Tweaked out Bose 901 series 6 mk 2

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Æ

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #180 on: 22 Dec 2011, 01:01 am »
Maybe HFSG is really Corey Greenberg having fun. It's got to be something like that. There's no way anybody could really be as weird and worthless in real life. I'm sure there's a joke behind this ..... or something genuinely malevolent.

I'm ready to see pictures too. Show us you are for real.

Why do you need a picture? He has some BOSE 901 loudspeakers and a Yamaha receiver. Close your eyes and imagine them.

Do you actually think he would even know who Corey Greenberg is?

HiFiSoundGuy

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #181 on: 23 Dec 2011, 06:33 pm »
When setting up these 901's you first need to find out which speaker is your left speaker and which speaker is your right speaker.

 These speakers will not sound right until you get this right first.  8)

TONEPUB

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #182 on: 23 Dec 2011, 07:10 pm »
just keeps getting funnier.

rollo

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #183 on: 23 Dec 2011, 07:13 pm »
just keeps getting funnier.


 Freaken hilarious. My quess he is having more fun than us. I think the joke is on us for responding.



charles

avahifi

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #184 on: 23 Dec 2011, 07:36 pm »
Here is my take on the Bose 901 speakers, lifted directly from my 1983 Audio Basics newletter set.

Design advantages: This type of system can, if properly located, produce a large and pleasing sound field on some types of music.

Design disadvantages: One cannot “turn off” the large sound field on music inappropriate for this (such as a solo voice in a small room).

We would also suggest there may be flaws in the logic supporting the claims for the desirability of a system with substantial “reflected” output. One could point out that if we took the orchestra outside, and recorded it playing on an open flat field and then played the recording back in our home on a “reflecting” speaker system that created a “concert hall sound field,” that we would then have a concert hall sound that did not exist. Although you may like this, it is a departure from the reality of the acoustic environment of the recording.

Another disadvantage is that many reflecting speakers, including the 901, are designed for active equalization. The raw system frequency response is down substantially at both high and low frequencies. The designers claim to overcome this by supplying with the system an active frequency equalization circuit, which, it is claimed, shapes the signal to the power amplifier to compensate for the raw response of the system, thus giving satisfactorily flat response.

The “catch” to this design technique is that for each 3 dB boost in acoustic output (an increase barely audible by most people) a doubling of amplifier power is required. Thus, if the boost at 20 and 20,000 Hz was in the area of 15 dB, for example, the amplifier would have to be thirty two times as powerful at these frequencies as in the mid-range where no boost was applied. Thus, if you were driving your amplifier to a 10 watt level on mid-range material, the equalizer would drive the amplifier to 320 watt levels at high and low frequencies, clearly beyond the capabilities of most amplifiers. Active equalization can only work well if the amount of boost is within the power capabilities of your amplifier. There ain’t no such thing as a free lunch.

Finally, remember that microphones are stupid. The mike cannot distinguish between direct or reflected sound in the recording process. The microphone picks up all the sound at its location, no matter whether it came directly from the instrument or was first reflected from the recording surroundings. This sound, a mix of direct and reflected acoustics, is sent on to the recorder, and if the engineering is good, will finally show up on your record. In a linear system, the output of front facing speakers will play back this mix of direct and reflected sound (what the microphones “heard”) in the proper proportion (assuming good judgement by the recording engineers in original microphone placement) and your system will play back the sound of the “hall” as it existed quite satisfactorily.

We would suggest that further deliberate “reflections” in your room is, at best, redundant. We prefer, in fact, a very “dead” and non-reflective listening environment in which we listen to the direct output of the speakers, with the acoustics of the listening room minimized. We desire to hear what is on the record, and only what is on the record. If the recording is bad, we want to know so, if it is great, we want to hear it, and nothing else. Fortunately, there are enough super recording engineers around (Jack Renner and Bob Woods of Telarc, for example) that our desires for well engineered records are met.

Frank Van Alstine

PS  All back issues of Audio Basics are available as free .pdf downloads at our web site, www.avahifi.com

Soundminded

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #185 on: 24 Dec 2011, 12:25 am »
Here is my take on the Bose 901 speakers, lifted directly from my 1983 Audio Basics newletter set.

