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Mastersound Compact 845 with Pvsane 845T

I own a Mastersound Compact 845 and Mastersound PH5 Pre Amp and orderd two Pvsane 845 T Valves.I was advised by the valve supplier that they would work ok as they were the top of 845 range of valves.I was then advised by my dealer that a mod had to be done to the Cathode Resistor on the Compact 845 to take account of the voltage increase.Otherwise the uit could in the future fail.Any body out there using the 845 T in the compact without modification to the resistor should be aware of this .Any comments welcome
patal
patal OP
21 posts
 
Thanks for that,the existing tubes are the originals as supplied with the amp.When contacting mastersound they said an engineer had to physicaly look at the valve.Cant understand that. Any way all the specs have been sent to them will wait and see what comes back .Another problem has arisen.Cant Bias the right right valve .Using the bias socket at the rear of the am p I can only get it to read 5.8 Volts max,albeit continuing to turn it turns the valve red (Ugh )immediately turn it down again.Can only gage level through comparing brightness of tubes .Trying to get info our of Mastersound is a nightmare,Trouble is I am working in Abu Dhabi which does not help as there is not a abundance of engineers who can tackle this .Albeit Dubai Audio have kindly offered to look at it.Patience is a virtue.
phaelon
1,038 posts
 
Sorry for your troubles Patal. I’m very lucky to have a friend who is a gifted tech (even though you make me wait too long, K). So far, I have never found the tubes provided by any manufacturer to be right for me, so by all means, keep searching for upgrades. Just determine what your amp requires and then make sure the new tubes meet the spec. Tubes make a difference.
patal OP
21 posts
 
,
You are lucky ,the amp sounds okay but I dont want to use it incase I damage something inside due to the wrong bias voltage.Probably best to wait till i get back home to Ireland next year ,but even that is a long time to be using it and putting it at risk.It is still under warranty so I believe the best option is to let Dealer/Supplier sort this out.Lets see what happens
jrmanders
54 posts
 
Hi, yes I spoke to Mastersound on the phone the other day and he confirmed that if I want to use the Psvane 845-T's a mod would need to be performed on my Compact 845.
brf
1,699 posts
 
Why doesn't someone simply ask Mastersound to provide the Compact 845's operating specs for the 845 tube???? I know of a couple of Mastersound owners who use the Shuguang 845B tube which has the same operating specs as the Psvane 845.

Is the Mastersound Compact 845 shipped with standard Chinese 845 from Shuguang?
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