I want to build a composite feedback amplifier with a TDA7293, Burson Audio V7 Vivid Pro single, and an OP07 servo.
Can anyone help me?
The idea behind a Burson Audio V7 Vivid Pro single-input stage amplifier with an OP07 servo combines two high-quality components to achieve excellent audio performance with minimal DC offset. Here's a detailed look at this configuration:
Burson Audio V7 Vivid Pro as a single-input stage amplifier:
* As already explained in detail, the OP07 is used as a DC servo to minimize or eliminate DC offset voltages at the amplifier's output. Its precision and stability make it ideal for this task.
The combination in detail:
In this configuration, the Burson Audio V7 Vivid Pro would handle the actual signal amplification in the first stage to preserve and enhance the sonic qualities of the audio signal. At the same time, a separate OP07 op amp would act as a DC servo, monitoring the DC voltage at the output of the entire amplifier (which includes the V7 Vivid Pro stage and possibly additional amplification stages).
The OP07's correction signal would then be fed back to a suitable location in the amplifier, ideally to the input stage with the V7 Vivid Pro or a stage upstream. This effectively compensates for the DC offset without directly affecting the sonic characteristics of the V7 Vivid Pro.
Advantages of this combination:
Combining a Burson Audio V7 Vivid Pro as a single-input stage amplifier with an OP07 as a DC servo is a promising approach for high-quality audio amplifiers. It aims to leverage the sonic advantages of the discrete Burson op-amp in the critical input stage while ensuring a clean and stable DC output thanks to the precise OP07 servo. This configuration can result in highly detailed, dynamic, and sonically convincing amplification with minimal DC offset.
Can anyone help me?
The idea behind a Burson Audio V7 Vivid Pro single-input stage amplifier with an OP07 servo combines two high-quality components to achieve excellent audio performance with minimal DC offset. Here's a detailed look at this configuration:
Burson Audio V7 Vivid Pro as a single-input stage amplifier:
- Burson Audio V7 Vivid Pro: This is a discrete operational amplifier (op-amp) from the renowned manufacturer Burson Audio. It is known for its dynamic, clear, and precise sound reproduction. Burson emphasizes a sophisticated design with multiple discrete components instead of a single IC to achieve higher sound quality.
- Single-input stage amplifier: This indicates that a single V7 Vivid Pro op-amp forms the first amplification stage for an audio channel. This stage is critical for amplifying the incoming audio signal with minimal noise and distortion before it reaches subsequent amplification stages or the output. Choosing a high-quality op amp like the V7 Vivid Pro in this position aims to optimize sound quality from the outset.
* As already explained in detail, the OP07 is used as a DC servo to minimize or eliminate DC offset voltages at the amplifier's output. Its precision and stability make it ideal for this task.
The combination in detail:
In this configuration, the Burson Audio V7 Vivid Pro would handle the actual signal amplification in the first stage to preserve and enhance the sonic qualities of the audio signal. At the same time, a separate OP07 op amp would act as a DC servo, monitoring the DC voltage at the output of the entire amplifier (which includes the V7 Vivid Pro stage and possibly additional amplification stages).
The OP07's correction signal would then be fed back to a suitable location in the amplifier, ideally to the input stage with the V7 Vivid Pro or a stage upstream. This effectively compensates for the DC offset without directly affecting the sonic characteristics of the V7 Vivid Pro.
Advantages of this combination:
- Excellent sound quality: The Burson Audio V7 Vivid Pro is designed to deliver very clear, dynamic, and precise sound reproduction, optimizing the quality of the first amplification stage.
- Minimized DC offset: The dedicated OP07 servo ensures effective suppression of DC offset at the output, helping to protect the speakers and reduce unwanted noise.
- Potential synergy: Combining a high-quality discrete op-amp for signal amplification with a precise IC op-amp for DC regulation can provide an optimal balance between sound quality and technical stability. The V7 Vivid Pro focuses on the sound, while the OP07 takes care of critical DC bias control.
