Well, I have Rowland 102 class D amp that "sound dry, unmusical, and strange in the treble ... kind of chalky and rolled off, and definitely lacking air" and unmodified Benchmark DAC1 that according to another review suppose to "sound lo-fi and shrill". In addition I listen to CDs that again according to opinion expressed on this forum "I found almost all cds way to harsh and shrill sounding" and overall sound is short of amazing. Keep going guys - you helped me a lot! |
There is no signal processing since most of class D amps are analog. As for the Zobel - Yes it is choke and output resistor and capacitor. Icepower calls it Zobel.
Excerpt from datasheet of Icepower 200ASC and 1000ASP modules:
"Due to the compensating Zobel network in the output stage, the maximum allowable short-term output power
is frequency-dependant." |
Simon, - my bad! I tend to attribute everything to DSP forgetting that even simple analog filtering is form of signal processing.
As for class D - I believe that it is very good for the money (important to me). Opinions vary a lot. Some believe that class D is at reference level while others that class D is LO-FI.
Stereophile reviewed Bel Canto REF1000M (Icepower) ending review with this conclusion:
"The Bel Canto Ref1000 Mk.II can be compared with the cream of the other amps I've had in my system: the Classé CA-3200, Mark Levinson No.433, and Ayre Acoustics V-6xe. Each of these distinguishes itself in different ways, and particularly with different speakers. Because of this, I think I must keep the Bel Canto Ref1000 Mk.IIs as a reference amplifieran easy decision even when based solely on its sound, but also: in my living room, none of the others can be so easily hidden in plain sight."
Class D amps might be very revealing showing shortcomings of the system but also might have better synergy with some speakers than others. Also, long break-in is most likely required. It took about 400 hours for my amp to sound best.
It is often said that Icepower sounds good only with linear power supplies. On the other hand newest linear class AB amps from Jeff Rowland (one costing $46k) use switching power supplies. |
Spectron,
Switching power supply offers many advantages such as ripple that is easier to filter out, voltage that is line and load regulated and transformer that can deliver same power at high frequency at 1/10 of size. The problem here is that SMPS got bad rap from designs utilizing them for the size and cost and not for the quality. Looking from perspective of manufacturers - why to develop SMPS while 90% of people believe that it is no good. Only very brave that already established their name like Rowland or Linn are not afraid to use SMPS in class AB amplifier.
Claim that class D amp work better with linear supplies is in a sense illogical since SMPS is class D with fixed voltage (that's how class D was invented). Most likely implementation of given type of supply is the key. Icepowers in REF1000M benefit from extra capacitors, according to reviews, but my tiny Rowland 102 keeps composure (having regulated supply) even under long heavy orchestral peaks.
Question to you. I read some of the Karsten Nielsen doctoral work and understand a little nature of the beast. Modulator is a little similar to Sigma Delta converters what doesn't surprise me since this idea (using byproduct of sigma delta) was already used in things like SACD.
What is different in Spectron amps? I heard a lot of good things but wonder if they share the same principle. I'm not asking of course for any design details, just adantages in general. |
Simon, I checked Spectron website - very impressive. 100kHz bandwidth and 65A max current is not easy to do. I am especially impressed with bandwidth - less phase shift in audio band. Spectron will be possibly my next amp. |
Dob, I'm confused. I thought that warmth of tubes IS euphonic coloration since tubes enhance even harmonics (artificially added warmth).
What is "absolutely artificial origin" and why it is attributed to class D only. Why details are supposedly lost in class D but not in tube amp that also enhances even harmonics? Claim that class D has no transparency and low levels detail is unfounded, in my opinion, and is just opposite to opinion of many, that class D is too transparent/revealing and bright sounding.
When some people believe that class D has "murky veil" being too warm and the same time others claim that they couldn't stand it because it is way too bright - then perhaps it is just right where it should be, neutral, transparent liquid and very clean. It is also very dynamic sounding. |
"Audiofeil, you know how low ICE impedance runs"
It is 10k - just a little low but many class D manufacturers use additional input circuit that increases impedance. My Rowland Icepower uses THAT1200 instrumentation amp to obtain 40k input impedance. Others use transformers.
Low input impedance is not related to class of the amplifier or modules used but to practical implementation. For instance the newest Rowland 625 class AB amp has 10k input impedance - by designer's choice.
My Benchmark DAC1 has 60ohm output impedance at 0dB XLR output jumper's setting (that I use) - no problem even with 10k input impedance. The worst case is at -10dB jumper's position making output impedance 1.6k. It might look to high for use with Rowland 625 but this impedance is resistive (output divider) and will only alter output level by -1.3dB |
I think it is just that to SOME people class D sounds great and for OTHERS not so great. You happened to be in the second group. Some reviewers and makers (like Jeff Rowland) love class D while others hate it. It is all subjective.
On the other hand it would be hard to find 2x1000W class A amplifier to compete with BC Ref 1000 not only for monetary reasons but also for power requirements (10kW@110V=91A) |
"First off, the Ref 1000 is not a 1000 WPC amp, it is a 500 WPC amp (but that is really only for peak/short periods, not continuous)."
REF1000 is rated 1000W/4ohm. By "short periods" only you probably referring to specification of Icepower module 1000ASP used in REF1000 showing only 150W FTC?
First of all in reality it is much better than that (attached test below conducted by DIY member - read below), second of all it is rating of the module WITHOUT ANY HEATSINK!!! REF1000 uses heatsink and I suspect can output 1000W per FTC requirement but it is not even necessary because average music power is only few percent of the peak power.
Originally posted by dmfraser
"I operated a sample 1000ASP on the bench delivering 350W average of pink noise into a 4 ohm load for over one hour with no additional heatsink and the metal case stayed below 55°C.
However, higher levels would make the power supply voltage go down to act as a thermal compensation. Much nicer than just shutting down.
However, with 1214W of sine wave, partly into clipping, after about 35 seconds, the output level would drop to about 600W by the protection circuitry. Remember this is with no additional heatsink." |
Ckoffend - I might be wrong about heatsink since they talked about ADDITIONAL heatsink (module has its own) but I don't really know If REF100 has additional heatsink (picture shows some heatsink).
Continuos power rating doesn't make much sense anyway since average music power delivered is only few percent of the peak. |
"No signs of stress or distortion"
- that might be due to line and load regulated power supply in your REF1000. 99% of the other amps have completely unregulated supplies - that is why class AB amps have monstrous size toroidal transformers and a lot of capacitors (to minimize voltage drops). |
Mapman - second generation of REF1000 not only have huge bank of additional capacitors but also converts huge narrow spikes of current to more of resistive load. Was it worth extra price? I'm sure it was. Any small improvement at this point costs a lot and is worth any money if you know that it works in your system. I might upgrade to this amp in future. I understand that "m" stands for mk II (new generation) but am not sure about "s" suffix? |
Atmasphere,
Carvin makes 2050W class D bass heads. Ampeg makes 2500W one. |
