Bose 901 Series VI Active Equalizer Measurements

[Mr. Widget]

"I wonder how a design like this could be made to sound if you just replace the front full range speaker with a modern 5-inch midrange and tweeter."

Say, like using the coaxial KEF drivers?

 

[milosz]

You used a 300b SET to drive this? So, like 5 watts RMS? Odd choice. Did you subtract the high THD of the SET amp from the speaker THD curves?

 

[beagleman]

I sold these and there was a certain amount of people that said “WOW”. The rest like me were horrified with how bad they sound. I have a buddy that has a pair and uses them turned around backwards and doesn’t use the eq. I just smile when he has them running.

I am not sure if that tells me more about the actual sound of the speaker or your notions about bashing Bose as a company and name.

I have heard them randomly over many years set up wrongly and so on and just very recently at a friends, and "Horrified" and "How bad" would never even come close to describing them.
They are not perfect for sure in regards to all ideals of "Audiophile Standards" and they have a huge, unusual at times, large soundstage for sure, but "Bad"??

They are relatively flat response, not annoying in the least, in fact relatively pleasant.
I feel if anything they lose some detail and clarity and so on, but nothing that would be even close to bad.

But, I have heard probably hundreds of speakers, rack systems, compact systems, cheap stereos, top of the line stuff...my standards of "Bad" may be different.

 

[Rottmannash]

Yeah, and one of the rarest 901's is the VI ver 2 which has the different foam surround.

The advantage of the 901 as "end game" speaker is that you stop looking for something new. If you're happy with something that objectively measures poorly, it is "end game" since you probably won't be able to find something to upgrade to. If you're looking for end-game high performance, that's where the extra 0.1dB of smoothness or noise can be tempting when cost is taken out of the equation.

It appears they are still for sale on Amazon. Are these still manufacutured??

 

[GXAlan]

It appears they are still for sale on Amazon. Are these still manufacutured??

Discontinued in 2016. So 1968 to 2016 production. (But lots of revisions over the years).

 

[Spkrdctr]

I am not sure if that tells me more about the actual sound of the speaker or your notions about bashing Bose as a company and name.

I have heard them randomly over many years set up wrongly and so on and just very recently at a friends, and "Horrified" and "How bad" would never even come close to describing them.
They are not perfect for sure in regards to all ideals of "Audiophile Standards" and they have a huge, unusual at times, large soundstage for sure, but "Bad"??

They are relatively flat response, not annoying in the least, in fact relatively pleasant.
I feel if anything they lose some detail and clarity and so on, but nothing that would be even close to bad.

But, I have heard probably hundreds of speakers, rack systems, compact systems, cheap stereos, top of the line stuff...my standards of "Bad" may be different.

I feel the same way. After listening to so many speakers over the years, my bad would be considered "horrible" on ASR. Good would be "listenable and my great to awesome would be the same as the ASR Great and awesome. So many consumers just buy a minimal system and get years of enjoyment out of them. I keep saying and I know many are tired of hearing it, but soundbars are the perfect example of what people want. Something VERY EASY to set up (plug and play) and that delivers good decent sound. Or in the high end soundbars delivers Dolby ATMOS pretty well. I think AVR sound systems are getting better and better. In 10 years we may have a unit that you hook up and hit a button and it dials in room correction and such. Very simple for the average guy or girl to do. It is coming in the future. A simple easy 5.2.4 ATMOS with almost no setup required other than to set up a mic and push a button. Especially if you get it with all wireless speakers and sub. Just drop everything in place and your off to good listening for music or movies. The future looks very bright for home audio.

 

[computer-audiophile]

Bose had original ideas, you have to give him credit for that. The Bose 901 'direct reflecting' was such an unusual idea. However, at the time I found the OHM-F e.g. much better soundwise as a full-range omnidirectional speaker.

I only heard a good combination once in the old days with the Bose 901 as bass support for large Magneplanar MG-1 magnetostat walls. That was absolutely great! The amplifiers were Bose 1801, which were above average at that time. Active crossover was from Sony. There were already brand-new LED VU meters on the front panel of the Bose amp in addition to classic pointer meters. There were other interesting details about this amp, e.g. its service-friendly construction. You could simply pull out the cooling rails with the power transistors.

These were luxury devices that I could not afford in my younger years. But I don't want to complain, because I always had pretty good audio stuff. For example, I had a pair of Sonab OA14 speakers for omnidirectional surround sound.

 

[GXAlan]

I only heard a good combination once in the old days with the Bose 901 as bass support for large Magneplanar MG-1 magnetostat walls. That was absolutely great! The amplifiers were Bose 1801, which were above average at that time.