- Low-noise design: Both the Burson V7 Vivid Pro and the OP07 are engineered for low noise, contributing to an overall low-noise amplifier design.
- Servo implementation: Correct implementation of the DC servo is critical to ensure that it only affects DC and very low-frequency signals and does not interfere with the audible range. The sizing of the filter components in the servo circuit is important here.
- Servo coupling to the input stage: The way in which the OP07 correction signal is coupled to the input stage with the V7 Vivid Pro must be carefully chosen to avoid unwanted interactions.
Combining a Burson Audio V7 Vivid Pro as a single-input stage amplifier with an OP07 as a DC servo is a promising approach for high-quality audio amplifiers. It aims to leverage the sonic advantages of the discrete Burson op-amp in the critical input stage while ensuring a clean and stable DC output thanks to the precise OP07 servo. This configuration can result in highly detailed, dynamic, and sonically convincing amplification with minimal DC offset.
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The OP07 is bipolar, so its bias currents are rather high for a DC-servo, they will certainly limit the accuracy far more than the offset voltage of the device. FET opamps are normally used for servos for this reason, meaning the capacitors can be much smaller as 1M or higher resistors don't cause appreciable DC-offsets in a FET opamp. I suspect you'd get better performance with a TL072 as DC-servo for this reason. The DC-servo has minimal effect on sound quality as its feedback isn't effective in the audio band.
Normally the output offset of a power amplifier is kept low by using a capacitor in the feedback network - I presume you are seeking to remove the need for this capacitor (it is problematic for several reasons) hence wanting a DC-servo. So you want the input offset to be small to keep the output offset small?
That logic would imply using the OP07 in place of the Burson, then you won't need a DC-servo, as its 75uV offset is plenty low enough. However its not high enough bandwidth for low-distortion audio.
But there are other opamps with low offset and suitable for low-distortion audio. The LM4562 for instance has a typical input offset of +/-100uV
Normally the output offset of a power amplifier is kept low by using a capacitor in the feedback network - I presume you are seeking to remove the need for this capacitor (it is problematic for several reasons) hence wanting a DC-servo. So you want the input offset to be small to keep the output offset small?
That logic would imply using the OP07 in place of the Burson, then you won't need a DC-servo, as its 75uV offset is plenty low enough. However its not high enough bandwidth for low-distortion audio.
But there are other opamps with low offset and suitable for low-distortion audio. The LM4562 for instance has a typical input offset of +/-100uV
Its OK, its nothing that special compared to some of the Burr-Brown devices... Integrated opamps have a huge advantage for input offset voltage. Discrete opamps excel when the output requirements are high current, or high supply voltage is needed, they can be much higher dissipation, and the much higher cost is justified as integrated opamps aren't available for those parameters.
There is a guy that has designed excellent composite amps utilizing TDA7293, TDA7294, LM1875 and LM3886. Here is his website - www.kaltecs.com
He is very responsive and you can ask him for help.
I personally own a few of his kits.
Absolutely great performance - ultra-low distortions and noise, especially when paralleling a couple of 60W kits.
His circuit is very well optimized so there is no need for servo and still the DC offset is less than 1mV.
I hope that helps.
He is very responsive and you can ask him for help.
I personally own a few of his kits.
Absolutely great performance - ultra-low distortions and noise, especially when paralleling a couple of 60W kits.
His circuit is very well optimized so there is no need for servo and still the DC offset is less than 1mV.
I hope that helps.
Thanks for the tip!
I also ordered two boards, and I'll build those as well.
But I need a circuit with the Burson Audio V7vivid Pro, because I own several of those, and the V7 sounds absolutely great to me.
I also ordered two boards, and I'll build those as well.
But I need a circuit with the Burson Audio V7vivid Pro, because I own several of those, and the V7 sounds absolutely great to me.
I've been building amplifiers on breadboards without copper plating for 30 years, wiring directly with silver wire. Unfortunately, I'm only self-taught and can't design professional circuits myself. Otherwise, I know my stuff pretty well.