Design advantages: This type of system can, if properly located, produce a large and pleasing sound field on some types of music.

Design disadvantages: One cannot “turn off” the large sound field on music inappropriate for this (such as a solo voice in a small room).

We would also suggest there may be flaws in the logic supporting the claims for the desirability of a system with substantial “reflected” output. One could point out that if we took the orchestra outside, and recorded it playing on an open flat field and then played the recording back in our home on a “reflecting” speaker system that created a “concert hall sound field,” that we would then have a concert hall sound that did not exist. Although you may like this, it is a departure from the reality of the acoustic environment of the recording.

Another disadvantage is that many reflecting speakers, including the 901, are designed for active equalization. The raw system frequency response is down substantially at both high and low frequencies. The designers claim to overcome this by supplying with the system an active frequency equalization circuit, which, it is claimed, shapes the signal to the power amplifier to compensate for the raw response of the system, thus giving satisfactorily flat response.

The “catch” to this design technique is that for each 3 dB boost in acoustic output (an increase barely audible by most people) a doubling of amplifier power is required. Thus, if the boost at 20 and 20,000 Hz was in the area of 15 dB, for example, the amplifier would have to be thirty two times as powerful at these frequencies as in the mid-range where no boost was applied. Thus, if you were driving your amplifier to a 10 watt level on mid-range material, the equalizer would drive the amplifier to 320 watt levels at high and low frequencies, clearly beyond the capabilities of most amplifiers. Active equalization can only work well if the amount of boost is within the power capabilities of your amplifier. There ain’t no such thing as a free lunch.

Finally, remember that microphones are stupid. The mike cannot distinguish between direct or reflected sound in the recording process. The microphone picks up all the sound at its location, no matter whether it came directly from the instrument or was first reflected from the recording surroundings. This sound, a mix of direct and reflected acoustics, is sent on to the recorder, and if the engineering is good, will finally show up on your record. In a linear system, the output of front facing speakers will play back this mix of direct and reflected sound (what the microphones “heard”) in the proper proportion (assuming good judgement by the recording engineers in original microphone placement) and your system will play back the sound of the “hall” as it existed quite satisfactorily.

We would suggest that further deliberate “reflections” in your room is, at best, redundant. We prefer, in fact, a very “dead” and non-reflective listening environment in which we listen to the direct output of the speakers, with the acoustics of the listening room minimized. We desire to hear what is on the record, and only what is on the record. If the recording is bad, we want to know so, if it is great, we want to hear it, and nothing else. Fortunately, there are enough super recording engineers around (Jack Renner and Bob Woods of Telarc, for example) that our desires for well engineered records are met.

Frank Van Alstine

PS  All back issues of Audio Basics are available as free .pdf downloads at our web site, www.avahifi.com

Mr. Van Alstine may be extremely talented tweaking the design of Dynaco amplifiers and preamplifiers but in this case he is badly mistaken. The speakers reproduce within their limitations of accuracy what is fed into them which in the case of commercial recordings is mostly the output of microphones located very near the sources of sound, the musical instruments. What's more most of the time the microphones are relatively directional. They pick very little of the reverberant sound field and in a form that is for all practical purposes useless. This is very different from where the listener in the audience sits far away and with each ear picking up an entire hemisphere of sound. There is no way Bose 901 or any other speaker can reproduce the sound of a musical performance heard in a concert hall from a commercial recording. The reverberant signal is not on the recording to anything like what is heard live and the reverberant sound field produced by Bose 901 in a home has nothing in common with the reverberant sound field heard in a concert hall. For all its flaws, Bose 901 is no better or worse in this regard than other speakers. Unless you live in an anechoic chamber all speakers reporduce some reflections in the listening room.

There are flaws in the logic of all hi fi speakers. That's why there aren't any that sound like actual music. Amplifier power today is cheap, you can buy an amplifiier with several hundred watts of output power for several hundred dollars. Equalization is a valid engineering technique without which LP phonograph records, analog tape, FM radio, and analog TV would not be possible. A crossover network is also an equalization circuit.

