Cello Audio Palette

Cello Audio Palette clone - My Photo Gallery





For years I have dreamt about this beautiful and versatile preamplifier.
However the pricetag of some 16-17.000 $ used on ebay + transport from the US kind of kept me from it.
So what other thing could I do than clone it.

The Audio Palette
The Cello Audio Palette was a six-band equalizer that came alone or with a build-in preamplifier.
It was the based on Richard Burwen many years of experience with equalizing, and was introduced as the only high-end equalizer. The Cello brand was Mark Levinsons comeback after being thrown out of ...Mark Levinson.
Now equalizers were not – and are still not – considered to be a component that belongs in a high-end system. (This is probably the reason why Cello chose to call it an Audio Palette and not an equalizer). Music lovers (thinks they) want the pure and clean original sound, and do not want to add any un-necessary circuits into the signal path, which might introduce more distortion and noise.

But first of all – this one was different.
Besides it was actually Mark levinson that invented the no-nonsense line, by removing bass and treble potentiometers from his amplifiers. However not many people know the actual reason, but in an interview Mark Levinson said:

” Even though Levinson pioneered the 'straight line purist approach' to audio, he feels that despite the extra path that the signal must pass through, the advantages of the Audio Palette far outweigh the disadvantages. "A purist philosophy does not mean fewer dials. I am not of the purist philosophy - I founded it! I never said that equalizers were bad, I just said that we don't know any that are any good.
"In our previous experience, whenever we put an equaliser into the system, it sounded worse. The Audio Palette is not simply an equaliser, it is a far more complex product than that and the objective is essentially the idea of music restoration. The ability to restore the quality to approximate lifelike sound is different from the design objective of most equalisers which is to allow the engineer the ability to adjust the sound to create a variety of effects. The Audio Palette is userfriendly, anyone can learn to use it in a few minutes and you don't have to be an engineer when you want to restore music. If you don't want to restore music then u are stuck with either listening to bad sound or playing recordings that your system likes to play and 1 don't think that it is a state of the art concept - to spend a lot of money to listen to six records and 2 compact discs."

When you read it, you just realize how true it is.
Okay so how did this Audio Palette achieve the magic goal of adjusting the sound without ruining the sound quality?
First and most important of all, the equalizing part is genious, no really ...GENIOUS!
Instead having a heap of 10 to 31 bands there are only six. Exactly enough to be able to adjust detailed enough for making most bad recordings sound great, and at the same time very easy to operate. This matters a lot, because if one have to go through maybe 31 bands for adjusting the sound, it might be easier just not to do it.

Besides the Q of each band is 0.7 which is a quite soft slope for an equalizer. Normal EQs operate with a Q up to 4 ! This will seriously impact the impulse response, where a low Q of 0,7 is equal to a first-order filter and is quite gentle with the signal.
And to make it even more brilliant the range of each band is wieghted against the human hearing. So in the two mid-bands where your ears are most sensitive, the maximum range is +/-6dB, the two bands on each side, operating in an area where your ears are a little less sensitive, the range is +/-12dB, and finally the two outer controls ( 20Hz and 20kHz) where your ears really needs a kick to tell the difference the range is +/-22dB.
The result is, that even if you dont know anything about deciBel and Herz, you actually feel that the six bands have exactly the same level of impact to the sound, in each their frequency range. Again: very easy to adjust, quite logical function-wise, and it is strange that no-one else has ever made it like this.

The Original
Being a high-end product and to ensure the Audio Palette didn’t add noise and distortion, the circuitry was ofcourse very special. The inside of the huge cabinet was packed with 20-some individual PCBs with discrete class-A modules (power consumption was 100Watt – quite a lot for a preamp!), top-of-the-range components for that era, separate power supply, and some very impressive rotary switches for most of the dials. Use Google for pictures of the whole shabang – very impressive!
Later Cello introduced a lower priced ”Palette Preamplifier” which was buildt with opamps and vishay pots.

My build
All right enough about the original. I might seem suspiciously extatic about it, but I have no economic interests in Cello, or any intend to hype this product for personal gain, I am just simply amazed by the function and the geniousness of this machine – hence as a DIY-lunatic I simply had to clone it.:D

I started out with making an equalizer that wasn’t a true copy, but which did exactly the same fitted with standard pots.
I used Rod Elliots discription of Ranes constant-Q EQ circuit, which must be very similar to the concept. I was amazed of how well it worked, and really enjoyed the possibility to adjust the sound. I have CDs which are almost unbearable to listen to without eq, but simply turns into magic when I turn a few dials. Suddenly I could enjoy some fantastic music which I couldn’t before.

Allright so I was hooked, and the looks on the original is also just up my alley. So a lot of surfing went into finding the right knobs ( got them on ebay from Hong Kong), and a drawing for the cabinet was sent to modushop/hifi2000 in Italy.
I also did a lot of surfing to find some nice rotary switches. The original had some very nice in-house made 59 position ones, and the closest thing would be a Glasshouse 43 pos but they are quite pricey. Eventually I found some used 26 pos On ebay, which I bought a bunch of. It took me quite some time to clean them and to solder resistors to make linear attenuators from them.

