I am going to second the excellent advice of the above poster and head you in the direction of an SP14, which uses 6SN7 octal tubes in its gain stage. It will be a bargain if you can build it yourself. I have a long term relationship with Don Sachs, who has taken the excellent SP14 and upgraded it with better volume pots, caps and other tweaks, and this version of the preamp, which cost about $1600-$1800, is the heart of my system. Insanely fine for the price, the pinnacle of preamps I have had for 45 years in my system.
Don's preamp recently compared favorable with my my audio friend's $10K ARC tube preamp in a comparison. I also have a stock SP14 with a Clarity cap upgrade, I would say that the stock SP14 is outstanding in every way, but Don's preamp is 50% better. I personally am of the opinion that a Don Sachs preamp and a great SS amp is your pathway to audio nirvana. I recently got a McCormack DNA .05 ss amp and with Don's preamp and my Spatial Audio Hologram M4 Turbo S speakers, I have never been so happy with the sound of my system. Good luck |
Build the tubes4hifi SP14 kit at under $1000 and get something to compete with those $7000 tube wonders. Totally killer. http://tubes4hifi.com/pre11.htm#SP14For a modest amount more, they'll build it for you. |
My Manley Shrimp ($1000 used) is a good match for my First Watt F7, but I would love to try a Linear Tube Audio microZOTL 2.0 as a linestage ($1100 new) as many have given it high praise for its tonal character and flexibility.
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Another possibility is a different form of passive that employs a transformer volume control. Instead of attenuating by burning off the signal in a resistor, transformer volume controls (TVC) attenuate by converting voltage to current. At lower volume levels (lower voltage and higher current), the sound seems to have more drive and vibrancy (passives tend to sound just a bit dull dynamically). To me, most TVCs are not very practical because they are stepped attenuators with too large a volume change between steps, and most are not remotely controllable. But, there are a few exceptions. MyEmia sells TVCs made by Dave Slagle that employ autoformers. While not cheap, these offer 1 db steps and are remotely controllable. Also, they offer 7 db of gain (again converting current to volume), which might be enough gain to cure your problem. I would contact Dave Slagle at MyEmia or at his own site Intactaudio.com (a supplier to the DIY crowd). He probably can offer ideas even if his stuff might not be your solution. |
Light speed atenuator.... |
First Watt specifies the input impedance at 100k ohms, but does not give a sensitivity number.
The manual for the J2 indicates a sensitivity of 1.4 volts for full power, and a gain of 20 db. 20 db of power amp gain is relatively low. For example many of the Pass Labs amps are spec'd at 26 db, and many others from other manufacturers are higher. Best regards, -- Al |
Thanks, Larry. Yes, I have plenty of gain with my DAC/CDP so the gain issue is definitely with the phono stage. My passive is a very good build using top quality parts, so I agree that going to a lesser active pre may not be advisable, even though it would solve my gain issue. It's looking like my best bet may be to buy/build a SUT tailored to my Rondo Blue, and replace my Coph Nia with a good quality MM phono stage. |
Tom,
First Watt specifies the input impedance at 100k ohms, but does not give a sensitivity number. When you play CDs, you achieve adequate volume without the amp distorting? If that is the case, then you do indeed need more gain from your linestage or from the phono preamp. If the phono stage does not have a MM input, putting a step up transformer in front of the phonostage might not work because even a modest amount of gain might cause overload problems. An active stage with modest amount of gain probably is the answer, but, it would be hard to find something in your stated price range that would compare with a well done passive.
As for an alternative phonostage, most MC phonostages deliver, at most, 60-66 db of gain, and if your phonostage delivers 60 db of gain and it is notably inadequate, you are probably looking for at least 66 db of gain or more. The alternative is a phonostage with MM input and then using a high gain step up transformer to get you more than the 60 db of gain from your current stage. A friend of mine had a J2, which I got to use in my system for about two weeks. It is a very good amplifier. |
A $450 solution you might want to consider would be to put an Antique Sound Lab Line Two DT between your passive preamp and the amp. It can be calculated from its specs that with its volume control at max (which would presumably eliminate any sonic effects of the control itself) it would provide a gain of 22.5 db. As you can see at the link it has specified impedances of 100K in and 1K out. While I wouldn’t be surprised if the output impedance rises to perhaps 3K or 4K at deep bass frequencies, that shouldn’t be a problem working into the 100K input impedance of the amp. Several years ago I used its predecessor model, the Line One, for a few months while my main preamp was down, and it seemed quite transparent, even with the stock 12AU7 tube. It inverts polarity, which of course can be compensated for by reversing the + and - connections to your speakers. Good luck. Regards, -- Al |
10-4. The whole reason I am even considering an active pre is to add some gain when using my phono front end. With the passive in the system with the J2, my Coph Nia (at 60dB gain) and my .4mV or .5mV MC cartridge, I'm at about 90-93dB when the J2 is maxed out. Loud, certainly, but not Led Zeppelin or Pink Floyd loud when the situation demands it. I realize I can go to a SUT and a MM phono section and pick up gain there, or replace the Coph Nia with a MC phono pre with more gain. But the Coph Nia, with it's dual-mono design, is very good sounding, and I think I'd have to pay considerably more to upgrade it. I could also go to a mid-output MC cartridge, but there aren't that many available. So I'm just trying to determine the best path to take by investigating my options. Anyway, I'm not sure the Wyred pre would do what I'm looking for, although I could be wrong about that. The First Watt B1 buffer/passive a similar design, I think? |
I'm not sure if you misread my comments. The Wyred 4 Sound is NOT a passive preamp. It is an active preamp. This is the closest active preamp that I know which keeps the idea (and sonic signature) of a passive preamp, but it adds gain where the signal level and impedance requires it. If you are looking for other active preamps, most will have some sort of sonic signature which adds coloration and changes the sound (which I assume is not what you're looking for). Based on your post, it seems you're looking for the most transparent preamp. |
Thanks, but I'm not looking for another passive. The passive I have now is excellent, but I'm looking to add some gain into my system. |
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There's a Wyred 4 Sound STP-SE on audiogon for $1100. It is designed to act like a passive preamp, but with added gain when the signal level and output impedance requires it. You can research more on the web. Currently, the retail for a new one is $2k. |
