By "Clip off" I mean to send to the other amp. Here is what I mean.
My expectations Bose 901 and setup
whoaru99
Epic Member
This is not much of a concern since you're using multiple amps to drive the different speakers, not putting multiple speakers in parallel off one amp.
whoaru99
Epic Member
Sure. Most of us know what the low pass, bandpass, and high pass of a crossover do.
Last edited:
whoaru99
Epic Member
I see no technical issue. It's simply a matter of connection, tuning, and in the end whether it meets or exceeds your expectations (or not).
Terrific. Thanks for the drawing. Has anyone tried this with the 901s?
the skipper
Professional Curmudgeon
Depending on how set you are in forcing this miscegenation of parts working together, you might be well served by forgoing the Bose altogether and start searching for new speakers, perhaps with an eye on a subwoofer as well..
Blue Shadow
Waiting for Vintage Gear from this century
No one has tried it. What you are doing is removing the highs and lows from the 90s signal and those are the parts of the signal that gets lots of EQ from the 901 EQ so your 901s will become midrange drivers for which they are very capable.
If you are using a sub and it is not in the EQ stream from the 901 EQ and use it with the 901s and you still need more bass...Houston we have a problem. But that isn't critical, it leads one to believe you are looking from WAY more bass than a normal stereo produces. No problem, just need to make this rig sound the way you want it to sound without overdriving anything.
The diagram w99 drew up is correct. Do not Bose EQ anything except the 901s. Other speakers do not like that excessive boost at the top and bottom.
Depending on the sub you could run that without the crossover. But you need to crossover to get just the highs for whatever speaker you subject to that.
This is just a very odd request. That is the reason there are no specific do this and that to get what you want, no one has done this before.
How much bass and treble to you need to add? How much of each end of the audio spectrum are you trying to augment? If you have to go to all this maybe other gear would be better but...we'll see what we can do to make your scheme work.
What music and how loud do you listen? Has that been covered? What bands just can't get the top and bottom end loud enough for you with the 901s and the Pioneer?
If you are using a sub and it is not in the EQ stream from the 901 EQ and use it with the 901s and you still need more bass...Houston we have a problem. But that isn't critical, it leads one to believe you are looking from WAY more bass than a normal stereo produces. No problem, just need to make this rig sound the way you want it to sound without overdriving anything.
The diagram w99 drew up is correct. Do not Bose EQ anything except the 901s. Other speakers do not like that excessive boost at the top and bottom.
Depending on the sub you could run that without the crossover. But you need to crossover to get just the highs for whatever speaker you subject to that.
This is just a very odd request. That is the reason there are no specific do this and that to get what you want, no one has done this before.
How much bass and treble to you need to add? How much of each end of the audio spectrum are you trying to augment? If you have to go to all this maybe other gear would be better but...we'll see what we can do to make your scheme work.
What music and how loud do you listen? Has that been covered? What bands just can't get the top and bottom end loud enough for you with the 901s and the Pioneer?
Thanks for the great reply. I wouldn't say it's a matter of louder, but cleaner highs and Lows. Right now I feel these speakers give me highs and lows but not the outer ranges. I do have the ability to keep my crossover flat in the mid section, which would deliver the full sound the Bose where intended for.
I appreciate all the replies, and I feel a little more assured in my "science project". Worst case scenario, I end up with a Crossover and a Spec 2 for sale, which I very doubt will lose value in time.
I purchased a pair of first series 901s back when they first came out, IIRC that was in 1971. Powered them with a Mac C28/2105 combo.
The 901s suck up an incredible amount of amplifier power. In fact it's a rare amp that can fully power them. I blew a channel of my 2105 twice in the three years that I owned the 901s. The amplifier repairs were performed at the McIntosh factory in Binghampton, so there should be no question there. Bose's "Direct/Reflecting" scheme (or whatever they called it back then) was initially attractive to a young listener such as myself but after the honeymoon was over it showcased its faults as well as its attractions. I fooled with the 901s for a total of three years before I gave on them.
My advice (since you asked for it) is for you to forget your 901 scheme. You'll wind up wasting your time and money chasing an unobtainable goal.
The 901s suck up an incredible amount of amplifier power. In fact it's a rare amp that can fully power them. I blew a channel of my 2105 twice in the three years that I owned the 901s. The amplifier repairs were performed at the McIntosh factory in Binghampton, so there should be no question there. Bose's "Direct/Reflecting" scheme (or whatever they called it back then) was initially attractive to a young listener such as myself but after the honeymoon was over it showcased its faults as well as its attractions. I fooled with the 901s for a total of three years before I gave on them.
My advice (since you asked for it) is for you to forget your 901 scheme. You'll wind up wasting your time and money chasing an unobtainable goal.
The Realistic Optimus 1's are sort of Radio Schaak's clone of a KLH 5 (or 6?)...ten inch woofer, two 2 1/2" tweeters, with a "serious" RLC crossover network. Mine are old...real old, maybe even prototypes as the are USA-made. But by themselves all bass and some midrange...so the Op-1's have a problem as the type never sounded like that. Just as you, experimenting, ran them with the Bose 901's (Series II) and the combination sounded really good. Didn't lose the "band playing in the next room" feel, but bass was really enhanced for the better. Ran the two pairs (without the Bose eq) like this for quite a while.
