2. amps-preamps
  3. 1369518273

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
 
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.
krell888's avatar
krell888
12 posts
 
Finally the replacement of my 825 arrived. Was told by the local agent that Jeff made some modification to prevent the capacitor from giving way in the future. It was sheer joy just looking at the 825. It's beauty second to none. After about 4 hours of listening, I can't say much about it. Only that it sounds bigger and larger than my previous 625. Vocal now sounds more prominent and the tonality sounds sweeter. Overall it still doesn't sound warm and bloom as my well run in 625. Btw, just got the Aeris. Sounds excellent. Never mind about it can't play DSD files or upsample PCM more than 192khz. It just play more of my CDs musically. It's holographic, detail without sounding clinical but organically pleasing.
guidocorona OP
4,298 posts
 
Hi Bernard, glad that your M825 replacement has arrived.... Its sound will keep evolving for a couple of months. You can play 24/7 as the unit generates very moderate heat. When you are not listening to music, you can feed it interstation white noise from an FM tuner.

Expect that, particularly during the first few hundred hours, you might experience a few sonic ups and downs.... This is normal.... But overall, the performance curve will point very much upwards.

Do keep us posted,

Guido
krell888's avatar
krell888
12 posts
 
It's ashamed. The amp blew again after 10days. When it arrived, I have it switched it on for 9 days even without playing and it was alright and did fine. The sound was promising as times but some times it went into a mood swing. This I presumed is normal as it needed to run in as Guido has described. But even then, I was enjoying playing symphony pieces thru the vinyl like Handel's Watermusick. It plays the symphony music very well. Handles the crescendos superbly and piano notes and violin sounded so real and natural. Yes the highs, the crispness and the abilities to separate percussion highs from electric guitars, etc, essentially able to create a sense of space between instruments were fantastic. Soundstage, though already better than my 625, is still evolving. In fact in all aspects, the sound is still evolving. Only one area that the 825 has not yet come to match the 625, is the female vocal. Linda Ronstald tracks in the album, Simple Dreams has not sounded as sweet and warm compared to 625 but then it's jusr 30 hours of playing. The 825 plays bass excellently and has a tight grip on the woofers of my sonus Faber amati Anniversario. It fully controls and plays the Amati to the fullest never once I suspect it doesn't have the power and grip. This I realized when playing Carl Orff's Carmina Burama Paul Hindernith: Symphonic Metamorphosis, Robert Shaw The Atlanta Symphony Orchestra and Chorus. For all I knew over the short time I had with the amp, I was confident that the amp will show up its best (no doubt) later when fully burnt in. On the tenth 10, I switched it off in the morning and on the evening I switched in on and played for an hour or so before I switched it off to switch the gain from 32db to 27db. After selecting the gain, I switched on the amp again and heard that eerie, "clung" sound again inside the amp. I knew it.

I called my dealer immediately and they got a reply from Jeff that it would be replaced as soon as possible ..... With a 725 without topping up. The 725 now cost USD800 more than and the 825 now. Yes, I reckon I am fated with class A/B and had no luck with 825. Will upgrade to 925 in future. No worries.
More to discover