Is it Ok to bypass a Subwoofer pass through.

[J B S]

I have an 80s vintage BSA 15” end table Subwoofer. It has a pass through crossover. Both left and right speaker leads go in and then come out and to the regular speakers on the opposite side. The crossover filters off the low end non stereo bass from both channels, or that is what it is supposed to do. My question is can I just go in and out on the same side of the crossover and allow the full bass to go to both the subwoofer and the regular speakers ? Will this effect impedance ?, system is 8 ohm.

[shadowlord]

shouldn't do any harm.
i had my subwoofer connected to the B speaker posts of the amp for many years with no ill effects.

[J B S]

shouldn't do any harm.
i had my subwoofer connected to the B speaker posts of the amp for many years with no ill effects.

This is all on "A" the "B" has a set of Infinity speakers.

[laatsch55]

What amp??

[J B S]

What amp??

Marantz 2385

[laatsch55]

One way to know for sure unhook the speaker wires at the amp and slap a meter on em. If the Speaks are in parallel you will have a problem. Especially driving both A & B sets. Do you have the owners manual for the 2385?

[laatsch55]

What Infinity's??

[J B S]

What Infinity's??

1986 SM150, woofs upgraded, cabinets beefed up, and interior lined with sound deadening.

[laatsch55]

Got a meter?

[shadowlord]

is the subwoofer in question an active or passive one?

[Socal Sam]

Meter is the key. If your all passive combination results in a nominal impedance < 4 ohm, the amp will have a tough time keeping up. In this situation, it is better to use a second amp to power the passive sub and split the signal somewhere up stream.

[shadowlord]

sam is right here, but if it's an active sub you wouldn't have a problem running it "parallel"

[laatsch55]

I guess I'm confused, if a sub is powered it's active correct? If it's powered by the same amp as the rest of the speakers there can be problems.

[Socal Sam]

I guess I'm confused, if a sub is powered it's active correct? If it's powered by the same amp as the rest of the speakers there can be problems.

You got it! If you are looking for "audiophile" bass that is tight, passive is the way to go. If you are looking for video game bass that rumbles the floor, active is the way to go.

[J B S]

Sorry for no feedback, A/C system failure for past week. House is cool again. Anyway the subwoofer is now powered by its own amp.

[Socal Sam]

Sorry for no feedback, A/C system failure for past week. House is cool again. Anyway the subwoofer is now powered by its own amp.

So your sub is being driven by a built-in amp or an external amp?

[J B S]

So your sub is being driven by a built-in amp or an external amp?

external amp

[macman007]

Your nominal impedence load is critical here. If you are using A and B speakers on your Maranrz, you are running the speakers in parallel already with the summed load being the combination of all speakers on both A and B systems, if running simultaneously.

This can be a serious issue, as most older recievers and amps such as yours (and a gread deal of expensive new ones) dont like seeing a total load under 4 Ohms total, 8 Ohms being prefered, for sound quality, safety and longevity.

Even at low volumes, going under 4 Ohms will strain the output transistors, some of which are unobtanium, if destroyed. The unit will put out a lot of heat, indicating that the amp transistors are working too hard. HEAT AND EXCESSIVE LOADS ARE THE ENEMY! Units not designed to operate with such a low load can easily self destruct, even at moderate levels.

Some amps/recievers are designed to run both speaker systems (A&B) at the same time with no issues, at low loads, but you get what you pay for these days. If it doesn't say it can do it , dont assume no matter what the age/condition of the unit.

To be safe, IMO, I would run 1 side at a time, A or B, after measuring your total parallel impedence with the sub and speakers measured and connected together then subtract an Ohm or 2 to be safe, as speaker impedence isn't steady and can vary widely in real world listening.

Even running your main speakers on output A and sub on B, the amp section will still see the total impedence of all speakers connected, when A&B are running together, not to mention any other speakers connected.

Results besides high temperatures could also include, blowing fuses, damaging components in the amp section, clipping, which can easily damage speakers, and the amp section or a meltdown in the power supply, etc.

Been there done that when young and inexperienced, and learned the hard way.

