Mark Hardy Posted November 30, 2005 Share Posted November 30, 2005 harman kardon A401 :-) Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 Tom, "(and I am not sure how it is being generated)" HP 3325A Function Generator. "By this I mean should one substitute an actual speaker to the output of the amp rather than using a power resistor. I am still referrring to measuring the electrical output of the amp" Yup, I agree with that. Like you said depending upon the amp you may see little change in the measurements or you may see a lot of changes. There are problems with trying to measure that way though. The first of course if measurements like this could likely damage speakers. Feeding full power 20kHz square waves to a tweeter likely isn't the best thing to do for its health. Also since impedance varies widly between models of speakers (and even between crossovers in the same speakers) that throws a huge variable into the mix. Trying to measure all the possible permutations of load presented to the amp is going to be basically impossible. Are you familiar with Ken Kantor's 'speaker simulator' dummy load circuit? I have the parts to build one... just haven't gotten around to it yet. When I have a chance I'll whip one of them together and duplicate a few of the measurements powering that to see if/how they change. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 John + Mark, This is much newer and in this case is actually a DIY amplifier. I have had the parts to build it for about a year but just hadn't gotten around to it as I tend to hate chassis work. I have the parts to build another one.... I just hate chassis work so I don't know when I'm going to get around to building it. Shawn Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted November 30, 2005 Share Posted November 30, 2005 Dr Who, see if the amp would act up if fed high frequency signals. Shawn speaker fryer ...!!! ....SSSSSSSSSSSSSSSSSSSSSSSSmoke Quote Link to comment Share on other sites More sharing options...
DrWho Posted November 30, 2005 Share Posted November 30, 2005 So when are you going to plug her in and let us know how it sounds? Btw, I love that you post these measurements and actually spend time measuring your equipment...a lot of people have all these different notions about the validity of measurements (often citing random cases where things sound good deviating from the ideal) and I often wonder if they have any personal experience with the subject (ie, taking their own measurements). I was just at a guitar pickup and amplifier seminar last night discussing many of these various issues. Apparently UIUC actually has a program where they go about measuring the crap out of all sorts of equipment and put it into databases for later comparison studies...perhaps in the future having a library of poor equipment matches (good equipment matches would be far too subjective). One thing that was discussed that I found very interesting was how any amplifier behaves very differently during times of very fast transients....would you happen to have any tone burst measuring capability? I've got a 60dB transient response of a tribal drum hit that might be interesting to see [] Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 "So when are you going to plug her in and let us know how it sounds?" Honestly.... I don't know. That isn't an easy thing to do in my system now with it Tri-amped. For one thing the gain/input sensitivity of the amp is too high. I'd need to at least add attenuation on the input to drop that down to better take full advantage of the crossovers resolution or adjust the gain of the amp itself. It takes some time to work it out such that the loudest material I play is using just about all the resolution of the digital crossover (without clipping) while at the same time having enough attenuation on the amp to have its driver balanced with the rest of the system. And then even after I do that how the amp sounds from 80-500hz, or 500hz-8000hz, or 8kHz+ probably would not tell someone too much about how it sounds that are looking to run the amp full range. I do want to compare this amps noise floor to the Teacs to see how they compare. If they are quieter then the Teac then I'd be more inclinded to go through all the above. Shawn Quote Link to comment Share on other sites More sharing options...
