Bose 901 Equalizer Questions

Well,I saw a pretty nice pair of Bose 901 SeriesV at GW last week,and I just couldnt resist.Yeah,Im not a big Bose fan,either,but at $20 for the pair you just cant pass up a chance to try them out.Thing is,they didnt come with the equalizer,and I was wondering.Should I buy one from Ebay,or is there a way I could use another graphic equalizer and shape it to approximate the same tone controls?Any and all hints in this direction would be greatly appreciated.
Jimmy

You really have to have to Bose EQ, and there are several, so you should have the right one.

I believe the series I and II EQs are different electronically than the III and IV. I think III and IV are interchangeable, but don't quote me on that.

V and IV may be similar also.

They go on eBay for about $100, but are quite common.

Thanks.I have been looking at a few of the Series V equalizers on the bay,and it doesnt seem like a bad investment for curiousity value.If they turn out to sound halfway decent,I might do the Chain them to the ceiling thing and use them for HT.
Jimmy

That's how I recommend placing them. About 18" from the side walls, point about a foot from the back. For $20 you can't go wrong.

Series III and IV notoriously have shredded driver surrounds. Might want to check that as well.

bordeno said:

Series III and IV notoriously have shredded driver surrounds. Might want to check that as well.

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There's lots of Series III refoam kits on ebay for quite good prices - although there's an awful lot of drivers to do!

How do you get the grilles off of those puppies to check?
Jimmy

2DualsNotEnough said:

Thing is, they didnt come with the equalizer, and I was wondering. Should I buy one from Ebay, or is there a way I could use another graphic equalizer?

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.....I'm very glad to see this topic arise....I had a Super-Bose System for 10 years....needed to sell it in early marriage....hated to see it go.....

.....no, Jimmy, other eq's are not the same outcome, or none I tried sounded the same....but, you'll need "two" 901 eq's to hear that pair of 901's come to life....you won't be impressed toward realism using only one eq....and, this is not really receiver-territory, the 901's sing only more sweetly as power increases to around 300+ at 8....two 901 eq's....think tape loops, pre-out/main in's, etc.....

mulester7 said:

.....I'm very glad to see this topic arise....I had a Super-Bose System for 10 years....needed to sell it in early marriage....hated to see it go.....

.....no, Jimmy, other eq's are not the same outcome, or none I tried sounded the same....but, you'll need "two" 901 eq's to hear that pair of 901's come to life....you won't be impressed toward realism using only one eq....and, this is not really receiver-territory, the 901's sing only more sweetly as power increases to around 300+ at 8....two 901 eq's....think tape loops, pre-out/main in's, etc.....

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For two Bose 901s, you only need one Bose EQ. As far as power, the series one and two were the most inefficient. The IVs I had were pretty efficient. But they all can handle enormos power which makes 'em a good party speaker.

2DualsNotEnough said:

How do you get the grilles off of those puppies to check?
Jimmy

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The IVs I had were velcroed on and easily came off. Some of the others arent so easy...

.....I used a Marantz 3300 pre-amp, and the Bose 1801 Stereo-Amp-250 a side at 8, 400 a side at 4, and was 2 ohm stable by testing....you'll need a good stereo-amp that's 2 ohm stable, even though your load of resistance rating is only 4 ohms with two 8 ohm 901's paralleled, it really needs to be a higher-end stereo amp that is Powerful and preferably HEAVY....if you push only one pair of 901's, just have a lot of clean watts like I said....I had four 901's with two paralleled on each side of the stereo-amp....that was one ohmage-change that was very good toward authority....the two 901 eq's brought the realism....my sound-quality "approached" McIntosh realism, no kidding....I would be glad to take a Super-Bose System and Chamber further by PM.....

bordeno said:

For two Bose 901s, you only need one Bose EQ.

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.....Bordeno, I talked with a Guy at Bose one time and asked him if he'd ever heard 4 901's paralleled off a stereo-amp using two 901 eq's....he said yes he had....I asked him why Bose hadn't been advising the use of two eq's the whole time....he said he didn't understand why either, but that was the call of a different department....I really don't want this to turn into what I got at another site where NO-ONE tried two 901 eq's....there it is.....

I do not understand why you would need to EQ's as all it is doing is EQing the signal pre-amp. :scratch2:

Whereabouts does the Bose EQ come into the signal path?

The EQ can be tied into a tape monitor look on an integrated amp or preamp. At least that way, if you use other speakers too, you can easily switch over to something else without affecting them. I have a pair of Series IV's and the grills were a biotch to get off as they were nailed in the corners of each grill. It took me awhile to figure that out and they will be velcro'd back in place when the time comes. I ordered a complete surround kit that comes with a test tone CD to keep from having to cut the dust caps...I'm kind of curious what they'll end up sounding like. I tried them "a little" but a couple surrounds are bad so it was rattly on a couple and couldn't be judged well. From what I was tinkering with them, you definitely want the EQ. I was going to try a different passive EQ but I opted for finding an original. I figure, I'm out around $140 with the speakers, EQ and new surrounds. If I don't like them when I'm done, I'll be able to recoup my money and then some. But at least I can give an honest opinion on them having fixed them up. If I don't like them, someone out there will I'm sure.

Oh, and you can call Bose and they will tell you which EQ's are compatible with each other. I'll admit, their CS department was very helpful. I may have a link to a site somewhere that also told which ones were compatible. I'll check and edit if so.

Have fun!

Ok. First to answer the question the back grille just pops out. The front has to have 10 staples removed to pull the front cover off.

