Passlab vs LTA ZOTL MZ3 Preamp for First Watt SIT-3

longinc

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Hello,

I have Nelson Pass's First Watt SIT-3 power amplifier. I am using a ~15 year old VAC (Valve Amplification Company) Standard Preamplifier using NOS Telefunken 12AU7 and 12AX7 tubes for the 2 stages. I am looking to upgrade the preamp and am considering the Passlab XP-12 or the Linear Tube Audio MicroZotl MZ3 preamp. My impression is that both preamps are fairly popular when pairing with First Watt amps. Anyone have paired both these preamps with the SIT-3 and can provide impressions that might help me in deciding? Thanks in advance for any advice.

Andrew
 

jeffrey_t

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Andrew,
Although I have not tried either preamps with my SIT-3, I can say that the Lamm LL2.1 Deluxe preamp is a wonderful match with the SIT-3 and I'm getting excellent sound. My friend Keith is going to bring by his LTA preamp in a few weeks to demo with the SIT-3 as well. I'll report back after I hear the combo.

Jeff
 
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longinc

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Andrew,
Although I have not tried either preamps with my SIT-3, I can say that the Lamm LL2.1 Deluxe preamp is a wonderful match with the SIT-3 and I'm getting excellent sound. My friend Keith is going to bring by his LTA preamp in a few weeks to demo with the SIT-3 as well. I'll report back after I hear the combo.

Jeff

@jeffrey_t thanks! Can't wait to hear your impressions of how the LTA compares to your Lamm preamp. out of curiosity, did you consider any of the other first watt or passlab power amps before settling on the SIT3? If you did, how did they compare to the SIT-3?
 

jeffrey_t

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I've had a lot of pass products, I'm a big fan of the brand.

-X350.5
-XA30.5
-First Watt J2
-First Watt SIT Monos

The Pass amps and the J2 are really good, warm and engaging SS amps. The SIT mono's were special, they had a more holographic sound than any SS amp I've owned, almost tube like. The SIT-3 is on an entirely different level than any SS amp I've ever had. It has the texture and midrange bloom of a tube amp in my opinion. It's a keeper for life.
 

longinc

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I've had a lot of pass products, I'm a big fan of the brand.

-X350.5
-XA30.5
-First Watt J2
-First Watt SIT Monos

The Pass amps and the J2 are really good, warm and engaging SS amps. The SIT mono's were special, they had a more holographic sound than any SS amp I've owned, almost tube like. The SIT-3 is on an entirely different level than any SS amp I've ever had. It has the texture and midrange bloom of a tube amp in my opinion. It's a keeper for life.
Thanks @jeffrey_t for sharing your experience. Super insightful. I had a chance to compare the Aesthetix Atlas tube/SS hybrid power amp and the SIT-3 for an extended period of time at my home. I kept going back to the SIT-3. The Aesthetix had more of that tube harmonic richness - pleasant to the ears, but felt thick and slow. I just love the transparency, timbral accuracy and strong presence of the SIT-3. That said, my Chapman T7 speakers are a 4 ohm 89db set of speakers (loudness is not an issue since i don't listen loud) - although it sounds wonderful with the SIT-3 and the T7 are very neutral/accurate/transparent, but I have this nagging feeling that it's a tough load (4 ohm) for the SIT-3. Have you a preferred speaker (or know of any speaker) that pairs really well with the SIT-3?
 
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jeffrey_t

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Thanks @jeffrey_t for sharing your experience. Super insightful. I had a chance to compare the Aesthetix Atlas tube/SS hybrid power amp and the SIT-3 for an extended period of time at my home. I kept going back to the SIT-3. The Aesthetix had more of that tube harmonic richness - pleasant to the ears, but felt thick and slow. I just love the transparency, timbral accuracy and strong presence of the SIT-3. That said, my Chapman T7 speakers are a 4 ohm 89db set of speakers (loudness is not an issue since i don't listen loud) - although it sounds wonderful with the SIT-3 and the T7 are very neutral/accurate/transparent, but I have this nagging feeling that it's a tough load (4 ohm) for the SIT-3. Have you a preferred speaker (or know of any speaker) that pairs really well with the SIT-3?
I went back and forth with Nelson Pass on email regarding the amp. He said that the SIT-3 actually seems to perform very well on a 4 ohm load. My speakers are 4 ohm and there are zero issues.
 
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Sablon Audio

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@longinc - I recommend you speak with Reno hifi as they are a big seller of Pass / FW and should be well placed to advise you.
 

