Great deal on a 6 channel amp

[scottw]

Question.....

If you don't use the preamp box would that give you the same results if you had the volume on the preamp all the way up.

Does that make sense???

[Marbles_00]

Yeah, things are really starting to make sense as to why there is no info. I guess that 1-800 number will be useless too. As scott mentions, if using it for just some background music, it may be okay.

[rembetis]

Well, my twins are still sleep, its Friday afternoon, and I'm still fu*^ing around on the Internet, so...

In addition to the Intensor, BSG Labs definitely had some weird patents.

Four dimensional acoustical audio system for a homogeneous sound field

Tubular Loudspeaker System


But wait, it gets even weirder...

Was BSG Labs a weird Christian cult?. Thanks to the Smoking Gun, you can actually read the affadavit filed by a former employee accussing them of religious coercion and all sorts of really weird behavior.

Why is this man's face obscured in front of the BSG Labs building?

Hell, with this kind of history, this thing is a collector's item

[rembetis]

If you don't use the preamp box would that give you the same results if you had the volume on the preamp all the way up.

Technically, yes, assuming the input gains are set at equal levels, though there is probably some miniscule amout of attentuation (doubt that's the right word) using the preamp at all. But if you're referring to my "harsh" comment -- again, take everything I write with a grain of salt. It was my ears, on crappy speakers, sitting on my basement floor.

[scottw]

Thanks.
I am not taking anything you are saying as "golden", those are your opinions and I will have mine once it arrives

I appreciate your views, they help ALOT.

[Marbles_00]

Scott,

There are two solid ways to set the gain controls on amplifiers.

1) the more proper way, though most people don't have the equipment is to set a signal generator up on the input of the amp. Use a typical sine wave at a frequency of 1kHz. Hook an oscilloscope up on the amps output so you can measure the 1kHz signal. Then turn the gain up until what was once a nice sine wave on the scope starts to turn into a square wave. That indicates that the amp is clipping. So turn back the gain so you see that nice sine wave again. Finally sweep the generator from 10Hz to 20kHz and verify that the signal looks fine through that range on the scope.

2) the every-day Joe way. Turn your source to 3/4 volume (in this case Winamp). Turn the gain pot up on the amp until the music sounds like crap (amp clipping). Turn back until music is loud, but still sounds all together. You'll know what I mean if you experience it. That's all folks.

Rem,
Very interesting finds on that company. You may be right, this could be a novalty item worth having on it own, never mind its original intended use.

[scottw]

Scott,

There are two solid ways to set the gain controls on amplifiers.

1) the more proper way, though most people don't have the equipment is to set a signal generator up on the input of the amp. Use a typical sine wave at a frequency of 1kHz. Hook an oscilloscope up on the amps output so you can measure the 1kHz signal. Then turn the gain up until what was once a nice sine wave on the scope starts to turn into a square wave. That indicates that the amp is clipping. So turn back the gain so you see that nice sine wave again. Finally sweep the generator from 10Hz to 20kHz and verify that the signal looks fine through that range on the scope.

2) the every-day Joe way. Turn your source to 3/4 volume (in this case Winamp). Turn the gain pot up on the amp until the music sounds like crap (amp clipping). Turn back until music is loud, but still sounds all together. You'll know what I mean if you experience it. That's all folks.

Awesome, thanks for the info. Can't wait till it gets here.

Scott

[sharp_1]

Thanks Marbles and Rem for all your input!!!

Rem - have you had a chance to try the 100ft 16g speaker wire test as marbles talked about or are the 201s below the 87db he was talking about?

[Marbles_00]

I went to the Bose website to find out info on Rem's speakers. I'm pretty dissappointed with the site. It gives you alot of useless literature on their speakers and very little in the way of specifications. Under specifications guess what I found: Speaker cabinet measurements and speaker weight. Hell the manual only talks about wattage ratings. Where's the frequecy response, or the sensitivity (efficiency) measurements. It pisses me off when companies dish out a bunch of "black magic" jargon to try and temp us. Look at Paradigm's website (http://www.paradigm.com) or Polk Audio's website (http://www.polkaudio.com) to name two, you can find a wealth of information on their products.

ERRGG. Companies that think the consumer is so gullable...shove your product right up your own poop shoot.

Now, concerning the 100' speaker wire. What you don't want to happen is for the amplifier to start to ocsillate. If it does, what you may notice is that it gets very warm. What you should do is with a normal length of wire attached, make a case temperature measurement. Attach the 100' speaker wire and monitor the temperature again. If the amp is oscillating, then there will most likely be a rise in temperature. Not all is lost, this will mean that a zobel circuit will have to be used on the outputs.

