It is not all lost…
Lots of great advice here, As for me my P15 only needs 1
fuse as does the rest of my system…so Don’t know how to
advise. Save for 1 thing if the your fuse holder serves one on left
channel and the other the right channel…you will then need 2 identical
fuses…
Hope this helps
I had swapped two weeks before the master fuse , my XLR from the preamp to the mono amp. Audioquest Earth xlr vs Dragon. That’s when I first noticed that my system was getting louder. When I took the Purple out of the power station and put in my new SR Master, there was an increase in volume again. I made my preferred level control a little smaller.
There was also someone who reported that he installed the master in both directions. He chose the direction in which his system sounded louder. According to his experience, there should be differences in the volume of the direction. Yours seems to be dampened in both directions? 
Have you turned the master around again and paid attention to the S to R direction with the R in the holder? Donald reported that his master took a week. Maybe it needs some more time. According to your post about your loudspeakers, which I read with interest, I would have a different construction site. That’s not to say your speakers are bad, just old.
Which doesn’t have to be bad. Some old things are good in spite of everything and you cling to them. Your DSP and Bacch are probably already ironing out a few things. I like to build speakers myself. But also had classics wi it was worthwhile to carry out updates. If it were mine, I would have disassembled it and looked at the crossover. Also because of age. If there are electrolytic capacitors, they age and are best replaced with MKP capacitors. Where we end up back in the Netherlands. Tony Gee Capacitor Test. Especially the capacitors for tweeters is very important in terms of sound. This could be exchanged for a high-quality one. What also helps a lot is to bridge the capacitor with a small bypass capacitor. The duelund JDM silver is my favorite. That would probably be a major improvement. Many high-quality loudspeakers have inferior components on the crossover. Greetings Andrew
R in the the fuse holder ca was noticeably louder. So yes there’s a difference. The attenuation is more one direction. Maybe a half to 3/4 dB more.
I considered reworking crossover. I discussed wit Roger Russell. He designed with capacitors that he stated should last 40 to 50 years. In addition the surrounds he chose cloth versus foam or rubber and drivers were made internal. In addition i have doe scans wit and without dsp at 3 feet each speaker and At listening position
No DSP
With DSP
There’s no appreciable issues at crossover frequencies that suggest replacement is need. The bacch binaural plots show high frequency roll of but I chose not to upgrade to the more expensive microphones that are flat in 18 to 22K region since I am not using Bacch4mac to record and the more expensive ones were $1800 more. That the designer said would not improve the head transfer function noticeably for DSP
I appreciate you think I should replace my speakers or have them overhauled to make the master fuse sound and measure bette so they match your fuse experience.
My listening experience with systems from 500 K to over a million I felt I was not missing out on anything and some sounded ver lacking in comparison, but that was with M-1 fuse not the way the Master fuse has made my system sound at this point so far using Master yeah i feel I’d need to spend at least ja half a million or more on equipment fo like a 6000 fuse.
I listened to a podcast of an audio show recently that the paired new equipment to older classic speakers. The od caster stated some of the rooms with old speakers was outclassing the new latest designs for enjoyment to listen too. Speakers do wear out. Perhaps I update or buy others when the joy is gone.
The fuse has nothing to do with the speakers that the master does not sound working. That with the loudspeakers is a different construction site. As long as the sick are in order. Elkos not dried out. Tweeters that have ferrofloid in the air gap could also dry out over the years. Otherwise speakers are very durable if they are not damaged. The frequency response looks pretty good. Your loudspeakers probably emphasize the lower registers and have a powerful bass foundation. They must not sound slim or thin. It is often the case with modern systems that you have a very high hi-fi resolution but it sounds thin or cool. There are different capacitors and their sound and presentation are different. When you get to the crossover look at the tweeter capacitor. You could swap if you want. If you get a Duelund JDM Silver 0.01uF Capacitor to bypass your existing capacitor, you will get a much more detailed, open and harmonically great sound without the graininess that simple capacitors often have. There are also various resistors and coils. In your case I would start with the capacitors for the tweeter. Check out Tony Gee’s capacitor test. He also builds and optimizes Loudspeaker. He had helped me with the selection of components for my crossover. You wouldn’t believe what a small bypass capacitor alone can do for your System.
