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High Output Preamp for First Watt SIT-3?

I'm new to the audiophile world and recently purchased a First Watt SIT-3 with Magnepan .7s.  I have a Mytek Brooklyn Bridge for streaming, though I prefer to play vinyl with my Mofi Ultradeck.  The Mytek serves as the phono stage (69dB gain for MM?), and I don't use a preamp;  the Brooklyn is connected directly to the First Watt. 

I understand that the SIT-3 is only 11.5 dB of gain, and that's extremely low compared to most amps.  I like most everything about the system except for the fact that I have the Mytek maxed out volume-wise many days.  Certain LPs are cut quieter, and I wish I had more power.  There are times streaming where the Maggies aren't getting to their sweet spot.  I realize the Maggies are a lower sensitivity speaker. 

What should I look for in a preamp to fully drive the SIT-3?  Eventually, I'd like to replace the phono stage instead of relying on the Brooklyn.  Is there a tube preamp featuring a phono stage with sufficient output to drive my amp in the $4k range?  Otherwise, I'm eyeing the Modwright PH 9.0 and a linestage preamp, realizing that this will probably be costlier.  I'm looking for a warm sound, not analytical but engaging. 

Any help is greatly appreciated.  I'm a working musician with a basic understanding of related electronics but little experience in this world. 

murphbass
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almarg
9,670 posts
 
Hi Jose ( @jg2077 ),

No, I don’t see a Speltz autoformer as being helpful in this situation. As you most likely realize it is mainly useful where it is desirable for an amp to be presented with a higher load impedance than the speaker would present by itself.  But in this case, where maximizing the amp’s power capability is particularly important, the maximum power capability of the amp into an 8 ohm load is considerably less (18 watts) than its capability into the Maggie’s 4 ohm impedance (30 watts). Also, Maggies present a flatter and therefore more amplifier-friendly impedance curve than many and probably most other speakers having 4 ohm nominal impedances.

The thinking behind my earlier post was motivated by the OP’s statement that ...

I’m at the cusp of where I want to be. Many hotter LPs and digital files sound fantastic. I can coax a bit more streaming a lower level file with Fidelia or my UAD interface.

... coupled with my suspicion that depending on the particular cartridge he is using he may very well not be able to utilize a considerable fraction of the 30 watt capability of the amp when playing many LPs, even with the volume control at max. If so, inserting some additional gain in the signal path, such as with the simple one-tube line stage I cited, may result in performance that is satisfactory for his purposes.

Best regards,

-- Al

br3098
969 posts
 
IMO, sell the ,7s and find a pair or refurbished Quad 57s. That would be magical

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charles1dad
10,229 posts
 
I find it pleasantly surprising that murpbass is getting the good sounding results relatively speaking. I recall from the Stereophile review the S.I.T.-3 put out less than 20 watts into a 4 ohm test load rather than the rated 30 watts. So on paper quite a bad match yet able to yield very good sound in ’some'  listening circumstances per murphbass. Impressive when you really consider the obvious handicap involved.

In my mind an excellent circuit and design execution by the iconic Nelson Pass (no surprise in that regard). Logic dictates that matching with a compatible speaker = sublime sound quality that joeinid alluded to earlier in this thread.
Charles
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almarg
9,670 posts
 
Hi Charles,

The reason for the discrepancy in power capability that you cited relates to the amount of distortion the ratings are based on.

JA's measurements in Stereophile indicated that:

Into 4 ohms (fig.5), the SIT-3 delivered 16.8Wpc (9.24dBW) at 1% THD+N, and 36Wpc (9.55dBW) at 3%.

And in the graph at the bottom of page 10 of the manual for the SIT-3 it can be seen that the amp can provide 30 watts with distortion of about 2.3%. The distortion being "dominated by second harmonic with a “negative phase”, the signature that we have come to prefer with the previous SIT amplifiers." Which would seem to be a relatively benign distortion characteristic.

Best regards,
-- Al
   
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