# Mid 70's Bose w/Modern Receiver?



## ODog4523 (Jan 6, 2009)

Hey all, apologies if this is posted in the wrong spot!

I inherited a set of Bose 501 Series II's and am thinking about trying them out as the front left and right channels on my Sony STR DN 1040.

I'm not an audiophile or speaker expert, but I'm just assuming there will be some big performance differences between these and a modern pair of home theater speakers that are specifically designed for that application.

They would be replacing a set of hand-me-down Pioneer CS-VX110's, so it's not like I'd be taking out high performance speakers anyway. Question is, is it worth the experiment?

Thanks for any insight!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Sure, it’s certainly worth the experiment!

Regards,
Wayne


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## RobKnapp (Nov 30, 2020)

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ODog4523 said:


> Hey all, apologies if this is posted in the wrong spot!
> 
> I inherited a set of Bose 501 Series II's and am thinking about trying them out as the front left and right channels on my Sony STR DN 1040.
> 
> ...


I love vintage speakers. I found this article to be a good read .

* Bose 501 Series I Speakers*

​


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## thescher (Feb 15, 2015)

ODog4523 said:


> Hey all, apologies if this is posted in the wrong spot!
> 
> I inherited a set of Bose 501 Series II's and am thinking about trying them out as the front left and right channels on my Sony STR DN 1040.
> 
> ...


Very much recommended!! I run an old set of Bose 901s with a Modern Yamaha A/V receiver & an old 70s Pioneer SX-1280 pushing the front bus 901s that also have a Sony 12" sub connected. Movies & music sound awesome alike!! The Pioneer has 180w/channel. I use a set of 501s for the rear surrounds. It's a little overkill but I like the tweeter set up on them to bounce the rear program sound/info around.


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## Da Wiz (May 8, 2019)

No Highs---No Lows---Must be Bose 

NOTE that the speakers you got are now probably 40 years old or more. Depending on what materials were used in manufacture, the speakers could still be fine, or they could have essentially decomposed to uselessness. If you can remove the grille... look at the drivers. If the cones have no rubber-looking surround around the outer diameter of the cones, that rubber (foam on some speakers made in the 70s and 80s... the foam decomposes much faster than rubber) has completely disappeared and the drivers are worthless as they are (the rubber surround keeps the cone centered while it moves back and forth and seals the sound inside the box). There are DIY kits you can buy to replace torn and decomposed rubber surrounds, but unless you are moderately talented at repairs like this, it will not be an easy thing to do. Also note... electronic components, primarily capacitors, can change properties over time and end up being so far from the original value in microfarads that the crossovers are pretty messed up. Some capacitors survive 40-odd years fine, others are worthless at that age, or at least not reliable at that age. Rubber and plastic tend to get harder and more brittle as they age. The glue used in the cabinets is also subject to failing by the time a speaker gets to circa 40 years old. The original 501 was made from 1971 to 1977. The 501 Series II was made from 1977 to 1980. When you connect the Bose speakers to an amplifier or receiver, it should be an amplifier or receiver that has "protection" built-in for the amplifiers. Typically this "protection" includes a capacitor in series with the final output so DC voltage cannot get to a speaker, or from a speaker back into the amp/receiver PLUS some sort of circuit that senses the load the speaker is presenting and shuts off amplifier power if that load is approaching a short circuit (likely due to failed electronic parts in the speaker). If you hear scraping or metallic rubbing while the speakers are working, that's a strong sign the cone is not being properly supported at the edges due to the age and decomposition of the rubber around the outer edge of the driver. A place called Madisound has carried speaker repair kits and even in some cases, new-old-stock drivers (which, if stored in plastic bags, might still be OK) or "production-like" drivers that are very close equivalents to the original drivers, but not necessarily identical to the originals. If the amp or receiver has no protection, you could damage the amp or receiver if the electronics devices in the speaker have failed in a way that draws too much current from the amp/receiver and that can damage an unprotected amp or receiver. So use caution and be ready to yank cables from the speakers very quickly. I would suggest if you are going to do this, just connect 1 speaker at a time so you can focus on that ONE speaker and only have to worry about pulling 2 speaker cables if something goes wrong.


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## DEANO222 (Aug 20, 2013)

After inspecting them for foam rot and Bose are notorious for that presuming you replaced them, check the capacitors too . Using them as fronts should be easy especially if your surrounding receiver has Audessy correction or proprietary equalisation to manage the midrange dip most Bose have .


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## Brian Steele (Jan 3, 2011)

The Bose 501s were the first Bose speakers that I heard many years ago. I liked them. I suspect that they would probably be outclassed by any good modern speakers, but if that's not an option for you at the moment...


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## BP1Fanatic (Mar 28, 2011)

Go for it! I got old speakers in my son's bedroom in a 5.1 system.


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## rdcollns (Oct 13, 2013)

I picked up some old speakers from the early 80s at a garage sale. They are Dahlquist brand and blow away anything else I have owned. I highly recommend trying them out and see if you like them.


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## ODog4523 (Jan 6, 2009)

Thanks all for the replies! 

My mom bought them in the 70s, and while my dad hasn't ever opened them up to inspect them, they have gotten use for all these years. 

When I get my hands on them soon I will certainly try the one-at-a-time approach to see that they're functionally ok, then go from there. 

Will update when I get to play around.


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## ODog4523 (Jan 6, 2009)

Got the speakers home today, and stopped short plugging them in. On the back of the cabs I nocited they're rated 4 ohms, 100 watts each. The back of my receiver however says to use 6 - 160. 

So where to go from here? I know very little about this, but that sounds like a no-go...


