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Experiencing Rowland M925 4-chassis reference amps

My pair (or should I call it my quartet?!) of the new SS Rowland M925 reference mono amps were finally delivered yesterday.... Needless to say, I am excited!

The 430W M925 monoblock amplifier is a hefty affair: The amp is formed by four chassis: two power supply chassis and two audio chassis, amounting to a total weight of 380 Lbs in the four boxes, and 320 Lbs in their birthday suits. Each chassis is double boxed, protected by heavy urethane foam inserts, and then bagged in a heavy cloth sleeve tied with a drawstring.

Each power supply box also contains an accessory carton, featuring a power cord terminated at one end with a 20A IEC connector, a heavy ombilical to carry DC current to the audio chassis, and a skinnier ombelical, which I conjecture carries control signals and may have an additional grounding line. A baggie contains 3 1-inch spherical delrin footers that can be screwed into the divets at the bottom of the SMPS chassis if if you do not use 3rd party spikes/footers. A smaller baggie contains 4 smaller delrin beads... They fit into the dimples milled into the top of each the power supply chassis, and are used to keep top and lower chassy from touching when the two are stacked.

I am using Nordost Titanium Sort Kones instead of factory-provided footers. Each power supply chassis stands on top of 3 divet-centered Kones. The whole thing sits on top of 1.5 inch thick granite slabs, which have been patiently waiting in place for the M925 amps since 2011.

The audio chassis are even heavier... They will get into place in the next few days, one way or another. Rowland recommends the stacking be a two-person job.

In order to break-in both output terminal in each unit, I will connect each amp to my Vienna Die Muzik with a form of shotgun wiring: Aural Symphonics Chrono and Cardas Golden Ref for the time being. The Aural Symphonics speaker wire connects to the single 5-way binding post of the Muzik speaker with bananas; the Cardas Golden Ref connects to the same posts with spades... I have already tested the configuration using other mono amps... Works flawlessly. Of course, I have no idea if M925s benefit from shotgun wiring... This will be part of the discovery fun!

The amps will be fed by the Criterion linestage through Aural Symphonics Chrono B2 XLR ICs.

Power cords will be Aural Symphonics Magic Gem and Ultra Cube XXV, plugged into a dedicated 20A circuit served by Furutech outlets.

According to Jeff Rowland, breaking may be excruciatingly long, because of the oversized input transformers and power supply. I suspect that the process may extend well into the summer months... I will log my periodic observations on this thread.

For sake of completion, here are the amps specs as far as I know them:

Monoblock Power Amplifier OUTPUT POWER: 430 watts @ 8 ohms/850 watts @ 4 ohms
Monoblock Power supply: 2400 W regulated DC SMPS per channel, with Active Power Factor Correction (PFC).
FREQUENCY RESPONSE: 5 Hz - 50 kHz
INPUT IMPEDANCE: 40k ohms
THD + NOISE: 0.004%, 20 Hz- 20 kHz
OVERALL GAIN: Switchable 26/32 dB
Combined AMPLIFIER chassis & POWER SUPPLY chassis WEIGHT: 160.4 lb / 73 kg (per channel)
TOTAL DIMENSIONS (H/W/D): 16.5" x 15.5" x 16.25" (per channel) 419mm x 394mm x 413mm

Saluti, Guido
guidocorona
guidocorona OP
4,298 posts
 
Sorry Bernard, the generalized class X versus class Y discussion is meaningless... In practice, no class is inherently superior to any other class... There are amps ranging from superb down to mediocre in every class... The only thing which matters is the individual design, and how its sound is in synergy with your particular taste in sound and in music.

The only SS brand in a similar price level as M825 and M925 that peaked my interest at RMAF 2013 was Solution.

Guido
krell888's avatar
krell888
12 posts
 
Hi Guidoo

I was so excited to receive the 825 last Thursday. Setting up took quite awhile as a large effort was made to put this monster into the Finite Elemente Pagode Aps rack as the space just only fit the monster. After playing for 2 hours I realized the potential of what it can do to my sonus faber Amati Anniversario. It presents a bigger soundstage better imaging and detail except that its raw and lack the finesse as compared to my previous 625. The bass was already better than 625. This is without doubt as the 825 packs with much more power. However, the next day when I switched the amp on again, i heard a loud crank sound inside the chassis and thereafter there was no sound coming out from the speaker. Yes no signal. Following day, the dealer took it back promising to replace a new one. This happening prompted me to learn more about class d amp. I saw this website below and read it had to say. I m particular concern that it said that the switch mode power supply is so complex that if it stay on operating pass 7 years, then you are lucky. More often than not it wouldn't survive pass the 7 year mark. What it is trying to say is that the reliability is limited in a switch mode power supply and that it virtually can't be repaired AT ALL. What's your take on this?

http://education.lenardaudio.com/en/12_amps_6.html
krell888's avatar
krell888
12 posts
 
Found out that a condenser (capacitor) swelled and that it also emits a smell when the cover was opened on the main unit (not the power supply). The power supply unit was alright.
guidocorona OP
4,298 posts
 
Hi Bernard, I spoke to Lucien at Rowland this morning... Your dealer is in close contact with the factory... They are working together to solve your issue ASAP.

Concerning your other questions...

The audible performance of a brand new M825 is not faintly close to what the amp will be doing once it has completed break-in of 1200 to 1500 hours... I fully expect that a brand new M825 would not sound as sweet as a well broken in M625.... But before long, will leave the lovely M625 in the proverbial musical dust. As you can read in my M925 break-in log in this thread... Patience is golden.

Switch mode power supplies (SMPS) range from 25 cents parts for charging cheap phones to sophisticated and highly reliable units developed for aerospace and mission-critical applications... Rowland uses these highly reliable and expensive SMPS in its amps... Fact is that Rowland has been using exclusively high grade SMPS for the last 15 years because of their superior sonic performance and high reliability, and failures in Rowland SMPS are extremely rare.

Guido
ebm
9,311 posts
 
Im using a Rowland 8T which i love i once had granite you will get much better sound using Symposium Ultra Steath amp stands just my thoughts.
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