About design philosophy _ are minimalists right or not ?

[gino1961]

Another part of the tale behind simple circuits is every component matters. If your circuit is simple, you can afford to use the highest quality components. If your circuit is complex those are cost prohibitive. And that tale is easy for people to think about just that way. In fact all that matters is input vs output. If complex works with cheap components then it can be better or even as good as possible. That isn't an easy concept for those who don't know circuits. If going thru every component leaves a trace on the signal the fewer of those and the higher quality each is the less degradation occurs or so the story goes.

Thank you very much Interesting to know that more complex designs allow to use cheaper parts But i tend to prefer the less but better parts approach
Then parts selection becomes of paramount importance for the final result
I am pretty sure that excellent performance can be obtained by very good parts used at best

 

[Chr1]

I don't actually use a preamp as I only play digital files from either my DAC or AVR. Both of which have volume controls. But I am curious as to the state of play with current preamps.
What is the best bang for buck these days?
Presumably it's mainly about the quality of phono sections for vinyl fans?
Not much coverage of preamps here as it is mainly either power or integrated amps folk are buying.

 

[Waxx]

I for a long time believed in the simple circuit. Built some myself for preamps. They can be good to excellent. But minimalism is really a misguided myth in audio. Really no reason for any modern preamp not to be op-amp based. That is simple functionally, but it hides some complexity inside the op-amp. Doesn't matter though, it is possible to have very low noise, very low distortion and a very wide bandwidth at rather low cost. Most of the cost will end up being in how fancy the case is made.

that is true if you want a neutral preamp, many want some colour in it and then jfets or tubes are needed.

But for a neutral preamp an opamp based circuit is indeed the easiest and cheapest way to make a good preamp. And even a very basic and cheap opamp like the NE5532 can be enough, altough there are better opamps availeble also today. But in the right circuit you can get an sinad of over 110dB with a good genuinee NE5532 opamp, something that will be hard with jfets and impossible with tubes. And that circuit does not have to be complex, as long as the psu gives clean dc to power it.

​

 

[gino1961]

I think the less is more ethos can be attractive depending on the context, for example when I, a contrarian, am feeling oppressed by the more is more consumer ethos, which is not exactly uncommon in audio. But I don't think it is a very useful engineering concept. It's too simplistic. A good engineer will not over-complicate a design but that's completely different from seeking to minimize its complexity.

Hi yes but as i said at the beginning one good designer has designed a line stage using just one mosfet
Another one has decided to use more than 20 active parts Why ?
If i had to say something i think that just one active stage is not enough to get very low distortion But just with one more and some negative feedback the distortion can be minimal That is the case of the Sziklai pair for instance Of course there will be more optimized circuits and less optimized circuits

System function and performance goals are primary. Cost and your resources/capabilities are constraints and complexity is what it is. If we let minimum complexity dictate function and performance then we just build zero dB amplifiers.
In this thread we discussed a block diagram hinting at the complexity in a typical powered speaker. With only one quibble we agreed that all the complexities in the design make sense and, properly implemented, would improve the sound of the system. I get that some people are attracted to much simpler systems but improved sound is hard to argue with.

as i said i am mostly interested in line stages that have to provide very little Vgain and decently low Zout
power amps must be more complex i agree

 

[Blumlein 88]

Hi yes but as i said at the beginning one good designer has designed a line stage using just one mosfet
Another one has decided to use more than 20 active parts Why ?
If i had to say something i think that just one active stage is not enough to get very low distortion But just with one more and some negative feedback the distortion can be minimal That is the case of the Sziklai pair for instance Of course there will be more optimized circuits and less optimized circuits

as i said i am mostly interested in line stages that have to provide very little Vgain and decently low Zout
power amps must be more complex i agree

It is like asking why someone makes a steel belted radial which is complex, requires machinery few can afford, when one can build a perfectly serviceable wooden wheel with simple hand tools. There are people still making such wheels. In the larger context it is a non-starter. An op-amp has tons of research, optimization and manufacturing know how behind it to make it very simple to use in all sorts of ways. You can treat them as the simplest black box. In use there is nothing simpler, in use there is nothing more cost effective, and for anything in audio in use there is no higher performance.

