Bose 901 IV Advice

[50nstillhifi]

OK, let's get a few things straight here. First, Original Generation and Series II are the ONLY series that are power demanding. This was due to being Acoustic Suspension design. All other series are ported (bass reflex) and more efficient. According to the Official Bose website the Series III were introduced in 1976, which means development started well before this. That was also on the heals of the "power wars", when S.S. equipment began to exceed 100wpc. If Bose waited it out longer they wouldn't have had to go more efficient (IMHO). That aside, because the later model 901 were Bass Reflex the power demands were reduced. They can still "take" gobs of power, but are less demanding than their earlier brethren. I've powered my Original 901 with an 75wpc receiver and was quite pleased. However, the second point is the EQ is a must. I've spoken with people who haven't used an EQ and they were happy, until listening to a set with an EQ. The difference is quite huge. As for bass response, without the EQ they are pretty much gutless. With a parametric EQ you can improve things. Those are still pretty cheap and pretty common. But for the best bang you will need the correct EQ. Original and Series II can use either EQ interchangeably. Series III and IV, the same applies, as does Series V and VI, meaning the stated pairs will work with the same EQ Series. Example: you can use the Series VI EQ with a Series V 901, but not with the Series III or IV. I've had people shocked at the bass and highs from my 901 speakers, every time. Never fails. They've read the same BS, "Bose, no highs, no lows". Without EQ, sure, with EQ a whole different animal. Keep us posted. Those of us who OWN them are here to support.

I believe you to be "spot on" about Bose and their EQ matching. I have not had the privilege to own the 901s, but my brother did get the Series 3 after serving a tour in Germany. The speaker system was phenomenal! Of course, he had the complete system; EQ, amp and controller .

I am not sure why there is Bose-bashing when it comes to the design but you may have answered this if these speakers are used without proper EQ. The direct-reflecting technology is very curve dependent and to me can only be enhanced with the matching/comparable equalizer .

I have a set of Bose 301s, purchased back in..... I think the early 80s? I still enjoy this relatively low powered speaker set with all types of music. With proper EQ tapering the power fed (I use a 9100 Kenwood) .. they can be very loud, increasing proportionately up the scale. Unbelievably vivid, as well.

Anyways... I suppose I am wholly in support of your tribute !

 

[tarior]

The Bose 901 EQ provides about 40db of boost at the frequency extremes. Which makes sense as they are trying to coax full range sound out of 9 midrange drivers in a very small box, and they do it surprisingly well when placed and powered correctly.

 

[cmcvey]

I do have the matching EQ so I'm not sure... I guess I'll continue to play with the placement a bit more before I make a final decision.
Would you guys attempt fixing the broker speaker or just buy a replacement? I found an original one for $30 on ebay.

 

[50nstillhifi]

I do have the matching EQ so I'm not sure... I guess I'll continue to play with the placement a bit more before I make a final decision.
Would you guys attempt fixing the broker speaker or just buy a replacement? I found an original one for $30 on ebay.

Go with the original ... as a replacement!

 

[dshoaf]

Let's figure out what's wrong with the old driver first. What does it do - or not do - that leads you to believe it is bad? Did it rub, has the foam surround rotted away, etc? Bose Warranty Repair procedures called for the speaker to be swept with a frequency generator to determine which drivers might be bad. I've discussed this here at AK in other threads how this is done.

And what, exactly, did you do to remove it? The reason I ask is that Series IV drivers are wired in series but are mounted in individual chambers each venting into a shared vent tube to the back. If one is removed, then the entire speaker should have stopped working yet you report that it continues to work unless you reconnected the 2 wires.

Lastly, the Bose EQ should be wired into the Tape In/Out and switched into the circuit or placed between the preamp output and the power amp input. If it isn't connected, then you'll be missing the proper effect of the speakers.

Cheers,

David

 

[nclh77]

The Bose 901 EQ provides about 40db of boost at the frequency extremes. Which makes sense as they are trying to coax full range sound out of 9 midrange drivers in a very small box, and they do it surprisingly well when placed and powered correctly.

15db was the max on on the acoustic suspension version and the ported versions about 22db. Ironically, max gain on the acoustic suspension was in the bass regions and for the ported, in the high frequency. Seems they gave up on deep base in the sake of efficiency. Each eq box had a slight variance.

 

[dshoaf]

15db was the max on on the acoustic suspension version and the ported versions about 22db. Ironically, max gain on the acoustic suspension was in the bass regions and for the ported, in the high frequency. Seems they gave up on deep base in the sake of efficiency. Each eq box had a slight variance.

This is incorrect. The entire 901 cabinet and drivers were completely re-engineered. This is why there were the changes made - not because they gave up on anything.

The problem with the Series I/II 901s was that they were terribly inefficient at a time when top end receivers delivered about 50-60 wpc. To address the problem, Bose set out to improve efficiency to lower that technical obstacle to purchase. This is why there were substantial changes made to the EQ - not because there was some sort of change of heart on the part of the engineering team.