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## Da Wiz (May 8, 2019)

A 4-Ohm speaker requires a lot more current than an 8-Ohm speaker. And you don't have to have 100 watts, you can have 20 watts. But remember, if you play the speakers too loudly with an underpowered AVR or amp, you'll get clipping and the first thing that blows up when you have clipping for any length of time is the tweeters because they get extremely hot when presented with bursts of DC at high frequencies (clipping causes bursts of DC to reach the speakers unless there is a capacitor in the output stage of the amplifier--some have that, some don't. You can use a 4-Ohm speaker with a 6/8 Ohm receiver, just don't go nuts with the volume level. And depending on how the AVR is designed, the 4-Ohm impedance may cause a load the AVR doesn't like much. If the speakers sound good on your AVR at modest volume, they will probably sound OK with something more suited to them. It was incredibly stupid of Bose to make low impedance speakers like that for the general public since only an audiophile might know enough to realize you don't just connect any 4-Ohm speaker to any inexpensive AVR. There are receivers with a "4-Ohm" feature, but all they do is insert a 4-Ohm resistor in series with each speaker so you end up with an 8-Ohm speaker that doesn't play very loudly before the AVR runs out of current. You can do that also by manually inserting a 4-Ohm resistor in series with the new speakers, but that's not a real solution. Your best bet is to find a used amplifier you can afford that is suitable for 4-Ohm speakers and use the preamp outputs from the AVR to drive the amplifier (if your AVR has preamp or line level outputs for left and right speakers.


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## AEIOU (May 3, 2011)

Da Wiz said:


> A 4-Ohm speaker requires a lot more current than an 8-Ohm speaker. And you don't have to have 100 watts, you can have 20 watts. But remember, if you play the speakers too loudly with an underpowered AVR or amp, you'll get clipping and the first thing that blows up when you have clipping for any length of time is the tweeters because they get extremely hot when presented with bursts of DC at high frequencies (clipping causes bursts of DC to reach the speakers unless there is a capacitor in the output stage of the amplifier--some have that, some don't. You can use a 4-Ohm speaker with a 6/8 Ohm receiver, just don't go nuts with the volume level. And depending on how the AVR is designed, the 4-Ohm impedance may cause a load the AVR doesn't like much. If the speakers sound good on your AVR at modest volume, they will probably sound OK with something more suited to them. It was incredibly stupid of Bose to make low impedance speakers like that for the general public since only an audiophile might know enough to realize you don't just connect any 4-Ohm speaker to any inexpensive AVR. There are receivers with a "4-Ohm" feature, but all they do is insert a 4-Ohm resistor in series with each speaker so you end up with an 8-Ohm speaker that doesn't play very loudly before the AVR runs out of current. You can do that also by manually inserting a 4-Ohm resistor in series with the new speakers, but that's not a real solution. Your best bet is to find a used amplifier you can afford that is suitable for 4-Ohm speakers and use the preamp outputs from the AVR to drive the amplifier (if your AVR has preamp or line level outputs for left and right speakers.


If you are going to give information, at least endeavor be accurate about it. When an amplifier clips it breaks out into oscillations, high frequency oscillations, not bursts of DC. Since you understand that some amplifiers utilize capacitors at the output stages to block DC, didn't it also occur that the loudspeaker high pass section of the crossover which has a capacitor also blocks DC from going to the tweeter? The reason why it affects the tweeter is simply because the crossover directs the high frequency oscillations to the tweeters, that's why it is called a "high pass filter." The amplifier clipping produces something akin to a square wave, which has substantially more power than just simple undistorted sine waves. One other thing, hardly any amplifiers are DC capable, unless of course the amplifier is malfunctioning there will be no DC going to the loudspeakers. If there is DC present at the amplifier output, you'll see dynamic offset of the woofers, because the loudspeaker crossover allows DC to be sent to the woofers.


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## AEIOU (May 3, 2011)

Da Wiz said:


> A 4-Ohm speaker requires a lot more current than an 8-Ohm speaker. And you don't have to have 100 watts, you can have 20 watts. But remember, if you play the speakers too loudly with an underpowered AVR or amp, you'll get clipping and the first thing that blows up when you have clipping for any length of time is the tweeters because they get extremely hot when presented with bursts of DC at high frequencies (clipping causes bursts of DC to reach the speakers unless there is a capacitor in the output stage of the amplifier--some have that, some don't. You can use a 4-Ohm speaker with a 6/8 Ohm receiver, just don't go nuts with the volume level. And depending on how the AVR is designed, the 4-Ohm impedance may cause a load the AVR doesn't like much. If the speakers sound good on your AVR at modest volume, they will probably sound OK with something more suited to them. It was incredibly stupid of Bose to make low impedance speakers like that for the general public since only an audiophile might know enough to realize you don't just connect any 4-Ohm speaker to any inexpensive AVR. There are receivers with a "4-Ohm" feature, but all they do is insert a 4-Ohm resistor in series with each speaker so you end up with an 8-Ohm speaker that doesn't play very loudly before the AVR runs out of current. You can do that also by manually inserting a 4-Ohm resistor in series with the new speakers, but that's not a real solution. Your best bet is to find a used amplifier you can afford that is suitable for 4-Ohm speakers and use the preamp outputs from the AVR to drive the amplifier (if your AVR has preamp or line level outputs for left and right speakers.


If you attempt to make a pair of 4 Ohm loudspeakers into an 8 Ohm load by adding a 4 Ohm resistor, you end up wasting half the amplifier power heating up the 4 Ohm resistors. In such a circumstance one better make sure that the 4 Ohm resistor can dissipate the all the heat, otherwise. . . Fire!


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## ODog4523 (Jan 6, 2009)

So the consensus is proceed with caution? Don't proceed as is?

Apologies if this is blaspheming, but I had also considered finding someone to open them up for restoration and/or modernization to use with my system. It's the object as a whole that holds sentimental value for me. Not so much the internals.


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