I've been a bit hesitant to declare these as I haven't decided on the finish yet. But as I haven't seen any 2.5 examples with this woofer I might as well throw it out there.
A bit of back history. I picked up a pair of Advents over 4 years ago after reading about them on the Asylum. I had zero vintage gear in use at the time except tuners. I found them nice but nothing to get overly exited about. Their best attribute was I could play them at night and still fall asleep. And yes, that is a good thing. Like an old console stereo I listened too at night as a kid.
Anyhow I was given a second pair when I bought some other speakers and as this seemed to be the rage tried stacking them. They were of course louder but did not sound quite right. Possibly comb filtering overall but more specifically the 2 tweeters I'd guess.
So I started trying to figure out how to improve them. I decided that the boxes needed improving so I built a slightly larger version (to accommodate bracing). About this time some brash young whippersnapper named Zilch joined AK and jumped into an Advent thread butting heads with a few to remain nameless folks. He further convinced me that stacking was not the way to go so the Advents went into the garage and gathered dust.
Time passed, this thread started. I lurked but only made 1 or 2 posts as work had turned into a 12-13 hour 6 day a week thing and well, I have very nice speakers already. But this project had a few things going for it. I had already made the internal boxes of double wall mdf and I wanted the space back that these boxes and the other 4 Advent speakers were taking. So I kept thinking about what could be improved and also waiting (I have to admit) to see if this waveguide mod was just another flavor of the month. Because by then I had bought into this thread as part of the solution.
Although I tend to bi and tri amp everything I was hoping to be able to use one amp and was reassured to read about how bracing the cabinet and adding FG in place of foam smoothed the impedance a bit so I built the cabinets with 3 layers front and back and 2 on the side. They also have 9
braces, the most important of which is between the woofer and waveguide as I put the openings very close to each other. A benefit of the triple baffle, actually 4 at the waveguide opening as I time aligned it that way, is that you can make each cut progressively smaller. I can stand on it and feel zero flex. I did have to screw the driver in from behind as the hole was too small from the front.
BTW, obviously at this point I was perhaps overdoing this based on the quality of the drivers but it was an experiment. At one point before the waveguide holes were cut I compared 2 Advents stacked with tweeters disconnected against the woofer in the new box. There is a IMO positive difference when running a 30 hz tone and when listening to music. As you would probably expect when reducing cabinet resonance that much.
This is running a bit long so I'll just add that I also attempted to address diffraction a bit which requires test equipment that I lack but RayW made some good ballpark recommendations.:thmbsp: And I feel that going first order on the helper woofer is the way to go. Less phase shift. You can hook up the extra .5 inductor after the woofer crossover (go 4 ohm in that case) and minimize phase shift even further I believe. That's the way to go if using 1 amp in my opinion.
So I could go on about the last few things I'll do like a add felt around the waveguide step to smooth diffraction. A John Dunlavy (and others I'm sure) idea he used on my SC-IV/A's. But I'll just thank Zilch and Bauhausler and spkrdtr for those advent plots you posted on another site.
Lastly how do they sound. Well here's the problem. They are too heavy to move upstairs to my heavily treated room so I can't compare them to the sound I'm used too. But if you like Advents these sound (and I'm not given to hyperbole) a lot better. But they should with all the changes. In fact they would probably qualify for the upgraded deluxe WG version. I have them in a 18 by 35 foot room that opens into another room and they fill the room to concert levels. I'm sure my neighbors will be thrilled.
Again sorry for the long post but since this was an evolution kinda "thang" I wanted to explain. Sides I hardly ever post here so I'm making up for it.:yes:
Until they are stained no closeups though.
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