Mastersound PF100 PSET Amplifier

[Falcon_wizard]

Feedback on mastersound amps for bi amping Coincident PRE

Good day Ellie,

Based on your extensive experience with the mastersound amps, I would appreciate your thoughts regarding what I have experienced to date with my setup. I have a 845 Evo, with a pair of Concident Pure Reference Extreme mkII speakers (94db with impedance between 6 and 10ohm throughout) , which are in effect a bass cabinet that goes from 20 to 110hz and a head that goes from 110hz up, each wired independantly. Toying with my father’s Mastersound 300B SE, To date, I have found the best sound to be when I bi amp the CPRE speakers with the 300B on the heads and the 845 evo on the bass, with my Space Tech Lab preamp feeding them both and using the volume on the 845 to match the bass with the 300B (which is direct).

I am very pleased with the mastersound amps and plan to stick with the brand, my evo 845 has been my favourite amp by far to date. I have shuguang 845Bs on it, and black treasure 300Bs on the 300B. I would appreciate your thought on what could be an ideal/optimized setup based on the mastersound amps available on these speakers. Would for example a pair of pf100 be substantially better than both integrated ? I guess like yourself it would be tricky to make it work in my room, The 300B being lower and generating less heat, can fit in my audio furniture, but who knows...

Thanks in advance for your thoughts...

Cheers

 

[AudioLibertarian]

Good day Ellie,

Based on your extensive experience with the mastersound amps, I would appreciate your thoughts regarding what I have experienced to date with my setup. I have a 845 Evo, with a pair of Concident Pure Reference Extreme mkII speakers (94db with impedance between 6 and 10ohm throughout) , which are in effect a bass cabinet that goes from 20 to 110hz and a head that goes from 110hz up, each wired independantly. Toying with my father’s Mastersound 300B SE, To date, I have found the best sound to be when I bi amp the CPRE speakers with the 300B on the heads and the 845 evo on the bass, with my Space Tech Lab preamp feeding them both and using the volume on the 845 to match the bass with the 300B (which is direct).

I am very pleased with the mastersound amps and plan to stick with the brand, my evo 845 has been my favourite amp by far to date. I have shuguang 845Bs on it, and black treasure 300Bs on the 300B. I would appreciate your thought on what could be an ideal/optimized setup based on the mastersound amps available on these speakers. Would for example a pair of pf100 be substantially better than both integrated ? I guess like yourself it would be tricky to make it work in my room, The 300B being lower and generating less heat, can fit in my audio furniture, but who knows...

Thanks in advance for your thoughts...

Cheers

Hey Falcon,

I am not familiar with your particular speakers, however I would venture to guess that the PFF100 monos will provide much more "wholesome" sound with a bigger soundstage, better separation, provided you room &set-up allow for it, and much better dynamic range & swing... Why are you using 300 se and 845 together? I would guess that your set up leaves much to be desired in such a set up, as issues of timing, phase shift , etc pop up, etc.... But if it floats your boat, who am I to argue... The Evo 845 in my experience is much more practical and musically natural sounding than ANY 300 based amp, and should sound pretty good on its own with your speakers..... You also don't mention the rest of your system, cables, etc., that are very important....

 

[jrmanders]

Does anyone know the rating and type of fuses inside Mastersound Evo 845. Bought 3 years ago the wide one with the wooden cheeks. Thanks.

 

[AudioLibertarian]

Does anyone know the rating and type of fuses inside Mastersound Evo 845. Bought 3 years ago the wide one with the wooden cheeks. Thanks.

I ve no idea, but your best bet is to contact Antonio at the Mastersound....

 

[jrmanders]

Thanks AudioLibertarian I’ll drop him a line.

 

[Falcon_wizard]

Hey Falcon,

I am not familiar with your particular speakers, however I would venture to guess that the PFF100 monos will provide much more "wholesome" sound with a bigger soundstage, better separation, provided you room &set-up allow for it, and much better dynamic range & swing... Why are you using 300 se and 845 together? I would guess that your set up leaves much to be desired in such a set up, as issues of timing, phase shift , etc pop up, etc.... But if it floats your boat, who am I to argue... The Evo 845 in my experience is much more practical and musically natural sounding than ANY 300 based amp, and should sound pretty good on its own with your speakers..... You also don't mention the rest of your system, cables, etc., that are very important....

