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This document edited down from John Jankowitz's original


 Specifications for the Paramount Pix Amp

  • Manufactured for Paramount Pictures by HTP International
  • Mounted on an aluminum plate 6" x 14.25"
  • Uses two LM3886T semiconductors by National Semiconductor
  • Power supply includes two 10,000 mfd capacitors
  • Two channel design for dual woofers or a single DVC sub
  • Approximately 50W/channel into 8ohm loads with a 48VCT transformer, or can be bridged (a little work is required)
  • Line and speaker level inputs and outputs
  • Built in active 60Hz to 120Hz crossover and volume control
  • High Pass crossover at 125Hz for satellite hookup
  • Built in Bass Boost that adds 12dB below 33.5Hz

Modifications & Bridging

Bridge the ParaPix Amplifier

  • Bridging into an 8 ohm load can be done with a 48VCT transformer, and no changes need to be made to the MUTE circuit. I do not suggest that you bridge the ParaPix for use with a 4 ohm speaker, but if you plan to try bridging to a 4 ohm load, you are going to need to use a lower voltage, possibly 36VCT transformer, and do the MUTE circuit modification below
  • Bridging The ParaPix amp the easy way:
    • Remove the jumper JP2
    • install a 20k ohm resistor for R8/6
    • Then just hook your speaker wire to pins P3/1 and P3/3
  • Modifying MUTE circuit -- If you want to use a lower-than-designed-for power supply voltage, you need to modify this. All you have to do is solder a 10k resistor over CR1/3.
  • Here's my bass boost switch mod -- Use a 3 pin switch that has two "on" positions on it. Drill a hole in the plate to mount the switch. Remove the jumper J1 and wire your switch in. The middle pin on the jumper is the constant, and the other two are what you switch between.

Info about Transformers for the Parapix amp

Well, everyone wanted info about different transformers for the parapix. I thank Tom Woods for just about all the information on this page. If I've made a mistake here, please let me know. Here is what I found out about the transformers.

Power specifications

  • With a 48VCT transformer it will put out around 50WRMS x 2 into 8ohms. It can theorecically be bridged to run a single 8ohm load at aprox. 196W, but the output is limited to about 150WRMS because the amps will get to hot, and go into protection mode. Using two 4ohm loads with the ParaPix and a 48VCT transformer can be done, but the amp will heat up, and go into protection mode, so be careful, and take it easy with the volume knob.
  • With a somewhat smaller transformer, 45VCT for example, it will be safer to run 4ohm loads. This will give approximately 78WRMS x 2 into 4ohms. DO NOT attempt to run the amp in bridged mode with a 4ohm load without doing the modifications listed above, and even then I don't really think it's a good idea. If you run the amp with a 45VCT transformer bridged with a 8ohm load you will get approximately 156WRMS, and about the same with a 48VCT transformer.

Wiring the Transformer

  • This is the part of the schematic that has the transformer hookup. NOTE: pin #1 of the Plug 1 goes to the switch and not to the chassis.
    *****NOTE-The pins for Plug 1 on the amp are each labled as AC, AC, GND, SEC, CT, and CT. Where it says "Pin1" on the amp does not mean pin one of the plug. Pin one of the plug starts on the other end.****

What can the Paramount Pictures Amp be used for?

This amp is a two channel, aproximately 50W/channel amp. It can be used to drive a pair of woofers, or a single DVC woofer.

  • John E. Jankowitz's Stryke ParaSWAN Subwoofer Project
  • You can also use two single VC woofers with the ParaPix Amp. John is also using a pair of 8" drivers in a 4th order BP box [a lot of output from them over a small range] with the ParaPix in a clamshell isobarik. The total size is 15"tall, 15.5" deep, and 10.5"wide. It has a low F3 of 35Hz, and plays nice and loud.
  • Steve Houlihan's El Nino with a ParaPix driven Woofer, a Madisound 1252DVC sub, and a Madisound 81524 DVC woofer sub for his computer
  • A suggested woofer is the Madisound 10207 10" DVC woofer
  • Jerry Lynds has a Swan/ParaPix Sub he calls the Monolith
  • Brian Steele's Subwoofer DIY site has a Hsu Subwoofer with a RD75 Dipole Baffle

Schematics of the Paramount Pictures Amp

Links

Back to the ParaPix