Lindsayt wrote: ↑Tue Apr 27, 2021 9:40 am
Geoff.R.G wrote: ↑Mon Apr 26, 2021 11:16 pm
Lindsayt wrote: ↑Mon Apr 26, 2021 10:39 pm
Because World Class amplifiers by sound quality can be made / sold / bought for less than £3000.
So that even if this amplifier is World Class by Sound Quality, it's still an example of incompetence from the designer because it's so bloody stupidly expensive.
And it's quite a big IF that it is actually World Class by Sound Quality. Because it's Class D.
If Rowland was a leading exponent of amplifier design - and not just going for Veblen marketing - the 925 would sell for less than £3000.
It has often been said that a product is only worth as much as someone will pay for it. That is misleading because there are products that a small number of people will buy simply because they are expensive and, said buyers perceive, exclusive. However once the claims in the brochure are considered it becomes apparent that
the Rowland 925 is expensive because, if we believe what we are told, it is massively over engineered.
Active power factor correction, why, if it mattered other people would have been doing it for years.
Aircraft grade aluminium, aircraft alloys are generally about strength rather than heat dissipation, at 35,000 feet the temperature is -56c, losing heat isn’t actually very difficult. Getting it from the electronics to the outside can be challenging when the structure is an insulator (Carbon composite).
Specially made XLR connectors, expensive because of the very low production. The recording industry and live sound people use Neutric connectors, or similar. They are more concerned with what a Grand Piano does to it.
You don’t sell a $50,000 amp to a musician, you sell it to someone with too much money.
That is a very good point about believing what we are told about the massive over engineering.
Is the Rowland 725 really over-engineered when compared to - for example - NVA M600's? Or Urei 6290's?
Or is there some Wizard of Ozery going on here? The amplifier behind the curtain, and the price tag?
Well since you ask lets look at the spec and see what it says in simple English
MACHINED ALUMINUM CHASSIS
Precision-machined chassis with integrated heatsinks, milled from a solid block of aircraft grade 6061-T6 aluminum, provides exceptional thermal heat transfer/dissipation, RFI/EMI shielding, and resonance control.
6061 is used to make coke cans and the Audi A8 chassis
6061-T6, refers to the temper state of the material, for an amplifier casing T6 is completely unnecessary (but it looks good in the brochure). If the A8 doesn't need T6 then neither does an amplifier.
CERAMIC CIRCUIT BOARDS
All audio circuits are implemented on mil-spec, multi-layer, low dielectric constant, Rogers™ ultra-rigid ceramic circuit board substrate for extremely low energy retention and absorption. Large low impedance ground plane areas for extended internal star-grounding.
Ceramic circuit boards to mil-spec are used in military circuits but probably (I say probably because the spec isn't quoted so I can't look it up) to resist the effects of vibration and hostile EM emissions. Not too many hostile EM emissions in the average house. *
The large low impedance ground plane, I can see the point but isn't that large 6061 lump the PCB is mounted in a low impedance ground plane too?
BALANCED TOPOLOGY
Inherent cancellation effects of balanced topology implemented throughout all power and input/output circuits ensures greatly reduced distortion and noise under dynamic signal conditions.
Great, except that unless you have a balanced source it isn't actually doing any good. Balanced mics and transmission are used to reduce noise from external influences, if you can't control interference noise inside a massive aluminium case you have other problems. If you have a balanced source e.g. a magnetic cartridge or a CD player there are some benefits but note that almost every tone arm I have looked at has unbalanced phono sockets. If you can stretch to an SME series V then a balanced output is an option.
HIGH CURRENT COPPER BUS-BARS
High current, dual polarity, ultra low impedance copper bus-bars distribute both power supply input current and signal output current, virtually eliminating intra-circuit EMI signal contamination, greatly reducing internal wiring, while increasing circuit board rigidity.
Bus Bars are internal wiring but instead of being round and covered in insulation they are rigid copper bars. Increasing circuit board rigidity? I thought the ceramic boards did that?
HIGH-PRECISION SURFACE MOUNT COMPONENTS
Extensive use of Lead (Pb)-free, low temperature coefficient, active and passive surface-mount components results in significantly smaller loop areas, reduced circuit capacitance and inductance, and introduces less noise than conventional leaded components.
Quite right, except that surface mount makes repairs difficult, impossible for the average person without lots of expensive tools.
TRANSFORMER-COUPLING AND ISOLATION
Transformer coupled input circuitry provides universal component compatibility and virtually eliminate ground loop noise and RFI/EMI. Transformer coupling ensures identical amplifier overall gain when using unbalanced input adapters.
When all the rest of the pro audio manufacturers are using "servo balanced" input circuits (which mean that loss of one side of a balanced line doesn't mean loss of the source). Identical overall gain must mean that balanced inputs are attenuated by 3db or there is additional gain on unbalanced inputs. For DQ, the transformer is another component in the signal path if it isn't necessary why use it.
POWER FACTOR CORRECTION
Power Factor Correction (PFC) in the power supply reduces AC line harmonic noise pollution and increases AC line power utilization to 99%.
Running at a power factor of .99 is getting pretty close to having a resonant circuit on the mains input.
HIGH-EFFICIENCY SWITCH-MODE POWER SUPPLY
Highly efficient, compact, light weight, 1500 watt DC switch-mode power supply provides optimum voltage regulation for all circuits and operating conditions, and allows for quiet operation over a wide range of AC mains power sources.
I am no expert on Switch mode power supplies but from what I do know there is no point in applying power factor correction to the input and then creating all sorts of phase changes to get to DC.
Note: Power Factor Correction is commonly used in three phase supplies to ensure a balanced load on the generation system (not to be confused with balanced audio) i.e. the same current and phase relationship on all three phases of the supply.
PARALLEL BINDING POSTS
Dual CE approved speaker output terminals require no tools for secure, low resistance connections, and allow for easy bi-wiring applications.
To sell in the EU the CE approval is mandatory
FLEXIBLE 20 AMP AC POWER
20 amp AC power inlet accepts a wide variety of after-market high-performance power cables.
In the UK and Europe read 10 Amp (UK max 13A, EU max 16A from a mains socket)
FRONT PANEL STANDBY BUTTON
Illuminated front panel push-button switches the amplifier into standby mode (< 1 watt consumption).
So what?
REAR PANEL REMOTE JACK
12V 3.5mm jack on rear panel permits amplifier power on/standby switching in remote and home theater applications.
If you must!
SELF-LEVELING SUPPORTS
Removable 3-point self-leveling Delron chassis supports provide high frequency mechanical noise isolation.
Really?
The 725 is a class A/B amplifier. From my comments you may well gather that I think the 725 is over engineered, by all means mill the chassis from solid but don't try to tell me that you need 6061-T6. The rest, I just don't see why much of it is necessary. I'll not comment on the use of a switch mode power supply.
By the way, feel free to disagree, these are my reactions to the claims made for this amplifier and if you know better please correct me.
*If you manage to use all 330W per channel in an average house hostile EM might be a problem as the neighbours try to stop the racket. Vibration as they belt the case with a sledgehammer might also become a problem
