Modding an old EQ for seperate main/sub inputs
Ok... I wanted to modify an old eq to take separate inputs for main and sub and have main and sub outs with separate gain and volume for each.
Not many companies are doing this and I wanted to keep the use of the time alignment from my HU. Plus like most, I hate fumbling through the menu's to change a setting.
This is what I did...
Used an old EQ form the late 90's and drew a schematic with TINA.
Added a small board to add one more 072 and removed the fader and the rear output jacks. I put in a power connector like the ones on audio control units.
I took out the main/aux switch and used the aux input for the sub input and wired it to the 072 I added.
Cut the trace that goes to the sub crossover section and wired to the out of the 072 I added.
It's dead quite at idle and clean sounding for old 072 opamps. I did replace all the electrolytic caps.
With 1.6 vrms in and sweeping from 20hz to 20khz the output stays at 4.6 vrms. It starts clipping at 6.4vrms.
The sub out with the same input but sweeping from 20 to 160hz is 4.7vrms. It starts to clip at 6.6vrms
Pretty even...
Ok... I wanted to modify an old eq to take separate inputs for main and sub and have main and sub outs with separate gain and volume for each.
Not many companies are doing this and I wanted to keep the use of the time alignment from my HU. Plus like most, I hate fumbling through the menu's to change a setting.
This is what I did...
Used an old EQ form the late 90's and drew a schematic with TINA.
Added a small board to add one more 072 and removed the fader and the rear output jacks. I put in a power connector like the ones on audio control units.
I took out the main/aux switch and used the aux input for the sub input and wired it to the 072 I added.
Cut the trace that goes to the sub crossover section and wired to the out of the 072 I added.
It's dead quite at idle and clean sounding for old 072 opamps. I did replace all the electrolytic caps.
With 1.6 vrms in and sweeping from 20hz to 20khz the output stays at 4.6 vrms. It starts clipping at 6.4vrms.
The sub out with the same input but sweeping from 20 to 160hz is 4.7vrms. It starts to clip at 6.6vrms
Pretty even...
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Modding an old EQ for seperate main/sub inputs
The reason I wanted to do this inexpensively, (except time), is I could not find much of what I could use in my car. To me there's nothing like a knob to turn quickly.
I found this item, ARC AUDIO XEQ but for $300.00+.... Wow!
This AudioControl isn't bad but they used 5% carbon resistors and cheap NJM opamps throughout!
AUDIOCONTROL OVERDRIVE PLUS $99.00
I have one in the car but the optional $18.00 ACR-1 BASS KNOB REMOTE CONTROL has a very NON-Linear taper, very sensitive above one-o'clock and up.
Been thinking about modding one of these..PLANET AUDIO PEQ15
..Cheap... $40.00 and newer than what I did already.
The reason I wanted to do this inexpensively, (except time), is I could not find much of what I could use in my car. To me there's nothing like a knob to turn quickly.
I found this item, ARC AUDIO XEQ but for $300.00+.... Wow!
This AudioControl isn't bad but they used 5% carbon resistors and cheap NJM opamps throughout!
AUDIOCONTROL OVERDRIVE PLUS $99.00
I have one in the car but the optional $18.00 ACR-1 BASS KNOB REMOTE CONTROL has a very NON-Linear taper, very sensitive above one-o'clock and up.
Been thinking about modding one of these..PLANET AUDIO PEQ15
..Cheap... $40.00 and newer than what I did already.
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!!!The reason I wanted to do this inexpensively, (except time), is I could not find much of what I could use in my car. To me there's nothing like a knob to turn quickly.
I found this item, ARC AUDIO XEQ but for $300.00+.... Wow!
This AudioControl isn't bad but they used 5% carbon resistors and cheap opamps throughout!
AUDIOCONTROL OVERDRIVE PLUS $99.00
I have one in the car but the optional $18.00 ACR-1 BASS KNOB REMOTE CONTROL has a very NON-Linear taper, very sensitive above one-o'clock and up.
Been thinking about modding one of these..PLANET AUDIO PEQ15
..Cheap... $40.00 and newer than what I did already.
The reason I wanted to do this inexpensively, (except time), is I could not find much of what I could use in my car. To me there's nothing like a knob to turn quickly.
I found this item, ARC AUDIO XEQ but for $300.00+.... Wow!
This AudioControl isn't bad but they used 5% carbon resistors and cheap BA opamps throughout!
AUDIOCONTROL OVERDRIVE PLUS $99.00
I have one in the car but the optional $18.00 ACR-1 BASS KNOB REMOTE CONTROL has a very NON-Linear taper, very sensitive above one-o'clock and up.
Been thinking about modding one of these..PLANET AUDIO PEQ15
..Cheap... $40.00 and newer than what I did already.
So why does AudioControl cost quite a bit, but use these "BA4560" They cost $0.64 from mouser and what about there slew rate???... I've found them in most everything they have....
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The BA4560 is better than what others use (TL072). PG uses the BA4560 in many (if not all, well not all) high end amplifiers such as the M series, MPS , ZX, TI's and others.
Trust me they cost much less than 0.64 when you purchase them by the thousands, that doesn't make them less suitable.
Could you imagine replacing all those with BB, you will spend around 40.00....that's a lot of $$$$, as a manufacture you would have to increase the MRSP of your product just to justify the use of the BB.
Trust me they cost much less than 0.64 when you purchase them by the thousands, that doesn't make them less suitable.
Could you imagine replacing all those with BB, you will spend around 40.00....that's a lot of $$$$, as a manufacture you would have to increase the MRSP of your product just to justify the use of the BB.
After reading a-lot about this.... It all comes down to "The higher the slew rate the better the amp, high slew rate means the amp will reproduce subtle nuance and dynamic music."
So is 1V/μs good enough? The 072 seem to be better...
And whats with the 5% carbon resistors in AudioControls stuff?
So is 1V/μs good enough? The 072 seem to be better...
And whats with the 5% carbon resistors in AudioControls stuff?
There are other thing you have to look for when reading datasheets for op amps than just slew rate. Keep in mind that not all IC's are made by the same manufacture so they may vary in specs from different makers most will be identical but will have minor changes in certain areas.
Nothing wrong with 5%.
Nothing wrong with 5%.
Just finished with the final mod. Tested it with and alpine deck, Soundstream 500s and a Phoenix Gold 1.0x. OK, this thing is dead quiet at idle. I was a little worried since there are no power-supply bypass caps on any of the op-amps plus it does not introduce any turn-on/off noise. I added 1 op-amp so it would have a separate input for the sub channels.
I opted to make the bass knob and parametric control separate for the sub channels.
I eliminated the crossover for the sub also.
Now to test it in the car.
Hear it is...
I opted to make the bass knob and parametric control separate for the sub channels.
I eliminated the crossover for the sub also.
Now to test it in the car.
Hear it is...
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