Also recall that the mighty 1801 power amp and 4401 preamp had also just been marketed, too. I can assure you that the good Dr. Amar Bose would have not put up with such silliness.

Cheers,

David

 

[nclh77]

This is incorrect. The entire 901 cabinet and drivers were completely re-engineered. This is why there were the changes made - not because they gave up on anything.

The problem with the Series I/II 901s was that they were terribly inefficient at a time when top end receivers delivered about 50-60 wpc. To address the problem, Bose set out to improve efficiency to lower that technical obstacle to purchase. This is why there were substantial changes made to the EQ - not because there was some sort of change of heart on the part of the engineering team.

Also recall that the mighty 1801 power amp and 4401 preamp had also just been marketed, too. I can assure you that the good Dr. Amar Bose would have not put up with such silliness.

Cheers,

David

Nope. Bose did give up fundamental bass for efficiency with the ported versions. They could have tried to eq some of it back, but would then have to give up on efficiency which is exactly what they were going for with the ported version. There is no free ride in life or speaker design. And an eq curve isn't going to change that.

 

[the skipper]

I dunno about anyone else but I see the "bose bashing" as reserved for their more modern "acoustimass" type of speaker systems for being overpriced and underperforming.

I think that many here respect their "real" speakers like the 901, 301, etc, etc..

 

[dshoaf]

My last post in this thread: When I ran a Bose warranty repair station as part of a Bose full-service dealership while in engineering school, I was on the front lines with the change over from the Series II to Series III 901s, the introduction of the 301/501/601 series and the preamp/power amp products.

We received lots of procedures and training to support the products which we used to provide guidance for customers. This came directly from the Bose dealer support team in Framingham. We even had Mr. Bose visit the store and my shop about the same time along with the Bose regional sales rep whom we knew quite well. While that was 40 years ago now, I learned a lot from the entire Bose sales and dealer support people back then.

From that experience, they were well engineered and innovative products for that generation of manufacturing, IMHO.

Cheers,

David

 

[nclh77]

I dunno about anyone else but I see the "bose bashing" as reserved for their more modern "acoustimass" type of speaker systems for being overpriced and underperforming.

I think that many here respect their "real" speakers like the 901, 301, etc, etc..

Bose bashing started with the original 901. The design was polarizing. Dr. Bose even had management turnover at Bose with concern regarding the design/viability of the 901 which I find a bit surprising considering the design and market failure of the 2201.

 

[whoaru99]

The Bose 901 EQ provides about 40db of boost at the frequency extremes. Which makes sense as they are trying to coax full range sound out of 9 midrange drivers in a very small box, and they do it surprisingly well when placed and powered correctly.

It's more like 20dB, but 20dB is still a lot.

 

[the skipper]

Bose bashing started with the original 901. The design was polarizing. Dr. Bose even had management turnover at Bose with concern regarding the design/viability of the 901 which I find a bit surprising considering the design and market failure of the 2201.

I have to say, I never heard of the 2201 before today While similar in intent, I do see significant differences between the two. Both seem to be striving for the same goal but using dissimilar methods.

I'd say the 901 was an evolutionary step from the 2201 aimed at making a more universal, more marketable, speaker

1) the 2201 used multiple drivers, more than the 901, and facing the listening area. The 901 had them facing away from them, using the wall for reflection.

2) the 2201 had built in amplification and equalization. The 901 still used equalization but depended on an external amp thereby reducing the overall cost of the system.

that being said, I heard he original 901's and with proper placement, ample power, and the right source material they actually were quite good.

.

 

[nclh77]

I have to say, I never heard of the 2201 before today While similar in intent, I do see significant differences between the two. Both seem to be striving for the same goal but using dissimilar methods.

I'd say the 901 was an evolutionary step from the 2201 aimed at making a more universal, more marketable, speaker

1) the 2201 used multiple drivers, more than the 901, and facing the listening area. The 901 had them facing away from them, using the wall for reflection.

2) the 2201 had built in amplification and equalization. The 901 still used equalization but depended on an external amp thereby reducing the overall cost of the system.

that being said, I heard he original 901's and with proper placement, ample power, and the right source material they actually were quite good.

.

Dr. Bose felt a spherical shaped transducer was the optimum way to produce sound. He stated an 1/8 sphere placed into a corner mimicked a sphere. This became the 2201. He and the market didn't particularly like the 2201. Dr. Bose had to go back to the drawing board. By then, it became a matter of survival for the Bose corporation despite its small size, there were already loyal employees and investors. The 901 was really a different direction than the 2201 though utilized reflected sound in a manner which Bose felt was necessary for optimum reproduction. Dr. Bose had a difficult time initially selling the 901. His big break came after a well respected reviewer gave the 901 a good review. Bose was able to capitalize on this, it's sucess financed a string of other well designed speakers and the rest is history.