It’s still an 82 lb solid state amplifier of which 41 lbs was the transformer… “above average” really is underselling it.

I think that’s a good concept. Running the Bose 901 as a musical subwoofer would be really interesting!

The other thought is adding a super tweeter to enhance the high frequency response.

 

[Mr. Widget]

The other thought is adding a super tweeter to enhance the high frequency response.

Hmmm.... I have a pair of Arum Cantus ribbons looking for a purpose.

Has anyone developed accurate PEQ filters to match the outboard equalizers? I realize they have been roughly approximated, but measuring the voltage drive should be fairly straight forward. It seems reducing the VHF EQ and adding a front firing tweeter would reduce much of the distortion and noise.

FWIW: When I first heard the 901s and was blown away, they were powered by a Mac MC-2300.

 

[computer-audiophile]

It’s still an 82 lb solid state amplifier of which 41 lbs was the transformer… “above average” really is underselling it.

I didn't know it was that heavy, didn't see it directly on it. In Heidelberg in the seventies, there was a very ambitious HiFi studio in a former movie theater. They had a lot of US 'audio flagships' which was quite unusual. But Heidelberg was also the European headquarters of the US Army.

 

[gnarly]

Hmmm.... I have a pair of Arum Cantus ribbons looking for a purpose.

Has anyone developed accurate PEQ filters to match the outboard equalizers? I realize they have been roughly approximated, but measuring the voltage drive should be fairly straight forward. It seems reducing the VHF EQ and adding a front firing tweeter would reduce much of the distortion and noise.

Unusual project for sure.
PEQ's would be easy enough, except for duplicating the variable boosts the 901 processor has. And as I figure you know, PEQ and shelving filters aren't always the same across platforms.
Do you have FIR? I could make a FIR file to duplicate the processor in about 10 min. (And easy to make multiple files for various boost schemes.)
They would be accurate no matter what platform.
Would you bi-amp? I'm pretty certain I would.

 

[NoxMorbis]

Yes, I agree.
As to the hanging from the ceiling, that was my 1 experience also. At a party in some point 1975-ish

Same here. The first time I heard the original BOSE 901s was about 1979. My best friend's brother in law borrowed a pair from his friend for a party large party. They opened all of the windows in the house, and had them hung from the ceiling about half way down an 8' ceiling, about 10' apart, and about 3' from any walls. The first time I heard them was about 3 blocks away. lol. My friend and I were on our motorcycles and he pulled us over, and we shut off our engines. He said, "Listen, that's Wiggy's party" (his brother in laws nik name). I still remember it was some song by Chicago with lots of horns. I asked me friend, "They got a live band!?" He laughed, and said, "No, they are BOSE 901s."

 

[computer-audiophile]

I think that’s a good concept. Running the Bose 901 as a musical subwoofer would be really interesting!

In this combination with the magnetostats it fitted. Magnetostats or electrostats simply can't make enough bass. I first used electrostats from Rennwald in Heidelberg in the early seventies, but only in the mid-high range.

Compared to the performance of today's subwoofers, the 901 can't keep up in the low frequencies, but it's actually sufficient, I think.

By the way, the term 'subwoofer' was not known at that time. I don't remember exactly when it first appeared. Also here in the forum you can see that some people seem to have a very special joy in powerful very low bass. It bothers me more sometimes because it excites the room too much. I prefer a slim crisp bass.

 

[kencreten]

Headphones eliminate the room effect, but speakers are more enjoyable to listen to even though it's not as transparent. Most of us end up having both a headphones and speakers and may choose different setups for different music/moods. The 901's, for me, add a third "effect" category though it is more subtle than the headphone/speaker comparison.


This is a great point. Still, audio science isn't restricted to the goal of identifying the best speaker for the biggest number consumers (though that is important). We still want to use science and understand the best speakers for our own room.

Take a look at my in-room measurements. The JBL 708P is setup in a small home recording studio. ~7 speaker width, ~8 ft listening position. The Bose 901's are in a large family room. I'll estimate ~14 ft speaker width, ~15 ft listening distance. Room is ~20 ft wide and I'd say 2 feet from the back wall.

First, the completely un-smoothed recording, showing how the comb filtering sort of gets filled in even though your phase will probably be wrong. I have adjusted the levels digitally to ensure that they are easily to overlap and compare.

