King-Cello tape repro with added meters and pots

[Mike Lavigne]

yesterday received back my King Cello tape repro from Charles King, the original builder, after some modifications. the basic repro circuit is a Tom Coangelo design from the Cello years, and Charles added his own power supply. i've had it since 2008. back then i had Charles add a 50 ohm 'zeel' output interface to allow it to be optimized into my darTZeel preamp......which allows me to have my -3- big Studer A-820 decks reside on the opposite side of my room without any sonic penalty for that 20' + distance.

the original King Cello was pretty basic, and did not lend itself to any adjusting to particular heads or tapes. i was using it for both my 1/4" Studer and my 1/2" Studer with the same basic set-up.......a compromise for sure. yet i loved the sound of the King Cello with my tapes. however; recently there have been a number of Tape Repro preamps come to market and so i was considering making a change as these newer ones all came with the ability to adjust the frequency response to particular heads and tapes.

but before i go down that road i figured i would see what the King Cello could do if it had the flexibility to be adjustable. so i contacted Charles and we came up with a plan to add pots and meters, also added was a second input so i would not need to plug and unplug the direct out's from the 1/4" and 1/2" decks. and while he was at it i had him add a Furutech FI-09 NCF IEC inlet to optimize my NCF plugged power cords. the meters required a 3rd box, and the preamp box had to have new front and rear panels.

i'm very happy about how it all looks and i did hook it up and using the Pot adjustments that Charles recommended i listened last night zero noise or hum of any kind and to my ears it's a little better even after it's cross country trip. either today or later this week a local friend will come over and walk me through the process of adjustment. Charles did send some guides for me but i'll wait for some hand holding.

 

[Scar972]

That looks fantastic, Mike! You will not regret adding the ability to adjust the HF/LF and the VU meters are pretty sweet too. Let us know how it performs after you have it dialed in.
Anthony

 

[RogerD]

Looks fabulous...Congrats Mike

 

[christensenleif@msn.com]

great looking, but maybe more practical to have on shelf above?

 

[audioguy1958]

Thanks for posting this, I enjoy reading about outboard playback preamps on the market now.

One question, are the meters in the signal path and if so could that deteriorate the output signal?

 

[Mike Lavigne]

Thanks for posting this, I enjoy reading about outboard playback preamps on the market now.

One question, are the meters in the signal path and if so could that deteriorate the output signal?

my recollection from my discussion from Charles King is that the meters don't affect performance. which does not answer your question.

i can switch the meters off (or unplug the meter box) and there is no change in performance i can hear.

i have dialed in the King Cello now. i'd say adding the pots and the meters have advanced the overall sense of top to bottom balance and coherence significantly. pulling out tapes i had not listened to for awhile, and like what i hear.

i've done quite a bit of tape in the last week or so, it is sounding superb. very happy.

 

[stellavox]

Thanks for the kudoes Mike.

Audioguy1958: Yeah, the meters "kind of have to be" in the signal path. But to minimize any "sonic degradation" I used the old "rule of thumb" and set the input impedance to their conditioning circuitry to be at least 2 orders of magnitude greater than the output impedance of the pre. The other meter panel customers seem happy. Did put that "off" position on the meter selector switch just in case.

Charles

 

[microstrip]

Thanks for the kudoes Mike.

Audioguy1958: Yeah, the meters "kind of have to be" in the signal path. But to minimize any "sonic degradation" I used the old "rule of thumb" and set the input impedance to their conditioning circuitry to be at least 2 orders of magnitude greater than the output impedance of the pre. The other meter panel customers seem happy. Did put that "off" position on the meter selector switch just in case.

Charles

IMHO the main question is wether the metering box is in series with the signal path or just samples it in parallel. From what I read it seems you are using the second possibility, that should not affect sound quality.

Some people are critical of meters because some nice looking A80 versions sent the signal trhough the adjust/metering bridge, degrading the signal along this path.

 

[stellavox]

Microstrip,

I see now that I was unclear. Using your wording, the meter panel samples the output - in parallel

Charles

 

[Scar972]

Thanks for posting this, I enjoy reading about outboard playback preamps on the market now.

One question, are the meters in the signal path and if so could that deteriorate the output signal?

I have also wondered if the King Cello would sound better without the vu meters. After multiple times disconnecting and reconnecting the vu meter cable, I can report that I wasn’t able to consistently tell the difference so I left the vu meters in place. There’s also a AUX input on the back of the King Cello vu meter box that can be used to connect any other component, thru the AUX input I can consistently hear a degrade in sound quality.
When Charlie added the ability to adjust the HF and LF to the King Cello a few years ago, and how customizable it is, it really became somewhat of a no brainer and bargain for me. I was able to sell my phono preamp and have Charlie put in a phono input for my turntable and tape input for my Studer. Using a 5 tone MRL calibration tape, the playback system is a plus minus 2dB which is good enough for me.
Anthony

 

[awsmone]

Haha

Under the Heisenberg uncertainty principle you cannot observe without effecting the output

Whether you can hear that is another matter

 

[stellavox]

Hey Scar972,

Shucks Anthony, so I DO have an unhappy customer.

Sorry to hear that you can hear the Aux input. When I put it in I guess I was "fixated" that whatever might be plugged in would be of really low impedance - like the pre output or maybe the output of a power amp. Should I ever sell another one I'd consider raising the impedance another order of magnitude or so. BUT I'm actually thinning out my pre parts stock and thinking of hanging up my shingle. What's a shingle??