Future plans
So here I am, I would say 2/3 finished, but with a working unit. The EQ board and the preamp part are made with OPA2134 and TL084 opamps on veroboards. They work, and has decent sound quality. But ofcourse I wil at some point replace the circuitry with somenthing more elegant. I have done some reverse-engineering of the original modules based on pctures, but my personal taste in circuits goes in another direction, I am thinking discrete J-fet opamps on real PCBs. The input relay board is scavenged from a autostereo demoboard.
Anyway: I have the cabinet and the switches as I want them to be, so I am going to:
a) Put some text on the knobs
b) Make a remote control circuit of volume and input selection
c) Eventually replace the circuits inside.
...But I just felt like sharing allready at this stage.
Questions? ...just shoot.:cool:

All the best from Henrik
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Felixx and lowpoke: The supersexy buttons I found on ebay from a shop called Tube-Buyer, but seems now to be called U-Barn.
link I had to order 20 pcs to get them made without the groove in the top.

Felixx: The cabinet is from the one-and-only in Europe.... hifi2000/modushop in Italy.
They can mill their 10mm aluminium-frontpanels if you send them a drawing. The rest of the cabinet was painted black, so I had to swing the spraycans myself to get it silver.

Lowpoke: I use a 10band analog grahic EQ ( modified Onkyo) for room correction, and then this one for 'music correction'.
Everybody should re-try an EQ with an open mind, you will suddenly dig out all the forgotten gems of your music collection.


2004-10-29 9:09 pm
I think that the attitude of cloning the aspect of a well know product is just a sign of mental hillness. Trying to understand what is making a product good or excellent is a very valid attitude but copying a product only for the look with kluge type electronics is not honorable.
LeSuisse I 'hear' what you are saying, and you have a good point.
However -to my 'defense' I will say:
1) I am only making one for myself. I am not in the business of capitalising on others hard work. Honorable? Probably not! Fun for me? Yes indeed! Did anyone get hurt? No!
2) The quality of the internal electronics are indeed not in the top-range, but as I write in my future plans, this will change. Anyway I am not deluding myself into thinking my work (even if/when I upscale the internal electronics to a higher level) will match the quality of the original product.
3) In my long description I am trying to descripe my fascination - and honoring - of the original concept. I hope it is obvious, but if you don't believe it or approve it, it is not going to annoy me.
4) I realize that some folks finds the 'magic' to be in the specific circuit schematic with exactly the utilised components, and that any deviation makes it different - meaning poorer. Since this is a DIY-forum, and since this is my personal project, I will claim the freedom of choosing my mix of components, circuits and looks.
5) If cloning the aspect of a well known product is mental illness... then take a look in the Nelson Pass-forum! You will find a bunch of lunatics cloning away, and the original creator/artist to participate, approve and even give away free stickers with his logo on. Count me in with this bunch, and maybe you will find peace of mind.
Honorable is a word used to control people.

Next you will be saying it undermins Capitolism.

From wikipedia
"The concept of commodity fetishism (in this case a Hi-end pre/Eq amp) plays a crucial role in Marx's theory of capitalism, because it links the subjective aspects of economic value to its objective aspects, through the transformation of a symbolization of value into a reification which attains the power of an objective social force.[1] It plays an integral part in Marx's explanation of why economic relationships and interactions in capitalism often appear quite differently from what they really are."

Yet some say "Imitation is the most sincere form of flattery"

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I think that the attitude of cloning the aspect of a well know product is just a sign of mental hillness. Trying to understand what is making a product good or excellent is a very valid attitude but copying a product only for the look with kluge type electronics is not honorable.

That's harsh. "kluge type electronics"? I doubt it. The OP took the time to learn about constant-Q equalisation and put it in a nice cabinet. Who cares if the look is reminiscent of the original product if he had a good time building it and it sounds good?
From unbearable to enjoyment

I have CDs which are almost unbearable to listen to without eq, but simply turns into magic when I turn a few dials. Suddenly I could enjoy some fantastic music which I couldn’t before.

Hi Henrik,
I appreciate your enthusiastic post. From unbearable to enjoyment is an experience I am interested in reproducing in my home.
Please list a few examples of your successes to illustrate the process. The disc title, what was unbearable, the specific adjustment with your equipment, and the resulting sound which brought you enjoyment.
Thanks for the support guys.
Jordheis I listen mostly to Swedish/Danish music, which you probably don't know anyway, but here are two good international ones:

Pink Floyd - Animals, a recording from the 70ies with great music but a dark, closed almost claustrophobic sound. By setting the dials: 2kHz -2dB, 5kHz + 4dB, 20kHz +12dB, the recording opens up: The vocal gets clear ( and one can now easily follow the lyrics), the acustics guitars goes from nylon-strings to metal, the drums sounds like you removed some old t-shirts from the hihats etc. The albums gets extremely enjoyable, and I finds myself listening to the end, again and again.

