These speakers are well reviewed (Infinity Primus P363 Floorstanding Loudspeaker Review — Reviews and News from Audioholics), so I decided to buy them on a whim to see what all the fuss was about. Product specs at Primus 363 - Infinity
Well, they're not half bad. They're actually listenable and one of the few speakers I've owned that pairs well with my NAD C720BEE integrated.
Positives:
Not-so-Positives:
In short, .. I think there are definitely some improvements that these speakers could benefit from. Some are obvious to me, and I'd like your feedback on others that may not be that obvious. As it stands, these are a great value, but I'm sure they can be improved somewhat, without busting the bank.
Well, they're not half bad. They're actually listenable and one of the few speakers I've owned that pairs well with my NAD C720BEE integrated.
Positives:
- They do the midrange very respectably, if a tad forward
- Likewise, the treble is clear as a bell, with the faintest touch of sibilance
- Decent mid bass, for their size
Not-so-Positives:
- A bit flabby bass
- I think they could benefit from some cabinet bracing
- May benefit from some judicious cabinet lining
- All caps in the crossover are electrolytic
In short, .. I think there are definitely some improvements that these speakers could benefit from. Some are obvious to me, and I'd like your feedback on others that may not be that obvious. As it stands, these are a great value, but I'm sure they can be improved somewhat, without busting the bank.
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Disassembling one of the speakers, here's what I notice
PIcs:
cabinet, cabinet with drivers being removed, midrange, tweeter, woofer
- The midrange is enclosed within a plastic cup with some sort of stuffing in it
- The midrange and the woofers appear to be shielded and have a metal can of some sort enclosing the motor. This can rings a bit and has a rather thick lip.
- The woofer basket ribs could use some dampening
- The Tweeter is flimsy but sounds good and looks to have some sort of tar / goop on the back. That has to help with dampening
- All drivers wired via flimsy crimp spades
- Electrolytic caps
- Some of the interior cabinet window braces ring when rapped with a knuckle
- The rear wall of the cabinet directly behind the woofers has no lining
- The bottom and top walls of the cabinet have no lining
- The bottom third of the cabinet appears to have insufficient bracing (maybe an effort to create some reverb/harmonic resonance)
- The reflex port is barely 1" in length (got to be tuned fairly high as a result. possibly for midbass emphasis)
- MLTL theory would lead me to believe that situating the port closer to bottom would yield more bass
PIcs:
cabinet, cabinet with drivers being removed, midrange, tweeter, woofer
Attachments
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Next, modification plans
Please respond with any potential tweaks I might have missed
Thanks
- Add some ductseal to the midrange lip, followed by a bit of felt to kill unwanted reflections
- Likewise for the woofers
- Add some peel & seal (adhesive tar sheets) to the woofer basket ribs to dampen them
- Dampen and/or stiffen some of the flimsier braces
- Add more cabinet bracing as needed
- Remove existing cabinet lining, an add some peel & seal to the cabinet walls before replacing the lining
- Add more lining to the bottom of the cabinet and directly behind the drivers
- Cut off crimps and solder wires to the drivers
- Cabinet feet
- "May" consider bypass film caps on the tweeter and midrange crossover
Please respond with any potential tweaks I might have missed
Thanks
Completed the following tweaks on one speaker and can say the project ( or at least half of it) was a success
Applied duct seal to the drivers/ basket legs
Used cotton wadding around the midrange basket legs
Applied peel&seal ( 2 layers) to the cabinet where possible
Applied peel&seal to parts of the window brace
Applied peel&seal to the midrange plastic cup
Added fiberglass lining (2") to unlined parts of the cab ( below the port, at the top of the cab and directly behind the bass drivers )
So far, I've lost a smidgen Of bass volume but it's become more even. I can actually follow a bass line. Bass extension doesn't seem to have suffered audibly
The midrange is also less busy (less spurious cabinet resonances) and its easier to listen to and follow a song
Applied duct seal to the drivers/ basket legs
Used cotton wadding around the midrange basket legs
Applied peel&seal ( 2 layers) to the cabinet where possible
Applied peel&seal to parts of the window brace
Applied peel&seal to the midrange plastic cup
Added fiberglass lining (2") to unlined parts of the cab ( below the port, at the top of the cab and directly behind the bass drivers )
So far, I've lost a smidgen Of bass volume but it's become more even. I can actually follow a bass line. Bass extension doesn't seem to have suffered audibly
The midrange is also less busy (less spurious cabinet resonances) and its easier to listen to and follow a song
Hi,
If they are anything like these they should be pretty good :
Infinity Primus 360 loudspeaker | Stereophile.com
They are tuned to to around 45Hz, and IMO dropping the tuning
would not hurt, 38Hz is 1/4 octave lower, 33Hz 1/2 an octave.