To be safe, if you can, I would either run a active (self powered sub) or in the case of a passive sub an seperate amplifier matched to the subs power with a little more wattage than the sub rated, for safety..whatever meetes your needs and desires/wallet. Some Marantz equipment had a center channel pre out that was controled from the rear, and allowed you to connnect a mono amp to run a seperate center speaker(s). Frequency being full range wont matter as either the amp or sub will have a provision for setting your cutoff points in Hertz. You will also be able to control your subwoofer volume level this way.

If you dont have any way of adding an amp I would go for a nice active sub (self powered) and use the subs filters and gain controls to dial in your main speakers to the cutoff points, and gains that you require for your room and taste. Some even use remote controls and room adjusting software to prevent standing waves and such by including a microphone to set up and test designated positions in your listening area. Connect the speakers as the subs directions indicate, not in parallel to the main speakers

Remember when in doubt, err on the side of caution, I wouldn't want that unit to see less than 4 ohms with all speakers running and connected. Thats looking for trouble.

Feel free to ask any questions if you dont understand any of what I have said, and require further clarification. I would be happy to help you further if I haven't already.

I apologise for the length of this post but I have tried to address any and all questions or issues you may have, will have, or have had.

Phil *bigthumbup*

[Socal Sam]

Your nominal impedence load is critical here. If you are using A and B speakers on your Maranrz, you are running the speakers in parallel already with the summed load being the combination of all speakers on both A and B systems, if running simultaneously.

This can be a serious issue, as most older recievers and amps such as yours (and a gread deal of expensive new ones) dont like seeing a total load under 4 Ohms total, 8 Ohms being prefered, for sound quality, safety and longevity.

Even at low volumes, going under 4 Ohms will strain the output transistors, some of which are unobtanium, if destroyed. The unit will put out a lot of heat, indicating that the amp transistors are working too hard. HEAT AND EXCESSIVE LOADS ARE THE ENEMY! Units not designed to operate with such a low load can easily self destruct, even at moderate levels.

Some amps/recievers are designed to run both speaker systems (A&B) at the same time with no issues, at low loads, but you get what you pay for these days. If it doesn't say it can do it , dont assume no matter what the age/condition of the unit.

To be safe, IMO, I would run 1 side at a time, A or B, after measuring your total parallel impedence with the sub and speakers measured and connected together then subtract an Ohm or 2 to be safe, as speaker impedence isn't steady and can vary widely in real world listening.

Even running your main speakers on output A and sub on B, the amp section will still see the total impedence of all speakers connected, when A&B are running together, not to mention any other speakers connected.

Results besides high temperatures could also include, blowing fuses, damaging components in the amp section, clipping, which can easily damage speakers, and the amp section or a meltdown in the power supply, etc.

Been there done that when young and inexperienced, and learned the hard way.

To be safe, if you can, I would either run a active (self powered sub) or in the case of a passive sub an seperate amplifier matched to the subs power with a little more wattage than the sub rated, for safety..whatever meetes your needs and desires/wallet. Some Marantz equipment had a center channel pre out that was controled from the rear, and allowed you to connnect a mono amp to run a seperate center speaker(s). Frequency being full range wont matter as either the amp or sub will have a provision for setting your cutoff points in Hertz. You will also be able to control your subwoofer volume level this way.

If you dont have any way of adding an amp I would go for a nice active sub (self powered) and use the subs filters and gain controls to dial in your main speakers to the cutoff points, and gains that you require for your room and taste. Some even use remote controls and room adjusting software to prevent standing waves and such by including a microphone to set up and test designated positions in your listening area. Connect the speakers as the subs directions indicate, not in parallel to the main speakers

Remember when in doubt, err on the side of caution, I wouldn't want that unit to see less than 4 ohms with all speakers running and connected. Thats looking for trouble.

Feel free to ask any questions if you dont understand any of what I have said, and require further clarification. I would be happy to help you further if I haven't already.

I apologise for the length of this post but I have tried to address any and all questions or issues you may have, will have, or have had.

Phil *bigthumbup*

Phil, excellent advice that all would benefit from following.*bigthumbup*

[J B S]

All straight now. From the manual.

[stereorob]

ha! i used to have one of those things. big bsr end table sub. sounded pretty decent for what it was. i bypassed the xover completely and used a pioneer sx-1000td with a blown right channel as the power amp for it.