Mikem53

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Oct 1, 2020
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Hello,

I have Nelson Pass's First Watt SIT-3 power amplifier. I am using a ~15 year old VAC (Valve Amplification Company) Standard Preamplifier using NOS Telefunken 12AU7 and 12AX7 tubes for the 2 stages. I am looking to upgrade the preamp and am considering the Passlab XP-12 or the Linear Tube Audio MicroZotl MZ3 preamp. My impression is that both preamps are fairly popular when pairing with First Watt amps. Anyone have paired both these preamps with the SIT-3 and can provide impressions that might help me in deciding? Thanks in advance for any advice.

Andrew
I have the SIT3 paired with the XP12, today is one week since I received the SIT3.
They work well together, the SIT3 needs more volume than most to reach same listening levels, but the XP12 does the job no problem. They Sound very “musical” together. Quite pleased so far..
 

longinc

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I have the SIT3 paired with the XP12, today is one week since I received the SIT3.
They work well together, the SIT3 needs more volume than most to reach same listening levels, but the XP12 does the job no problem. They Sound very “musical” together. Quite pleased so far..
Thanks @Mikem53 for the insight. I notice you are using the Daedalus Athena V2 speakers. Those speakers are 95db sensitive. Are you finding yourself having to turn the volumn knob on the XP12 past 12noon? (my speakers are only 89db efficient).
 
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Mikem53

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Thanks @Mikem53 for the insight. I notice you are using the Daedalus Athena V2 speakers. Those speakers are 95db sensitive. Are you finding yourself having to turn the volumn knob on the XP12 past 12noon? (my speakers are only 89db efficient).
I am using about 10db more gain from the preamp to get the same level of volume I was getting with the XA25. My preamp works in 1db increment, 0-99. 89db is unity gain, all attenuation under that setting.
my room is 19’ x 28 x 13H wide open to other areas. I’d listen anywhere from about 68 to 80db on the dial.
Depending on recording level and music type. More than comfortably loud and there’s plenty left. Hope that helps. From what I’ve read the sit3 prefers a 4ohm load. You would have to take your room size and music type, loudness,etc Into consideration. For normal listening, I think you would be fine. You can tell this amp is built on the typical pass type power supply which is beefy and underrated. The XA25 Has more weight and heft when pushed, a trade off for midrange purity and SET like presentation.
 

KeithR

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the SIT-3 is optimal "between 4-8 ohms" according to Nelson's white paper. the issue is high impedances like AG, Zu Druid, Devore O etc. where it's been well discussed that you need resistors to bring it down. it actually measures less than specified - 8 watts/17 watts with 1% distortion and has increasing distortion with wattage like SET, so you really want to run it on high efficiency speakers that only use a few watts.

meanwhile, the XA25 is class A 25/50 watts (80/130 measured, much higher than spec) but then 100 watts Class A/B into 2 ohms I believe. it still will perform into lower impedance better, but not ideal. for fun, I popped it on my YGs and while it was soft due to sensitivity mismatch, just felt it died south of 200hz (where YG gets down to 3ohms).
 
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longinc

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I am using about 10db more gain from the preamp to get the same level of volume I was getting with the XA25. My preamp works in 1db increment, 0-99. 89db is unity gain, all attenuation under that setting.
my room is 19’ x 28 x 13H wide open to other areas. I’d listen anywhere from about 68 to 80db on the dial.
Depending on recording level and music type. More than comfortably loud and there’s plenty left. Hope that helps. From what I’ve read the sit3 prefers a 4ohm load. You would have to take your room size and music type, loudness,etc Into consideration. For normal listening, I think you would be fine. You can tell this amp is built on the typical pass type power supply which is beefy and underrated. The XA25 Has more weight and heft when pushed, a trade off for midrange purity and SET like presentation.
Thanks again for sharing @Mikem53 !
 
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longinc

New Member
Nov 27, 2020
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the SIT-3 is optimal "between 4-8 ohms" according to Nelson's white paper. the issue is high impedances like AG, Zu Druid, Devore O etc. where it's been well discussed that you need resistors to bring it down. it actually measures less than specified - 8 watts/17 watts with 1% distortion and has increasing distortion with wattage like SET, so you really want to run it on high efficiency speakers that only use a few watts.

meanwhile, the XA25 is class A 25/50 watts (80/130 measured, much higher than spec) but then 100 watts Class A/B into 2 ohms I believe. it still will perform into lower impedance better, but not ideal. for fun, I popped it on my YGs and while it was soft due to sensitivity mismatch, just felt it died south of 200hz (where YG gets down to 3ohms).
Thanks @KeithR !
 

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