To answer the question of Why, is really because I am experiencing with using two amps as a result of having the ability to do so with my speakers, so really I've been trying things out... the Evo845 when compared head to head with the 300SE was better in pretty much every way, but when I tried putting both to split the load, I got better air and overall a less compressed sound, but I as you said there are probably other trade offs and why I was seeking some thought as well from fellow audiophiles. The Eco 845 has been my main amp ans been great, But I had my dad's 300B on hand so was just able to try it.

Heres the full setup:
Sources: Resonessance Lab Mirus Dac with Audio sensibility (AS) Signature occ silver into preamp.
Kronos Sparta TT with Helena tonearm and Zyx Fuji cart with siltech occ silver cable into coincident Statement phono with airtight selected 12ax7 tubes (EH gold pins).
Phono goes to preamp with AS signature occ silver I/C
Preamp is a Space Tech Lab qa-113mk3 with EL32 tubes and philips 5UR4GYS Rectifier and 6sn7 input Tubes., fed into the Mastersound Evo 845 with an AS signature occ silver I/C, with Shuguang 845B tubes, 6sn7 drivers and JJ gold pins 12au7 inputs.
Speaker cables are two pairs of Audio sensibility Statement occ coper cables, into the Coincident Pure Reference Extreme mk II speakers.

Power cables are AS statement occ copper for amp/preamp and testament occ copper with the others. Each connected directly into furutech gtx duplex into a dedicated circuit.

Room is 11.5'x14' with system on the long side, treated with RPG bad panels behind the system and badarc panels on ceiling, and thick curtains behind as well.

Then I've tried putting the Mastersound 300B se on the heads of the speakers and evo845 on the bass cabinet. It has black treasures 300B tubes, 5687 drivers and gold lion 12au7 inputs.

The electronics and the speakers are on Modulum isolation platforms.

I think that's the full run down...! I have had these speakers for a short period, so I am still experimenting with the updated setup.
Any thoughts welcome...

Cheers

 

[Falcon_wizard]

Regarding my ability to fit the pf100 in my room, it would require some major change to my audio set-up, but it would be physically possible. My biggest concern would be the heat. With the Evo845, the generated heat in the summer requires us to open the windows during longer sessions to keep the smallish room at decent temperature and is somewhat borderline in terms of comfort. So if I was to double the generated heat, I would have to find a way to actively cool the room without generating noise, and I'm not sure how I could do that. Any experience on doing this would be welcome.

Cheers

 

[DSkip]

Regarding my ability to fit the pf100 in my room, it would require some major change to my audio set-up, but it would be physically possible. My biggest concern would be the heat. With the Evo845, the generated heat in the summer requires us to open the windows during longer sessions to keep the smallish room at decent temperature and is somewhat borderline in terms of comfort. So if I was to double the generated heat, I would have to find a way to actively cool the room without generating noise, and I'm not sure how I could do that. Any experience on doing this would be welcome.

Cheers

Hello Falcon,

I am working with a client right now who is about to pull the trigger on the PF100. If/when this happens, I should be able to comment on heat and compare directly with the Evolution 845. I should get some play time in on them before he picks them up. He currently owns the Evolution 845 and would be making the same jump. I'll keep you posted.

 

[bazelio]

Out of curiosity, what kind of damping factors are provided by these high power SET amps such as the PF100 and Absolares?

 

[Falcon_wizard]

Hello Falcon,

I am working with a client right now who is about to pull the trigger on the PF100. If/when this happens, I should be able to comment on heat and compare directly with the Evolution 845. I should get some play time in on them before he picks them up. He currently owns the Evolution 845 and would be making the same jump. I'll keep you posted.

