, it’s a glorious amp. I absolutely love it. I have Duo XD.

Use this calculator to figure out the actual resistance.

https://www.allaboutcircuits.com/tools/parallel-resistance-calculator/
 
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Montage said:
I'm in the UK and have a SIT-3 driving an older pair of Avantgarde Duo Omegas (17Ω). The SIT-3 has been a bit disappointing compared to my Yamamoto SET because it is less dynamic, an issue I didn't notice with the SIT-2. I was not aware of this impedance issue, I'll search out a copy of Stereophile today.

Mike, it looks like you are using 15Ω resistors in parallel with the speakers. What is the wattage rating and type please? I can obtain locally some 20W Mundorf M-Resist Supreme resistors in 15Ω or 18Ω.

Thanks in anticipation.

John T
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Hi John - welcome. The 15ohm resistor works beautifully. I like the SIT-3 with a tube preamp.


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Montage said:
I'm in the UK and have a SIT-3 driving an older pair of Avantgarde Duo Omegas (17Ω). The SIT-3 has been a bit disappointing compared to my Yamamoto SET because it is less dynamic, an issue I didn't notice with the SIT-2. I was not aware of this impedance issue, I'll search out a copy of Stereophile today.

Mike, it looks like you are using 15Ω resistors in parallel with the speakers. What is the wattage rating and type please? I can obtain locally some 20W Mundorf M-Resist Supreme resistors in 15Ω or 18Ω.

Thanks in anticipation.

John T
Click to expand...

In one of the online reviews of the SIT-3 Nelson mentions this amp is not good for speakers over 8 ohm. He sussgests adding resistors as Mike has. I’d point you to it but I don’t remember where it was.
 
Thanks for all your replies. Unfortunately the Feb. edition of Stereophile with the SIT-3 review has not reached my locality yet. However, I found the review kindly pointed out by Vortrex; it was by Steve Guttenberg on CNET. He exchanged emails with Nelson Pass, who explained that 'the SIT 3 sounds best with 4 to 8Ω speakers, and the Soul Supreme is one of the rare high-impedance 16Ω speakers.' He then suggested hooking up a 16Ω resistor in parallel with the speakers.

Accordingly I've ordered a couple of 15Ω 20W resistors for my 18Ω Duo's (not 17Ω as I said previously) which should bring the nominal impedance down to about 8Ω. I'm keen to hear their effect next week. The SIT-3 is driven by a Lampizator Pacific, alternating with 300B and 45 power tubes, so there are still some tubes in the signal path!

John T
 
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