Ideally it would be good to use a sinewave input at a known frequency, then measure the output with a scope. If you get something more than an amplified sinewave on the output, then you may have oscillations.

I've been reading up more and more on that since I've been designing some gainclones I was thinking of building for multizoning purposes. But if this amp works, then I may shelf the project.

Also, Rem, what do you notice lacking in the sound? Wouldn't surprise me that it is lacking bass. Lacking bass is a sign that the filter caps are under-rated. This is usually an easy modification...and well worth it.

Keep us informed.

[rembetis]

Rem - have you had a chance to try the 100ft 16g speaker wire test as marbles talked about or are the 201s below the 87db he was talking about?

Unfortunately, I have no current plans to use this as a zoning amp, so I don't happen to have 100ft of 16g speaker wire sitting around, but if you want to send me some I'd be happy to give it a whirl

Also sorry to say I have no idea what the sensitivity is of the 201s off the top of my head. If I had to guess, I'd say below 87db. I may have the manual around somewhere. I'll see what I can find.

FWIW, Marbles, Bose is infamous for obfuscating specs. Never in a million years would I buy their product now, especially after owning several sets of speakers (Ascend Acoustics) with a VERY flat frequency response. But like I said, for my woodshop, they are just fine...

[rembetis]

Also, Rem, what do you notice lacking in the sound? Wouldn't surprise me that it is lacking bass. Lacking bass is a sign that the filter caps are under-rated. This is usually an easy modification...and well worth it.

Now that you mention it, bass did seem a little weak, but I chalked that up to the Blows. Give me a day or two to run higher quality speakers with the amp and I'll report back.

[Marbles_00]

Sorry Rembetis, that's partially my fault about the 100' speaker wire. I was assuming that was the purpose for you purchasing the amp, was to run multizoning audio. That's why I assumed you had that length of wire kicking around. Sorry

[Marbles_00]

To let you all know, here is some testiment on the amplifiers that I have received from other ebay members who have also bought the amp:

Get one. Solid little bugger. 30 watts definite, new condition. See the tech board at wwwdot partsexpress dotcom... I think these were made for PA/industrial type sound systems - you know, those things with umpty speakers in the ceiling? If it'll do 2 ohm loads (and the sheet says it will...), that's 24 speakers/unit all wired parallel. The speaker connections are about 14-16 gauge max, but that can be worked around... I'm thinking this could be nice for the tweeter section of a line array I've got in the works.

Haven't powered it up but it's built like a tank & as a long-time Zapco fan I am very stoked with the design. It has ARPA stickers all over, was definitely built in Modesto at their facility. Not sure what I will use it for but what a nice piece for the money!

And the most promising one of them all for using long speaker runs:

It seems to be very nice. We are using it as a narthax amp for our church's narthax speakers. The amp is mounted in the main sound equipment rack, and the remote controls allows our ushers to control them independant of the sancturary. Plenty of power for our needs, and no discernable distortion. Perfect for our needs.

For anyone in the blue, like me, as to what a narthax is:

The narthex of a church is the entrance or lobby area, located at the western end of the nave, at the far end from the church's main altar.

Along with what Rem has indicated, this amp may be a winner after all.

[sharp_1]

That's great news Marbles...I am going to order 2 today.

Question: Does anyone know if winamp will output in mono, I can't see anything in the prefs. If it can we may be able to gain additional zones by running winamp in mono to each channel???

[rembetis]

OK, had a chance to do a little more testing with this amp. I hooked it up to a pair of Ascend Acoustics 170s (classics, though, not the SEs). These are very revealing bookshelf speakers, with an almost linear frequency response (69Hz - 20 kHz, +/- 3db), and an in-room sensitivity of 91db.

First impression: A little thin and crispy. Although the 170s are not known for their bass output, and they need to be paired with a sub to really shine, they still put out decent bass for a small bookshelf, and have excellent midbass. However, the lower end was all but gone running off the BSG amp. I believe this is a general criticism of digital amps, particularly low-watt ones, but in this case I'm fairly certain it has everything to do with the crossover in this thing's preamp.

To test this, I first hooked the speakers up to channels 5 and 6 and all I got was muddled low end, so I then hooked up a 8" passive sub to channel 6. Now things were filling out nicely. Next step was to bridge 5 and 6 on the sub and with this setup I was quite happy with the sound. With preamp volume at about 1/2, I was filling a 16' x 22' basement with sound.

So, to sum up, don't use the preamp if you want full range channels. I'd love some info on exactly what the crossover is, as I can see great potential using one of these to drive some DIY towers. It will also make a great 2.1 or 4.1 computer amp.

But be careful with those speaker wire inputs. Shorts are a major danger given how close together they are...