View attachment 285238 View attachment 285240

And then a Psychoacoustic smoothing to show what it may actually sound like:
View attachment 285241



The point of the fun is not just that it presents the music spatially in a unique way, but that it actually can sound and measure great in the right room. That's the incredible science part. Maybe it's the equivalent of a broken clock that's correct twice a day, but we're still talking about a measurement-based comparison between one of the most state-of-the-art active studio monitors in production today, the JBL 708P, against a bunch of full-range drivers put into a box with a largely unchanged concept from 1968. Then with our science pointing out that stereo makes it harder to hear frequency flaws compared to mono, it's easy to understand how it is possible for 901 Direct/Reflecting to make it even harder to hear frequency response flaws compared to a standard stereo setup.

Like you, I had no real respect for Bose as a hi-fi product. It was just scientific curiosity that made me want to try them.

The 708P is vastly superior at high SPLs and vastly easier to room correct with DSP. Dream setup? JBL M2 with the SDP-75. I'm a super big JBL fan, having stuff from the Los Angeles, Northridge, and present era including products that were Japanese-market only. I've owned many of Allan Devantier's original designs including the HLS line as well as their sub/sats designed to compete with the Acoustimass 5 series. I've been a fan of Revel from the very first generation Revel F30 and B15 combo. I've owned a number of Infinity's including the original Modulus and dreamt of owning the Prelude MTS until the CMMD delamination issue popped up. I've had lots of Proceed electronics. My cars have Harman developed sound systems.

Still, the Bose 901 data is jaw dropping to me. Maybe it's pure luck that the 901's end up with this response at the listening position, or I won the lottery with the 901/room combo.

That's great that it worked out that way. I love audio in general and love reading about it, but personally, I'm into the studio stuff.

But, my room is exactly why I sit very close to my monitors, to reduce the influence of the room as much as possible. I'm interested in accuracy. I'm into professional audio gear. I want my setup to be similar to a studio control room. I want to hear what was recorded as accurately as possible. I have the small Neumann KH80s, with a good sub. I sit about 2.5 feet from the monitors at a 45 degree angle, with the tweeters basically ear level, and keep the levels down. I don't have 5.1 here. I'm not into that. My head sits in one spot, if I'm actually trying to listen. When I'm doing stuff around the place, then sound for me is a toss away, I'm not then listening for detail. So, again, for me the room is the enemy. I have Shure SRH1840s which are really comfortable. I think they sound great, and the are very sturdy.

I use REW to measure my room, but.. if I keep the volume down (loud for me is 86db) that reduces reflections a lot, and gets me most of the way to where I want to be.

I use my Kia's stock awful sounding system because I hardly drive. But there's so many good auto audio stuffs out there.

I love these Neumann kh80s, with my sub. I've never had a system that sounded this... amazing.

 

[NoxMorbis]

By the way, the term 'subwoofer' was not known at that time. I don't remember exactly when it first appeared. Also here in the forum you can see that some people seem to have a very special joy in powerful very low bass. It bothers me more sometimes because it excites the room too much. I prefer a slim crisp bass.

Indeed. I think Bose still refers to it's separate bass box as a "bass module." I too prefer a tight and crisp bass, not "sub" window rattling bass. My brother had a Paradigm UltraCube 10 that weighed in at 29lbs and power output was 1950 watts Dynamic Peak/650 watts RMS. My GOD that thing could rattle windows, and he had a concrete foundation. When he moved to an old foundationaless house with raised wood floors, it was insane. It was about 95% overkill. Of course you could always turn it down, which he did, to about 15%. But still, I never really liked how it would rattle everything in his house -- all the time.

 

[pseudoid]

The Bose901's intricate, internal labyrinth seems like unnecessary and circuitous pathways for audio signals to reach your ears.

<< Link >>

<< Link >>

 

[sfdoddsy]

Say, like using the coaxial KEF drivers?

I doubt the expense of 9 KEF coaxes would be rewarded.

Given the USP of the 901s was front back radiation, I suspect a good open baffle dipole would be the modern equivalent

 

[EJ3]

I doubt the expense of 9 KEF coaxes would be rewarded.

Given the USP of the 901s was front back radiation, I suspect a good open baffle dipole would be the modern equivalent

That did not answer the question.

 

[sergeauckland]

I doubt the expense of 9 KEF coaxes would be rewarded.

Given the USP of the 901s was front back radiation, I suspect a good open baffle dipole would be the modern equivalent

Main differences are that an open baffle has the front and rear radiation which is of opposite polarity and of nominally equal amplitude front and back, whereas the 901s have all drivers of the same polarity and only 11% is to the front.

S.

 

[GXAlan]

The other thought is if I can decrease IMD and THD by using two pairs of 901’s with a crossover either at 300 Hz or 3 kHz.

You still preserve the 11/89% ratio, have no crossover through the “critical midrange” but potentially can decrease IMD.