 

[50nstillhifi]

Well..... I base success on "real world" circumstances, and the fact that some vintage audio folk, call them "Bosers"... I suppose ; do have working 901, 301, and 201 systems performing at spec for these many years, says something "positive" about the design.

Truly, I have yet to hear a speaker system that delivers the clarity, efficiency, and reproduction across the audio curve as most Bose systems will...and my wife loves her vehicle Bose system.. she says its "awesome" !

Now I preface this with the following; Bose purists and even the instruction manuals ask you to place and EQ the speakers in a certain manner. Following that guidance, I can't see why the average listener would not admire the performance. Perhaps this is where most challenges are with satisfaction and performance ?

Yet, I would think this is an influencing factor with most consumer products... particularly audio..

Currently, I have 301s, 201s, and would leap to get a pair of 901s!

 

[Copa1934]

For 40 years I lusted for a pair. I either couldn't afford a set, or I didn't have appropriate rooms to take full advantage of the design. When we bought our first home we had 3 children and more than enough other things on our plate. I was deep into restoring a 1967 El Camino, woodworking, photography, and of course activities with the family. The only thing audio, for me at the time, was Surround Sound. We gathered as a family and watched movies. After the kids were out and we moved to a new home in a new location I met up with an Audio Addict. This rekindled my interest in the Bose 901. Thankfully the Man Cave was ideal in shape for 901 speakers. My first pair were first Generation w/o EQ. I enjoyed them somewhat. I borrowed a parametric EQ and that helped, but it also inspired me to acquire a Bose EQ. Once I had that things changed dramatically. Out of curiosity I purchased a Series II EQ, since I learned that they could be used interchangeably. What I discovered was the first gen sounded better still with the Series II EQ. Not a lot, but enough to be notable. Why? Maybe the design, maybe the Series II was newer or "fresher" (caps not as aged). I eventually made a deal on a very nice, well cared for pair of Series II Continentals. They sounded slightly better than the first gen. Prior to this I had a pair of 501, which were nice. Had very good bass. But other speakers I owned sounded better to me so I parted with them. I eventually picked up a pair of 601 II that were in rough shape. Restored them, including replacing the two non Bose woofers with correct Bose woofers. I really enjoyed them, but a friend enjoyed them more (or he thought). We swapped speakers and he wound up NOT being so happy with them. So we traded back. I was elated. I was so happy to have them back. I still own them. Quite amazing speakers. I agree that most of the bashing has to do with the Wave and some of the other general purpose consumer goods. I'm quite happy with my Bose speakers. They don't do everything great, but with the right music they are wonderful. I don't consider them the end all be all, but of all my speakers they are among the top two pair.

 

[jdmccall]

I'm coming up on 7 years with my Series VI 901's. Also, I just bought a pair of 201's for the front L&R spots in my humble surround set-up. So I guess that makes me a Boser. Or a Boso (Bose-O?). But I'd have to be a "born-again" Boso because I first had 901 IV's in the mid-70's, but after selling them in the late-70's, I didn't own another Bose product until 2009. In the "missing years" I owned ESS, klipsch, Amrita, a/d/s/, B&W, Mobile Fidelity Sound Lab, Energy and Polk. I probably left some out. Actually had klipsch three times. I've been a speaker slut.

 

[toxcrusadr]

I had the same questions for the OP about the 'blown' driver. I didn't know they had individual enclosures that joined up somewhere, but in any case, any speaker cabinet with an extra hole in it is not going to sound the same. Plus the obvious problem with removing a driver wired in series.

I don't know what the bass boost is in db with the loudness control on this receiver but cranking any system up with the loudness on is a recipe for trouble. If the bass seemed anemic, it may be room placement, but check the polarity on ALL the connections - receiver to EQ and back and then the speaker cables. A misstep anywhere puts the channels out of phase. Or, you might just be a bass hog who has gotten used to listening to music with bass boosted far beyond what the recording engineer intended. It's your choice but be aware this can be really hard on speakers.

Another possibility is that whoever did the refoam on these miswired the drivers internally. Also that the 'bad' driver was refoamed with a rubbing voice coil in the first place. If you feel a scratchy feeling in the cone when you depress it with your fingers, it's rubbing and that will eventually short out or open up the voice coil. Refoaming may fix it.

Sorry for the actual on topic post, return to your Bose debate folks.

 

[jberger]

One simple test to see if all of the drivers in the cabinet are in phase: disconnect the speaker wires from the speakers, and use a 1.5 v battery and a couple of wires connected to the terminals. By convention (not absolute). if you provide positive voltage to the positive terminal, all of the drivers should move out. If you find one that moves in, it's working against you and cancelling your bass, and its polarity needs to be reversed.

toxcrusadr, the Series III used three different ported chambers that interconnected; that's one reason why they switched to molded plastic cabinets from all wood. I believe they tuned them to different frequencies intentionally.

 

[toxcrusadr]

Ah, the old multiple Helmholtz resonator chamber trick, eh? Cool. Did not know they switched to a molded plastic cabinet. Huh.