Donald Fagan - The Nightfly. A classic, but it sounds like Mr. Fagan wanted his album to have an 'european' sound on some cheap westcoasts U.S. speakers with a blown midrange. So from thin, sharp sounding with a stereo image that sounds like the bass-player is standing 200 meters away, and the kick-drum in the other room from the rest of the drumkit, I turn: 20Hz +6B, 120Hz +8dB, and 2kHz -2dB.
Again, the results are amazing, the music becomes alive, it has a 'swing' to it, the rythm and the tunes are impossible to listen to without some bodyparts are moving. And now it sound like the whole orchestra is playing in the same room - interacting like only musicians do. Whenever I put this CD on, I usually pres the play-button between 3 and 5 times that day.

Now one could argue that my CD's are badly recorded, from a wrong label, printed in Germany and so on, and that there are this and that super-gold-editions of the same album available which sounds great ( ...because some sound technician dialed HIS eq's and calls it 'remastered'), but this is actually just supporting my point of eq'ing, because:

Not all albums are being re-isued, remastered etc, simply because of lack of economic returns for the record companies. A new edition wouldn't necessarilly sell enough copies, so they leave us 'stuck' on the old ones. :violin:
Not to limit your choice of music to the ones that are well recorded was exactly Mark Levinsons point of inventing the Audio Palette. This gives one the freedom to go bananas in all kinds of music-types, in second-hand stores etc. There is a lot of great music out there, and I can go and get it, while people with two-knob-preamps can stay home with their single-instrument test-CDs from hi-fi magazines.
People: Liberate youselves - get an equalizer!:nod:

Besides I am in my mid 30'ies, most of my favorite music was recorded on analog tape, originally mastered to be played on LPs and cassettes, where speakers had paper-cones as tweeters and cabinets from low-density particle-wood, and the red Sony walkman without a rewind button was the only music-player for many. Then CD arrived and all these mastertapes were simply put directly on digital, and because of lack of investment returns, and because music has moved on, the vast majority of these mastered-for-analog-medias albums never gets remastered and reissued. Too bad for most people.
...but I am beyond that with my Audio Palette equalizer.

Happy saturday.
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2007-05-08 4:19 am
Nrik, great work. I wish you success with your project.

As you state the design was from D Burwin

I had the opportunity to hear the Palette in action a couple of times, 25 years ago. The first time was at a demonstration of the Cello system at a show in NYC. Levinson took a recording of the Goldberg Variations recorded by Glenn Gould from the late 50's if I recall correctly. The recording was steely and harsh, listening to the piano was like fingernails on a chalkboard. ouch. Levinson adjusted the Palette and played the same passage. The recording was totally transformed, very listenable you could focus on the performance.

I went to his showroom in NYC a few months later, the room was treated acoustically with RPG diffusers creating a Reflection Free Zone at the listening position. I was able to use the Palette with recording I was familiar with, Jazz Rock and Classical. It was very easy to use and I was able in a few seconds to 'improve' all the recordings, even records I felt were well recorded. I believe the High End Community has really missed the boat not looking to have an eq for 'correcting recordings in your listening space.

When a recording is made think about the amount of eq used in mixing boards (and the number of op amps the signal is exposed to) or in the case of old recordings the limitations of the recording media. Then think about the control room where the mis occurs, different acoustics, different speakers with different freq response. What we hear in our listening rooms isn't ever the same as what the recording engineer and artist was hearing when mixing the recording. This makes a device like the Palette invaluable to music lovers.

BTW D Burwin is still working with Levinson (as well as doing his own sales) Levinson has a new company Daniel Hertz. Burwin is using instead of his Equalizer (the model for the Palette) a Palette done in software called the Burwin Bobcat


This has the functionality of the Palette, it also treats a digital signal (adding Hi Freq reverb as I understand it to make a digital signal sound better). Levinson was showing a D/A converter at the lase CES show that will bundle in the Bobcat
Levinson's new company:

Daniel Hertz SA - Switzerland

So your work isn't interfering with anything either person is doing comerically these days.

I look forward to you keeping us up to date on your progress.


2010-03-03 12:33 pm
I have never used an equalizer in my setup. I have to recognise that some of recordings are awfull to listen to. Good example is album "Animal" like Nrik mentioned above.
The question is, how do we know the right setup of the equalizer for particular recording.
Many people rather wont use the equalizer in fear they could make things worst.


2007-05-08 4:19 am
I have never used an equalizer in my setup. I have to recognise that some of recordings are awfull to listen to. Good example is album "Animal" like Nrik mentioned above.
The question is, how do we know the right setup of the equalizer for particular recording.
Many people rather wont use the equalizer in fear they could make things worst.

Your ears are the guide. I have audio equipment so I can enjoy music I love. You play the recording and use the tone controls to optimize the recording for your system in your room.

No mistakes to be made, the criteria is your enjoyment of the recording.