Here's what I've got so far.
It started as a pair of "acoustic response" 'white van' speakers. Someone gave them to me, I think in was back in the 90's.
I replaced the tweeter w/ the fostex ff85k, left the mid in place, but disconnected. Replaced the 30ohm pots w/ an l pad. Replaced the woofer w/ an MCM 12" die cast. (it is definitely not the advertised 96db/w, but it was cheap).
Xover is 500hz 18db for the 85k, and 12db for the woofer (it's what I had on hand).
The cabinet walls have acoustic damping foam glued to them, and poly stuffing.
Today I increased the port length, which was recommended by speaker calculators. The port's about an inch longer, but I really think I can hear a noticeable difference in the bass! It's good. I also stuffed a thin black aquarium foam pad in the port, to cover the white extensions, which must do something to the sound. The ff85k is turned down maybe 2db, if my guess of a linear range of 6db is accurate.
They sound great right now. Maybe because I've gotten used to them
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It started as a pair of "acoustic response" 'white van' speakers. Someone gave them to me, I think in was back in the 90's.
I replaced the tweeter w/ the fostex ff85k, left the mid in place, but disconnected. Replaced the 30ohm pots w/ an l pad. Replaced the woofer w/ an MCM 12" die cast. (it is definitely not the advertised 96db/w, but it was cheap).
Xover is 500hz 18db for the 85k, and 12db for the woofer (it's what I had on hand).
The cabinet walls have acoustic damping foam glued to them, and poly stuffing.
Today I increased the port length, which was recommended by speaker calculators. The port's about an inch longer, but I really think I can hear a noticeable difference in the bass! It's good. I also stuffed a thin black aquarium foam pad in the port, to cover the white extensions, which must do something to the sound. The ff85k is turned down maybe 2db, if my guess of a linear range of 6db is accurate.
They sound great right now. Maybe because I've gotten used to them
.Attachments
Is that contraption on the floor next to the speakers the latest generation high-tech retro mouse trap?
Here's what I've got so far.
It started as a pair of "acoustic response" 'white van' speakers. Someone gave them to me, I think in was back in the 90's.
I replaced the tweeter w/ the fostex ff85k, left the mid in place, but disconnected. Replaced the 30ohm pots w/ an l pad. Replaced the woofer w/ an MCM 12" die cast. (it is definitely not the advertised 96db/w, but it was cheap).
Xover is 500hz 18db for the 85k, and 12db for the woofer (it's what I had on hand).
The cabinet walls have acoustic damping foam glued to them, and poly stuffing.
Today I increased the port length, which was recommended by speaker calculators. The port's about an inch longer, but I really think I can hear a noticeable difference in the bass! It's good. I also stuffed a thin black aquarium foam pad in the port, to cover the white extensions, which must do something to the sound. The ff85k is turned down maybe 2db, if my guess of a linear range of 6db is accurate.
They sound great right now. Maybe because I've gotten used to them
Is that contraption on the floor next to the speakers the latest generation high-tech retro mouse trap?
Close, it's a bird toy! my birds love my amps for some reason.. I think because birds are crazy thrill seekers, and they know their lives are in danger if they are near the amps.
It's a parallel push pull 829b amp. Those shiny heatsinks on the tubes have about 620v on them. Haven't figured out how I am going to design the chassis yet.. I'd like the tubes on display, but don't want anyone/anything to touch them! (my wife thinks I should just stick HV stickers on the chassis, and be over it.. hah.. (no we dont't have kids yet)) Maybe glass chimneys around each one.... The red PCB is Pete Millett's universal driver board. I regulated the screens and the bias supply for the 829's. I don't have proper test equipment, but I should be getting at least 80 watts out of it. That's a mono channel in the pic. (big amps!)
I'll do some more experimenting w/ the speakers later this week. It's been a fun project. I swear though, extending the port an inch really seems to have changed the bass... more than I would have ever expected. Maybe it was interfering w/ itself w/ the higher frequency port.. sounds good now, though.