DrWho Posted November 30, 2005 Share Posted November 30, 2005 lol, just connect a cd player to your amp and then wire into a pair of speakers...you've gotta have a speaker somewhere in your home with a passive crossover in it. I could never imagine building an amp and then never listening to it! Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 "...you've gotta have a speaker somewhere in your home with a passive crossover in it." Sure, (Dzurko Acoustics Jaguars, North Creek Music Systems Borealis Unlimiteds, NHT SZs, AR LSTs) but none of them will really work well with 20w. How it acts with them is likely not going to be the same as how it acts with horns. "I could never imagine building an amp and then never listening to it!" I'm sure I'll listen to it. Just not as sure how any of my impressions of it would be useful to anyone here since it would be on very different speakers. I also haven't really critically listened to those other speakers in awhile and I don't think I have heard any of them in my new room either. Shawn Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 Couple of more measurements on the amp... this is a zoomed in 20kHz sine wave.... one the downward slope of the wave look just below the 0v point.... Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 Same thing but at 50kHz.... Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 100kHz.... Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 500kHz (btw the relative levels between pictures is the same.. the amplitude of the wave is getting smaller because the amp is rolling off) Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 30, 2005 Share Posted November 30, 2005 So how does it sound? Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 30, 2005 Share Posted November 30, 2005 Shawn: I have a clue -- but I appreciate the posting of both the pictures and accompanying explanations. 'Dzurko Acoustics' That name is familiar to me, but I can't remember why. Audio Concepts, Maybe? Wasn't the husband and wife team there the Dzurkos? I am in agreement concerning the possibility that two or more people may in fact have different ideas about what constitutes 'good performance.' Disagreement does not necessarily imply deafness or lack of experience, either. Displaying the test results in the absence of the name of the product reduces chances of 'led' responses, IMO. Erik Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 30, 2005 Share Posted November 30, 2005 "My latest SET amp wouldn't even pass the Stereophile 1KHz square wave test. It's just awful. Nonetheless, it's the best freaking SET amp I've ever hooked of my Lamhorns. The "you are there" factor is present at the nth degree. In some way, that is interesting too..." I'm curious. What kind of SET amp is this? I'm someone who can and does believe in the amazing sense of presence good single ended amps are capable of. Erik Quote Link to comment Share on other sites More sharing options...
Piranha Posted November 30, 2005 Share Posted November 30, 2005 I know, I know. It's a Moondog? Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 30, 2005 Share Posted November 30, 2005 Craig: "Craig thinks the entire topic is a flame bait game as always." Craig shouldn't worry about it then. Why does Craig always respond and contribute this way when other technically experienced forum members share ideas and experiments? Honestly! What is the deal with the 'flame bait game as always' proclamation, Craig?! Right, someone asked you about your opinion, but I don't understand the negative response. How is the sharing of this information flame bait? Erik Quote Link to comment Share on other sites More sharing options...
sfogg Posted November 30, 2005 Author Share Posted November 30, 2005 Erik, Yup, it is the amp you think it is. "'Dzurko Acoustics' That name is familiar to me, but I can't remember why. Audio Concepts, Maybe? Wasn't the husband and wife team there the Dzurkos?" Exactly, Mike and Brenda Dzurko. In the mid '90s Mike introduced a line of dealer sold speakers under the Dzurko Acoustics name. The Jaguar was a stand mounted larger two way moniter using Scan/Speak drivers in a two way setup. Rosewood body with green marble Fountainhead front and rear baffles with matching 5 post stands with the FountainHead on them too. He ended up ending the line and selling off the remaining inventory direct. " Displaying the test results in the absence of the name of the product reduces chances of 'led' responses, IMO." IMO too. Shawn Quote Link to comment Share on other sites More sharing options...
OldGuy Posted November 30, 2005 Share Posted November 30, 2005 Interesting measurements. Is it possible that the amp has a bit of very high frequency oscillation as noticed on the scope traces when set to a higher freq. time. Also what are you using for a analyzer? Nice to see the effort to document what you have spent time building. Norm Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 30, 2005 Share Posted November 30, 2005 Shawn: That's right, I remember them now. I guess I mentioned I came close to one of the products they produced back then. I liked the Sapphires, but couldn't afford them. ...I'd be curious to see how this Moth amp performs in a similar test situation. My feeling, based on what I know about it, is that it probably wouldn't 'do' particularly well. It sounds great to me, though, and I interpret that (rightly or wrongly) as merely the fact that I like the way this particular design lends it's own color/s to the signal by the time it gets shot out to the Klipschorns. The amp is not alone in that respect, though, because I think all components (low power or high) do that to some degree. We choose the colorations that work best for us. I'm interested in how the measurements correlate with your listening impressions when you get around to that. Erik Quote Link to comment Share on other sites More sharing options...
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