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Jeff Rowland model two sounding thin With Mini Utopia

Hello everyone, 

i have been following the forum for years, but never had the chance to have an active participation.
I apologise if there are any errors but english is not my native language, as i am Portuguese.

I have recently added a Jeff rowland model 2 to my system, in order to give my beloved Bat VK60 some res,t due to high hours of usage.

Much to my surprise, the Model 2 paired with the preamp Bat Vk5 and driving JM Lab Mini Utopias sounds quite
"thinner" then the VK60. I don't think it is just the "valve vs transistor" sound diference, and i am wondering what are the causes.

I have chosen the high input impedance 36Kohm and normal 26dB gain to match with the Vk5, and altought have yet to change the pinout of the xlr's (waiting to receive some Neutrik NA3FMX wich is a phase inverter between pin 2 and 3 (BAT uses pin 2 hot and JF Model II has pin 3 hot) i have tried inverting the speakers phase but with no sucess in regard to achieving somewhere close to the sound i had with the VK60.

Everything else in the system remains the same, apart from the power cable of the Model 2, because i am waiting for a IEC Tupe 19 i orderes from the States, in order to be able to use my power cables from Van den Hull.
Have tried to change the nordost valkyria between amp and preamp for another one i use for the cd palyer, but with no improvments.

With the Model 2 i have lost the wheight in the midband as well as a certain roundness in sound. The model 2 is quite smooth, but the analogy that comes to mind i is like you are feeling a fresh wind instead of a warm wind embracing your body. Everything else is as expected, good image and tonal accuracy. Harmonics are not as good as VK60, bass response surprisingly presents itself  leaner compared to the vk60 wich is quite good (had a Krell KSA 200s before tjhe Bat so i could compare both). All in All a less satisfying sound.

I have opened the Model two and it looks in pristine condition (inside and out), and becasuse the capacitors are hidden, can not see how they are looking.

Is this a mismatch between the model 2 and the Mini Utopias, the current phase inversion, the caps that are due for a replacment, bias adjustment (no idea if it even usess bias adjustmente) or anything else i am skiping?

Your thoughts will be apreciated, as i keep on trying to squeeze the sound i was hoping for.

PS: the next JF dealer is over 800kms away in another country, so i would rather sort it out first before i think of sending them the amplifier for a check in. Also currently still waiting for a reply from the Jeff rowland site, with no replys.




c_n_m
c_n_m OP
5 posts
 
Grannyring i  have the normal version, so according to what you are saying the caps should be 1 uF.
I took a picture of the inside a few days ago, when replacing tubes.
https://servimg.com/view/19857002/14

Prior to buying the model 2 it I did not think older Jeff Rowlands had a lean sound, and i knew i should avoid lean sounding amps by all means, in order to have good synergy with the Mini Utopias.

That is why i was wondering if there was anything wrong with the amp, or just a case of synergy between elements.






c_n_m OP
5 posts
 
Stereo it is not class D. As Jond pointed out, it is prior to classe D amps.
I am absoluty shure the wires from amp to speakers are "in fase", meaning amp output + to speaker input + and amp out - to speaker - 

As said before, the rowland however as pin 3+ on the inputs of the xlr, and the Bat has the more conventional pin 2+ on the ouput. I am waiting to try some neutrik or switchcraft phase inverting adapters in order to correct that, as i dont want to change the wiring on the Nordost Valkyria.
c_n_m OP
5 posts
 
Mission yes theu can be lean with the wrong amp, but i can assure you they are amazing with the BAt VK60, and with no trace of leaness. Together they sound like a high perfomance 100m sprinter. Speed, muscle and agility. These are the fastest speakers i ever had, and i have had Apogee and Dunlavy prior to these.

With the Model Two, things have shifted to a Marathon type of atlete if you know what i mean.
roberjerman
4,319 posts
 
The BAT VK60 has an output impedance over 1 ohm (or higher!). So it will act as a tone control when following ANY speaker's impedance curve! OHM's LAW!  The Rowland amp has an output impedance BELOW 1 ohm - so it will have a FLAT (neutral) response with ANY speaker! 
roberjerman
4,319 posts
 
The Rowland is, by far, the BETTER amp!   Tube amps with their high output impedances act as "tone controls" and are NOT accurate (contrary to what the "golden ears" crowd says!). So burn me at the Stake for heresy! And I am a tube amp owner for 40+ years!
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