See my previous posting on this thread for a more complete and objective analysis of the strengths and weaknesses including the fatal flaws in Bose 901.

JerryM

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #186 on: 24 Dec 2011, 12:39 am »
Mr. Van Alstine may be extremely talented tweaking the design of Dynaco amplifiers and preamplifiers but in this case he is badly mistaken.

In my experience, you are wrong on every possible level and account . The rest of your post thus rendered useless, to me.

HiFiSoundGuy

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #187 on: 24 Dec 2011, 12:51 am »
                         . 8).

werd

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #188 on: 24 Dec 2011, 01:29 am »
In my experience, you are wrong on every possible level and account . The rest of your post thus rendered useless, to me.

I like Frank`s account of the 901`s also. They are a speaker that do one thing rather excellently but everything else poorly. When properly situated especially high up there ability to become unlocalized is excellent. Better than anything out there i have heard. But they do everything else so poorly that they cant be recommended for anything other than generic pa systems like in a work out gym.

TONEPUB

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #189 on: 24 Dec 2011, 02:22 am »
Frank is one of the most no-nonsense guys in hifi. 

HiFiSoundGuy

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #190 on: 24 Dec 2011, 02:51 am »
I think the >Tweaked-out 901 system.. version< are in a league of their own ! BEST SPEAKER MONEY CAN BUY....(PERIOD) !!...   8) 

bside123

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #191 on: 24 Dec 2011, 03:00 am »
My most memorable experience of Bose 901 Speakers was in the late 1970s, when during a Bose demonstration, the sales rep in a local, hi-fi shop said, "Watch this!" and proceeded to fasten an electric cord (zip cord) to both terminals of the speaker's binding posts. He then took it one step further and plugged the speaker into the AC wall socket. For real!

It made an unearthly amount of noise, drove everyone out of the listening room and apparently didn't blow the speakers. Me thinks that was the whole point of the demo. :scratch: In other words, these speakers are so badass, that you can plug 'em right into the wall. Phil Spector eat your heart out.

I didn't stick around to listen to anymore "music" at those volume levels :no_hear:, and I haven't ever been interested in Bose since. Am I the only one to have seen one of these early Bose "demonstrations"?  :wtf:

Pez

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #192 on: 24 Dec 2011, 03:15 am »
Hifisoundguy, can you try this with your 901s and report back?

Andre2

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #193 on: 24 Dec 2011, 03:24 am »
Hifisoundguy, can you try this with your 901s and report back?

 :rotflmao:

In my quest for a audio system this year, I went downtown Houston to a Bose store.  Listened to them, got out of there in 10 minutes never to go back.  what a piece of junk and overpriced those speakers are.

Æ

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #194 on: 24 Dec 2011, 04:02 am »
My most memorable experience of Bose 901 Speakers was in the late 1970s, when during a Bose demonstration, the sales rep in a local, hi-fi shop said, "Watch this!" and proceeded to fasten an electric cord (zip cord) to both terminals of the speaker's binding posts. He then took it one step further and plugged the speaker into the AC wall socket. For real!

It made an unearthly amount of noise, drove everyone out of the listening room and apparently didn't blow the speakers. Me thinks that was the whole point of the demo. :scratch: In other words, these speakers are so badass, that you can plug 'em right into the wall. Phil Spector eat your heart out.

Hey, no big deal. You can do that with many a loudspeaker. All you have to do is use a woofer(s) in an enclosure that has its impedance peak (fs) close to 60Hz! Let's do the math, Voltage Squared, Divided By The Impedance. Suppose you have a woofer with a Zo of maybe 60 ohms, then you plug it into your 115VAC wall outlet, the woofer only gets 220 watts. The trick is having the loudspeaker resonance at or near 60Hz.

I did this once with a really cheap three way loudspeaker that had a 15" woofer, the woofer just hummed loudly, producing a 60Hz tone. Then I deliberately put my hand against the woofer cone to damp it. The impedance immediately dropped down to its nominal value and pssst, goodbye woofer.

tesseract

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #195 on: 24 Dec 2011, 07:32 am »
I think the >Tweaked-out 901 system.. version< are in a league of their own ! BEST SPEAKER MONEY CAN BUY....(PERIOD) !!...   8)

Well, isn't that ...  http://www.youtube.com/watch?v=RmwqnqL3Hbg

Soundminded

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #196 on: 24 Dec 2011, 01:29 pm »
In my experience, you are wrong on every possible level and account . The rest of your post thus rendered useless, to me.