Eq's are interchangeable to a certain extent. I and II work with I and II eq's III and IV work with III and IV eq's and same for V and VI. You can interchande II's eq's with series I's and IV's Eq with III's but not V's eq's with I you get my point.

I have the power and pre that go with these speakers. the 1801 power amp and the 4401 pre amp. This specific pre amp has four amplifier outputs. which means i can hook 4 stereo amplifiers to it. It also has input/output for external eq's. Or the eq can be hooked into the tape monitor.

kfa888 said:

I do not understand why you would need two EQ's as all it is doing is EQing the signal pre-amp. :scratch2:

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.....KFA888, a Bose 901 eq strengthens the lowest lows and the highest highs 18 db....think of a smile sitting on straight-flat....two Bose 901 eq's take it to 36 db on both ends, it's that simple....try it, don't try it, fry it, fish with it, whatever.....

.....btw, the Guy I was talking to at Bose said 901 eq's are totally compatible....he said all they do is add 18 db on both ends....newer ones may have a rocker-switch on them or something flippy, I don't know......

mulester7 said:

....two Bose 901 eq's take it to 36 db on both ends, it's that simple....

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....and get away with it wonderfully, because 901's reflect 87% of their output off the walls....MAJOR BREAKTHROUGH, especially for the '70's....Sales-Meetings in The Bahamas!....The Bose Series-One 901 Loudspeaker W/Bose Series-One 901 EQ, put Bose on the map.....

mulester7 said:

.....KFA888, a Bose 901 eq strengthens the lowest lows and the highest highs 18 db....think of a smile sitting on straight-flat....two Bose 901 eq's take it to 36 db on both ends, it's that simple....try it, don't try it, fry it, fish with it, whatever.....

.....btw, the Guy I was talking to at Bose said 901 eq's are totally compatible....he said all they do is add 18 db on both ends....newer ones may have a rocker-switch on them or something flippy, I don't know......

Click to expand...

huh? your running them in series? That would not be good. I am well aware of what the EQ does, it takes a mid range driver and forces it lower and higher. Not a good solution in my book but whatever floats your boat. 36DB will introduce a lot of distortion and amp killing spikes. Heck, anything over about 6 DB ether way seems extreme to me. :yes:

kfa888 said:

huh? your running them in series? That would not be good. I am well aware of what the EQ does, it takes a mid range driver and forces it lower and higher. Not a good solution in my book but whatever floats your boat. 36DB will introduce a lot of distortion and amp killing spikes. Heck, anything over about 6 DB ether way seems extreme to me. :yes:

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.....the Super-Bose system was 25 years ago, KFA, and that's reasoning talking, not your ears....we're talking about nine 4 and 1/2 inch drivers that are actually putting out measureable degrees of distortion, but the distortion is left at the wall.....

.....no, the 901 eq's weren't in series, although that's fine....one was between the pre and the amp, and a second 901 eq was on a tape-loop of the pre....I'll say this....I listened to the Bose 4401 pre-amp when it came out after the Bose 1801 amp, and I decided to stay with my Marantz 3300, but never demoed the 4401 in my home stuff.....

.....anybody got two 901 eq's and at least one pair of good-quality 901's?....if so, it's time for a gatherin'.....

Ok, folks, there's some confusion over the 901 EQ thing, here, yet everyone is correct. I installed many, many 901s in the 70s both in residences and in discos, too, and was a warranty repair shop for Bose gear, among others back then.

Here's the scoop:

* The original 901 Series I and IIs were an inefficient speaker due to the cabinet being sealed a la KLH and AR speakers. The equalizers for these 2 models were different in the boost and cut curves. This means that the 2 equalizers are sufficiently different for one to want to locate the proper one.

* The Series III 901 is a completely different animal as it was a ported design in an attempt to overcome the large investment in amplification and grow the installed base of 901s. IMHO, it worked. The equalizer for this model was, again, completely different in cosmetics as well as in the boost/cut curves.

* The Series IV/V/VI series were pretty much tweeks on the same basic design of the IIIs. Although the equalizers changed in cosmetics and switch placement, the boost/cut curves changed very little, IIRC. These were mainly the result of changes in production of the drivers.

How many equalizers to use........

* One equalizer is a 2-channel device so you need only one equalizer when you're:
- Using a 2-channel power amp or receiver to drive one or two sets of 901s, assuming that you're paralleling the 2 sets of 901s

* Two equalizers will be required if 2 stereo power amps are used to drive 2 pairs of 901s.
- That is, one channel of the equalizer will be needed for the boost/cut for each of the 4 channels in this configuration.

On connection of the equalizer(s):

- The 901 equalizers were designed to be placed into the Tape Monitor loop of a receiver or integrated amp. You'll find a Tape Monitor on the equalizer itself to replace the one that was used up on the receiver.

- For a preamp/power amp configuration, the equalizer would be placed between the preamp and power amp that drives the 901s.
- Alternately, the equalizer _could_ be placed in the Tape Monitor loop of the preamp, just as with the receiver.

BTW, can you reproduce the same Bose boost/cut curves with a parametric equalizer? Possibly. I recall I once cascaded 2 SAE equalizers (one connected into the other to get as much as +/-24db of boost/cut) to try to get it to sound like the Bose EQ with a set of the then-new Series IIIs. It was difficult but costly to achieve. IMHO, its not worth the effort and expense. I can't believe I even had that much time to dink around back then.

Caution for any of the older Series I, II and III equalizers. These are getting to be 30 - 40 years old and will need to have some components replaced in order for them to remain reliable. I suspect there will be a deterioration in sound quality due to aging components, too.

Hope that helps.

Cheers,

David