Speakers are an even deeper rabbit hole than the amps! yikes...
Ok, 'later this week' turned out to be 'later this afternoon', so I've modified them w/ what I had... some 4" flexible tubing, like for drier vents, or this was specifically for venting the bathroom out the roof.
anyway... Sound difference is subtle, but I think some mid frequencies that were a bit soft(low volume), are good now. And, it sounds more open and 'full range'. (by the way, I know this turned in to a multi-way-ish project, so thanks for discussing it here)
-Just in case it isn't clear, that tube is sealed around the back of the ff85k hole and curves around to the hole where the mid driver used to be located.
anyway... Sound difference is subtle, but I think some mid frequencies that were a bit soft(low volume), are good now. And, it sounds more open and 'full range'. (by the way, I know this turned in to a multi-way-ish project, so thanks for discussing it here)
-Just in case it isn't clear, that tube is sealed around the back of the ff85k hole and curves around to the hole where the mid driver used to be located.
Attachments
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I can't edit anymore, but it's worth mentioning... Stuffing the tube more made a big improvement. It maybe stiffened up my flex-tube, and definitely evened out the frequencies.. They sound great! Much better than before the ff85's were in their own chamber. The sound fills the room more now... Not sure exactly how to describe it, but the full-range magic is there, stereo imaging is great. Maybe that simply means I'm getting them dialed in properly.
tubes are not the best to use for mid chamber, so I guess the stuffing helps a bit
and further, routing it back to the front, like you say it does, means you have unintentionall 'phased signal' from the tube
or maybe I have misunderstood, and the 'old' midchamber is closed
means it could work as 'acoustic buffer', which might be positive
Thanks, I was wondering about that (phase)... I have been thinking it would be better out the back. I'm just not prepared to cut a hole.. And, I liked the idea of using the original hole that's in the box, but that's silly.
It's definitely in 'alpha' stage, and these aren't the materials I will use in the end!
It's definitely in 'alpha' stage, and these aren't the materials I will use in the end!
I was thinking about phase.. And could be completely wrong, so I 1/2 expect a "NO", response..
Could I extend the tube below the outlet (the old mid-driver location), and then bring it back up, and out, similar to a folded horn? Would that correct it somewhat?
Lifting the speaker from the floor and slightly tilted is true for all (or most) speakers, isn't it? I'll try it.. It helps my full range horns.
Could I extend the tube below the outlet (the old mid-driver location), and then bring it back up, and out, similar to a folded horn? Would that correct it somewhat?
Lifting the speaker from the floor and slightly tilted is true for all (or most) speakers, isn't it? I'll try it.. It helps my full range horns.
Inadequate stuffing could allow this to be an issue. With an aperiodically stuffed midTL there should be next to no output from the terminus. Stuffing should get denser as you approach the terminus.
dave
I think I'd just stuff it as much as possible, giving approximately ideal TL response (in the classic sense of TL - all the backwave attenuated etc etc).
Extending the flexi-tube would give, er, interesting results. To be honest, I wouldn't bother: the response will be flat to 500Hz anyway, so there's no reinforcement needed.
Extending the flexi-tube would give, er, interesting results. To be honest, I wouldn't bother: the response will be flat to 500Hz anyway, so there's no reinforcement needed.
Thank you again. That is exactly what I ended up w/, going by ear. It is dense in that tube. But, maybe the whole curved and out the front thing is pointless or even detrimental. I'll keep trying different things when I've got time.
It's amazing what I've turned these trash speaker cabinets in to. All I had to purchase was a pair of woofers. (Thanks to several old projects worth of leftover parts)
I also still want to lower the xover, but that will be a relatively expensive purchase (for this cheap project) so I want to think about that more for a while.
It's amazing what I've turned these trash speaker cabinets in to. All I had to purchase was a pair of woofers. (Thanks to several old projects worth of leftover parts)
I also still want to lower the xover, but that will be a relatively expensive purchase (for this cheap project) so I want to think about that more for a while.
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