olds1959special Posted May 22 Author Share Posted May 22 The four amps with 48V PSU's and the Sparkos op-amps cost under 1K total, and I don't need a lot of space to place the amps. Each of the four amps provide 235 watts in mono mode into 4 ohms. Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 (edited) I already sold one of my Hafler amps, and waiting for the other to sell, so I'm -really- hoping this works out. I get the second pair of amps tomorrow and will test with the stock op-amps on the bass drivers. I'll get the Sparkos op-amps the following day and will install them then. I think this will provide something along the lines of 470 watts of power to the speakers? Getting an equivalent setup with Class A or Class A/B amps would take a lot more space I don't have, and cost more. In the future maybe if I had more room I would try other stuff, but for now, this should work better than just using the 60 watt Haflers. Edited May 22 by olds1959special Link to comment Share on other sites More sharing options...
TomicTime Posted May 22 Share Posted May 22 Happiness is the KEY !!!!!! enjoy the music and the journey 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 (edited) I tried the Fosi in dual mono without the Haflers again and something is not right. I even thought I heard distortion. But I’m assuming it’s because these amps have overrated power ratings and adding a second set should work much better. We’ll see. I am wondering about the load dependency issue. The Vandersteen 2ci’s are 5 ohm minimum and 7 ohm nominal I guess. Edited May 22 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 (edited) Also concerned about this: https://www.mtg-designs.com/tips-tricks-tests/amplifier-testing/amp-frequency-response-variability-with-load "What this means is that if you are using a Class-D amplifier with a poorly designed output filter then the frequency response from the amp can change quite dramatically depending on the speaker you have hooked up. One speaker may cause the treble to be several dB too high another several dB too low. Thus you can't trust the amplifier will correctly reproduce the input signal. This frequency response swing often extends outside of the audio range as well and in extreme cases can be so severe as to cause amplifier instability effecting operation and causing potential damage to the amplifier." I read the newer mono V3 has PFFB (post filter feedback) implemented - so no load dependency, but the ones I have, the ZA3, the frequency could vary up to 1db with a complex speaker load. Edited May 22 by olds1959special Link to comment Share on other sites More sharing options...
Holmz Posted May 22 Share Posted May 22 2 hours ago, olds1959special said: Also concerned about this: https://www.mtg-designs.com/tips-tricks-tests/amplifier-testing/amp-frequency-response-variability-with-load "What this means is that if you are using a Class-D amplifier with a poorly designed output filter then the frequency response from the amp can change quite dramatically depending on the speaker you have hooked up. One speaker may cause the treble to be several dB too high another several dB too low. Thus you can't trust the amplifier will correctly reproduce the input signal. This frequency response swing often extends outside of the audio range as well and in extreme cases can be so severe as to cause amplifier instability effecting operation and causing potential damage to the amplifier." I read the newer mono V3 has PFFB (post filter feedback) implemented - so no load dependency, but the ones I have, the ZA3, the frequency could vary up to 1db with a complex speaker load. ^That^ is also what tube amps can do in the bass. I would not really sweat this stuff too much… The 2C is a pretty tame load compared to a lot of other speakers. (Especially out in the higher octaves.) The graph is from Erin. 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 I got the amps. I'm listening now and not hearing distortion or anything that is grossly off. I'm using the stock NE5532 op amp for the bass driver amps, which I'll change to Sparkos SS3602 tomorrow. My impression is that the bass and overall sound is more 'spread' sounding, but for now everything is working okay and I'll see how it goes with the new op-amps tomorrow and listening over the next few days. I already sold both my Haflers. Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 (edited) I'm curious how much the next op-amp swap will change things. Probably not much, as it's just for the bass driver. It's actually sounding pretty good now, listening to Chet Baker sounds very smooth and detailed, with lots of air in the sound. There is enough power and no distortion happening. What's nice is how the amps fit on my entertainment unit, under my TV, with room left for my other gear. There's just no way I'd be able to fit 450 watts or whatever of traditional amps in this situation! Edited May 22 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 (edited) I think the bass is not focused enough now, and feels weak. Everything else is perfect. Hoping the op-amp swap will help. Edited May 22 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 I changed the op-amps to MUSE02 in the midrange treble and used the Sparkos for the bass. I felt an improvement in the punchiness of the bass this way. Link to comment Share on other sites More sharing options...
olds1959special Posted May 22 Author Share Posted May 22 (edited) Okay, I've been going back and forth with the MUSE02 and Sparkos SS3602 in the bass and midrange / treble. The Sparkos has more dynamics and treble, the Muse is more smooth. But I have a sense of how this will turn out once I change them all for Sparkos. I think it sounds great in the highs, and I'm assuming bass will not be the strong point of the setup. Highs are extremely clear and open. I hope this is helpful to someone else wanting to try class D amps. Ultimately the question will be, can I live with how the bass sounds? I think using class A/B for bass wouldn't be a bad idea, like I tried briefly, if I had the room, and could perfectly match the power of each amp, which I wasn't able to. Edited May 22 by olds1959special Link to comment Share on other sites More sharing options...
