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Author Topic: Kalart Victor 70-15 external amplification Brian Elm Film Handler Posts: 5 From: Stone Mountain, Ga. Registered: Oct 2019 posted 11-03-2019 11:21 AM                     I would like to amplify the sound coming out of the Kalart Victor 70-15 into a integrated amplifier (100 watts) into (2) Altec speakers, is this possible?  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 11-03-2019 11:37 AM                     Yes it is possible with a few important caveats: You MUST use a transformer-isolated setup between the speaker output and your line input on the integrated amp. Simple resistor based devices (commonly used to add external amplifiers to older car stereos) will not work safely in this case. You can do it by finding a device specifically made to work with older tube equipment or by using a separate 8 ohm primary to 1kohm (or higher) audio transformer AND one of the devices used for car stereos. Once connected, power up the integrated amp at a low volume, and then the projector at low volume. While playing a film, slowly increase the projector volume until you hear sound, then raise the amp's volume a bit. Raise the projector's volume a bit and so on. What you are going for is the best compromise of signal to noise, i.e. the best sound with the least amount of hiss and hum from the projector (also without distortion or crackling from overdriving the amp's input stage.) Once you find that "sweet spot" on the PROJECTOR's volume setting, mark it and use it as the reference point. Then only use the amp's volume to set your desired volume for each film. Too bad you weren't looking for Kalart parts about 20 years ago, a colleague of mine purchased about 50 Kalarts from a school in Southern California. Guess who had to go pick then up?  |  IP: Logged Brian Elm Film Handler Posts: 5 From: Stone Mountain, Ga. Registered: Oct 2019 posted 11-03-2019 12:11 PM                     Is this isolation transformer similar to this setup? https://www.instructables.com/id/Isolation-transformer-upgrade-for-old-guitar-amps/ Just found a 70-15mc3, it was in just good condition and cost me $665, the first one I purchased was in excellent condition and cost $550. The marc-300 bulbs are getting scarce and the 350's I can't find any of those anymore.  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 11-03-2019 12:13 PM                     As far as the projector is concerned, it doesn't matter if the amplifier is 10 or 100 watts or how many speakers you are driving. Your only concern is the signal going INTO the amplifier. While I have seen the output of a 70-15 plugged directly into a line level input of the room amp of a local library meeting room, and it seemed to work OK for them, I would do it slightly differently to avoid grounding issues & hum problems. What I've done, on several occasions when I've needed to do a quick hookup of a 16mm projector into an external amplifier is to use an inexpensive ground loop isolater, similar to the one below. Most of the Kalart projectors used a Cinch-Jones type connector, so you'll have go get one of those, or cannibalize a Kalart speaker cable and change the RCA plugs on the isolator or buy the necessary adapters to work with whatever connectors your amp input has got. > The signal needs to go into a LINE LEVEL input on the amp. > The volume knob on the projector needs to be set pretty low to avoid overdriving the amplifier input. While this usually works just fine, if you find you're still overdrivng the amplifier, you'll need to drop the level with a simple resistance pad you can make or find online. Yes, I know this set-up doesn't make an ideal impedance match, but given the limitations of 16mm sound tracks, I haven't found this to be a big problem. I carry a couple of these little audio isolaotrs and a complete set of connector adapter-thingys in my "bag of tricks" and have used this on dozens of occasions to feed 16mm projectors into room or theater amps, and have never had any complaints about the sound. I used to be able to get these at Radio Shack, but since they're no longer around, you can find them online, usually for about US$10 or less. Just make sure you get one that uses transformers (as opposed to just capacitors) inside, as they are usually better quality. (and you KNOW this one is good, because it says "High Quality" right there on the label! )  |  IP: Logged Brian Elm Film Handler Posts: 5 From: Stone Mountain, Ga. Registered: Oct 2019 posted 11-03-2019 12:42 PM                     Thank you very much Tony Bandiera Jr & Jim Cassedy for all your help, this information will help greatly in accomplishing my goal. My old father (80) is getting ready to start up a film-club here in Atlanta and this will resolve any issues with the sound quality we are aiming to achieve. My father has a cold storage facility filled to the roof with 16mm prints and a basement with rack after rack of projectors and editing equipment. While his Kalart speakers are good they might not be good enough for a larger room and why we recently purchased 2 Altec 9842-8D speakers and recently 2 Kalart 70-15mc3 Marc-300 projectors. Your help is greatly appreciated. Just found these on eBay https://www.ebay.com/itm/Plessey-Cinch-Multicon-Painton-Jones-Bell-Howell-16mm-Projector-Speaker-Plug/323767018717?hash=item4b6204a4dd:g:aTcAAOxydlFSrujD  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-03-2019 05:45 PM                     I'm a fan of RDL products for such things. In your case the TX-8a might be the ideal choice: https://www.rdlnet.com/product.php?page=666 It provides speaker->line level conversion AND transformer isolation all in one step.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 11-03-2019 06:07 PM                        I do this with a home-made changeover switch box (just a regular DPDT switch) that connects two speaker outputs from two projectors to a DI box to a mic preamp. This works fine, but adds noise, since the signal is being knocked down to a mic-level signal, only to go back through another preamp. With most 16mm tracks and a half-decent preamp, the noise issue is minimal. A DI box (by definition) provides transformer isolation). This won't work properly with a tube amplifier, though, for reasons that I don't remember offhand. A better option is to re-wire the projector solar cell directly to a preamp, bypassing the projector internal amplifier. This will give the best sound quality, but also requires re-wiring the projector. This may or may not be a problem, depending upon whether you ever intend to use the projector with its internal amplifier.  |  IP: Logged

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