IMO its good if a siting can be found that works with such a tuning.
I'm ambivalent to upgrading capacitors, especially when its
unnecessary. However if you feel like it upgrade the series
capacitors only, these are in the high pass sections to the
midrange and tweeter. Don't upgrade parallel low pass.
YMMV but I'd suggest : Solen Fast Caps
rgds, sreten.
If they are anything like these they should be pretty good :
Infinity Primus 360 loudspeaker | Stereophile.com
They are tuned to to around 45Hz, and IMO dropping the tuning
would not hurt, 38Hz is 1/4 octave lower, 33Hz 1/2 an octave.
IMO its good if a siting can be found that works with such a tuning.
I'm ambivalent to upgrading capacitors, especially when its
unnecessary. However if you feel like it upgrade the series
capacitors only, these are in the high pass sections to the
midrange and tweeter. Don't upgrade parallel low pass.
YMMV but I'd suggest : Solen Fast Caps
rgds, sreten.
I did line the walls with tar sheets
The mids already come with their own plastic "cup" chambers. I did line the outer walls of the cup with some peel &seal tar sheet pieces
I'm pretty sure they're the same. The x-over even has "primus 360" silkscreened on it
If I do any crossover mods, they'll be limited to adding bypass film caps to the mid and high series caps
Thanks
I have had the opportunity to play with the Primus 360 a bit. Actually, I had to rework the tweeter crossover to replace the tweeters with an alternative unit after one tweeter was destroyed by the original owner.
These are fairly good speakers, but I did find that the tweeters (I measured the working one) start rolling off at around 17kHz. Also, the woofers are high-Qts (for a bass reflex enclosure) and can sound boomy. The current owner resorted to stuffing the port.
They were impressive in spite of the lower-grade materials used in construction. I doubt that changing capacitors will yield a major improvement.
These are fairly good speakers, but I did find that the tweeters (I measured the working one) start rolling off at around 17kHz. Also, the woofers are high-Qts (for a bass reflex enclosure) and can sound boomy. The current owner resorted to stuffing the port.
They were impressive in spite of the lower-grade materials used in construction. I doubt that changing capacitors will yield a major improvement.
Good to know. What tweeter did you end up using as a replacement (and did it physically fit the recess without the need for cosmetic surgery)?
I dont' intend to replace the caps,.. at the most , I'll bypass the tweeter and midrange series NP electrolytics with inexpensive film caps. I realize that this is a budget speaker. I've spent $15 tweaking them so far (granted I already had most of the stuff lying around).
Re. the woofers, I suspected that they were high-ish Qts from their heft (or lack thereof) . I briefly plugged the port with a cushion and didn't seem to lose much bass (further affirming my theory that the port doesn't do much in this design: . it's about 1" long , max ).
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Hi,
TBH I don't know, I know the theory about gas tight spade connectors,
but don't trust it. But then again IMO soldering a spade and its connection
is likely to be better than bare wire ends, its really a long term issue IMO.
IMO if you have spades, solder the whole lot, that will be gas tight.
rgds, sreten.
It was Audax TM025F1 fabric dome tweeter see Audax TM025F1 1" Textile Dome Tweeter 276-152
I did indeed have to do a bit of baffle modification.
I ran a comparative sweep this morning with ARTA with both speakers in the same location. On the frequency response (1/9 smoothed), I observe the modified speaker to be slightly less peaky and slightly quieter. I couldn't make out any meaningful changes on the decay (bit disappointed in that). I ran the tests indoors, so maybe I need to repeat outdoors.
