Bell and Howell 3592 speaker amp advice

[Steve Klare]

Yes, I remember seeing that in Cinema in Miniature!

A lot of this is kind of lost art: these machines wore out years ago.

[John Fedko]

Looks like I don’t need the box . I went straight to receiver and to passive speakers with an amp and both sounded good enough without the box to pass through . In fact for some reason the box didn’t even work with the passive speakers amp setup - I may have wrong cables . Anyway - I’m happy with the powerful sound I’m getting just going straight into receiver for my 5 speaker indoor theater and amp for two speaker outdoor setup . I’m actually going to combine the system for a 7 speaker system - I’ll send pics if it works - I’ve got an rca output splitter box coming from Amazon !!! John

[Janice Glesser]

Great John! Glad you're getting your sound system together.

[Steve Klare]

You can operate an amplifier input from a speaker output, but you need to keep the volume turned way down. A typical amp input is looking for something like 1 Volt RMS maximum ("line-level"). But let's say you have a speaker output meant to drive an 8 Ohm speaker at something like 25 Watts. That channel will produce about 14 Volts RMS if you crank it full.

As you raise the volume on the source, at first it will sound fine, and then as you keep going, the sound will become distorted. This is because amplifiers are powered by DC voltages and can't produce an output signal higher than the positive DC and lower than the negative DC that powers the Amp circuit. You're hoping for a nice sine wave coming out that looks exactly like the nice sine-wave you put in on an oscilloscope, just capable of pushing more power through a speaker. Instead you get a wave with the peaks chopped off: this is called "clipping" and sounds pretty awful!

I'm always concerned doing this direct hookup might damage the Amp's input circuitry (-and I'd really rather not find out!). That's why I put a voltage divider in between so even with the projector's speaker volume turned up to levels that it may have been at when driving just a speaker, the voltage into the amp is in the neighborhood of line-level and should do no harm.

This comes with a little caution: doing this substitutes the 8 Ohms the Amp is expecting with something over 3,000 Ohms.

A transistorized Amp is literally really cool with this. In a typical amplifier, for every Watt through the speaker, there is also a Watt in the amplifier wasted as heat. Heat brings temperature, and temperature is the mortal enemy of semiconductors. The much lower watts in the 3,000+ Ohm connection means the projector's internal amp will barely budge higher than room temperature and the circuitry will last much longer. The sound is good, and can be cleaned up further before the external amp gets a hold of it, so this is a win-win.

-BUT-

From what I've been told, this will not work with a tube amplifier. If you operate one of those with less loading than the speaker that's supposed to be connected, the voltage on the output will rise to spectacular levels and things will spark and fry and burn and fail. (BOOM!)

-so a setup like this for a tube Amp would need to have the same resistance as the speaker it's normally supposed to drive. It would of course need to be rated for the power and would heat up as your program went on.

We're getting out of my comfort zone here: I studied Tubes in high-school electronics (-they were on the Exams!) and haven't done a thing with them since I was a teenager!

(Maybe after I retire and ALL of my electronics returns to being for hobbies, Tubes and I will become reacquainted!)

[Brian Fretwell]

Yes, it is the output transformer that causes the problem with valve amps, I was once told.

[John Fedko]

I agree that this is not ideal but the audiophiles that I trust here in Pittsburgh have signed off on my setup as an option . I won’t put the projector volume knob past 33 per cent . With projector knob at 33 per cent and Sony receiver volume at 50 percent , I get loud powerful sound from five speaker system - two speakers up front , two in back with a Polk subwoofer in back . I’m adding two more speakers powered by separate amp later this week . I’ll send pics of setup .

[John Fedko]

Watched Frankenstein Meets the Wolfman tonight and when they blow up the dam, the theater felt like it was shaking !!!! No distortion so far at 33 percent volume on projector - I won’t push that ever .

[Steve Klare]

I get it, John!

A big part of the joy of this hobby is taking these machines and films and exploring their full potential. There is actually a lot more there than most people ever imagine.

I was told when I first started messing around with Super-8 back in my teens that beyond 3 feet diagonal, S8 was downright blurry and dim. Who knows. maybe this is even true with a 50W lamp and a plastic projection lens, but when you start getting into brighter lamps and better optics this 3 feet can grow a lot bigger. At many conventions, they run theatrical-sized screens and Super-8 looks really good. At CineSea we show on a floor to ceiling screen 14 feet wide and Super-8 goes toe-to-toe with 35mm and really holds its own.

I hung an 8 foot diagonal screen at home and have never looked back!

Same thing goes with sound: film sound through a 3 inch speaker mounted in the machine is very...ok, but when you start putting it in external speakers and cleaning up things like hum and hiss, it starts to sound really, really good!

I first started connecting up a sound projector to an external Amp around 2007. It sounded so awful (ground loop!) that I retreated back to internal speakers until about 3 years later. In the meantime I worked on understanding the problem and figuring out what to do about it.

-that first time I was able to make it work was a definite burst of endorphins!

-and isn't that why we have hobbies? They are ways we can feel achievement without the stress of for example a job responsibility. Truth be told, had I never made external sound work, nobody would foreclose on my house. When my boss asks me to solve a problem, that's a whole different matter!

