Particularly Nasty in Wall Sub

[TLS Guy]

I just came across this dual 8" sub on the Monoprice website. I am posting it here, as it seem to me it be a wrecking ball in the hands of the inexperienced.

It is a sub with two 8" drivers and a passive crossover to each driver. Crossover frequency is stated as 120 Hs, and there is a crossover to each driver. There is a port which can be plugged. The sub is entirely passive. There is a terminal set for each driver which come bridged, and one driver could be used, or I suppose two amps could be used, each connected to each of the terminals unbridged.

Now, sealed and ported enclosure volumes are always very different. The sealed also needs Eq or the F3 will be much higher than ported.

However, the impedance of this unit with two drivers in the bridged terminal format is around 2 ohms. The impedance curves below must be with the port sealed as there is only one peak of impedance.

Now the frequency response.

With the internal crossovers, the FR is particularly obnoxious. If used from pre outs with external amps the FR is much better, but it does not really justify being called a sub with an F3 of 36 Hz.

This unit really concerns me, as used in passive form, this unit is likely to blow up a lot of amps. The unit is unlikely to be connected to an amp capable of safely driving the unit on grounds of cost.

The only way I can see to use this unit safely, is from preouts, and use an external two channel amp, with the terminals UNBRIDGED.

I can foresee this unit causing a lot of grief for those not technically competent, which is likely to be the majority of customers in the market for this unit.

 

[BoredSysAdmin]

Any thoughts on THOR IW-SUB10 as an alternative? I couldn't much measurements or in-depth reviews.
Tom Andry did a preview 20 years ago, so it's quite an old design.

 

[TLS Guy]

Any thoughts on THOR IW-SUB10 as an alternative? I couldn't much measurements or in-depth reviews.
Tom Andry did a preview 20 years ago, so it's quite an old design.

By spec, that is a genuine sub, but I suspect the specs are a little optimistic. No F3 point is quoted. The bigger issue is that the cutout is very close to the standard 2 X 4 stud spacing. That is fine, as long as the framers were really accurate, but they usually are not, as they go so fast.

If you do want a decent in wall system, then I think you have to be prepared to rebuild the wall and re-sheetrock. That is not a big issue as the materials are cheap. Labor however may be a different matter. New construction is an ideal time to install an inwall system.

 

[Kingnoob]

I just came across this dual 8" sub on the Monoprice website. I am posting it here, as it seem to me it be a wrecking ball in the hands of the inexperienced.

It is a sub with two 8" drivers and a passive crossover to each driver. Crossover frequency is stated as 120 Hs, and there is a crossover to each driver. There is a port which can be plugged. The sub is entirely passive. There is a terminal set for each driver which come bridged, and one driver could be used, or I suppose two amps could be used, each connected to each of the terminals unbridged.

Now, sealed and ported enclosure volumes are always very different. The sealed also needs Eq or the F3 will be much higher than ported.

However, the impedance of this unit with two drivers in the bridged terminal format is around 2 ohms. The impedance curves below must be with the port sealed as there is only one peak of impedance.

Now the frequency response.

With the internal crossovers, the FR is particularly obnoxious. If used from pre outs with external amps the FR is much better, but it does not really justify being called a sub with an F3 of 36 Hz.

This unit really concerns me, as used in passive form, this unit is likely to blow up a lot of amps. The unit is unlikely to be connected to an amp capable of safely driving the unit on grounds of cost.

The only way I can see to use this unit safely, is from preouts, and use an external two channel amp, with the terminals UNBRIDGED.

I can foresee this unit causing a lot of grief for those not technically competent, which is likely to be the majority of customers in the market for this unit.

Wouldn’t suprise me if this brands drivers blow amps , maybe it’s passive because of there higher end model amp failures? Most people who want inwall subs , are doing so to Save floor space ??

 

[TLS Guy]

Wouldn’t suprise me if this brands drivers blow amps , maybe it’s passive because of there higher end model amp failures? Most people who want inwall subs , are doing so to Save floor space ??

Yes, to save floor space and above all clutter.

The above system was designed at the request of my wife. She wanted no floor space taken up and absolutely no 'boxes" in the room.