Greetings Andrew
There is no way you need or want to change the speakers for a fuse! My speakers are close to 20 years old and they were retailed for $50k, and I have not found a pair that I liked better yet!
I am looking for a pair of FR30 potentially because I want something smaller. But I need to make sure I like the sound so a trip to PSA maybe required. I am not changing anything for a fuse for sure! 
I replaced the Master with stock a few hours ago. The SQ is okay, but it sounds brighter and flat. I will soon go back to the Master. it is sounding better, unlike some of other fuses.
When you swap out your speakers they have a significant impact on the overall sound. This can mean that the previous optimizations do not fit and the game starts from the beginning.
The measurements were with the M1 or the Master ?
I have the maintenance manual and the crossover is behind the lower woofer and fairly accessible. I opened one u once one I had some mids out and was i wire socket not seated in an aircraft style connector. But sound now is open and bass goes flat to 16 Hz. Tweeters are not ferro fluid and not harsh the distribution of power over 24 tweeters per speaker means 250 volts of highs are no problem Sound is still modern but not thin. If i updated anything it would be 5 inch mids with ones with copper shorting rings but at 24 count and messing up crossover thats big risk for limited payback. Plus fact they are McIntosh collector pieces that sell immediately and come up for sale once or twice a decade. When someone dies.
The dueland is a good tip but need a place something that big would not rattle in a huge pressurized cabinet or break free. If i replaced an equivalent envelope cap would be a must.
The duelund JDM is not too big as a bypass for the existing one than 0.01uF. With my Mundorf Supreme silver/gold oil in front of the tweeter, I only heard how much the tweeter could be improved after I bridged the duelund as a bypass.
Fasten with a hot glue gun.
So I talked to Daniel Weiss, pretty much told me I’m going to need TWO fuses. Oufff the wallet took a hit.
I also asked him questions about the directionality of the fuses and the best way to orient them and he sent me this.
Can anyone clarifythis for me?
Well orientation matters. I would set volume one level at preamp fuses in same direction. Listen same source. Switch fuses then listen again. The master plays 3 DB louder in its most responsible direction if you look at the frequency response curves four post before this. Choose loudest. BTW the AM-1 plays even 3dB louder. I have yet to hear the Master sound better or even half as good. I am letting it burn in though but so far have not heard anything I’d pay $5.95 since for but maybe your system is different.
A 6 dB increase in the sound level corresponds to a doubling of the sound pressure. A 3 dB increase in the sound level corresponds to a doubling of the sound intensity. An increase in the sound level by 6 dB corresponds to a quadrupling of the sound intensity.
With that variation due to direction, sounds like a bad fuse to me and the distinct possibility that there is limited QC at best.
So set Fuses in the same direction, listen, then switch directions and pick the direction that was the loudest.
That’s what I felt would be the best way, but my concern is what Weiss said with the alternating current. Is the way my DAC is designed just not compatible with directional fuses? Is this true with other AC designed DACs?
I felt like his suggestions of having two fuses oriented in different ways just adds a whole new layer of complexity. I’m new to this stuff but I’m learning a lot here
It seems that metals have a lattice in which free atoms conduct current and can move better in a certain direction. Alternating current has a positive signal and a negative signal. If so, with a preferred direction of the conductor, the electrons conduct the current better with the positive signals, allowing them to move better. Then it can also be that they can return better with the negative wave (reflux).
As far as I know, the free electrons do not flow through the entire cable, but just bump into each other. They probably only move within their limits. Just my explanation.
So based on this picture, how would you install the fuses with the knowledge that mains voltage is AC?
It’s a question of where the hot phase is. Usually at the back of the device. So that the current flows from the device into the holder and from there back into the device. I would also put R in the holder for both fuses and S to the front of the device. Otherwise measure with a phase tester. Or with a resistance meter from the ICE socket to the holder. Other ways to listen how you like it best. Greetings Andrew
