Can DIY preamps be competitive vs commercial preamps

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Fast Eddie D

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Joined 2010
I'll bet you could put modern circuits with modern parts in the Krell chassis and it would kick butt. The transformer and heat sinks are matched to each other. Replace everything else.

But it's a collector's item. It's a piece of industrial history. It was awesome for its time. I wouldn't change it, just like I wouldn't put a Chevy small block in a Maserati.

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konst

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Joined 2006
well as I have said several times, point me towards something that sounds as good and I will certainly go take a look....

Out of curiosity, what do you think you could improve with modern circuitry, meaning how would it sound better, as that really is in the end, that is all that is important?
 
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RJM1

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Joined 2010
You can definitely build a DIY preamp that is better than some pre-amps that have been made.
Back in the 70's Integral Systems made a pre-amp that its list price was $350.00 USD. It's store cost was$35.00 USD It was a 19 inch rack mount about 6" tall and consisted of 3 741 op-amps per channel plus assorted resistors and capacitors with 1000uf on the power-supply. The wood case for this cost the seller more than the pre-amp. The pre-amp weight was about 3 to 5 lbs.Integral Systems did not last long as their amplifiers were reported to catch fire in failure.
 
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Fast Eddie D

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Joined 2010
konst said:
meaning how would it sound better,
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Lower noise, better linearity, etc

as that really is in the end, that is all that is important?
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How it sounds is certainly very important.

I guess you missed my point where I pointed out that the Krell offers things that are missing in a lot of products. Distortion caused by sagging power supplies can be very audible.
 
analog_sa

analog_sa

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Joined 2002
Fast Eddie D said:
Distortion caused by sagging power supplies can be very audible.
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One of the easiest things for a diyer is to put together a kVA+ transformer and a lot of giant caps. It is certainly not enough though :)

Back to preamps. It has always been the most mysterious component in a system for me.

On one hand, it is not strictly required in a digital system with a good digital volume control and a decent output buffer. Yet, otoh, such minimalist systems, whether diy or using top shelf commercial components are seldom very satisfying musically. Same with resistitive passive attenuators. Even in systems offering sympathetic impedances and sensitivity passives seldom sound any good.

After decades of building and using commercial offerings i am not any closer to understanding why the sound with a really good active preamp is so much better. It is also the hardest component to get right, especially if you are buying a commercial unit.

It is really weird but i can relatively easily settle with a decent power amp, yet the vast majority of available preamps are just atrocious. Little wonder people build a simple opamp circuit, add a good quality attenuator and a decent power supply and voila: the sound is better than all sorts of "audiophile" and "reference" products.
 
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mikey_audiogeek

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Joined 2004
Schmitz77 said:
Its not that easy to compete with pro designs.


First of all there has to be the engineering knowledge to be learned to compete with pro equipment. Because pro equipment was designed, calculated and build by professionals, not amateurs.


At this stage, most DIY struggle with own designs that meet or exceed the excellent pro designs. They stuck in the Kindergarten of electronic designs, forever. Because they don't have the energy, the time and the resources to go on furter to exceed good designs.


Proof is in the thousands of DIY gears and schemos, that have spread all over the internet today. Most of them show big designs flaws by the task of designing a tube amp right from the scratch. They copy parts from other amps, understand just half the theory behind it, or modify parts of the amps plans and combine whatever they want or think that sounds good. The results are design errors, the gear may be funtioning, but suboptimal. Most DIY is in heaven, when its gear just produces some right tones. Then an audio forum has to be there, in which the hymns of their own designs must be written for the next generations of DIY. Of course its the best of the world design, an award winning tube amp, if there were ever such things as DIY- design awards.


Most of them struggle even with the practical approach, that is given when it comes to the building stage. Seen all those wood- frames with an aluminum top plate, looking like audio gear of the late 1950's in today times? That is, because its the most simple method to build a frame and chassis for a tube amp. You will rarely see someone, who is able to handle the metalwork and capable of designing something more professional. Thats because it has to be made most often by own machinery in the basements or on the kitchen table at night, when family is sleeping.