My Bose 901's are 8 ohms, the Optimus are 8 ohms, so running them off one receiver I never (theoretically) got below 4 ohms total impedance. If you are using two other amps besides your receiver, you are probably good, but don't double up on the receiver without checking...presume she must have requirements on back panel that pretty much says don't go below 4 ohms. Do not know what the impedance of your ceiling speakers are, nor how the sub gets connected. Don't hurt your Pioneer!
My Bose 901's are 8 ohms, the Optimus are 8 ohms, so running them off one receiver I never (theoretically) got below 4 ohms total impedance. If you are using two other amps besides your receiver, you are probably good, but don't double up on the receiver without checking...presume she must have requirements on back panel that pretty much says don't go below 4 ohms. Do not know what the impedance of your ceiling speakers are, nor how the sub gets connected. Don't hurt your Pioneer!
Blue Shadow
Waiting for Vintage Gear from this century
The Bose 901 will not do clean clear highs and lows. They are a 4" midrange driver driven to +18dB on the bass and +20dB on the high end to simulate as best they can some highs and lows. They just don't do the extremes very well. Maybe a pair of piezo tweeters and a couple powered subs is all you need with that crossover and you could use a smaller amp if the subs are powered with built in plate amps.
The first two series of 901s were sealed cabinets and sucked power. The Series III on are ported cabinets and they can play louder with the same power input but they still need power because of the gross distortion of the flat frequency response most amplifiers are designed to do. That +18dB boost on the bottom end is a serious power sucker for amps.
Put a pair of 901 V and a Crown PSA-2 into a friends 30x50 out building, half loft for the rig and just hanging, lift on the other side for wrenching. That system really rocks but it also fires the IOC LEDs regularly when cranked. But that is enjoyably loud but not quite concert levels. For that he needs another pair and three more PSA-2 amps to run mono at 725 wpc as the measly 275 in stereo is only adequate.
JoeESP9
ESL's & tubes since 83
Since you asked for opinions I'll give you mine. 901's need so much equalization to sound halfway decent I wouldn't rely on them sounding very good even when used only as midrange speakers. The Eq they need is so radical and extends to include so much of the midrange, I can't imagine them sounding good in the connection you're asking about.
I strongly suggest you check out how much of the Eq extends to the midrange. You may think twice about what you propose.
Personally, I'd sell the 901's and buy just about any other speakers. As should be obvious, I'm not a Bose fan. The only thing they've ever made that I would have the slightest interest in is the 1801 amplifier.
What he said.
Even though you asked them not to in your original post, Bose-hate seemingly cannot be contained...
You've received replies from many learned members (not intended as a shot), I hope that you have fun with your experiment and you get the result you're hoping for.
You've received replies from many learned members (not intended as a shot), I hope that you have fun with your experiment and you get the result you're hoping for.
the skipper
Professional Curmudgeon
We're not Bose haters. We just realize the limitations of some of their products. If used within their design limits they can be quite nice.
And, yes, I do respect the 901 series when they are properly placed, sufficiently powered, and playing certain material.
But, in this case, he seems to be trying to make a silk purse out of a sow's ear.
Last edited:
BilboBaggins
Addicted Member
This thread caught my eye because I’ve had 901 series 2, 901 series 3, a Pioneer Spec 2 amp, and I still have two Bose 1801 power amps with a 4401 preamp. I had the series 2 901s hooked up to one of my 1801s. These are the only speakers that have ever made those meters move significantly. In fact they pegged.
That was while playing Avril Lavigne's Sk8TR Boi. I had been playing a mix as I tested out the 901s, but I never expected them to draw so much current during that part of the song. I turned the volume down real fast! Nothing was harmed, and I learned to be more cautious going forward. I found that there is plenty of bass and high frequencies. Personally, I believe that high current amps are required for these speakers to sound best. And because very few match the 901 with a proper amp, they don't really hear what the 901s are capable of. The Spec 2 should drive the 901s very nicely. You might want to try them just with the 901s and the Spec 2s before you invest any further.
I sold both sets of 901s. Compared to my Kef 105s, they lost. As the skipper was saying, you will lack in quality lows and highs. And as suggested, getting a new set of speakers that will meet your needs is more efficient. But interesting experiment, and I will keep an eye on this thread.
Frank Sol
Lunatic Member
Have heard 901s without Bose's EQ... Maybe they were bought used without EQ
Guy added a power Sub with high level in/out -- set the sub XO at 120hz (thereabout)
Also added super tweeters sitting on top of each 901 (not sure of XO point)
IMO... SQ was ok if one likes the 901's 'sound'
Guy added a power Sub with high level in/out -- set the sub XO at 120hz (thereabout)
Also added super tweeters sitting on top of each 901 (not sure of XO point)
IMO... SQ was ok if one likes the 901's 'sound'
whoaru99
Epic Member
901s without the matching EQ (or approximate equivalent, e.g. miniDSP from Deer Creek Audio) are not 901s. The EQ is paramount to any semblance of good sound from them, even if 901s aren't your thing.
Interesting stuff there from Deer Creek Audio...