0.005% Distortion Tone Control Preamp, NJW1119A Chipset - diyAudio
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Old 15th January 2015, 06:55 PM   #1
kouiky is offline kouiky  United States
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Default 0.005% Distortion Tone Control Preamp, NJW1119A Chipset

Hello DIYers,

This active analog chipset is stated to offer very low noise (-120dB, Typical Performance with Tone Off, -110dB Typical with Tone On), low distortion (0.0002%, Typical Performance with Tone Off, .005% Typical with Tone On). The tone control offers frequency cut and augmentation over three bands in 1dB increments, and is set using a 3-pin digital logic interface. The boost/cut frequencies in each band can be altered by changing a few out components on the pinouts. Power requirements are +/-7VDC and 15mA per stereo chipset, making this a prime candidate for a battery powered device.

After identifying the real average output level of the sources (DAC, AppleTV, or analog audio sources) for their application, the input should be suitably attenuated to adhere to the required gain structure and prevent unnecessary distortion from driving the input too high, without over-attenuating the input signal. 1% THD is reached under two conditions; 9.5V output level; 4.3V input; either condition with Tone On, which is easily avoided. The best performance is at 2V input and lower. The tone task is carried out actively (instead of the more common Bandaxall passive types that are often found between two stages). Because of this, the tone accentuation functions are boosted above the nominal gain of the chipset. The nominal gain of the chipset is unity, so a low-noise & low-output impedance follower chipset could be added after the NJW1119A to provide any desired amplification. A stereo volume potentiometer should be inserted between them to control the output level. This finishes the assembly, serving as a comprehensive preamp with respectable dynamic performance and especially low noise at comfortable listening levels.

NJW1119A Three-Band Integrated Circuit Stereo Tone Control
http://www.njr.com/semicon/PDF/NJW1119A_E.pdf

I would like to hear if anyone has experience with the logic control aspect of using a chip like this (details in the PDF file above). Arduino seems appropriate. Also, if there is a better performing chip to suit, that would be great to hear about, too.

Last edited by kouiky; 16th January 2015 at 06:12 PM.
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Old 17th January 2015, 03:37 AM   #2
Bonsai is offline Bonsai  Taiwan
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Looks interesting - is it a prelim spec because some of the date is not complete.

Distortion numbers are also not too bad and the tone curves are ok as well m

Nice find!
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Old 17th January 2015, 03:44 PM   #3
kouiky is offline kouiky  United States
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It's interesting, isn't it? I have never seen a tone control, here or abroad, that could accomplish distortion and noise that low. Analog Devices makes some opamps with distortion in the 0.0000X% area, and Texas Instruments has some opamps with a noise floor of -130dB, these largely approaching the limits of mass-produced capability at this time and are exceptional. But, anything with a tone control was far noisier and distorted, often enough that its presence was noticable.

Some vendors online stock this NJW chip and several variants. If it really can do a noise floor of -110dB and .005% THD (-86dB) with the tone function active, it would represent a major advancement over the usual types. It would be sonically invisible except for the effects of phase shift on transient response when a wide range of concidence frequencies are present at once, while tone is set high. Then again, if it compensates for phase, it might explain the exemplary performance.

I'm surprised that with all the talk about tone controls this one has slipped under the radar.

Last edited by kouiky; 17th January 2015 at 03:55 PM.
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Old 17th January 2015, 04:58 PM   #4
jerryo is offline jerryo  Isle of Man
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It would be nice to see a full pcb implementation for this.
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Old 26th January 2015, 08:15 PM   #5
kouiky is offline kouiky  United States
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Agreed. We'll need an experienced resident () that knows logic encoders, the rest is all about layout and routing. Here is a diagram I created showing what I have in mind. Following input attenuation the relay is required, because the NJW chipset will not like audio signals on the input when it's off. The output relay would be to prevent power on-off transients. The volume must be used after the NJW1119A, between it and the output opamp for the best signal-to-noise ratio if a single opamp is used. Alternatively, someone could use a discrete stage at that point if they wanted. The output opamp could provide some gain for lower level recordings and low sensitivity power amplifiers, or even be followed by a second stage to drop the output impedance into single digits. No coupling capacitors are shown, and if the opamp has some drift, a DC error-correction amp stage could be added to null it.

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Old 27th January 2015, 03:43 PM   #6
kouiky is offline kouiky  United States
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I learned today that the NJW1119 is the tone IC used in the McIntosh MC2300, and that it's used in a similar manner to which I proposed above.
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Old 29th January 2015, 05:32 PM   #7
kouiky is offline kouiky  United States
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Correction: McIntosh C2300 preamp.

Last edited by kouiky; 29th January 2015 at 05:37 PM.
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Old 2nd February 2015, 08:19 PM   #8
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Quote:
Originally Posted by kouiky View Post

Some vendors online stock this NJW chip and several variants.
I am really interested to build tone control with this chip. Where did you find it available online?

As for digital control, I would suggest to have separate controller, like Arduino, and to build tone control/volume as I2C periphery. In this way you will be able to expand the system later.

Cheers,
Boris
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Old 5th February 2015, 04:13 AM   #9
rsavas is offline rsavas  Canada
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Now try to get one of these chips, I do not think it is so easy.
It has a spi type NOT a i2c interface with TTL sort of levels, 2.4V min high
Suggest to place the volume control in front of the tone control and add a means of bypassing it. It will probably need to have an output buffer and of course the volume control chip? or a pot.
I do not think you need a relay at the input but for sure one at the output with ac fail detection etc.
I was looking at NJW1191 recently, it is i2c
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Old 5th February 2015, 05:39 AM   #10
erik777 is offline erik777  United States
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Take the proven low thd+n O2 amp and make it pre amp duty
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