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
The Pvsane 845T is manufactured to the Amperex/RCA 845 standard with a rated filament current of 3.25A at 10V. If your amp uses "standard" 845 tubes, the Pvsane should be drop in replacements. What tubes are in the amp now?
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.
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.
,
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
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?
HI All,
This gets a bit more complicated,I recieved a e mail from mastersound which advised the only way they could advise on the value of the resistor as a mod for the 845t was if they physically had the valve so a engineer could do the required checks.
I dont see that to be rocket science and would have thought they would or could do this quite easily.Even then they stated that it could not be a definite solution in regard to determining the exact value of the resistor.
One would have thought it would be in their customers interests to go down this path and advise customers bearing in mind the PVsane 845T is a god valve and likely wanted to be used by mastersound 845 Amp owners .
If that was not enough I got home last night and was watching TV when the PH5 Pre Amplifier switched on by itself.I thought I had ghosts.checked the on off switch this was okay reconnected the power with the switch removed it still came on.There was a small LED flashing on a circuit board on the same side of the switch.
Both amps are going back to mastersound for repair.It never rains but it pours.Anybody know of a Valve P0wer Amp which would be as good as the Compact 845 which is integrated.going to keep the PH5 when fixed
HI Brf
Sorry for not anwsering your questions .The 845 compact is shiped with standardc 845 Shuagang valves.The shuagang 845B is somewhat different to the 845T hence the need for the mod.Albeit the 845B is compatible with the compact 845 without any modifications.
Re operating specs you are quite correct but I find it very difficult to get detailed information from them.I think this is caused to a considerable extent by the language barrier.They should suply it withe the operators manual which is also scant in this regard.
Brf, the first responder to the OP, is correct. The 845-T operates to the RCA/Amperex spec, as does the stock 845A tube, and the B. Every Mastersound Compact 845 amp I've ever seen shipped stock with the prosaic Shuguang 845A, a cheap'n'cheerful power tube. 845-T is a drop-in replacement for 845A and 845B, but it is not a clear improvement over 845A, while 845B generally is. If for some reason you don't want to use 845B, consider the cryogenic 845A sold by ATSI.

Precise bias is desired, but these SET amps have enough latitude to allow drop-in replacement for RCA-spec tubes. If you want to address tube-to-tube inconsistency, then sure have a tech install the right resistor. But doing so is prompted by wanting to address inconsistencies rather than an intrinsic incompatibility with the 845-T. My guess is Mastersound's techs in Europe have no experience with the 845-T and are reluctant to endorse a tube substitution they haven't previously tried.

Phil
Cobra /Phil
Thanks for that,am I right in understanding that the 845 t would be ok as drop in and have no adverse effect on the existing resistors.Plus, that the 845B is better than the 845T. The amps are going back tomorrow for repair can you suggest any upgrade that would be worth doing such as capacitors etc which would be worth while.Might as well have it done while they are in the hands of a competent tech from Jordan Acoustics in scotland.
Thanks Guys
Patal,

Unless something has been done to your amp to make it incompatible with RCA-spec 845 tubes -- and if it's running 845A, nothing has -- you can replace 845A with 845-T or 845B. It may be that if subsequently you had the bias checked, testing might suggest that a precise adjustment to the value of the associated resistors can dial in the amp more perfectly. Maybe. But you're not going to harm anything by that simple change of tubes.

Whether you will think the 845-T is better sounding than the 845B, or not, is your call. I did not find the 845-T to have clear advantage to warrant using it, and in my own experience with the tube and observation by others who have reported results to me, I have to conclude the 845-T is less reliable than the 845B. Others may have a different experience. Other than the B tube, my suggestions for not-too-exotic alternatives are the Sophia 845MkIII, and the cryo'd 845A sold by ATSI. Interesting exotic alternatives include the KR -- likely requiring some changes to the filament supply -- and the super-scarce Elrod; expensive! Or for that matter, go hunting for a pair of NOS RCA or Amperex. Also dear.

The major area for upgrade that I suggest you have your tech investigate is recapping the power supply. The power supply caps have a strong influence on the voicing of vivid tube amp like this, and on its dynamic character. The Mastersound SET amps sound a little "slow" compared to my Audion equivalents, to me, and I think this can be easily corrected by judicious selection of capacitors to recap the power supply, and you can pick up more transparency in the bargain. Certainly while a tech has the amp for repair it is easy enough for him to precisely bias the amp for the tubes you choose, too.

