Help needed

Paul_Bui · « **on:** 22 Dec 2004, 07:23 pm »

Hi John and everyone,

I've just got a FirstWatt F1 amp to drive my new 90db FTA2000 single driver speakers. While the volume is loud enough for 90% of my listening, sometimes I feel I could use some gain to have the system really sing out loud. Currently the built in volume control of the Shanling SCD-T200 is taking care of the task.

So, that leads me to thinking of getting a most simple 2 channel transformer based pre-amp. The F1 has XLR/RCA inputs, but the CDP outputs are just RCA type. Should I look into a NOH or a TX102, or are they essentially the same?

Thanks in advance for any thoughts and advice.

Paul

Bemopti123 · « **Reply #1 on:** 22 Dec 2004, 10:06 pm »

built around the Fostex F200A?

If this is the case, how does it sound with the 10 watts the First Watt provides? You do not think it is underpowered for what I can read, you just want more gain?

I have a 10 watt battery powered op chip amp that can put out 17 watts at clipping and I wonder how would it sound with around 10 watts +- in solid state terms.

BTW, I am running this amp with a preamp that gives me tons of gain....active, but at the same time passive in design.

Doc Jr 8156 · « **Reply #2 on:** 22 Dec 2004, 11:34 pm »

Paul,

The NOH is essentially 2 TX102s dressed-up. Depending on the wiring, the Tx 102 can provide up to 6db of gain. The downside however is that, like other owners of NOH concurred, the NOH (Tx 102) sounds better without the gain. I have the FX 200A in a Bob Brines design cabinet and its awesome! I'm powering mine with a 150 watt SS amp right now. I also alternately been using my El-34 based tube amp rated at 35 watts and a MAC amp at 40 watts. I'm not familiar with the First Watt amp but in my experience with the FX 200A, using my 12-watt Scott 222c and my 8-watt 300B SET, the more watts the better the sound. In short, I don't think that with the sensitivity of the FX 200A with or without BSC that 10 watts can really drive them. YMMV. Godspeed.

Paul_Bui · « **Reply #3 on:** 23 Dec 2004, 03:02 am »

Bemopti123,

The FTA2000s (F200A driver)/F1 is a very special combo that I would never call it underpowered. What I meant was, sometimes there are recordings recorded at really low level that I needed to turn the CDP all the way up to get a loud enough volume. I think I need a good preamp with some gain to bring the F1 up to its max output (just like the TORII needs 3 volts to get its full output). Otherwise, for the sake of a purist approach, most of my CDs sound fantastically good (or bad) on the combo, due to its high resolution.

Doc Jr 8156,

Glad you also enjoy BB's FTA2000s. In my moderately large room (24 X 16 X 9) and with my listening distance (10' - 12' from speakers, against the front wall) I feel satisfied most of the times. JLM used the 12w TORII to drive the same speakers to very loud volume level, and I don't see how the 10w F1 can't do the same with authority.

Thank you both for the inputs. Looks like I need an active ( tube?) preamp that gives the F1/FTA2000s some more juice WHEN necessary. It will really be icing on a cake, as I am happy with the way they both are breaking in now.

John Chapman · « **Reply #4 on:** 23 Dec 2004, 01:59 pm »

Hello!

Those firstwatt amps are a really neat design. Some good thinking there. I think you already have your answer but wanted to reply in any case.

If you need a bit above unity gain from time to time then a tx102 wired with a gain select switch might do the trick. The +6 mode works pretty well if your source is a fairly low output impedance. The lowering of output impedance as you turn a tx102 down in level (a good think and one of the benifits of a tvc) is reversed as you start to use it for stepping up the voltage to get some gain. This is why we chose +6db as the top of the gain 'mode'. Much above that and the increase in impedance would be quite pronounced.

If you need more than a bit-o-gain from time to time then you'll be best to get an active stage in there somewhere.

Thanks!

John

flocchini · « **Reply #5 on:** 23 Dec 2004, 04:33 pm »

Hi All:

When I was setting up my TVC I wasn't sure of what would happen because of long interconnects (5.5m) and the "strength" of my sources (Borbely DAC and Hagermat Cornet2) so I wired through a switch which after the transformers either went to the amps directly or through my 20dB gain Borbely linestage. After listening for 3 weeks or so I concluded that I didn't need the extra amplification. The linestage is now dedicated as a balanced headphone amp although if necessary I can switch it back in. As an aside my speakers are 96dB/W and the amps are AKSA 55s.
Hope this helps.

Bob

Paul_Bui · « **Reply #6 on:** 23 Dec 2004, 05:09 pm »

Quote from: John Chapman

Hello!

If you need a bit above unity gain from time to time then a tx102 wired with a gain select switch might do the trick. The +6 mode works pretty well if your source is a fairly low output impedance. The lowering of output impedance as you turn a tx102 down in level (a good think and one of the benifits of a tvc) is reversed as you start to use it for step ...

Hi John,

Thanks for the response. Please let me know more specifics about the above configuration, in which I might be inrerested. My source is a Shanling SCD-T200 Mod 1 by Underwood. I hope its output impedance is low enough for the purpose.

Paul

John Chapman · « **Reply #7 on:** 23 Dec 2004, 09:55 pm »

Hello!

I can not offer a finished product right now - I am in-between preamps and am working on a new revision. Same tx103 MK III transformer though so all these impedance and gain issues are the same for it and any other tx102 based pre-amp for that matter. If it looks like a go I can point you to options for finished products availiable now.

I am not able to spot an output impedance spec for that player. If you could find out what it is then report back that would tell if a TVC (or any passive device) can likely work well in your system.

Thanks!

John