So beyond the artisan experience what are you hoping to achieve? Other goals are perfectly fine, but you started this by asking are minimalists right or not? The obvious answer is no, they are not right. It takes super careful design, possibly component selection and know how to make a high performing discrete preamp, while any tech school student or reader of Walt Jung's Cookbook can put together a near SOTA preamp with op amps. The finest circuit designers available can do the heavy lifting to design an op amp of extraordinary performance which can be mass produced for cheap, and then used in a variety of useful ways like an audio preamp. Designers like the recently departed Scott Wurcer. You are seeing the same thing in class D power amps. People like Bruno Putzeys design exceptional amp modules that get manufactured relatively inexpensively so many people can plug them in for superb performance.

 

[gino1961]

To be different, to justify prices, because customers like to see that, to improve measured performance.

i see many reasons not always related to objective performance Clearly only the last one is reasonable for me Improved performance

We're from the same production year.

i checked with a sweep test on headphones I hoped a better result

Noise should be below audible level.
THDistortion should be below 0.01%. Doing any better is technically fine but has no audible consequences.
Slew-rate: when you can reach 50kHz -0.5dB at max output voltage slewrate is more than sufficient. This can be achieved with most circuits, simple or complex and is never really an issue.
Crosstalk... >40dB is good enough. Just play one channel with 40dB attenuation and the other with no attenuation.
Listen with speakers and headphones and see if you can actually hear something on the attenuated side.

this level of perfomance seems quite achievable I intend to simulate something soon I have some circuits to check
i hope to find the bjt models

Because people believe it is better.
Just look at how recordings are made. All that gorgeous recordings probably have passed through many opamps.
Hell... even the vast majority of DACs has opamps in the output ... and then ... with just 1x to 3x gain a pe-amp suddenly isn't good enough for line level signals ?

ok the last doubts are vanishing Opamps are everywhere You are very right One more could do little harm

In my younger years I built 2 pre-amp circuits in one pre-amp with a switch so I can select them.
Both 3x gain.
One with non-biased very old electrolytics (2 in series on the input and 2 in series with the output. It had the well known TL072 that amplified both channels. It also had a simple 7812/7912 regulators and ceramic cap for decoupling.
The other channel was DC coupled, better regulators with compound decoupling in factors of 10 (so 100uF//10uF//1uF//100nF//4.7nF) and used the (in those days as excellent considered) OP27 opamps (one for each channel and separate power supply circuits).
It was for my own 'education' and was made so I could show others what a big leap in sound it made. Switch was on the back.
I never could hear any difference nor could anyone that came to visit.
Of course I always used it in OP27 mode... At least until the day when I had left it on the TL072 section without me knowing. Probably listened to it in that position for years without realizing until I wanted to demo and reached for the switch again.

I trust you This has convinced me completely Actually i have listened to some comparisons between opamps without perceiving clear differences in sound
At this point the opamp option seems the more promising if low cost simplicity and good performance should come together

 

[Chr1]

So is it the case that decent cheap amp design is now pretty much a solved problem. Such that it takes some bad design to mess it up? Like DACs.

Seems it's definitely now really all about the speakers/room and any additional EQ/DSP/"colouring" you may choose to add then...

(This is a good thing.)

 

[somebodyelse]

Hi yes but as i said at the beginning one good designer has designed a line stage using just one mosfet
Another one has decided to use more than 20 active parts Why ?

One mosfet makes a good marketing story, and a section of the market demand it (see Nelson Pass's presentation of the analog crossover for the LXmini at AmpCamp explaining demand for it from the far east for example.) Better performance and/or lower cost for the extra components.