Sure thanks, looking again in detail at the space I have in my room, it would be very hard to fit the pf100s, so I'll try to maximize my Evo845 as much as possible, with or without a second amp to help split the load. There may be possible gains via tube upgrades to get the additional openness I heard when adding the 300B SE on the Speaker Heads (110hz and up)

 

[DSkip]

Sure thanks, looking again in detail at the space I have in my room, it would be very hard to fit the pf100s, so I'll try to maximize my Evo845 as much as possible, with or without a second amp to help split the load. There may be possible gains via tube upgrades to get the additional openness I heard when adding the 300B SE on the Speaker Heads (110hz and up)

If you are using the Evolution in Direct mode, then don't worry about the 12au7 as they aren't in the signal path. For upgraded power tubes I would suggest looking at the PSVane 845-T Natural. I've rolled some 6sn7 in a few amps' driver stage (including the Evolution 845 and haven't heard much difference. I might not be getting the right tubes though to hear a difference.

 

[Falcon_wizard]

If you are using the Evolution in Direct mode, then don't worry about the 12au7 as they aren't in the signal path. For upgraded power tubes I would suggest looking at the PSVane 845-T Natural. I've rolled some 6sn7 in a few amps' driver stage (including the Evolution 845 and haven't heard much difference. I might not be getting the right tubes though to hear a difference.

My understanding is that one triode from the input tubes is used when in direct mode. Surprisingly, I’ve had better result with feeding my oreamp via a line input rather than direct. Lowest noise in input tubes was key to get the best detail and resolution. Like yourself, swapping driver tubes did not show any difference I could notice. For power tubes, on my previous amp I had the regular shuguang 845 which I upgraded to the psvane 845 T2, however after two premature tube failures/reliability issue, I went to shuguang 845B.

 

[Ron Resnick]

Has anyone had any recent experience with the MastersounD PF100?

 

[Atmasphere]

Has anyone had any recent experience with the MastersounD PF100?

Are you looking for a high powered SET?

One thing that is a real problem for such amplifiers is bandwidth. For that reason 7-8 Watts is about all you can get and still have 'hifi' (20-20KHz) bandwidth.

This is due to limitations imposed by the output transformer. Its much easier to get bandwidth if the amplifier is push-pull (or if there is no output transformer at all...). Bandwidth is important if the amp is zero feedback. You need to keep phase correct so that the sound stage can be properly reproduced. Phase shift can also cause tonality issues. If you're running feedback the feedback can correct these things depending on how much is used. But most SETs are zero feedback so bandwidth becomes important if you are looking for the best sound.

That is why the lower power SETs, like those based on the type 45 power tube, are considered the best sounding. Its nothing to do with the linearity or bandwidth of the tube and everything to do with the bandwidth allowed by the output transformer. With the 0.75Watts that a 45 makes in class A, the output transformer can be quiet wide bandwidth. Of course you need a really efficient speaker to work with it, or else headphones.

 

[bazelio]

Are you looking for a high powered SET?

One thing that is a real problem for such amplifiers is bandwidth. For that reason 7-8 Watts is about all you can get and still have 'hifi' (20-20KHz) bandwidth.

This is due to limitations imposed by the output transformer. Its much easier to get bandwidth if the amplifier is push-pull (or if there is no output transformer at all...). Bandwidth is important if the amp is zero feedback. You need to keep phase correct so that the sound stage can be properly reproduced. Phase shift can also cause tonality issues. If you're running feedback the feedback can correct these things depending on how much is used. But most SETs are zero feedback so bandwidth becomes important if you are looking for the best sound.

That is why the lower power SETs, like those based on the type 45 power tube, are considered the best sounding. Its nothing to do with the linearity or bandwidth of the tube and everything to do with the bandwidth allowed by the output transformer. With the 0.75Watts that a 45 makes in class A, the output transformer can be quiet wide bandwidth. Of course you need a really efficient speaker to work with it, or else headphones.