So, this was designed on her orders. Two, 2-way MTMs for the left and right speakers, and a three way center that is not MTM, tweeter is above the mid. In wall sub is an aperiodic TL that really fills the space with accurate bass. Total power 1000 watts all channels driven.

My wife loves it. We do use it a lot, including when family and friends gather. It is not just good for an in wall system, but a really good audio system. It is used day in and day out.

 

[Mikado463]

By spec, that is a genuine sub, but I suspect the specs are a little optimistic. No F3 point is quoted. The bigger issue is that the cutout is very close to the standard 4 X 4 stud spacing. That is fine, as long as the framers were really accurate, but they usually are not, as they go so fast.

If you do want a decent in wall system, then I think you have to be prepared to rebuild the wall and re-sheetrock. That is not a big issue as the materials are cheap. Labor however may be a different matter. New construction is an ideal time to install an inwall system.

I assume you meant 2x4 stud spacing (16") ?

 

[highfigh]

By spec, that is a genuine sub, but I suspect the specs are a little optimistic. No F3 point is quoted. The bigger issue is that the cutout is very close to the standard 4 X 4 stud spacing. That is fine, as long as the framers were really accurate, but they usually are not, as they go so fast.

If you do want a decent in wall system, then I think you have to be prepared to rebuild the wall and re-sheetrock. That is not a big issue as the materials are cheap. Labor however may be a different matter. New construction is an ideal time to install an inwall system.

If the stud placement is not accurate, different framers should be hired- they mark the stud locations and someone should be supervising, to make sure the marks are in the correct locations (and tape measures have diamonds at 16" increments). It's kind of important because drywall, paneling and other materials depend on the studs being where the nails and screws are used but I won't say that rough carpenters are always accurate and my house is an example of that- five door jambs had one side 3/4" shorter than the other.

If the stud bays are a bit wider than needed, shims work very well. If the sub is wider than standard spacing and someone is willing to have it installed properly, the easy way is to open two stud bays, cut one at the top and bottom at the needed heights, install a cross member with blocking for the sides of the enclosure and re-rock it. It only requires cutting a hole the size of the opening.

The worst case for cutting a wall, re-framing and repairing the surface is lath & plaster.

 

[highfigh]

Yes, to save floor space and above all clutter.

The above system was designed at the request of my wife. She wanted no floor space taken up and absolutely no 'boxes" in the room.

So, this was designed on her orders. Two, 2-way MTMs for the left and right speakers, and a three way center that is not MTM, tweeter is above the mid. In wall sub is an aperiodic TL that really fills the space with accurate bass. Total power 1000 watts all channels driven.

My wife loves it. We do use it a lot, including when family and friends gather. It is not just good for an in wall system, but a really good audio system. It is used day in and day out.

Just curious- why not use grill cloth that's not such a stark contrast to the wall color? Doesn't need to be white (I would avoid that color if cloth is used). If they're metal grills, paint stores can match colors well.

BTW- I remember you posting that the cabinets came from Ikea- do you remember (or have info) about which series they are?

 

[TLS Guy]

Just curious- why not use grill cloth that's not such a stark contrast to the wall color? Doesn't need to be white (I would avoid that color if cloth is used). If they're metal grills, paint stores can match colors well.

BTW- I remember you posting that the cabinets came from Ikea- do you remember (or have info) about which series they are?

The cabinets are not from Ikea. They were in our former Townhome, which was our metro bolt hole. The cabinets in this home are all custom.

The interior design was done by my eldest daughter who is a qualified interior designer and architect. She wanted the speakers to match the TV. So that is why the frames are silver and the grills black cloth. I think she got it right. She found she could earn more working for Wells Fargo. She is a senior VP and designs their web pages.

 

[Squishman]

I have heard this system a couple times. Once with a few of my own CD's. I can confirm, it does sound great.

Yes, to save floor space and above all clutter.

The above system was designed at the request of my wife. She wanted no floor space taken up and absolutely no 'boxes" in the room.

So, this was designed on her orders. Two, 2-way MTMs for the left and right speakers, and a three way center that is not MTM, tweeter is above the mid. In wall sub is an aperiodic TL that really fills the space with accurate bass. Total power 1000 watts all channels driven.

My wife loves it. We do use it a lot, including when family and friends gather. It is not just good for an in wall system, but a really good audio system. It is used day in and day out.