Forgot about small batch series of own plans for building the framework by a professional company. Every company will laugh at you, because they hate prototyping, or they want some grand cash notes before even doing one step towards the final housing.


So there are many dificulties to become a good designer, a good practical worker for building its own tube gear.


Its like everything in life: invest the energy, invest the money and invest the necessary labor and time and you will receive the equivalent value in own tube gear.
For most of the working people, they have not enough time and effort for self educating, learning often took years or decades to master one subject of knowledge, not enough knowledge to be a superior electronic gear designer, not enough talent, not enough money it all takes to be able to produce own gear in a professional mannor.


And that is visible in the end result, the ready made object. Circuits with big design flaws and errors, housings that look not fancy but ugly and building style and practice of work that shows big difficulties to solder two wires together in the way it should have been done.


I just have read a sentence about the usual consumer of gear, living in a first world country.
For him (or her), the most advanced technical machine they ever work with in their lifes is their motor car.
And even with the maintenance, service, correct treatment of this machine most of the people are too inexperienced, not enough interested in the subject and show too low effort to handle it the right way it should be done.


And those people should DIY better gear than pro- companies?
There will always only a few which are being able to achieve such a goal.


Most of the DIY never will, but enjoy doing it anyway. Achieving some goals, is the best part of it. It could make for a happy man, and that goal should be always in the foreground, not to beat a pro company. Because, it won't happen easily.
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Beautiful summary, particularly the last paragraph. Thanks!
 
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mikey_audiogeek

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Joined 2004
jrdmedford said:
I'd actually say its much, much harder to beat commercial speakers than any other audio component. Speaker designers have at their disposal anechoic chambers and test equipment and go through many design iterations. Speaker designers also can negotiate with driver manufacturers for custom drivers and more-over, driver pre-testing and screening. So, they end up with both a repeatable product and an iteratively designed product.

To beat a Commercial Preamp is very easy:
1. Know what you are driving downstream. Do you need to drive fully balanced lines to distant equipment, or just Single Ended RCA. If fully balanced, do you want transformer coupling or cap coupling. Your preamp needs to drive whatever impedance is downstream.
2. How do you want to Attenuate and Switch Inputs? Are hand controls sufficient, or do you want IR Remote with relay switching. Do you want fancier switching (i.e. over TCP/IP)?
3. Choose your Class A line stage topology. Discrete semi or tube
4. Do you need Gain? In today's era, probably not much. Let your Phono Preamp give you gain. Plan on 2Vp-p input from a DAC or other Line device.

One you answer those questions, you can find solutions to all 4 questions with existing PCBs and developed/proven modules. The rest is planning the fancy case!
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Great points. The significant advantage that a DIYer has is that they are designing/compiling for ONE application, ONE room, and ONE (or two) sets of ears. Suitability is the most important aspect of quality!
 
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andy2

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Joined 2004
Going through these pages looking at the DIY designs, it seems that most DIYers probably do not have the time and skills to design proper circuits, then having to perform layout to PCB designs. And given most designs probably will not be optimal the first time, you have to go through a few iterations which is beyond what most DIYers can tolerate.

Some probably can, but not most.
 
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ticknpop

Member
Joined 2005
Paid Member
Well Fast Eddie, I did that to my Krell KSA 100, almost 700,000 uf of CRCLC (the last 100,000 uf is Blackgate FK and N caps), soft recovery dual hexfet bridges, separate regulated front end supply. Borbely Millennium, direct coupled all fet driver boards with Hitachi lateral fet output stage, 2.5 amps bias current, WBT hardware. I also have a KSA 250 but it’s stock and going up for sale soon, so no customization there. I have a couple of Krell KBL preamps with burnt main boards which I’ll transplant something into soon.
 
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