Fi 2A3 Amps

[neo33]

Kelly, do they worth the price? Have you listen to them? Tell me about their sonics compare to the Moondogs.

[Erik Mandaville]

I tell you, Neo, if those amps sound as good as they look, they would be really nice!

I know you have your heart set on a pair of Moondogs, but the Moondog circuit is actually pretty common and straightforward. There are other excellent options, including the pair of Fi-X shown here.

There is no rush with this; take your time and learn as much as you can, which is exactly what you're doing.

[jazman]

Erik,

I think the monoblocks are called just "FI". The FI-X is the integreted with the "X" like construction and he makes the FI-Y preamp. Here's an FI-X;

http://cgi.audiogon.com/cgi-bin/cl.pl?ampstube&1075150852.

I've spoken with Don and he's a brilliant, but low profile person. He builds limited numbers of his amps and preamps because he is a devoted family person which requires a lot of his time.

Klipsch out.

[neo33]

Eric, I know SET circuits are pretty straightforward. What I am going after is the OPTs. They are, to me, the single most important components not just in SET amps but also any type of tube amps.

[Erik Mandaville]

Ok...

I'm in agreement with that, and was just trying to help. I would submit that some SET designs are more straightforward than others, however. I'm working on a project right now that is combining what I think to be the best of the DRDs and JFL's Horus parafeed; and I think this combination is a little less straightforward than the Moondogs.

My point, is that there is nothing really very unusual about the Moondogs, but they are good SET amps. There have been instances where certain modifications have brought them to perhaps a higher level of perforance. I'm not just talking about swapping out coupling capacitors, although I loved the Jensen PIOs when I had Edster's Moondogs here for repair -- as well as LoneStarBlues Moondogs. A very well received gift of four brand new Jensen's came my way, and they are great capacitors -- liquid, detailed, musically very rich. 'Tender-crisp' might be one way to describe their sonic character!

OPTs are obviously very important, but it would be good to consider the circuit to which they are coupled, as well. An outstanding OPT is not going to make a less than good amp circuit any better. All aspects of the design need to be considered, not just the quality of the hunk of metal that help make better friends of output tubes and speakers.

All the designs you have looked at and are considering have been among the best available for the money.

If for whatever reason you can't acquire a pair of Moondogs, I would say that Welborne's DRDs are an incredible buy!

[neo33]

"I would submit that some SET designs are more straightforward than others"

What about SET circuits that have very short signal path without passive components (i.e. no coupling capacitors and inter-stage trannies)? The sonics on this type of circuits with good OPTs can be a marvel.

[J M O N]

As I mentioned in another post I made shortly after originally starting this thread, I was able to stumble across a Fi X and jumped on it. As Mobile mentioned, Fi products don't come up for sale on the used market very often. The first one I found sold within a day. The second one I found also sold within a day (to me). The amp that I have is just the power amp (not integrated as the one mentioned in the Audiogon ad above). It does have the Magnequest transformers option.

Just recently, I made another SET purchase -- a pair of Wright 3.5 monoblocks. At some point in time, I should be able to compare the Fi to the Wrights. However that is not possible yet as the Fi is in Michigan and the Wrights are in Texas. I also don't think I can fairly judge the Fi as the only speakers I have in Michigan are not exactly compatible with low power SET's. However, I can say I have heard some nice sound out of them, and they can produce more volume than I would have thought possible with the speakers I have. On the other hand, I have Khorns to use with the Wrights, but I have had very, very little time to audition them since I got them. Bu I have also heard some very nice sound with them as well. In both instances, I can't fairly pass judgment on either amps at this point in time. Hopefully, I'll be able to audition both at length under equal conditions soon.

[mobile homeless]

I am still more of a monoblock believer with SET amps although I know Jeff and I have argued this as well. It is possible to make a stereo amp with a good PS that overcomes some of the problems. On the other hand, I still think the totally dedicated PS with it's own power transformer and rectification etc still provides the best framework. Not to say that some good stereo amps dont exist. I just prefer the monoblock solution for the reasons suggested.

I have had monoblocks as an amp option since about 1984 or so. The big difference is they started out at 200w and moved to a whopping 3.5w.

On the cap or direct coupled issue (and what about transformer coupled)... Well, I think a good circuit is the sum of its parts and the way they work together. Just like a great push pull amp with many, many more parts count can sometimes sound much better than a poorly executed amp with the less is more goal. Less does not always mean better although I found that it's damn good start in many instances. IF one can design something that makes sense with less parts, then there is reward. Then again, I have heard some very simple amps miss the boat in the musicality department. And I have heard amazingly transparent amps that failed to grab me emotionally. I think there is a lot going on in amplifier design.

While doing a few things with my 2A3 amps today, I listened to my little EICO HF-81 since it was coming up in discussion. And I enjoyed the hell out of it, just as much as my 2A3 monoblocks if just counting pure enjoyment of listening to music, just from a slightly different vantage point.

kh

[neo33]

Kelly, you haven't given me an opinion on the said Fi 2A3 monoblocks.

[Erik Mandaville]

The circuit you described, Neo, is exactly what I'm building. You are talking about direct coupling, which is what is used on the DRD amps -- more accurately, the DRDs are a combination of direct and interstage coupling.

I built the Horus amps, which use two coupling capaictors in the signal path between input/driver/output.

The modification I'm making on the Horus uses a different input tube (6N1P), with its cathode, plate, and grid sections paralleled for low output drive impedance. In other words, although I think Jensens are really good coupling capacitors, the recent experience I had constructing and listening to the DRD 2A3s suggests that no coupling capacitors may in fact be (subejctively) better than good ones. I already have the DRD ultrapath output built into the Horus (which Jeff also didn't use on the original version). This helps provide immunity from power supply, and decouples the audio from the PSU, effectively removing all electrolytic caps from the signal path.

I'm in the building of building the EXACT design you just described.

I'll say it again: I strongly encourage you to ponder a DRD from Welborne Labs. It incorporates technology that few, if any, of the other amplifiers you've looked at use. And it is an extremely good value for the money. If you are under the impression that Electra Print transformers aren't very good, that impression might be reconsidered. You could also substitute for MagneQuest sometime down the road, if desired.

Gotta get to school....