Jeff Rowland 501s burn in ... a strange experience

I have received today my monoblocs 501 and borowed a ML 39:
ML 39
NBS monitor III
NBS Monitor III
monoblocs 501
NBS Monitor IV
Infinity Renaissance 90

around 2:p.m (Europe) I have installed the system:
sound very detailed, beautifull soundstage imaging & focus, great energy,
on the negative side, some high frequencies too harsch a little bit venomous

6 hours later (system working all the time) complete change ... do the monoblocs suffer jet lag? ... ;-)

the sound has become very fat and heavy, has the energy of a sleepy hypopotamus, everything is slow, too warm, without focus, like coming from bad tube components ...

from one extreme to another... how is that possible, so extreme, I am ???

any suggestions?

My experience is componets on initial startup will sound very good but bright and brassy. Then turn dark...closed and fat. Especially if the NBS cables are new...but the amps will continue to morph also. 100 hours should do it and be a lot better.
Just keep them 'burning in'. So far every new product I have purchased sounded great out the box then in time (from 20 hrs - cdp to 100hrs speakers - 50hrs int amp) they sounded miserable. Oh yeah cables too (almost 500 hrs for the PC's). From those points which all varied they only got better. Personally I would keep burning them in. Maybe some JR owners could tell you how long those amps take to burn in.
I have a different ICE amp, and what you are witnessing is well documented. Eventually it should sound fine. After break in you should try rolling what else you have in your system. Power cords should be upgraded first, and then you will find sources and speaker cables being of crucial importance to great sound. When you get it right...... you will know it.
After a few hundred hours if your not satisfied I strongly suggest upgrading your power source with a dedicated circuit and metal clad heavy gauge wire. Some switching amplifiers can be fussy about the AC their being fed. This is an inexpensive upgrade that your entire system can benefit from.
Sounds like common break in pains. Give it some time to settle in.
Nothing having to do with the JR 501's underwent any permanent or long lasting change from about 10 seconds after you powered it up to 6 hours later, or for that matter, till now. If it did, then the equipment is poorly designed. Since that company has been around for a while and has many satisfied customers I doubt that it is that poorly designed.
Clavil, the glib answer would be. . . take 2 Aspirins and call me in 6 months.

Here is a more useful answer. . . all new amps need real playing time break-in. . . during this time sound will fluctuate wildly. Different types of amps require different break in times. Seems that amps that operate at lower temperatures require longer break in time. Most class D Rowland amps require about 1,000 hours of REAL playing time to reach peak performance. You should also leave your Capri pre and 501 amps always turned on. . . this is JRDG's recommendation.

Once the amps are broken in, you may want to consider a pair of JRDG PC1 PFC external modules. . . they should yield greater authority and greater subtlety to the sound. Power cords should probably be after that. G.
Clavil, I have developed a fun to use Excel spreadsheet that helps with equipment break in tracking/logging. Drop me a note if you'd like to try it out. G on the 501 break in.
Aren't power cords all about eliminating AC line noise? Doesn't it make sense that the DC signal proceeding from the PC-1 to the Rowland amps would have no need for and could not benefit from a power cord upgrade?
I thought the primary purpose of the PC-1 was to provide a cleaner, quieter, stiffer current to the downstream appliances.
And wouldn't it be advisable to break in the 501s and the PC-1
concurrently, rather than sequentially? The latter just adds to the already cumbersome break-in period.
Hi Macro, the answer is. . . it depends. From an efficiency point of view, yes it's a good idea to break in PC1 and amps at the same time. From a financial point of view instead. . . it depends. As for power cords feeding a PC1. . . common sense would suggest that a PC should not have an effect on a PC1. . . reality is different, and power cords affect the sound of at least the JRDG Capri even when a PC1 is interposed. And if you ask, the answer is no, the PC1 IMO should not be used on a linestage like Capri. . . it is only recommended for high power applications. G
Guido - You should get in touch with Jeff and let him know about your "findings". He thinks the Capri benefits from the PC-1.
There are 2 camps on Capri+PC1. . . . my current opinion is that when Capri is brand new PC1 increases its resolving power to an extent. However, IMO, once Capri is fully broken in, PC1 inhibits full performance of Capri. . . it is worth remembering that Capri has a very small power supply and draws only 6W. Possibly the bank of capacitors in the PC1 may be an issue.
JRDG recognizes there are diverging opinions on Capri+PC1.
Interestingly, several weeks ago I had an interesting conversation with David Elrod about why some of his PCs like the Statement are not indicated for low power applications. . . he indicated that the relatively high capacitance in the Statement does constitute a power reserve for devices that can quickly draw it. . . but low power devices may be hampered by the extra capacitance.
Pls remember I am not an EE. . . the explanation above may be non factual.
You gotta love all this digital break in excuse 1000 hrs what a joke,then if that doesnt work ,try this,then something else ,the list never ends with dig amps,
Coffeey, admittedly switching amps are not good solutions for the seeker of instant gratification. . . . in fact, most of the hobby is rather for the obsessively inclined, to one extent or an other. G.
My class D amp builder, Henry Ho, told me this story. A buyer of his amp called him after a first listen, and said, "Henry, your amps have NO BASS!" Henry told him to be patient. A half hour later the guy called back, "Henry, your amps have TOO MUCH BASS!"

Henry now tells buyers he does not want to hear from them for at least a week of near continuous playing. Henry, who built class A amps first, didn't believe in breaking in gear either.