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- ALTEC LANSING ATP3 SCHEMATIC DIAGRAM DRIVERS
- ALTEC LANSING ATP3 SCHEMATIC DIAGRAM DRIVER
- ALTEC LANSING ATP3 SCHEMATIC DIAGRAM PLUS
- ALTEC LANSING ATP3 SCHEMATIC DIAGRAM SERIES
How about MF EQ on a 604-8G, or an 8-H, but simplified and with better parts and no switch? I have also added a note to this schematic concerning differing component values for users of the early High Frequency voice coil/diaphragm. See the Recommended Parts – Substitutions – Construction Hints page for a bit more detail on this, and other topics, that you may find helpful. Or, if you have already built the original 605 crossover contained in these pages, I urge you to remove the L-pad and substitute the 605 EQ circuit components in its place.įollow the Altec Lansing 605A/B Phase Correct Crossover with MF EQ link to view the circuit schematic. I believe you can build it with confidence however, as feedback from the first MF EQ equipped 605 phase-correct crossover constructor has been positive.
ALTEC LANSING ATP3 SCHEMATIC DIAGRAM DRIVERS
The previous paragraph applies as well to the Altec 605A or B, although I didn’t have either of these drivers on hand to audition.
ALTEC LANSING ATP3 SCHEMATIC DIAGRAM SERIES
Feel free to vary the series resistor following the contour circuit between 0 and 3 ohms to find the the high frequency slope that suits your ears and room.Īltec Lansing 604B Phase Correct Crossover with MF EQ
ALTEC LANSING ATP3 SCHEMATIC DIAGRAM DRIVER
These two changes put the MF EQ’s pot dial near its midpoint for normal listening, and really dialed in the compression driver balance above 4kHz to my ears. Don’t get me wrong – I’m not saying the B was now as good as the H! – but it was much improved over its standard shelving circuit/L-pad equipped brethren. It was still a bit too hot above 4kHz for my taste however, so I added a 2 ohm series resistor after the contour circuit to shape the rising HF slope a bit, and also lowered the resistance value between P1 and ground to achieve a wider -5 to -15dB MF EQ normal operating range. The improved transients were probably due to the phase correction through the crossover region.
ALTEC LANSING ATP3 SCHEMATIC DIAGRAM PLUS
Yeah, yeah, I know what you’re asking….but how did it sound?!? To make a long story short, I put the 604Bs back into the cabinets and immediately heard all the improvements listed above for the 604H, plus razor-sharp transient attacks from rim shots and piano. I chose not to add the high frequency trim circuit or driver side resistor as I had found myself running the 604-8H HF control wide open. I used a 7uf capacitor instead of Altec’s 6uf, and modified the resistor values slightly to achieve a -3dB to -9dB MF EQ normal operating range with a 16 ohm speaker load. The old style shelving circuit was deleted and a tweaked contour circuit was substituted in its place. Unfortunately, this Altec filter is not time domain corrected like the others – so I naturally wondered just how would it sound if applied to my phase corrected 604B filters? MF EQ on a 16 ohm 604B?Īdding the mid frequency EQ function to my 604B circuit was pretty straight forward. At the recommended dial settings the upper mids are appropriately depressed relative to the high frequencies, and results similar to the famous Mastering Labs and UREI 604 filter implementations are achieved. The older style shelving circuit is disabled, an adjustable, frequency dependent, contour circuit is pulled in for the upper mids, a high frequency trim circuit becomes active, and a driver-side series resistor further shapes the rising HF slope. However, when the EQ button is clicked inward to the depressed position, the similarity ends. It finally gets amplified in the brown power amp.Jim Easley supplied schematic of the Vintage Altec Model 19 crossover circuit for comparison.Īt the basic level the 604-8H filter is a parallel 3rd order HP and 2nd order LP filter, with L pad shelving of all horn frequencies when the EQ button on the front panel is in the released position. Signal then goes through a low-pass, a small equalizer and a compressor (the big purple box). The small green box on its left merges the left and right channels to forward it to the subwoofer section, which is the complete left half of this diagram (except the red box on the left, which is just power). In the middle yellow box there's some trebble/volume/bass control. The sound comes in on the right, in the green box. The block I want to short-circuit is the pink one on the left. My question is: should I disconnect the input and output from the compressor (in that case should I remove power supply as well, which would be very annoying), or can I leave it connected but short-circuited? I will connect the input to the output so it gets forwarded to the next stage. Its active components are a JFET and four op-amps. I have an Altec Lansing ATP3 2.1 audio system PCB which I reverse-engineered, and I would like to bypass the JFET compressor that's on it.