You are busy for a good reason - you have work that pays! And that's good.
It's all hobby for me so I make time to do it to have fun. Unfortunately the only time I have is to exchange for sleep as I am busy too. Can't do it too often but a few days here and there is worth the fun of a hot iron and smell of molten flux wafting up in the air.
I think "hi-fi" is often used with 2 different connotations. Positive one is when it really means high fidelity. Negative one is when it is "clinical"...
Which one is it?
The FX8 Bimo is "high fidelity" and the Jason K VSSA is also "high fidelity" but with some propensity towards being more "clinical".
The Circlophone, Quasi, and FH9 are definitely in the class of a "real DIY" sound that cannot be obtained via commercial means. They are engaging, dynamic, and fun sounding.
The Circlophone, Quasi, and FH9 are definitely in the class of a "real DIY" sound that cannot be obtained via commercial means. They are engaging, dynamic, and fun sounding.
I don't understand your question. It's a measurement microphone used to record the sound. Same position as mic that produces the measured frequency response and distortion plots. UMIK-1 calibrated by third party Cross Spectrum Labs with USB interface so microphone preamp and ADC is in the mic body. It's mounted on tripod located at 50cm from baffle and in between woofer and mid/tweet in vertical direction. So the sound it records will flow precisely the recorded spectrum presented.
Yes, this is an old topic...
But I believe that once we have a sufficiently good audio system, we don't want any alteration to the sound, especially if this alteration is "adding" (second order) distortion.
Distortion is distortion, but the way 2nd order distortion becomes a disturbance is very slowly, starting with giving good impression first.
Listening long as a background music in my laptop's speaker, I realized that FX8 was better than circlophone in distortion and fatigue. Listening again critically with external PC speaker at office, I found that human voice is really like human with FX8, compared to circlophone... (I can do perfect ABX only by judging which sound is more human, or more Norah Jones, and which one is not)
So, I tend to lean towards FX8 (than circlophone) to be my favorite. Cannot yet decide. May be I need to listen to the amp in my favorite speaker to know exactly which one is my favorite. And I agree, FX8 is the most "hi-fi".
That's a lot of good amps the FX8 is up against to still be your favorite Jay.
No bad for 8 transistors.
Yes, Im more convinced now with the importance of "balance" especially with simple circuit. FX8 is balance because latfet is good at midhi and LTP is good at low frequency. VSSA is terrible imho. The LF weakness makes the amp weird. The imbalance is due to latfet and CFA which both excel only at HF...
Unfortunately you dont have something like BG1-BJT. I like the combination of CFA and BJT, to balance the HF and LF.
That would be very interesting. Like Firstwatt's F5 (JFET or BJT input). It would have a good balance between HF and LF.
The Quasi here is sort of a BJT CFA isn't it? Well maybe half BJT
It's more a HEX-CFA to me. But the major feature is single ended design, both input and output. I think the problem with such topology is "compression" when the SPL is high.
CFH7 Sound Clips
My new amp finally works after spending a couple of days troubleshooting. Turns out I made an error on one resistor that is now fixed. This amp sounds real nice - I really am liking it so far. More info on this amp here:
http://www.diyaudio.com/forums/solid-state/294834-cfh7-amp.html
Playing in stereo:
Measures very flat and with low distortion at the speaker:
Attached are the usual 3 sound clips. As usual, change the .asc extension to .mp3 to listen. Playing with 170mA bias current.
My new amp finally works after spending a couple of days troubleshooting. Turns out I made an error on one resistor that is now fixed. This amp sounds real nice - I really am liking it so far. More info on this amp here:
http://www.diyaudio.com/forums/solid-state/294834-cfh7-amp.html
Playing in stereo:
Measures very flat and with low distortion at the speaker:
Attached are the usual 3 sound clips. As usual, change the .asc extension to .mp3 to listen. Playing with 170mA bias current.
Alright, so I have compared some clips (at home) with cheap speakers with no bass (I started with the laptop's internal speaker and then a Nokia earplug).
Played the CFH7, and my initial impression was that the distortion is high. I didn't like the sound coming from the shouting ("honey child...") and the background piano. The laptop's internal speaker can show distortion difference, but not the earplug. There is a possibility that one of the clip is louder so it triggers the small speaker to reach clipping or cone breakup... If there is no problem with level difference, then CFH7 has high distortion, but this is all below my usual acceptable threshold.
Compared CFH7 with VSSA (because they are CFAs) and I couldn't decide because each has plus and minus. Then I found out that this VSSA is not the latest version! When I made a comment few days ago that VSSA had a WEIRD sound, that was with the first version of VSSA. Indeed, today I found it weird...
Compared CFH7 with VSSAb (the latest version). It is obvious that CFH7 is too "soft", having less "resolution", as if having small dynamic, i.e. the contrast between the softest note and the hardest note is low. (N.B. At this point I know where VSSA was "weird" and VSSAb is not). Due to the better resolution, my preference goes for VSSA.
The CFH7 has neutral sound/vocal (better than circlophone), good rhythm (like circlophone). The distortion was not perceived with my earplug (may depends on the speaker used). The issue is only with it's "soft/thin" sound, which is not preferable.
Jay,
Thanks for the comments and careful analysis of the sound. Listening with cheap laptop speakers probably not the best way to judge. But based on my measurements, the CFH7 is one of the lowest distortion amps (as measured by effect on speaker distortion) that I have with only the JK VSSA having lower distortion. Interesting how you say it sounds soft. I will have to listen to the clips as only having listened to it live playing so far.
Thanks for the comments and careful analysis of the sound. Listening with cheap laptop speakers probably not the best way to judge. But based on my measurements, the CFH7 is one of the lowest distortion amps (as measured by effect on speaker distortion) that I have with only the JK VSSA having lower distortion. Interesting how you say it sounds soft. I will have to listen to the clips as only having listened to it live playing so far.
Motivated by your information, I tried to compare VSSAb with FX8 head to head. First by listening as background music using my laptop: The more I listen to the FX8, the more I'm impressed...
Next I compared using Foobar, segment by segment of clip#3, using an earplug. Again, I'm more impressed with FX8... And I found that the weirdness is still there with the VSSA...
I'm familiar with the basic VSSA. If the distortion is lower than the FX8, I suspect there has been a "mis-design". We cannot lower the THD without giving up other quality parameter such as transconductance.
FX8 looks special in my simulation... It shows: (1) Acceptable transconductance of the latfet (2) Good bass (3) Non-fatiguing character. (4) And surprisingly low distortion as well.
Higher (not lower) trans-conductance is better. The low trans-conductance is the main issue with latfets. The main reason why latfet is less preferred than hexfet.
I think high trans-conductance will have crisp attack, but usually it is easier to listen for problems than strengths. With less energy for current, fast musical passage becomes unmusical, "disconnected" (listen to the piano passage at the beginning of clip#3). I think the weird sound and the "soft" sound I mentioned are the symptoms.
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