Take the 845 or let's get even more extreme with the 833A,C power triode in a single ended configuration. With the latter, you're talking 150W RMS and transformers are designed with 8 to 66000 Hz bandwidth (core saturation 35 Hz @ 150W RMS). Now, granted, this is an expensive transformer but this is an expensive hobby. I think you might be alluding to the interrelated nature of bandwidth and phase, but haven't said so outright. And this is where my question lies. It's is a complex topic but my empirical observation seems to be that in order to have a flat phase response within the audible frequency spectrum, then the bandwidth of the transformer actually needs to extend out to 200ish kHz. I.e. I can't just let my transformer start to roll off shortly after 20 kHz or else my phase response will be all wonky. And when we're dealing with smaller cores for low power SETs, then we can start to design to those specs (roughly speaking). E.g. Monolith:

 

[Atmasphere]

Take the 845 or let's get even more extreme with the 833A,C power triode in a single ended configuration. With the latter, you're talking 150W RMS and transformers are designed with 8 to 66000 Hz bandwidth (core saturation 35 Hz @ 150W RMS). Now, granted, this is an expensive transformer but this is an expensive hobby. I think you might be alluding to the interrelated nature of bandwidth and phase, but haven't said so outright. And this is where my question lies. It's is a complex topic but my empirical observation seems to be that in order to have a flat phase response within the audible frequency spectrum, then the bandwidth of the transformer actually needs to extend out to 200ish kHz. I.e. I can't just let my transformer start to roll off shortly after 20 kHz or else my phase response will be all wonky. And when we're dealing with smaller cores for low power SETs, then we can start to design to those specs (roughly speaking). E.g. Monolith:

View attachment 112831

We're on the same page. I see I didn't mention that to get phase correct, the bandwidth has to extend to 10th the cutoff or 10X the cutoff depending on low frequencies or highs. So I'm 'saying it outright' here. If you have enough feedback this sort of bandwidth isn't needed, but that is moot when we're talking about SETs which are usuall zero feedback.

If those bandwidth numbers are real that's impressive! Once you get past 100Khz its not much of a problem since there is very little information above 10Khz anyway- so a few degrees of phase shift at 20KHz isn't a problem. On the bottom end though you can see how a cutoff at 6-7Hz can rob impact in the bottom octave and a half. Since you usually need multiple subs to break up standing waves in most rooms this probably isn't an issue if you let the subs do the work below 50Hz.

 

[bazelio]

I don't think the bandwidth in that chart is terribly unusual once you get into the good stuff. Those were standard product offerings on Monolith's website. My point was just that I would expect, at the price levels of Mastersound and such, that you're actually putting your money into well-designed OPTs. Because it actually is possible to have wide bandwidth ("hifi") transformers beyond 8 W.

 

[bazelio]

If those bandwidth numbers are real that's impressive! Once you get past 100Khz its not much of a problem since there is very little information above 10Khz anyway- so a few degrees of phase shift at 20KHz isn't a problem. On the bottom end though you can see how a cutoff at 6-7Hz can rob impact in the bottom octave and a half. Since you usually need multiple subs to break up standing waves in most rooms this probably isn't an issue if you let the subs do the work below 50Hz.

Do you have any thoughts on where phase rotation becomes audible at 10kHz? For example, I was looking at a Tango spec that showed -3dB at 100k and about 6 degrees at 10k. Is 6 degrees already audible?

 

[Atmasphere]

Do you have any thoughts on where phase rotation becomes audible at 10kHz? For example, I was looking at a Tango spec that showed -3dB at 100k and about 6 degrees at 10k. Is 6 degrees already audible?

6 degrees sounds like a lot when you're only -3dB @100K. The thing that gets tricky about transformers though is how the taps (even if not used) change the bandwidth due to the inductance of the winding in parallel with the interwinding capacitance. I'm glad I don't design transformers for a living...

 

[bazelio]

6 degrees sounds like a lot when you're only -3dB @100K. The thing that gets tricky about transformers though is how the taps (even if not used) change the bandwidth due to the inductance of the winding in parallel with the interwinding capacitance. I'm glad I don't design transformers for a living...

And the impedance characteristics of the transformer load!

The Tango (kinda hard to read, but I think that's showing about 6 degrees at 10K)...