Cello Audio Palette - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 31st March 2011, 10:40 PM   #1
Nrik is offline Nrik  Denmark
diyAudio Member
 
Join Date: Feb 2005
Location: Copenhagen
Default Cello Audio Palette

Cello Audio Palette clone - My Photo Gallery

P1010434.JPG

P1010421.JPG

P1010424.JPG

P1010425.JPG


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.

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.

All the best from Henrik
__________________
STOP - Hammertime!

Last edited by Nrik; 31st March 2011 at 10:46 PM.
  Reply With Quote
Old 1st April 2011, 06:10 AM   #2
felixx is offline felixx  Romania
diyAudio Member
 
felixx's Avatar
 
Join Date: Feb 2005
Location: in center
Nice work.
Where do you find the enclosure and knobs?
__________________
"I'm glad I can build my own mistakes."
https://picasaweb.google.com/115586837612433686520
  Reply With Quote
Old 1st April 2011, 12:22 PM   #3
lowpoke is offline lowpoke  Australia
diyAudio Member
 
Join Date: Mar 2009
Location: Australia
Send a message via Skype™ to lowpoke
Hi Henrik, it looks as sexy as hell. Fine choice of knobs and enclosure. Like you, I've never understood the anti EQ mentality in high end systems. Using a decent EQ of course, I've only ever had positive results. I'll never get rid of my White Instruments 4400's.
__________________
Show us what ya got at Homebuilt Hi-fi
  Reply With Quote
Old 1st April 2011, 05:47 PM   #4
Nrik is offline Nrik  Denmark
diyAudio Member
 
Join Date: Feb 2005
Location: Copenhagen
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.
__________________
STOP - Hammertime!
  Reply With Quote
Old 1st April 2011, 06:17 PM   #5
diyAudio Member
 
Join Date: Oct 2004
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.
  Reply With Quote
Old 1st April 2011, 08:00 PM   #6
Nrik is offline Nrik  Denmark
diyAudio Member
 
Join Date: Feb 2005
Location: Copenhagen
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.
__________________
STOP - Hammertime!
  Reply With Quote
Old 2nd April 2011, 01:05 AM   #7
lowpoke is offline lowpoke  Australia
diyAudio Member
 
Join Date: Mar 2009
Location: Australia
Send a message via Skype™ to lowpoke
If we're going to get all philosophical about it, the very nature of DIY undermines the hi-fi / professional audio industries ... the very industries we revel in. Using this rationale we should all be ashamed of ourselves, cloned schematics or not
__________________
Show us what ya got at Homebuilt Hi-fi
  Reply With Quote
Old 2nd April 2011, 03:14 AM   #8
tvi is offline tvi  Australia
diyAudio Member
 
tvi's Avatar
 
Join Date: Apr 2001
Location: Moonee Ponds, Vic, Australia
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"

rgds
James
__________________
The small part of ignorance that we arrange and classify we give the name of knowledge.
Ambrose Bierce

Last edited by tvi; 2nd April 2011 at 03:17 AM.
  Reply With Quote
Old 2nd April 2011, 04:13 AM   #9
diyAudio Member
 
QSerraTico_Tico's Avatar
 
Join Date: Oct 2004
The Cello Audio Palette is no longer made. So I don't see any problem cloning it or whatever.
  Reply With Quote
Old 2nd April 2011, 04:53 AM   #10
diyAudio Member
 
Join Date: Aug 2003
Location: Santa Cruz, California
Quote:
Originally Posted by lesuisse View Post
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?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cello-bodied stereo niccohel Instruments and Amps 2 11th May 2007 08:07 AM
Cello Palette voltage change? young_pup Solid State 3 27th September 2006 10:23 PM
Cello Amplifier Schematics moray james Solid State 5 12th April 2005 06:13 AM
cello theremin ouwerocker Instruments and Amps 5 31st December 2003 05:02 AM


New To Site? Need Help?

All times are GMT. The time now is 08:31 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2