Pictures
1. Damping the woofer with peel & seal around the basket legs and duct seal all over. Note the use of duct seal to fill the constriction between the magnet cover and the basket.
2. I also used a bit of teased out cotton wool around the midrange driver basket legs to kill secondary reflections
3. The vast empty volume at the bottom of the cabinet (below the port). This has been lined with half thicknesss R-13 held in place with spray adhesive)
4. damping the midrange cup
5. When I opend up the 2nd cabinet, I was horrified to discover that the midrange cup was loose. I was further confounded to notice that this cup was initially screwed in from the inside of the cabinet with no easy way of refastening it. What I resorted to after removing the screws (the cup was loose anyway) was drill 2 tiny matching holes in the baffle, and use a thin nut &bolt to keep things together. Once I was satisfied that everything had mated flush, I then proceeded to caulk the life out seam. the You can see my salvage attempt in the last pic (with the bolts visible at about 5:30 and 11:30 in the picture, roughly)
1. Damping the woofer with peel & seal around the basket legs and duct seal all over. Note the use of duct seal to fill the constriction between the magnet cover and the basket.
2. I also used a bit of teased out cotton wool around the midrange driver basket legs to kill secondary reflections
3. The vast empty volume at the bottom of the cabinet (below the port). This has been lined with half thicknesss R-13 held in place with spray adhesive)
4. damping the midrange cup
5. When I opend up the 2nd cabinet, I was horrified to discover that the midrange cup was loose. I was further confounded to notice that this cup was initially screwed in from the inside of the cabinet with no easy way of refastening it. What I resorted to after removing the screws (the cup was loose anyway) was drill 2 tiny matching holes in the baffle, and use a thin nut &bolt to keep things together. Once I was satisfied that everything had mated flush, I then proceeded to caulk the life out seam. the You can see my salvage attempt in the last pic (with the bolts visible at about 5:30 and 11:30 in the picture, roughly)
Attachments
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Here, you can see a cabinet being lined with doubled up peel & seal.
Finally, I also snipped off all the connectors and soldered the wires directly to the driver terminals. The original spades appear to be of the cheapest variety possible and don't inspirte any confidence.
Finally, I also snipped off all the connectors and soldered the wires directly to the driver terminals. The original spades appear to be of the cheapest variety possible and don't inspirte any confidence.
Attachments
In conclusion:
Benefits of the modifications:
* Midrange brought back in line (was a bit forward before)
* Clarity
* More even bass, fuller sound
* Somewhat less resonant cabinet
* Less internal reflections
* No more worries about the midrange cup falling off. I caulked both cups, just to be sure. Shame on you, Infinity for allowing speakers to leave your factory with this kind of an issue (I believe I'm not the only one to have this issue).
* No more worries about wires coming loose (soldered)
Drawbacks of the modification
* Maybe just a touch less bass (or maybe less peaky)
* Sound is a little less revery/live (if you consider that a drawback)
Remaining issues:
* I think the remaining weak spot in this design is the tweeter. It's a "BIT" sibilant. I'm guessing that perhaps the crossover is a touch too low. The cost to replace the unit and rework the crossover accordingly may not be worth it. Any suggestions.
All in all, a worthwhile modification
Benefits of the modifications:
* Midrange brought back in line (was a bit forward before)
* Clarity
* More even bass, fuller sound
* Somewhat less resonant cabinet
* Less internal reflections
* No more worries about the midrange cup falling off. I caulked both cups, just to be sure. Shame on you, Infinity for allowing speakers to leave your factory with this kind of an issue (I believe I'm not the only one to have this issue).
* No more worries about wires coming loose (soldered)
Drawbacks of the modification
* Maybe just a touch less bass (or maybe less peaky)
* Sound is a little less revery/live (if you consider that a drawback)
Remaining issues:
* I think the remaining weak spot in this design is the tweeter. It's a "BIT" sibilant. I'm guessing that perhaps the crossover is a touch too low. The cost to replace the unit and rework the crossover accordingly may not be worth it. Any suggestions.
All in all, a worthwhile modification