First Watt F8, passive preamp, DAC


The F8 is comparable to other First Watt amps in terms of wattage but the gain is only 15db. The Stereophile review says to be wary of using it with a DAC volume control and presumably a passive pre. Can anyone speak from experience? My speakers are Devore, 91db, 8 ohms, and I would like to control the F8 with my DAC. 

rfprice
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@johnk 

Yes, I definitely see the wisdom in that approach.  I heard a loaned Nelson Pass D.I.Y. First Watt S.I.T. Paired with my Coincident Statement Line stage (101D tubes) and it was exceptionally good sounding. I do understand that the goal per topic is however  DAC direct to amplifier.

Charles 

I have owned a good num of First Watt amplifiers I have had great synergy running high output tube preamps with them.

@charles1dad 

Agreed, the F8 isn't going to cut it. Besides, I want an amp that's going to drive the speakers well, not just adequately.

 

How about a Valvet E2/E3? Those are rated only 12w and 21 db gain, and supposedly are very powerful. Still, the 1.4 vrms would be a concern. 

 

I've only had a single opportunity to try the volume output on the DAC. I fed it through the HT bypass on my integrated. The result was poor, both in power and sound quality, but this one test doesn't really prove anything. Still, a DAC as preamp will typically have more noise than a dedicated pre or integrated, right? 

As I type I am running the same DAC with the volume at about 1:00 (so roughly 1.0V output?) into my preamp at 14db gain into the SIT-3 with 11.5 db of gain.  1V output with 25.5db of gain is plenty on my 94db speakers.  I typically listen around 83-84db average, so pretty loud.

The OP's scenario could "possibly" work BUT...

System gain is still 10 db less than yours. Not insignificant.

DAC voltage is 1.44 vs 1.8.

His speakers are 3 db less sensitivity than your 94 db.

Perhaps cutting it a bit close it seems.

Charles

 

 

Personally I’d go with an integrated as needing a DAC with a good volume control will reduce your DAC choices quite a bit.  Just my $0.02 FWIW.  Best of luck. 

As another data point, I ran my Pass Labs DAC (about 1.8V max output unbalanced) into my SIT-2 (18db gain) into 94db efficent speakers with no gain issues whatsoever.  

As I type I am running the same DAC with the volume at about 1:00 (so roughly 1.0V output?) into my preamp at 14db gain into the SIT-3 with 11.5 db of gain.  1V output with 25.5db of gain is plenty on my 94db speakers.  I typically listen around 83-84db average, so pretty loud.

 

The J2 would be a better option because it has balanced inputs, and if you run balanced interconnects from your DS DAC you will double the output voltage to 2.8V.

OK, the F8 isn't going to work. How about the J2 with 20 db gain? Do you think 20 db is sufficient?  don't want to get a preamp. My new mission is consolidation. I may need to either stick with integrateds or find speakers with higher efficiency. Frankly, the Super 9s are too big for my room anyway. 

1 Speakers are 91 db sensitivity.

2 Amplifier has 15 db of gain.

3 No use of an active preamp.

4 Desire to use DAC with volume control direct to amp.

5 Definitely a high voltage output DAC is required. With this scenario probably at least 4 to 5 volts or higher.

Charles

i believe the chord hugo tt2 has a high output voltage, and remote control of it as well, so it can run straight into the amp, low gain or not...

1.44v is pretty low.  Most DACs output 2v and higher. With that low voltage coupled with a low gain amplifier, unless your speakers are high sensitivity, you’ll likely need an active preamp to provide additional gain.

Charles

The DAC output is 100 ohm unbalanced, 200 ohm balanced. I guess that's pretty good. 

Those specifications (In ohms) are referring to the output impedance. What is the output "voltage" of your DAC?

The DAC output is 100 ohm unbalanced, 200 ohm balanced. I guess that's pretty good. 

I think you should be ok with digital, do you know the output of your DAC?

I have run a DAC directly into a SIT-2 which is 18db of gain and it worked great.  Running the same DAC into a SIT-3 with only 11.5 of gain was also fine, although I did run out of headroom on some CDs with really low peak levels.  But even inserting my Pass X2.5 preamp with only 4 db of gain fixed that minor issue.

I’ve run an F5 and a J2 with a passive pre. Speakers are, Graham Chartwell LS3/5,Nola Boxer 2, and Hornshoppe Great Horned Heils.  For the type of listening I do,and the small size of my listening rooms, this combo works well for me.