I could also do some calculations, but I think many people here have better options. That's why I asked in the first place, not to discuss my project.
I could also do some calculations, but I think many people here have better options. That's why I asked in the first place, not to discuss my project.
I can't remember where but if you look at the www.kaltecs.com project section you'll find some interesting info about the role of the op amp in composite amplifiers. As far as I remember not any op amp is suitable to work with TDA7293.
The amplifiers look good, but much too expensive. If I add customs duties, I'm at €200 for one module.
Use OPA828 as the master for a composite. Doesn't get any better than this. No DC servo needed.
And please, mark AI prompts and outputs as such.
And please, mark AI prompts and outputs as such.
You do know Texas Instruments makes opamps anywhere from 320 Mhz to 1000 Mhz
with slew rates over 1000 to 8000 V/us
And as far as DC servos, they no longer only have low drift opamps they have = ZERO drift op amps
Also have plenty of audio amplifiers with .00005 % distortion even lower.
So Burson Audio at 55 Mhz and .01% distortion is a absolute joke in op amp land for the price.
Any company listing " Color and texture" and " Soundstage" as priority features is pure snake oil bull crap.
TDA7293 no models available
Could build a model with LM3886, then again everyone will cry that sim cant show distortion improvement.
It will show oscillation for sure, long story short, crest power .01% distortion with composite .003 to maybe .001%
And prey you dont clip it. Something sim and real life can show.
probably might be beat with just a discrete front end differential instead
DC offset.....dont do dingle wingle already low enough. something a differential frontend would do anyways.
or be no different than stock.
with slew rates over 1000 to 8000 V/us
And as far as DC servos, they no longer only have low drift opamps they have = ZERO drift op amps
Also have plenty of audio amplifiers with .00005 % distortion even lower.
So Burson Audio at 55 Mhz and .01% distortion is a absolute joke in op amp land for the price.
Any company listing " Color and texture" and " Soundstage" as priority features is pure snake oil bull crap.
TDA7293 no models available
Could build a model with LM3886, then again everyone will cry that sim cant show distortion improvement.
It will show oscillation for sure, long story short, crest power .01% distortion with composite .003 to maybe .001%
And prey you dont clip it. Something sim and real life can show.
probably might be beat with just a discrete front end differential instead
DC offset.....dont do dingle wingle already low enough. something a differential frontend would do anyways.
or be no different than stock.
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Haven't read 7293 data sheet in awhile, far as I remember it has built in DC servo and other management built in.
No models regardless, proof of concept would be done with 3886.
No models regardless, proof of concept would be done with 3886.
Are you looking for someone to
- design a circuit for you
- set up a simulation and try to get a composite amp to work (without oscillating) for you?
That is a lot of highly sophisticated work. Will definitely not be cheap.
You could however use the burson op amp as input buffer and the 7293 as power amp. That is much easier to get working.
For 7293 composite amp also have a look at this thread (if you haven't already): https://www.diyaudio.com/community/threads/open-source-layout-for-a-tda7293-composite-amp.368974/
Yes. Don't.
Last I checked the Burson data sheets there wasn't enough information in the data sheet to design a composite amplifier. Specifically, the AVOL (open loop gain/phase) curve was missing. The same is the case for the TDA7293. Now, you could go and measure those. It's not super hard if you have the equipment to do so. Specifically you need a network analyzer that covers at least 100 kHz to some 10s of MHz, maybe 100 MHz to be safe. Once you have those data you can design a circuit that has a reasonable chance of working.
An alternative could be to find a validated simulation model for the two amps. I doubt you'll get one from Burson.
I question your desire for the OP-07. That's a very old opamp. Modern parts have better performance. As others have pointed out, using a modern part like the OPA828, OPA1612, LM4562, etc. as the controlling opamp in a composite amp could eliminate the need for a DC servo.
Many discrete opamps have a second order rolloff in the AVOL, which means they're really only stable at unity gain unless you apply external compensation. I covered this in my talk on discrete opamps at BAF last year. You can find it here:
+1
Tom