[Rob Young]

Steve,

"A big part of the joy of this hobby is taking these machines and films and exploring their full potential. There is actually a lot more there than most people ever imagine."

Couldn't agree more; this is what makes it such a great hobby, always more to learn and push.

Chatter and super 8...I do feel like I keep banging on about this and many folk here will probably just tell me, "enough already!" but honestly, Beaulieu super 8 machines really don't suffer from chatter. Of course, they ain't cheap either.

Steve, I know you use an ST1200HD and I have to say that chatter isn't really an issue on my machine (although WOW certainly can be). You win some, you lose some. But again, not so the Beaulieu.

Also, I did discover many moons ago that treating a film with Filmguard can really drastically reduce chatter when it's present; I used to use a Chinon SP-350 as a kid and it could chatter with some prints, but a treatment with a good film lubricant reduced it significantly.

As Brian says, most commercial outfits like Derann recorded soundtracks with pro recording machines that never went near an intermittent movement, so no "built in" chatter. Of course in the very, very early days with standard 8, Derann did use synced up projectors, but not since the '60's. I don't know about Blackhawk, but all of the big distributers in the 70's / 80's used recording machines and certainly not projectors.

Derann's magnatech machines were going until the end I believe (2011) and back in the day recorded many of the WDHM soundtracks too, amongst other recordings for different distributors. The only thing that wore out toward the end was the soundhead on the machine used to re-record out of sync returned stereo super 8 prints. It could not longer record the balance stripe. But the machine that did the high speed recording of double width super 8 stereo was still being used until the doors closed.

Of course, if the soundtrack has been re-recorded by a collector on a projector then it is possible (technically it's actually unavoidable to some degree) although I have a copy of Raiders of the Lost Ark re-recorded by the legend John Clancy on his GS1200 with zero audible chatter. It even de-codes into a nice Dolby surround and shakes the floorboards.

Steve, I know you were going to try filmguard and it would be great to know if this also helps with chatter for you.

John, you absolutely can get floor shaking Dolby surround out of super 8; I'm not saying it's easy but it can be done!

[Steve Klare]

Hi Rob,

Does your Beaulieu have the flywheel roller between the lower loop and the head? I've heard that is a big plus where keeping the film both flat and flowing steadily past the sound head. Many machines (-and all of mine) are loop-head-roller: good, but could be better.

I'm not sure if it's a North American thing, but I've never seen a Beaulieu here: Elmos, Eumigs, Chinons, Etc. by the boatload, but never a Beaulieu projector. -just their cameras, which are absolute top of the line.

Condition of the guides around the heads can play a role too. I had an Elmo where the guide at the downstream end of the loop was worn on one side. Chatter was worse with this machine and improved a lot when I found a set of like-new guides and swapped them in. My theory is the wear on that one side allowed the film to bounce up and down and allowed the stripe to vibrate at the point of contact with the heads

Chatter as I experience it is a pretty rare thing, and when I do experience it, it's not that bad. It's more of a "Oh, yeah..." than "Oh, Crap!". I'd be pretty content if that was the biggest problem I ever had. (Sit with me sometime and I'll tell you about the power lift-gate on my wife's car! -the more they overthink the plumbing, the easier it is to stop up the drain!)

I'm pretty amazed that Blackhawk got the quality they did with the setup they had: just the idea of syncing about six Eumig sound machines and a 16mm master machine and staying in sync throughout a 400 foot reel is just mindboggling to me! Somehow them being AC Motored on the same power lines must have been good enough once they exactly dialed in the frame rate on each machine.

I have dozens of Blackhawk sound prints and the sound is more than acceptable, so I guess the results speak for themselves.

(-not a job I would choose if I worked there!)

[John Fedko]

I use FilmGuard on all my films !!! I also have an RTI machine that I use with Film Renew. I blasted Mary Poppins Jolly Holiday yesterday on Sankyo 800 with incredible results - with the speakers booming - I think many Disney prints have great audio . I blasted 7 Brides for 7 Brothers log dance sequence and chatter was pretty loud . Proving maybe it’s print also or just maybe different music enhances chatter? I can live with it . I tried downloading video so you can hear how crisp and full 16mm sounds but this site tells me all my stuff is too large !!!

[Brian Fretwell]

I wonder if different film bases have different degrees pf chatter. Thick acetate, thiner acetate and plyester may have a different amount of springyness.

[Rob Young]

Steve, the lower loop is pretty standard (although not the slightly odd Elmo ST1200HD design where the lower loop goes upwards - never really understood why they did that other than to try and break cement splices!?) but the electronic capstan is the big design difference.

Unlike most other super 8 projectors with a heavy flywheel to govern the capstan, the Beaulieus have a dedicated motor with belt drive to the capstan and a motor control board to govern the speed. The result is practically no wow; not that I’ve ever heard.

This must help with chatter too as they just don’t have any audible chatter no matter what you put through them. They also have a horizontal sound head assembly and pressure pads pushing down. Plus the sound head assembly is longer than usual as it has 2 sound heads, one after the other so that you can monitor sound as you record it.

Just how exactly this all adds up to no chatter is maybe some kind of witchcraft, but it works.

Just to keep on topic; I wish they’d built a 16mm projector.