Topping D90 from before AK factory burned down, aka Audio Science review had it second from the top GACs then. What have you in mind.
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I would say so, Speakers are Rogers LS3/5a, I also have Apogee Scintillas, claimed to be the best but I am not so keen on them, besides I have a small room. 5 x 6 x 3 meters. They are big. My preference is the Rogers;
The Scintillas are only suitable for large room, say 15 x 20 x 4 meters, Also have Kef Concerto, but it is a little warm sounding to me but sometimes they can sound perfect especially uncompressed old rock songs such as Beatles, eagles, Dire Straits. But on modern jazz it sounds too thick. On the Scintillas obviously some Queen songs are King.
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The amp I am working on for the past few months will be an ELD but completely symmetrical dual differential, I suspect i cab get THD and IMD a magnitude lower. At the moment it is -164dB below full output (100 watt) just before onset of clipping. If you want a schematic for MC12 you welcome. Ten years are over and I won't be in any breach. Although the manufacturer dressed it up magnificently, the circuit was mine produced by them under license. They were charging $39000 for two mono blocs at last expona. In all honesty the parts was no more than $3300/amp
Already using Marantz MA9S2 mono blocks, originally $16k/pair. Also using Sound Lab Majestic Series large area ESL panels (2 ohms minimum). Sound Labs are good down to around 28-30Hz. REL subs extend that down to 14Hz. Good enough for me for now. However, I do have a diy dac that takes maybe $2,500 worth of parts to build (not including a nice case). I believe it will nicely outclass your Topping. It has a rather extraordinary sound stage, especially for depth. Already it has been suggested by a couple of people that I may get my 15-minutes of fame for this thing. Schematics and Gerbers are all open source, except for one thing: a squaring circuit for sine wave clock oscillators. There is also a remaining issue with the output stage. I can't share what I am doing for that because some of it is proprietary to other folks. However I know a few people are considering trying some possible open source output stage solutions. The above having been said, I would give the squaring circuit design away to someone willing to do all the work the build the rest of it, and who is willing to buy the best oscillators for this dac from a third party company not related to me (because without really good oscillators the squaring circuit would not be needed).
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I only recently bought the Topping to have a DAC on the PC so I can stream in the background but, my main source of music is Vinyl and then CD, in that order. I have been retired for the last five years and probably the reason that the "improved" amp has been taking forever, since there is no haste to complete it, there is probably no way that I would hear the improvements anyway, it is just something new. Currently DIY has really just became one of the hobbies and I have to still design the packaging, may take ages even if it is 3D rendered. Only once you have it machined it arrives maybe 3 months later, you don't like what you designed any longer. Take it from me, packaging and mechanics (bespoke heat sinks and transformers) cost orders of magnitude more than the electronics and being aesthetically pleasing is probably 50% of the listening experience. Since retirement I sold two businesses and our main house and now live leisurely in our holiday cottage in a village on the beach.
Let me guess.
100watts. Let's say 8 ohm. So about 28 Volts or say 30 dBV
Then we have 134 dB left.
Guess it is one of the harmonic component at max -134 dBV that is meant. That is normally total THD about -114dB to -120.
So that is impressive but acheivable if cost is no object and design skill is high.
Can be easily masured with a notch filter and normal DAC.
100watts. Let's say 8 ohm. So about 28 Volts or say 30 dBV
Then we have 134 dB left.
Guess it is one of the harmonic component at max -134 dBV that is meant. That is normally total THD about -114dB to -120.
So that is impressive but acheivable if cost is no object and design skill is high.
Can be easily masured with a notch filter and normal DAC.
It would be nice to see a graph after your extensive essays ... 😎
Jan
Jan
Been following this thread with interest as the subject of distortion measurement took me back to my early days in the audio industry. I recall in the 70s being sent to a well-known console manufacturer in the South of England to carry out acceptance testing of audio consoles for a number of studios we were refurbishing. I was armed with my trusty EP14/1 Audio Test Set which on a good day could measure down to 1% distortion. I can't remember the actual specification we were working to at the time, it would have been a few %, but I do recall as a young lad being quite disappointed at the number of modules that failed our tests. Even more so the amount of negotiation to try and get me to accept them, still out of spec, when they were returned from the rework bench.
That factory was full of consoles destined for studios all over the world. Any one of them could have been involved in the recording of some classic album that we now hanker to stream or download and playback on our DAC, with 0.01% or should it be 0.001% distortion? With those recordings being bounced between multiple tape tracks during the mix and subsequently tinkered with for remastering to HD digital I think we would be shocked at the true levels of distortion on our favourite music.
EP14/1 Audio Test Set
That factory was full of consoles destined for studios all over the world. Any one of them could have been involved in the recording of some classic album that we now hanker to stream or download and playback on our DAC, with 0.01% or should it be 0.001% distortion? With those recordings being bounced between multiple tape tracks during the mix and subsequently tinkered with for remastering to HD digital I think we would be shocked at the true levels of distortion on our favourite music.
EP14/1 Audio Test Set
IME, there is a difference between analog distortion mechanisms and some of the mechanisms found in sigma-delta oversampling dacs (not all THD is the same; for that reason THD as a metric as been seriously criticized) . Also, for some as yet fully unexplained reason, ADCs commonly used in studios and for mastering seem to work more accurately than DACs. This seems to be the case despite that every modern ADC contains a DAC. Could be that DACs internal to ADCs only have to be accurate during a narrow window of time where the input signal is compared to the dac output. OTOH, DACs used for reproduction of audio have their output integrated over the entire sample time before the next sample is output. There can be no signal-correlated, nor time varying errors at any time, or the errors will tend to be baked into the dac analog outputs. Thus, making an especially good dac is still a problem that is being actively researched and for which new patents are being granted. For such reasons, and IME, a good DAC can still be worth the investment.
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I think the way you naming your amp is a little bit odd like bird name, giving cheap impression for a high end user, anyway I am interested in such low distortion design.
Very true The look can be deceiving
An interesting test that i guess sincere
https://www.matrixhifi.com/ppec_eng.htm
That draping will change the sound. A lot of reflections off the equipment will be somewhat dampened.
In simulation - right!?
Only a person that lacked deeper knowledge would state such a figure.
//
i guess that the draping was left in place during the comparison
if this test was genuine it tells me that the major player in the game have been the speakers
same speakers with different amps sounded mostly the same
with one system costing a small fraction of the other