Analog design courses will usually start with the simplest arrangement and cover its deviations from 'ideal' behaviour. After that come the ways that these can be addressed. The 'one transistor' approach has little to do but find a more 'ideal' (and expensive) transistor, possibly with matched transistors for each channel (more expense.)The cheaper, more production-friendly approaches usually add 'complexity' in the form of more cheap components, stopping when enough issues have been addressed to get sufficient performance. Similarly there may be complexity added to make it self adjusting, rather than needing adjustment of trim pots etc. on the production line that could drift out of adjustment over the lifetime of the product. Then there's the power supply - the single transistor stage wil have poor power supply rejection so may need a more complex low noise PSU (more active components, but you still have your 'single transistor' design story.) You can add more to make your circuit robust - RF filters, ESD protection, output protection - go read the Topping L30 thread to see why the last 2 might be important!

If you want to see the process starting very simple then adding improvements you could look at Pass's Zen Variations - starting with a single transistor power amp and improving its performance step by step. Or read Self's various books on analog design.

 

[MaxwellsEq]

Hi @gino1961 personally I don't agree with your working hypotheses. I don't know what formal electronic education you have, so I may be teaching you to suck eggs. When you start with design, you analyse the three ways to wire a transistor and learn the limitations of each. Then you analyse multi-transistor combinations such cascode, Darlington pair, current mirror etc. and their benefits and limitations. Then onto combinations and chains of gain elements.

I don't believe that there's a "golden design" and I also have no specific love or loathing for 1970s designs.

These days state of the art modelling and measurements are where "golden designs" come from, not picking one "active mode" and tweaking it. If the best transfer function requires 400 transistors, then so be it. Component count simply has no validity as a measure of performance. More components though lead to costs. They also lead to an increased statistical likelihood of failures. So making things as simple as possible, but no simpler is the correct approach.

 

[LTig]

Tone controls degrade the signal too much They have no place in a preamp that wants to be true to the source signal

You really must read the book by Douglas Self where he debunks all these myths created by audiophools without real knowledge in electronic design.

A well designed tone control stage does not degrade SQ so much as to become audible. And you can still add a switch to defeat it anyway if it is not required. OTOH there are so many imperfect sounding recordings in this world which could sound better with proper applied tone controls.

You may also read about the circle of confusion described by @Floyd Toole. The source signal often is as true to the music played during the recording session as you might think.

 

[solderdude]

Many years ago someone asked me to make a design that had gain, was high input Z, low output Z and had minimal component count and would be different from other designs.

I came up with this design

It actually worked and did not even sound as bad as I initially thought it might. Not a pre-amp but could be made into one. At least it is different but produces quite a bit of heat

 

[gino1961]

Many of us don't use preamps. We just plug a DAC with 2V output into a power amp which will reach full power with less than 2V input and don't boost any frequencies in our streamer.

yes I just like the idea of a universal line preamp able to drive very well different power amps while being true to the source
Also to have a volume control can be handy

 

[gino1961]

You really must read the book by Douglas Self where he debunks all these myths created by audiophools without real knowledge in electronic design.

A well designed tone control stage does not degrade SQ so much as to become audible. And you can still add a switch to defeat it anyway if it is not required. OTOH there are so many imperfect sounding recordings in this world which could sound better with proper applied tone controls.

You may also read about the circle of confusion described by @Floyd Toole. The source signal often is as true to the music played during the recording session as you might think.

maybe it is one of the very few my certainties No tone controls

 

[LTig]

Many years ago someone asked me to make a design that had gain, was high input Z, low output Z and had minimal component count and would be different from other designs.

I came up with this design

It actually worked and did not even sound as bad as I initially thought it might. Not a pre-amp but could be made into one. At least it is different but produces quite a bit of heat

Here is my very basic DIY line stage with measurements. It was designed in 1997, to feed a power amp and a 300 Ohm headphone (HD580). Much simpler with just 1 opamp and 1 power Mosfet.

