Biasing The Ref-150(SE)

CDLehner

CDLehner

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I love the fact, that the 75 has the large meters on the front; that double for biasing.

Obviously, the 150 doesn't have them out front; but is there something inside the case? Or do you need a good, old-fashioned (and potentially dangerous...lol) Voltmeter?
 
From what I have read, you can still put the KT-150s in the non-SE Ref 75 but the Transformers in the SE are optimized for the KT-150 tube. Not sure how much sonic difference that makes but presumably some.
 
With KT-150's you'll get a bump in SQ. With the SE and 150's, even more of a bump in SQ. Every step brings more and better.
 
cmalak said:
From what I have read, you can still put the KT-150s in the non-SE Ref 75 but the Transformers in the SE are optimized for the KT-150 tube. Not sure how much sonic difference that makes but presumably some.
Click to expand...

Who told you that? If you send a Ref 75 amp to ARC to have it upgraded to SE status, they do not change out the output transformers. To my knowledge, the factory SE version has the same output transformers as the Ref 75. I have run the KT-150s in my Ref 75 since shortly after I bought it. They work perfect and the cover does fit on with the KT-150s in place.
 
I may be wrong. I thought I read one if the changes entailed in the SE line was a different transformer for the KT150s. If that's wrong, I stand corrected.
 
cmalak said:
I may be wrong. I thought I read one if the changes entailed in the SE line was a different transformer for the KT150s. If that's wrong, I stand corrected.
Click to expand...

I think it's wrong. No change in the power transformer or output transformers when you send in a Ref 75 to be upgraded to the SE version so I doubt there is a change in the production version either. There are few if any amps on the market now that are truly optimized to run the KT-150s to extract close to their maximum output power. These tubes are beasts and are loafing in most circuits they are used in which is good from the standpoint of long life. Assuming your amp can handle the KT-150, substituting them for KT-88s or 6550s should be an immediate upgrade in sound for most users.
 
I wouldn't let the lack of a meter on the Ref 150 be the determining factor on a purchase. You just need to stick the volt meter probes into holes in the circuit board. Then, turn a screw-like thing with a plastic screwdriver to adjust. I admit it was scary at first, but it really is pretty straight-forward. If a dealer can show you the procedure, you might feel better.

More importantly, how does the 75 sound compared to the 150. In my situation, the 75 didn't sound as good as the 150 in certain situations.
 
Deafone said:
I wouldn't let the lack of a meter on the Ref 150 be the determining factor on a purchase. You just need to stick the volt meter probes into holes in the circuit board. Then, turn a screw-like thing with a plastic screwdriver to adjust. I admit it was scary at first, but it really is pretty straight-forward. If a dealer can show you the procedure, you might feel better.

More importantly, how does the 75 sound compared to the 150. In my situation, the 75 didn't sound as good as the 150 in certain situations.
Click to expand...

And what situation might that be? The difference in output is 3dB between the Ref 75 and the Ref 150.
 
Deafone said:
I wouldn't let the lack of a meter on the Ref 150 be the determining factor on a purchase. You just need to stick the volt meter probes into holes in the circuit board. Then, turn a screw-like thing with a plastic screwdriver to adjust. I admit it was scary at first, but it really is pretty straight-forward. If a dealer can show you the procedure, you might feel better.

More importantly, how does the 75 sound compared to the 150. In my situation, the 75 didn't sound as good as the 150 in certain situations.
Click to expand...

Are you saying that the cover needs to be removed from the 150 to check bias?
 
Yes , you have to take it out.
But the correct way is with a digital meter. The REF75 analog meter is not as accurate as the digital voltmeter .

And There are many parts changed from normal to SE

I'm going to look for the list


Sent from my iPhone using Tapatalk
 
highEndguy said:
Yes , you have to take it out.
But the correct way is with a digital meter. The REF75 analog meter is not as accurate as the digital voltmeter .

And There are many parts changed from normal to SE

I'm going to look for the list


Sent from my iPhone using Tapatalk
Click to expand...

Please let us know when you find your list. To my knowledge, ARC isn't publishing a list of parts that are changed out in the upgrade and I didn't think it was "many." What I do know is that the 3 most expensive parts in the amp (power transformer and output transformers) are not changed out.
 
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