Holmz Posted May 23 Share Posted May 23 2 hours ago, olds1959special said: Okay, I've been going back and forth with the MUSE02 and Sparkos SS3602 in the bass and midrange / treble. The Sparkos has more dynamics and treble, the Muse is more smooth. But I have a sense of how this will turn out once I change them all for Sparkos. I think it sounds great in the highs, and I'm assuming bass will not be the strong point of the setup. Highs are extremely clear and open. I hope this is helpful to someone else wanting to try class D amps. Ultimately the question will be, can I live with how the bass sounds? I think using class A/B for bass wouldn't be a bad idea, like I tried briefly, if I had the room, and could perfectly match the power of each amp, which I wasn't able to. I am not sure how easy it will be to evaluate changes. Once we start listening for something (like the bass), then it grabs our subjective focus. Do you have a UMIK and a way to generate the response from pink noise? That would be more objective. Link to comment Share on other sites More sharing options...
olds1959special Posted May 23 Author Share Posted May 23 (edited) 1 hour ago, Holmz said: I am not sure how easy it will be to evaluate changes. Once we start listening for something (like the bass), then it grabs our subjective focus. Do you have a UMIK and a way to generate the response from pink noise? That would be more objective. I don't have one of those but it's on my to-get list for sure! I use an app on my phone called Audio Tools that has an RTA that would probably work with this! Things are starting to sound nice now after changing all the IC cables to Mogami 2964. I don't want to over analyze, but rather just try to enjoy music. I'm getting used to the changes in the sound and getting back to the music. There are no serious issues I think. I'll still be putting in new op-amps tomorrow just to experiment further, but I think this is working for me. Edited May 23 by olds1959special 1 Link to comment Share on other sites More sharing options...
Holmz Posted May 23 Share Posted May 23 3 minutes ago, olds1959special said: …Things are starting to sound nice now after changing all the IC cables to Mogami 2964….. The Neutrik Pro-Fi RCAs work like a champ with the Mogami. (As do the Neutrik XLR variants.) 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 23 Author Share Posted May 23 (edited) 10 minutes ago, Holmz said: The Neutrik Pro-Fi RCAs work like a champ with the Mogami. (As do the Neutrik XLR variants.) These are the WBC cables with the Amphenol ACPL connectors. Edited May 23 by olds1959special 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 23 Author Share Posted May 23 I did the last step and added the Sparkos SS3602 op-amps so now all four amps are the same. This add fullness to the frequency spectrum. It sounds good and I think I will enjoy this for some time to come! I would say that it is step forward for me in terms of sound quality from everything I've tried before with these speakers. Link to comment Share on other sites More sharing options...
olds1959special Posted May 23 Author Share Posted May 23 (edited) I'm still having issues with the sound of the bass not being satisfying. I have thought of adding a subwoofer, but I have no crossover to integrate the sub and 2Ci's, so the frequencies would overlap and it would sound boomy. My sub goes down to 50hz and the 2Ci's go lower? The 2Ci's have the woofer / passive radiator, so that should be enough. For now, I lowered the midrange and treble on the contour controls by 1db, to try to give the speakers more bass. Edited May 23 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 23 Author Share Posted May 23 (edited) Also I could try a tube buffer between the DAC and pre-amp. Edited May 23 by olds1959special Link to comment Share on other sites More sharing options...
Holmz Posted May 24 Share Posted May 24 (edited) 11 minutes ago, olds1959special said: Also I could try a tube buffer between the DAC and pre-amp. Personally I would not be adding more... 23 minutes ago, olds1959special said: I'm still having issues with the sound of the bass not being satisfying. I have thought of adding a subwoofer, but I have no crossover to integrate the sub and 2Ci's, so the frequencies would overlap and it would sound boomy. My sub goes down to 50hz and the 2Ci's go lower? The 2Ci's have the woofer / passive radiator, so that should be enough. For now, I lowered the midrange and treble on the contour controls by 1db, to try to give the speakers more bass. The old model is ~$100 used, not sure if they are still available new, or if one needs to go M5-LPF? You would need to add them before any splitter for the 2/amps per side. And the (maybe superseded) 2W subs also pop up. Edited May 24 by Holmz Link to comment Share on other sites More sharing options...
olds1959special Posted May 24 Author Share Posted May 24 (edited) 16 minutes ago, Holmz said: Personally I would not be adding more... The old model is ~$100 used, not sure if they are still available new, or if one needs to go M5-LPF? You would need to add them before any splitter for the 2/amps per side. And the (maybe superseded) 2W subs also pop up. Ugh Edited May 24 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 24 Author Share Posted May 24 I don't think the Vandersteen crossovers will work for me because I would be getting the subwoofer output from the back of two of the amps for left and right. Link to comment Share on other sites More sharing options...
olds1959special Posted May 24 Author Share Posted May 24 (edited) I could do this but would need to use RCA splitter cables and get two stereo crossovers. That way I could use an output from my pre-amp to go to the sub. Edited May 24 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 24 Author Share Posted May 24 (edited) Do I need to get solid state amps for the bass drivers? I did figure out where I could put them, behind each speaker and run longer rca cables. But how can I match the levels properly between them? Measurements? What a rabbit hole. Edited May 24 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 24 Author Share Posted May 24 (edited) My amps have a very easily movable volume knob and turn on and off with the same button, so all of this is not going to work that well, unless I can leave the amps at full volume somehow. So I would need an even more powerful SS amp with volume control to match it, and for space reasons, would need two to place each one behind each speaker. Edited May 24 by olds1959special Link to comment Share on other sites More sharing options...
olds1959special Posted May 24 Author Share Posted May 24 https://losangeles.craigslist.org/sfv/for/d/sherman-oaks-kenwood-amps-amazing-high/7743177365.html could these work for bass only? Link to comment Share on other sites More sharing options...
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