 

[gino1961]

Many years ago someone asked me to make a design that had gain, was high input Z, low output Z and had minimal component count and would be different from other designs.
I came up with this design
It actually worked and did not even sound as bad as I initially thought it might. Not a pre-amp but could be made into one. At least it is different but produces quite a bit of heat

thank you very much i was thinking to something much more basic that i have seen used in commercial old preamp vintage but TOTL at their times
Units like Onkyo P303 Kenwood 700c Radford ZD22

 

[LTig]

maybe it is one of the very few my certainties No tone controls

It's up to you to omit tone controls but you should question the reason to do so. Quite a number of members here had similar believes before coming here and learned better. Been there, done that.

 

[gino1961]

It is like asking why someone makes a steel belted radial which is complex, requires machinery few can afford, when one can build a perfectly serviceable wooden wheel with simple hand tools. There are people still making such wheels. In the larger context it is a non-starter.

i am a little confused by comparison with other devices I cannot see the relation
i understand that my doubt is very uncommon
Who want something simple and with great performance tends to go with opamps and stop
In favour of opamps i have seen them used inside very expensive units and TOTL of the brands
Maybe the people who instead prefer discrete solutions tend to go with more complex circuits

An op-amp has tons of research, optimization and manufacturing know how behind it to make it very simple to use in all sorts of ways. You can treat them as the simplest black box. In use there is nothing simpler, in use there is nothing more cost effective, and for anything in audio in use there is no higher performance.
So beyond the artisan experience what are you hoping to achieve? Other goals are perfectly fine, but you started this by asking are minimalists right or not? The obvious answer is no, they are not right. It takes super careful design, possibly component selection and know how to make a high performing discrete preamp, while any tech school student or reader of Walt Jung's Cookbook can put together a near SOTA preamp with op amps. The finest circuit designers available can do the heavy lifting to design an op amp of extraordinary performance which can be mass produced for cheap, and then used in a variety of useful ways like an audio preamp. Designers like the recently departed Scott Wurcer. You are seeing the same thing in class D power amps. People like Bruno Putzeys design exceptional amp modules that get manufactured relatively inexpensively so many people can plug them in for superb performance.

message received loud and clear I have not seen detailed lab reports of the vintage preamps i mentioned It could be that they were good for their era but quite obsolete now I tried some simulations and the results seemed promising in terms of THD at least but i could have done something wrong
as you said with basic circuits everything becomes more challenging from design parts selection and power supply
And the fact that are so rare must mean something

 

[Kvalsvoll]

Did many designs on the minimalist concept. Goal was to have as few amplification stages as possible in the signal path.

Reasons behind fall short of any logical and scientific evidence. It is something you make just because it is nice, and because it is difficult. Need to source obscure hard-to-find transistors, work on very delicate circuit designs. Nice. But it does nothing for sound quality.

One idea is that a simple circuit has a simpler distortion character, with less high order harmonics. Could make sense, if it wasn't for the fact that when the design is well executed, all distortion is well below audible levels anyway.

And the overall circuit design ends up being quite complex, because to make that simple amplifier stage work and perform well, all surrounding circuitry will be more advanced and complex. Such as power supply, with very low noise and low impedance.

 

[Multicore]

Hi yes but as i said at the beginning one good designer has designed a line stage using just one mosfet
Another one has decided to use more than 20 active parts Why ?

I would need to be at least somewhat expert in that specific field of design to comment but it's very remote from my field.

 

[JeffS7444]

Hi yes but as i said at the beginning one good designer has designed a line stage using just one mosfet
Another one has decided to use more than 20 active parts Why ?

If you're specifically wondering about the designs of Nelson Pass, you might ask my buddy 6L6 on DIYAUDIO, as he's well-connected in that regard. But so far as I can see, NP creates unusual circuits as a sort of thought exercise, and achieving the lowest possible distortion is not necessarily his goal.