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Author Topic: Soundhead upgrade DP70, FP5,6,7, 56 Rob J. Buskop Expert Film Handler Posts: 111 From: Rotterdam, the Netherlands Registered: Aug 2005 posted 01-30-2006 11:46 AM                     After discovering that BACP soundhead conversion, at least their pre-preamp output configuration, is NOT compatable with Kintek-like designs, which have asymmetrical inputs and are true DC CURRENT amplifiers, I started on the road to upgrade the well known Philips (Norelco) backscanner to higher performance levels myself. The first item to be altered was the mechanical slit width, which had to be reduced by more than 50% to get to 0.120 millimeter(less than 0.5 mil). Since the magnification of the track is 13.5x ,there will still be enough response from the large area of the solar cells behind the slit. Question: Are there any keen technicians who would like to participate? The slit conversion is made with laser micro cutting technology. They will cost around $75.00 each for a series of about three.. More will make them cheaper. Later on we will investigate the lens properties and the exciter light source which will need modification of course. Let me know if there is interest in this. It will bring the costs down and will keep the beautiful appearance of the original reader intact. Rob J. Buskop  |  IP: Logged Greg Mueller Phenomenal Film Handler Posts: 1687 From: Port Gamble, WA Registered: Jun 99 posted 01-30-2006 11:59 AM                        A few years back a film slit was offer for the DP70. I got one and it is quite impressive. You take out the old brass slit and put in this piece of film. It has the advantage of not having to be made mechanically. It was done with a photographic process. The only downside was that you had to make sure the rest of the light transport system was working at it best or you couldn't get enough light through the smaller slit to get up to Dolby levels  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-30-2006 02:22 PM                       Actually the BACP reader like all Dolby approved reverse scan readers is DC coupled for the specific purpose of making it compatible with Kintek. At the beginning of this project some 14 years ago there were a number of Kintek processors in operation so this was an important consideration. If you are having technical problems making this work, please contact me directly. BTW, we have sold over 150 readers for use with the Philips FP5 thru DP70 etc. This is a wonderful but dwindling series of projectors which is the only reason I went to the trouble of doing this. Some of the problems you will encounter in fitting this projector include a very lossy light bar, lenses that are lacking in HF response, and often the need to upgrade to a stereo solar cell (no longer made). The stereo cells are often defective as the output wires come loose internally. Last but not least, the original brass slits were often opened up to allow more light at the expense of HF response. The BACP reader replaces the light source, light bar, all the optics and the solar cell leaving all the mechanical part of the Philips intact. The only complaint I do occasionally get is that the operators miss being able to look into the peep hole and see the soundtrack displayed. Ah, Nostalgia!  |  IP: Logged Rob J. Buskop Expert Film Handler Posts: 111 From: Rotterdam, the Netherlands Registered: Aug 2005 posted 01-30-2006 04:32 PM                     With all due respect to Mr. Chavez: I sent you a complete 2 A-4's long description of the Kintek principle of which I use a derivative. BACP is NOT compatible, although on my explicit inquiries I got a one sentence answer. Fearing that my writings had'nt reached their intended target, I modified the contents a bit and so thereafter I approached BACP again explicitly explaining the working priciples of a DC preloaded asymmetrical preamp and my doubts as to the marriage to the BACP unit's output. Again an answer came that said: "..DC coupled, no problem.." Unless forced to, I'd rather not go into electronic detail here, but there is no reason whatsoever to suggest that the two are compatable. A high impedance source (solar cell) which is assymmetrically coupled to a DC CURRENT amplifier in my setup, is a completely different source than the output of the BACP pre-pre, which is balanced, low impedance, and suited for other more conventional designs. The BACP pre-pre should for all intents and purposes exactly emulate the characteristics of a solar cell: Because it is the connection to the original solar input that it utilises. However this unit's output stage is very different: 1. Of Low Impedance 2. Not asymmetrical (solar is, only the connection at the preamp looks like it is symmetrical) 3. Does'nt behave in other areas as a solar cell. That it works PERFECTLY on most processor inputs has a different reason. Coupled with a design as briefly outlined above however, it will not work. Anyway this is not what the posting is about. Make yourself known if you want to join the bandwagon! Rob.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-30-2006 05:41 PM                       Also with all due espect, reverse scan readers from Kelmar, Component Engineering and BACP have been successfully interfaced with Kintek processors. (As to your reaching BACP, I've obly received one e-mail from you to date). There may be some instances where this will not work and I do not claim to be the world's expert on Kintek processors. My main experience with Kintek was as a competitor during my time at Dolby Labs. Kintek equipment has a reputation for being unreliable so my first assumption would be that the lack of a successful interface is due to a fault in the Kintek processor. I could be wrong regarding this, it happens all the time. I wish you well in your task but I already have my own "bandwagon" to pull. I look forward to seeing you at Cine Expo and perhaps see what you develop.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-30-2006 07:23 PM                     quote: Sam D. Chavez Kintek equipment has a reputation for being unreliable Sam, Now thats an understatement.... You're being really nice about the Kintek! I am soooo glad they are long gone! Rob, Your Kintek would be the first thing I would replace to bring your sound system "up to date". If its analog you prefer the Panastereo CSP-1200 has no equal or should I say nothing else even comes close. If you don't mind digital processing then the Dolby 650 is the way to go. I've done close to 40 of the DP-70 reader conversions and have had great sucess with all of them on a variety of processors. We also split the lateral guide roller to improve lateral stability and stereo tracking as well as manufacture many parts for the DP-70 that you may find priced far more reasonably than from other sources. Xenon Lamphouse Tables, Sprockets, Gate Bands, Curved Compound Gate Runners, Motor Kits, changovers, etc. I would much rather modernize these machines and keep them as current as possible and running as long as is possible into the future than to convert and keep the old do-do parts. Keeping that old junk in the sound reproducer(and your Kintek) is false economy and very little will be gained! However, another thing to consider is that your Kintek may not be high enough quality overall to benefit from installing the BACP(or other)scanner, there are alot of very old analog I.Cs in your processor that may not allow the full benefit of a new style reverse scan system to be realized. There are many advantages in using the BACP sacanners over the old stuff... extremely low harmonic distortion is the first that comes to mind. With about 100 DP-70's running in the Mountain states we are certainly doing our part at keeping these fabulous machines alive till the end. quote: Greg Mueller A few years back a film slit was offer for the DP70. We have a full 11X14 Kodalith of those slits Greg in case you need one. Probably at least 50-60 of them....... but thats been shelved in favor of the BACP scanner. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-30-2006 07:55 PM                     All of the Dolby reverse scan readers are NOT compatible with the Kintek preamp...sure they will make sound but the sound will be clipped and wack out the already lowly SVA decoder (KT750 in the 700). It sounds like the input stage of the Kintek preamp is no longer properly biased. I can only presume (since I have not studied the Kintek preamp design) is that it used the DC voltage from the solar cell as a bias voltage/current. Note Kintek used the DC voltage off the cell to set levels ("cal" and "Bal"). The absence of this DC voltage combined with the high-impedence seems to have have very negative affect on the Kintek preamp circuit...to the point of what I would term non-compatible. Again, you will get sound out of it...it won't be good nor will you have any real stereo effect.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-30-2006 08:01 PM                     Steve, It should be possible to bias the inputs seperately from a small circuit and then capacitor couple the inputs from a reverse scanner and get the same results. I would still shitcan the Kintek though... it no longer a viable piece... was it ever? Mark  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 01-30-2006 08:05 PM                        I don't have anything to say about soundheads, but, damn, Mark--that machine is gorgeous!  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-30-2006 10:19 PM                       Well, Steve has spoken. I have several people who have interfaced the two but what do I know? The whole point of DC coupling was to make this so. In fact, the DC coupling makes for some interesting failure modes. Which readers are and are not compatible or are you saying none of them work? Lonny Jennings insisted they be compatible in order to please GCC who had a lot of them at the time. Now there is no GCC or Kintek. It turns out Robert Buskop is talking about a Kintek like device, not an actual Kintek. He sent the schematic and text to Clint who passed it to me. It appears to be a modified Dolby CP100 Preamplifier.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-30-2006 10:34 PM                     I have interfaced many Kelmar readers to KT800 processors and they work with out distortion but the old balance and cal LEDs were useless in calibrating the system but at the time Kintek did provid info on the audio level on the output pins of the preamp card for dolby 50% level Also the Panastereo preamp is a current coupled design  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 01-30-2006 10:57 PM                       Thank You Gordon, at last a witness and not Jehovah's either.  |  IP: Logged Rob J. Buskop Expert Film Handler Posts: 111 From: Rotterdam, the Netherlands Registered: Aug 2005 posted 01-31-2006 05:16 AM                     Steve Guttag is absolutely right. Other suggestions, like capacitors after the output circuitry of the BACP amp will block the necessary small DC offset needed to get the current amp to work. There is a solution, and that is to modify the "Kintek" based design to behave like a standard balanced input preamp. Have made the calculations and all. Have tried and done that. Then it works. But that's not the point! Let me say first of all, that BACP units are, in my opinion, the best mod units available ANYWHERE!! Secondly, somebody who claims that the two principles in question do match, cannot be really an established electronics designer, they are a rare breed. Thirdly, I have no Kintek equipment at all, nor do I have a standard CP100. My preamps use a similar DC current amplifier approach as Kintek did and were expertly designed and custom manufactured and perform beautifully. No early poorly designed, unstable Dolby crap preamps for me! Again BACP is great, Sam! That's not the point. And I am not fishing in your pond either. I only mentioned that the BACP preamp does'nt adapt to unbalanced DC current amplification. That's true and electronically elementary. I can modify my elegant input stages, but hate to do that.. Some appreciation for originality in appearance and dislike of modifying circuitry that is not only lovely to look at, but is undoubtedly of excellent design, made me interested to try and find an alternative way. I wish to retain my winning horse, which is my installation as it is. So I'll work out some mods, together with some specialised brainpower that I am fortunately enough to have around me and will retain the beautiful outward appearance of the original unit as a bonus that I personally really like. Call me old fashioned and conservative. So be it. We may even fail. But not without a fight..! It's a challenge and I'll keep you posted. Thank you all for your reactions.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-31-2006 07:05 AM                     Our attempts at connecting reverse scan readers to Kinteks were all KT-700s...without exception...all had significant amount of distortion and effectively zero stereo aferwords. The lack of the Cal and Bal LEDs should be the proof in the pudding that the signal represented on the output of the reverse scan reader does NOT mimick the solar cell direct since one does not have the DC bias voltage/current anymore. Could one put in a "phantom" supply...quite possibly...it isn't something that I will put any time towards. The problem with reverse scan and the KT700 preamps (KT-741, if memory serves) was the burial of the KT700 for us (like it needed that excuse but it definately drove the point home for the owners). As to Kintek...they were the BEST stereo synth out there, in a day and age where stereo films represented less than 20% of the market. The KT 21 and later 721 did a pretty good job of cleaning up mono soundtracks and expanding the dynamic range if you didn't go beyond 10-15% expansion. The Surround generator (KT24, or 724) also was best in class at its job and really helped the dialog steering. As an SVA processor...I never cared for it. The build quality of Kintek was definately lacking. Steve  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 01-31-2006 11:32 AM                        So, how far can one hurl a Kintek processor? Louis  |  IP: Logged

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