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
I confronted the same issue when I was shopping for 300b tubes for my New Audio Frontiers amplifier which is often compared favorably with Mastersound. An amplifier can operate with a range of tubes but will only perform to its potential if the numbers line up. Your dealer probably knows the performance parameters your amplifiers requires of a tube. A modification could work for you but it’s chancy - every component in your amplifier was chosen for the way it works with the other components. Good luck.
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.
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.
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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
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.