Cavalli Audio - Liquid Fire
Jun 12, 2012 at 11:21 AM Post #31 of 148
Quote:
Alex, thanks.  I love my LF, and have no real interest in additional features other than sonic improvements.

X2
 
BTW-no noise and I'm #4
 
Jun 12, 2012 at 1:27 PM Post #32 of 148
Quote:
 
The performance of the LF with the TKD pot seems to be at a very high level. It is hard to say how much improvement, if any, another type of pot would make.
 
I did consider other attenuators and pots and decided that the 2511 was a very good continous pot, made by a company that pioneered carbon plastic pots and sliders for mixer consoles, and would give the right cost/benefit trade for this amp. It is possible to put other pots into the amp, but I have not heard from anyone who may have done this.

Thanks for explaining your approach on this. There seems to be lot of controversy on whether you absolutely need a stepped attenuator for resolved sound, but with stepped ones and higher gain the lower steps needed are just too big for comfort,
so it's good to know that continuous ones are still in the running.
 
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Jun 12, 2012 at 3:00 PM Post #33 of 148
With stepped attenuators I somehow always find my sweet spot to be in between steps. Must be a mental thing.
 
I absolutely loved the fluidity and weighting of the TKD pot (edit: in my LF, forgot to add context)
 
Jun 12, 2012 at 5:05 PM Post #34 of 148
While I prefer the clicks of a stepped control I realize that putting in a 'good enough' (aka one that will actually work for sensitive cans with a high gain amp) is extremely expensive.
 
I agree that the LF's knob has a really nice 'weight' to it that I enjoy. I just want it to sound good either way, and it does.
 
Jun 12, 2012 at 5:39 PM Post #35 of 148
Quote:
While I prefer the clicks of a stepped control I realize that putting in a 'good enough' (aka one that will actually work for sensitive cans with a high gain amp) is extremely expensive.
 

 
The 40 step Acoustic Dimensions stepped attenuator is quite nice and doesn't cost any more than the 23 step DACT's and Goldpoints.
 
http://www.acoustic-dimension.com/attenuators/attenuators-main.htm
 
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Jun 12, 2012 at 5:53 PM Post #36 of 148
Jun 12, 2012 at 6:14 PM Post #37 of 148
Quote:
I meant more along the lines of 100+ steps. Then again maybe those are just unicorns.
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Well, there's a 60 step version. But things start getting a bit unwieldy in terms of size.
 

 
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Jun 12, 2012 at 7:16 PM Post #38 of 148
I also like the volume knob thingy on the LF except maybe its color...
 
Jun 12, 2012 at 9:53 PM Post #39 of 148
Or a 12-step. Oh, wait, that's a program, not an attenuator. Now where did I put that bottle?
 
Quote:
 
The 40 step Acoustic Dimensions stepped attenuator is quite nice and doesn't cost any more than the 23 step DACT's and Goldpoints.
 
http://www.acoustic-dimension.com/attenuators/attenuators-main.htm
 
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Jun 13, 2012 at 7:32 AM Post #41 of 148
My experience with the noise was over a two day (consecutive) period.
My LF had roughly 150 -160 hours on it and my replacement NOS Telefunken tubes around 50 hours at the time.
 
If it wasn't for the fact that I had accidentally tapped my LCD-3's 1/4" headphone jack (while plugged into the Hi-out of the LF),
I would have never heard it.  I didn't tap it hard at all (brushed it with my fingers) and the volume was set low on the LF.
The result was a faint but noticeable sound that sort of reminds me of pinging a bell. This was only observable in the LEFT
channel of my head phones. The right channel stayed quiet.
 
Over the next day or so I found that I could repeat this phenomenon on a consistent basis by literally tapping on the headphone
jack while plugged into the LF.
 
To check that my Telefunken tubes hadn't gone micro-phonic (They were pre-tested to be in good standing by Tubemuseum
- but they are old stock so you never know?), I tapped each tube with an eraser on the end of a pencil.
The results were that none of the four tubes seemed to be overly micro-phonic, but that the one second in from the right
(close to the volume pot) would ring slightly if I tapped it in just the right way. 
 
I then proceeded to gently press on each tube to make sure they were well seated into their sockets (which they seemed to be),
then I swapped the 1/4" headphone jack between the Hi and Lo outs of the LF a few times.
 
I also noticed that one of the RCA jacks on the back of the LF was slightly loose so I tightened it up
 
After this I haven't heard the ringing come back and it has been a week or more now.
Tapping on the headphone jack yields no noise at all.
 
In fact I've been quiet on these forums the past couple of days because I've been sitting back and enjoying the heck out of the Liquid Fire   
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Jun 13, 2012 at 7:43 AM Post #42 of 148
A stepped attenuator would probably solve the LF's channel imbalance at super low volume (nearly 0)
But that's about it.  Some say they sound better than continuous pots, but I think there's a lot at play there...
 