My replies #13 and #18 on page one are based on 40 years of experience with this product, detailed engineering analysis of it, and two tries to re-engineer it, the second one taking 4 years. If you can't learn anything from the knowledge I gained about what is right with it, what is wrong with it, and how to fix it, that is your problem. As for Van Alstine's opinion, I don't know what that is based on but it is most likely based on superficial limited knowledge and and casual experience of the product as manufactured. He should stick to tweaking the bias on triodes and pentodes, he's way out of his league here.

macrojack

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #197 on: 24 Dec 2011, 03:23 pm »
Soundminded sounds very credible to me if, in fact, he really devoted 40 years of his life to converting the Bose 901 from the garbage that comes from the factory to something useful and enjoyable. You gotta question the ROI on that project though. Was it really worth so much trouble? And why start with Bose rather than something else that actually sounded good in stock form?

bside123

Re: Tweaked out Bose 901 series 6 mk 2
« Reply #198 on: 24 Dec 2011, 04:38 pm »
Hey, no big deal. You can do that with many a loudspeaker. All you have to do is use a woofer(s) in an enclosure that has its impedance peak (fs) close to 60Hz! Let's do the math, Voltage Squared, Divided By The Impedance. Suppose you have a woofer with a Zo of maybe 60 ohms, then you plug it into your 115VAC wall outlet, the woofer only gets 220 watts. The trick is having the loudspeaker resonance at or near 60Hz.

I did this once with a really cheap three way loudspeaker that had a 15" woofer, the woofer just hummed loudly, producing a 60Hz tone. Then I deliberately put my hand against the woofer cone to damp it. The impedance immediately dropped down to its nominal value and pssst, goodbye woofer.

Yea... know that. My point was simply the absurdity of attempting to demonstrate the "superiority" of a speaker by plugging it into an AC wall socket... 60Hz and all... as if this somehow demonstrates superior sonics, fidelity, frequency response, imaging, material build, musicality, et al. The experience was impressive, not in a good way. It was just so dumb ass, and it proved nothing to me within the realm of Hi-Fi.  :rock:

Soundminded

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Re: Tweaked out Bose 901 series 6 mk 2
« Reply #199 on: 24 Dec 2011, 04:52 pm »
Soundminded sounds very credible to me if, in fact, he really devoted 40 years of his life to converting the Bose 901 from the garbage that comes from the factory to something useful and enjoyable. You gotta question the ROI on that project though. Was it really worth so much trouble? And why start with Bose rather than something else that actually sounded good in stock form?

I bought this speaker in 1970 and listened to it for a few years. It was in storage for most of the time I owned it. I'd read Dr. Bose's technical papers about it and considered what he had to say. Some of it was ingenius, some of it ludicrous. I'm not going into a detailed analysis of it here.

I began redesigning my other speakers in 1989 based on applying a mathematical model of sound fields I developed for another purpose in 1974. Bose 901 was the ultimate challenge. It's one thing to have a model, another to successfully impliment it. My first effort to redesign 901 was in the 1990s. That ended in failure. After more experience with other speakers I tried again in 2004. I was not satisfied with the results until 2008. It now bears no resemblance to the way other 901 systems sound. I'd considered publishing a paper about my model many years ago but decided against it as there is no profit in it for me. I experiment with audio equipment as a hobby, I'm not in the business although among organizations I belonged to in the past are the Acoustic Society of America and the Audio Engineering Society (IMO this later organization has degenerated into a consumer group of audiophiles.) As I also said earlier, based on common experience with this model, I don't expect anyone to believe me.

BTW, IMO plugging a loudspeaker system into a 120 volt outlet is about as stupid a thing as you can do even if you're lucky enough not to destroy it. Not only isn't it desgned for it, it also happens to be illegal, a serious and reckless electrical code violation that could result in tragedy.