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I got some of the upper bass and midrange drivers for the 3.3s, one of my favorite cone-and-box speakers. My idea is to do a design generally based on the 3.3, but with some appropriate updates. Jack was kind enough to give some suggestions based on their experience, most of which will be incorporated. These include multiamping, steeper acoustic crossover slopes, some rearrangement of the box loading of the upper bass driver, and the substitution of multiple 10" woofers for the 12" Foster 1259. I'll probably separate the bass cabinets from the other three drivers, but I'm still pondering that one.
If anyone else wants to participate in the design, construction, and modification of an updated 3.3 clone (it's not really a clone, it's a clown), I'd be delighted. The NHT version of the H453 seems to be an excellent midrange, and it's silly-cheap.
If anyone else wants to participate in the design, construction, and modification of an updated 3.3 clone (it's not really a clone, it's a clown), I'd be delighted. The NHT version of the H453 seems to be an excellent midrange, and it's silly-cheap.
It was SY who dropped in on NHT who are in his hometown, and was talking to Jack Hidley who mentioned he had lots of cool stuff for members at blow-out prices and viola: a great deal for us all.
I have to say , the first thing that I thought of was some kind of standard speaker that lots of us could build. So grabbing some of the drivers SY has might be wise 😉
I have to say , the first thing that I thought of was some kind of standard speaker that lots of us could build. So grabbing some of the drivers SY has might be wise 😉
I snagged some of the shielded and unshielded 4" seas drivers, dome tweeters, and the 8" woofers. Can't do speaker projects without the drivers!
SY said:
The NHT-3.3 crossover schematic was published on the web many years ago. I considered cloning it years ago and did some simulations. The upper mid is a custom version of the SEAS MP12 as I recall, Ken Kantor states that different adhesives were specified. It is a true midrange with a short voice coil and therefore throw.
I also considered separate bass cabinets, so that the mains could be simple towers.
Pete B.
The part number is slightly different on the midrange and the Xmax limitation (1mm) definitely marks it as a midrange. 300Hz acoustic 4th LR as a high-pass makes sense to me.
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wow, I'd like to make my own Sub Two with the VT-3 amp and the drivers. I wonder if using the amp is as simple as hooking up the power, adding RCA connections and feeding it a suitable low frequency signal? Jhidley's comment about posting design guidlines makes me wonder if there is more to it than that?
Not much more than that. Some active crossover work (probably about $10 of Radio Shack parts) and you've got a sub with an amazing ratio of performance to cost.
The SubTwo used the same Sunfire power amp as the VT-3. However, both the VT-3 and SubTwo controllers had some excursion and thermal limiters built into them. These would be very difficult to replicate. I don't think the thermal limiting is really needed, but the excursion limiter is needed if you are stupid with the program material and volume knob.
We are considering offering an option to the VT3 amplifiers, of an already installed RCA or XLR connector. This way the amp would be plug and play. If you combine this with an NHT X2 crossover, you can do basically any crossover stuff you want. I'll post some details on the site once we get it worked out.
We are considering offering an option to the VT3 amplifiers, of an already installed RCA or XLR connector. This way the amp would be plug and play. If you combine this with an NHT X2 crossover, you can do basically any crossover stuff you want. I'll post some details on the site once we get it worked out.
We've modified the sale site to reflect that all of the VT3 amplifiers now come with an RCA jack installed. Just turn it on and use it. The price has been adjusted to $90 to reflect this.
Hi:
I was hoping to get a little more info on the steel framed 10"s: most specifically, what kind of 'high' end response they have: could they be used to 300Hz? Any chance of getting more info on these?
I was hoping to get a little more info on the steel framed 10"s: most specifically, what kind of 'high' end response they have: could they be used to 300Hz? Any chance of getting more info on these?
The npt-11-075-2 10" woofers have a standard poly cone with a large rubber surround. The cone/surround combo will work fine up to 300Hz. It doesn't start doing bad things until 700-800Hz.
The voice coil is 50mm diameter and 34mm long. So we are talking about a lot of inductance. The general response shape from 100-800Hz will definitely slope downwards slightly due to this. Also the large inductance and inductance shift will cause more IM type distortion the higher in frequency you use the driver. I wouldn't use it above 300Hz from this standpoint, unless it was for some pro sound application.
The voice coil is 50mm diameter and 34mm long. So we are talking about a lot of inductance. The general response shape from 100-800Hz will definitely slope downwards slightly due to this. Also the large inductance and inductance shift will cause more IM type distortion the higher in frequency you use the driver. I wouldn't use it above 300Hz from this standpoint, unless it was for some pro sound application.
Jack, thanks for the info and updates on the VT3. I'm definitely going to be ordering a set. The question is whether to build one set or two! 😀
Dumb question: the 2 woofers are hooked up in parallel with the VT3 right?
Dumb question: the 2 woofers are hooked up in parallel with the VT3 right?
Jack Hidley said:
Well, I shall try to prove you wrong then! 😉
I'm thinking of ordering the VT3 woofers and amp. Based on the T/S parameters, I seem to get an F3 at about 30 hz in a sealed enclosure. I think the VT3 went down to about 22 hz so should I assume there is some equalization done at the bottom end by the controller as well as excursion control?
Thank you for your generosity and patience with these questions.
Dave
Dave,
Yes, the controller has a funky shelving circuit to eq the low end down to 22Hz. This part of the circuit design is stupid. It doesn't work well and is very hard to tweak. I would just use a normal shelving circuit (ie Linkwitz transform).
There are a bunch more stages in the controller for the various limiters, crossover filters, video/audio mode eq, etc. I can supply the controller schematic with the VT3 amps.
The VT3 amps also have a +/-18VAC output from the power supply. Just add a small rectifier with filter caps, and you can build your own eq circuit into the physical amplifier.
One of my friends is using eight of the tens in a cabinet with 80l per driver and a port tuning of about 18Hz. With only about 6dB of eq it will be -3dB at 16Hz or so. Luckily his A/V system is against one of the walls to his three car garage. The entire cabinet will be about 6' x 8', but only a foot or so thick. From inside the house, you will only see two 20" x 20" inwall speaker grilles.
Yes, the controller has a funky shelving circuit to eq the low end down to 22Hz. This part of the circuit design is stupid. It doesn't work well and is very hard to tweak. I would just use a normal shelving circuit (ie Linkwitz transform).
There are a bunch more stages in the controller for the various limiters, crossover filters, video/audio mode eq, etc. I can supply the controller schematic with the VT3 amps.
The VT3 amps also have a +/-18VAC output from the power supply. Just add a small rectifier with filter caps, and you can build your own eq circuit into the physical amplifier.
One of my friends is using eight of the tens in a cabinet with 80l per driver and a port tuning of about 18Hz. With only about 6dB of eq it will be -3dB at 16Hz or so. Luckily his A/V system is against one of the walls to his three car garage. The entire cabinet will be about 6' x 8', but only a foot or so thick. From inside the house, you will only see two 20" x 20" inwall speaker grilles.
Does a schematic come with the 250W@8 ohm amps? Which output devices do they use? Any other info you would like to share about them would be appreciated as well.
Thanx,
Casey
Thanx,
Casey
I added the VT3 amplifier and controller schematics to the sale site. I'll post schematics for the 250W amplifier modules and power supplies tomorrow.