In general I have always preferred the feel of a good quality continuous pot.
 
Jun 13, 2012 at 9:05 AM Post #43 of 148
re the noise issue - I will remove the grounding wire and see if it recurs. I will also, at some point, swap in the Nationals where I originally heard it. If it recurs, I have suitable tube dampers that I will try, in addition to swapping in the original JJ's and/or Gold Lions.
 
And I'll keep you posted.
 
re pre out - I'd love that.
 
re volume pot - prefer smooth, and I also absolutely love the fluidity and weighting of the TKD pot
 
Jun 13, 2012 at 8:53 PM Post #45 of 148
Gents, I promised some background on why the LF is designed the way it is. Here we go.
 
Background
 
I am about to make comments on the case designs of amplifiers. You guys should know that I am probably a bit older than you think. I grew up with tubes. I built lots of tube equipment, from push-pull 6V6 and 6L6 amps to test equipment to high voltage equipment (where I almost killed myself, no joke). I have seen a lot of tube stuff and I have seen many tube amplifiers, including the original Dynacos when they were, well, new.
 
Now before I go further, please realize that I am giving my personal opinions about looks. When I was at RMAF last October (first show where CA was a vendor) I had a chance to meet Ray, Todd, Justin, Jason, Jack, Craig and to say hello to Alex (Audeze) again. Everyone of these individuals was extremely gracious to me and CA.Everyone expressed encouragement for the new venture. I think we're pretty lucky to have these guys, as well as many others, making equipment for us.I appreciate each of their design styles and visions and some of the very cool things that they are doing.
 
But, I have seen sooooo many amps with tubes sticking out of the top plate. So many of them. Some of them really beautiful. I wanted to do something else that brought together some different ideas. Most of you have told me that you really like the LF design. Some of you don't like it much at all. Whether you do or don't, here's why it looks the way it does. 
 
Ideas behind the design
 
There are three things from my own experiences that I wanted to bring to the LF:
 
1. Tube consumer equipment always had some kind of ventilation back panel. Often this was pressed board with round holes or slots. I liked looking through the ventilation holes to the tubes inside. There was a very popular and widespread radio design called the All American 5. It had 5 tubes whose heaters, when in series, added up to about 110V. The circuit design is classic. You can find descriptions of it on the web. The amp was as dangerous as you can imagine. The plate voltage was taken directly from the line (no transformer), half-wave rectified. It was common for the actual metal chassis in these amps to be electrically hot. Hence, they were always enclosed completely in plastic, including plastic volume and tuning knobs. These were the radios that killed you if you dropped them into the bathtub while you were in it. Anyway, I liked looking into the tube equipment and this is why the LF has windows to look through instead of tubes on the top.
 
2. Sports cars and motorcycles. Many years ago I had two BMW motorcycles. One was a 750cc cafe racer with a quarter faring. The other a 1000cc full faring touring bike. I rebuilt the second one from a wreck. Increased the HP and had it custom painted. I drove way too fast in the canyons of Arizona and around the western parts of the US. If any of you wants to know, remind me to give you my four rules of motorcycling. I like the colors and custom work on motorcycles and I like the looks of very expensive sports cars (like Ferraris and Porsches). The color in the LF is designed to give the sense of the color and speed in sports cars and motorcycles. The red and black are common in high priced, fast cars.
 
The finish on the LF is designed to be the inverse of a red car with black tires. The powder coating (the tire color) is actually very difficult to do. A super flat black shows every imperfection in the paintwork. Although it may seem an inexpensive way to do a finish, it is more difficult to get it right and, hence, there are rejects that have to be discarded. It is much harder to do this than to anodize (although I have gone to anodizing on the LL because the LF finish has been difficult to control).
 
The red paint on the knob and power switch is put on by two very talented guys who do custom choppers here in Austin. These guys are artists at what they do. At one time they worked at Texas Custom Choppers until the owners were made an offer for the property by a Mercedes dealer that was impossible to refuse. When you look at the knob and power switch, they were totally custom painted to bring some high-speed motorcycling to your listening experience.
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BTW, the power switch has its own process. First I make the aluminum housings. Then I have them custom painted in the needed color. Then they are shipped to the piezo switch manufacturer who builds in the piezo switch and fills it with epoxy.
 
3. Weight - some of you have made comments on this. I wanted to create the opposite of a heavy tube amp. That is, I wanted something had high performance and light weigh like ... a performance car. It is easy to add weight to anything, but often very difficult to take it out. Folks who engineer jet fighters, racing cars, etc. are always looking to remove weight not add it. I realize that this is, perhaps, a different thought from much of the audio industry, but it was a design goal. Hence, the compact size, rcore transformer and some of the other design elements.
 
Naturally, some of you will agree and some not. That's ok. But, now you know.
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More to come...
 

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