Phil
I agree with everything that Phil wrote especially about new caps. I recapped my 845 amp with both teflon V-Caps which once broken in, offer the amp more speed and transparency. I also tried Mundorf M-CAP Supreme Silver / Gold & Oil caps which offer a very organic rich sound without sacrificing transparency. Two different excellent sounding caps, but in the end I kept the Mundorfs.
Dear Phil

Many thanks for that useful information
Hi Patal, let us know how you get on because I too have a Compact 845 from Jordan, so will be very interest in the outcome

Jonathan.
Hi Jonathan,
Will do .The amp is curremtly back in Scotland with Jordan for repair and I have asked the dealer to ask his tech over there for his opinion in regard to modifying the resister.This was asked prior to recieving the excelent e mail from Phil.Mastersound are still of the opinion that the modification is required.However they cant offer much more advice as they insist on seeing the 845T valve to test/check it.
The general feedback seems to favour the 845B.
Regardless will gladly let you know the outcome.
Regards
Alan (Patal)
Hi Jonathan ,
The amp is now back and running with the 845Ts and sounds great.The tech thoroughly checked it out and put it on test for over a day with the 845Ts and advised it ran fine with no problems.Have not tried the 845Bs but the 845Ts sound fantastic and they are nowhere near burned in.
I also bought a DAC from a company called Black Lion in Chicago called the Sparrow (White)this lifted the system to new frontiers totally.More than pleased.
Kind Regards
Patal
Hi Patal,
Glad you like the amp more now with the Pvsane T's. Did the tech need to mod the amp in anyway or did the tubes just drop in and need re-biasing?? I have some Psvane T's here now but haven't tried them yet. Still lovin' the 845A's at mo. If the T's are better then it will be seriously good,
Thanks for getting back to me,

Jonathan
Hi Jonathan,
He put in on test for over a day and done the required measurements and said there was no problem whatsoever.He did say there was a significant re biasing but there was still plenty of room up or down to spare. Re 845 Ts they sound very good still burning in, indicators say they can take 70 Hrs so using Isoteck burn in disc to help the process.
Hope this helps
Patal
The 845Ts have now been running for approximately forty hours and getting better all the time .Brightness and rough edges of high frequencies are slowly fading away .Soundstage is excellent .Vocals extremely clear and vibrant.No signs of amp overheating or valve problems.Will try these for a while give them a chance to settle down then try the 845B and determine the difference.
Regards
Patal
Another problem or perhaps not.The 845Ts have been running for approx 45 Hrs ,Sound is fine ,however there is a very very low buzz which does not effect the listening,coming from both speakers.This can only be heard when the music is off.the level of the buzz does not increase or decrease with the volume control.Could it be Bias or Hum adjustment which is required.ANY OTHER 845 COMPACT INTEGRATED OWNERS DOES THE LARGE CENTRE TRANSFORMER MAKE A AUDIBLE HUM/BUZZ.
Thanks
Patal
“…845-T is a drop-in replacement for 845A and 845B, but it is not a clear improvement over 845A, while 845B generally is….”
I can’t believe that someone having an amp of such a caliber could write this. The information is misleading and not true.
I’ll start from the beginning.
I’ve been using Mastersound 845 for three years, power tubes Shuguang 845B. I lost two of them in that period, one after 6 months and another one after two years (was plying 1200-1300 hours a year). After having done my homework I’ve decided to try Psvane 845T MkII. The difference between 845B and Psvane 845T is obvious, no need to do ABA listening tests, it’s obvious and instantly audible.
The thirst thing you notice immediately , Psvane is a cleaner sounding tube, less noise.
Psvane 845T MkII has much better HF extension and is a better resolving tube. You get better detail across the whole frequency range. There is more low level detail, soundstage has more “air”, more ambience info. Images are more precisely drawn within the soundstage, localization of instruments more stable. 845B images are a bit vague in comparison. Overall Psvane 845T has better clarity, better transparency and slightly improved dynamics.
If that’s not an improvement then what is?
I’ve been using Mastersound 845 for three years, power tubes Shuguang 845B. I lost two of them in that period, one after 6 months and another one after two years (was plying 1200-1300 hours a year). Recently I've replaced 845B tubes with Psvane 845T mkII. The difference between 845B and Psvane 845T is obvious and instantly audible.
The thirst thing you hear Psvane is a cleaner sounding tube, less noise.
Psvane 845T MkII has much better HF extension and is a better resolving tube. You get better detail across the whole frequency spectrum. There is more low level detail, soundstage has more “air”, more ambience info. Images are more precisely drawn within the soundstage, localization of instruments more stable. 845B images are a bit vague in comparison. Overall Psvane 845T has better clarity, better transparency and slightly improved dynamics.