First Watt to Pass Labs

Larryi,

Yes, as someone with high efficiency speakers, I have certainly found that I prefer amps with lower gain for the volume control reasons you mention. With some higher gain amps I found myself using inline -10dB attenuators.

Now with my Atma-sphere S-30, I can use a jumper from Atma-sphere to bypass one pair of the 6SN7s and reduce gain. One less pair of tubes to replace to boot!

I did read it again, not sure I get your reference though - Larry seems to be referring to issues of gain and input sensitivity. You make a reference to amp impedances and I'm not sure what the relationship is between one and the other - nor do I know that the J2 is in fact any less sensitive than the F3 though it does have much higher input impedance and signifactly more gain (should actually work with a passive and a 2v source, like the B1 for example).

Sensitivity has to do with the magnitude of the input signal (measured in volts/millivolts) needed to achieve full rated output. The F2 requires a fairly hefty signal to reach full output compared with most amps.

This is probably a deliberate design choice. First, it is not so insensitive that the normal output of devices like a CD player would not be adequate. Many owners of extremely high efficiency speakers would welcome being able to crank the volume control past the 7 o'clock position and not have the smallest change in position correspond with huge volume change. The amp is designed for such applications. Also, it may well be the case that not building in "extra" (unneeded) gain in the input/driver stage would have sonic advantages.

I just happen to "need" a bit more gain because my current phono cartridge is quite low in output given the 60 db gain of my phonostage. I don't have noise issues, but, I am nearly out of volume control range when cranking up the volume.

Read his post again. It's the reason I used insensitive in quotes.

Not sure impedance is directly (in any way?) related to
sensitivity.

Larry,
I'm currious that you found the amp "insensitive." It has an imput impedience of 100K which should make it very "sensitive." The F3 on the other hand has very low imput impedience.

Nice writeup, thank you Larry.

I can't compare any First Wattt amp with a Pass amp, but, just yesterday, I borrowed a friend's J2 to try in my system. It is being used to drive 99 db/w speakers with a nominal 8 ohm impedance, so the match seems reasonable.

On a basic, operational level, the J2 is very insensitive (needs higher line level to drive it to a given volume level than most amps). While that should not be an issue in most systems, this may be an issue with passive linestages. Also, it does take a while after turn on to sound its best. It tends to sound a bit dynamically dull, harmonically thin, and lacking in bass until it warms up (the first 5-10 minutes is particularly bad, and it continues to improve over an hour period). The good news, for people with really sensitive speakers, it make absolutely no turn-on or turn-off noise.

I was quite impressed with the overall sound of this amp--it is very clear, fast and dynamic, with only a hint of the kind of artificial "edge" to the initial attack of a note that is common to solid state amps. It does not have the bleached, "dry" sound that also found with some amps (both solid state and tube based). Music from this amp sounds very lively and engaging (very much unlike solid state with a lot of negative feedback, which sounds lifeless and flat).

In comparison to the parallel single-ended triode tube amp I use in my system, the J2 has some shortcoming when it comes to soundstage--it does not develop a huge, enveloping soundstage, and does not quite present the notes as blooming into a large space--the sound is much more directly in front of the listener and contained within the boundaries of the speaker, and the overall ambient "space" seems smaller. The other shortcoming is that it does not present the same kind of "dense" harmonic structure that my tube amps deliver. I don't want to overemphasize the shortcomings because, while apparent in direct comparison, the overall presentation is very musically enjoyable. Also, this comparison is not "fair" because my system has been tuned to my current amps, and these amps are WAY more expensive than the J2s. I will have them for a few more days, and I am sure I will have a lot of fun with them.

If your speakers are 104db efficient and don't have a passive crossover, I would check out the F2J or F1J. F2J is one of the best I have heard in my system. Easily the best solid state.

Very...104.

Jeff1225, your speakers are very sensitive, no?

I'm really enjoying the First Watt J2. I tried out a F3 first and there was an impediance miss match with my preamp (Hovland has a low output).

Mark at Reno Hifi is one of the greatest retailers I've worked with. He shipped me the F3 and then shipped me the J2.

Are the J2 and M2 both designed for similar types of speakers
and the choice would be based on preferred "flavor"
or is one better suited to certain kinds of speakers. Seems
like the J2 power output behaves more like a tube amp (lower
power into 4ohms) and the M2 for like SS (higher power into
4ohm). My speakers are Merlin VSMs which "on paper"
would seem to be well suited to the J2, but I have not heard
either. I have owned the Aleph J and XA30.5 with the Merlins
(smooth, highish impedance, 89db) and they both sounded very
good, but not sure that I did not prefer the J which surprised
me given the price difference at the time (good have been
better compatability with my Joule preamp I owned at the
time). Thoughts?

I would call Reno Hi-Fi and ask. Mark at Reno Hi-Fi owns and has ecperience with high efficiency horns matched to both Pass and First Watt amplifiers

Also, 6 Moons reviewed and compared all the First Watt amps. Check out the site.

I listened to the following Pass amps:

-FW J2
-FW F3
-Pass 350.5

And I have to say the J2 was the best in MY system. For 107 DB, the F3 should be awesome if the output impedience works. My Hovland needed more tan the F3.

Mark at Reno hifi is a great guy. Call him up, and audition a few amps to make your choice.

Great thread. I'm very interested in the First watt amps as well. Luckily, I have 107 db efficient horns and just assumed that the First Watt amps would sound better on efficient loudspeakers. Is that the case? Has anyone actually compared First Watt's offerings to Pass's offerings with efficient loudspeakers? Also, has anyone comapred the First Watt F3 to the new M2? If so, what are the sonic differences?

The First Watt amps ARE very speaker specific, and Pass or Reno Hifi one of their main distributors will be the first to tell you that. If you've low power requirements, i.e., Abby's, or a pair of monitors then sure one can hardly do better than a First Watt amp.

Observing more first generation First Watt first amps on the used market of late I assumed was attributed to the fact that Pass made a major design change with the use of mosfets. I was considering buying a used F1 a month back. An email to Pass requesting the cost for the upgrade received a reply stating Pass isn't even allowing upgrades to those first generation amps until all first generation buyers have had the opportunity to upgrade their amps. In other words, I as a second owner couldn't upgrade the amp. I first thought that's fair, until I observed upgraded first generation First Watt amps available en mass from distributor Reno Hifi. So obviously dealers get the head of the line too. Sonically speaking First Watt matches well with single source driver speakers. But they'll not drive 65% of speakers on the market, hence the reason for distributor's offering a 'buy and try' sales strategy.

I agree with both posts above. I have a J2 that I think is the best amp ive owned. The imaging, detail and articulation are beyond reproach. BUT...I have two other pieces of equipment that mate with the J2:

Hovland HP-100: Needs an amp with high input impedance, the J2 is 100K
Avantgarde: 102DB and horns need little dampening

I went from F5 to XA30.5. In my system F5 sounded more delicate and detailed, but didn't have enough power to drive my Electras. XA30.5 sounds warmer, more dynamic and has excellent bass control.

Although First Watt and PASS labs amps are from the same designer, they are designed with different philosophy. Each First Watt amps are designed with specific purpose. They are not for everyone and for every speaker. You should make sure that your speakers are compatible to the First Watt amp that you want to try. If you find First Watt amp that works well in your system you may never look back again.