Charles

 

[Scar972]

Hey Scar972,

Shucks Anthony, so I DO have an unhappy customer.

Sorry to hear that you can hear the Aux input. When I put it in I guess I was "fixated" that whatever might be plugged in would be of really low impedance - like the pre output or maybe the output of a power amp. Should I ever sell another one I'd consider raising the impedance another order of magnitude or so. BUT I'm actually thinning out my pre parts stock and thinking of hanging up my shingle. What's a shingle??

Charles

No Charlie, you know I'm very happy with the King Cello , it's a piece I've come to appreciate the longer I own it. For me, the Aux input on the vu meter box is just an extra add on that is really unnecessary. I tested it out of curiosity but it's not something I need or use.

 

[audioguy1958]

Meters are way cool. They go back and forth.

 

[Mike Lavigne]

it's 1/2", 15ips tape night tonight, and the King Cello is really allowing the music to flow.

so far tonight a couple of Tape Project 1/2" titles, Lee Morgan's Sidewinder, and Nat King Cole and George Shearing.

and now a really fine 1/2" dub of Steely Dan's Gaucho, this is a great recording to begin with, and this is a wow+. not sure the provenance of the source tape.....but it had to be pretty good. dynamics off the chart excellent. i've had an 'excellent' 1/4" dub for many years, this smokes it.

and please note; chicks dig meters. reels turning is also preferred.

 

[stellavox]

Mike,

Gotta get out to your place to hear it. God willing - next Sept.

And regarding meters (and the like); U47 intoned - "a lot of audiophiles listen with their eyes"

Charles

 

[Mat0633]

Hi Charlie,
Where I can talk to you because I would like to order your Tape head Preamp? Thanks
Mlton

 

[stellavox]

Deja Vu Milton,

Just logged onto the site. Don't visit it very often. AND saw your post.

Am getting out of the business - have one "final" pre to sell - a "back box unit" with the meter panel.

Have attached the "boiler plate" and a representative pic about the pre's below

Let's talk!

Charles









The K/C preamp is basically identical to the original Cello P603 Tape Module ($5000 list price) designed to plug into their wonderful Audio Suite (AS). The AS originally cost $5000, with its separate Master Power Supply (MPS) but no other modules. The P603 itself "descended" from the AS P100 Phono Module ($2500).

My preamp uses the same "mother/daughter board" electronic layout as the original AS modules. The mother board is slightly different - to utilize newer, smaller bypass capacitors. The four daughter boards are the same as the latest versions of the originals (the original 2N transistors in the original AS were obsoleted and Cello “updated” them with 2SA/SC Japanese units which were actually more linear). I’ve been able find these newer units NOS even though THEY’ve also been obsoleted. Like the AS, my preamp includes a separate outboard power supply. There are actually two levels of filtering/regulation - the first is a “pre-regulator” in the outboard supply; the second are two special, low noise, precision “post-regulators” (one per channel - "dual mono") located within the preamp itself. The power supply is physically smaller than the MPS but with similar electrical specs. It connects to the pre via a 6ft (~2 meter) umbilical that plugs into the back, and can be supplied to operate on any worldwide Mains voltage from 100 to 240VAC; 50 or 60Hz.

I was able to incorporate BOTH PHONO and TAPE capabilities into the K/C preamp via a front panel switch. The standard unit has this "PHONO/TAPE" switch, along with 3 positions of selectable dB gain "40/60/50". Customers seem to like 40dB for MM cartridges; 50dB for tape and 60dB for MC cartridges - although a few do use outboard, set-up transformers with MC carts. The final front-panel switch selects either NAB/IEC tape EQ. The ‘standard" input impedance is 47K in parallel with about 100pf. ONE IMPORTANT CONSIDERATION - the preamplifier is ONLY AVAILABLE with UNBALANCED inputs and outputs.

The preamp comes in two cabinet configurations; the standard "BLUE (or BLACK) BOX", or more expensive "CELLO BOX". The Blue/black box pre is a heaver steel enclosure measuring about 8"W X 3"H X 10"D (203mm X 76mm X 254mm), with the power supply about 2” (50mm) shorter . The Cello box is a brushed-aluminum cabinet consisting of 6 individual pieces, specially designed to look like the original Cello Remote Phono unit. It has the same width and height as the Blue box but is 4" longer. The base price for the Blue Box pre is. Cello Box enclosures add to that price, due to considerably more sheet metal and fabrication time/expense. I can supply the input / output jacks any way you want, both/either on the front and/or back panels. Because I wire the heads on my decks "out the front”, I put the input/output jacks on the front of my pre's. Most customers like all the jacks on the back.

The pre can be obtained with a number of options. First of all are "variable, front panel-control" of certain functions; including variable gain; variable High Frequency (HF) and Low Frequency (LF) cut/boost. My feeling on this is that if you plan to use the pre with one a single deck or phono cart, front-panel adjustments are NOT necessary. The "stock" unit includes internal, screwdriver-adjust, HF and LF adjustments, which I initially set for (as close as I can get to) your tape head, and which you can easily adjust with the aid of a test tape. If you HAVE to HAVE front-panel adjustability, it will cost UP TO an additional depending on how many controls you want.

The second option has to do with how many inputs you want. The "stock" unit has one input (and one output). Some customers want two switchable inputs. While I don't like to switch low level signals, I have successfully incorporated two sets of inputs and a switch. Another option has to do with adjustable phono cartridge loading. What I have done for these customers is to provide TWO sets of paralleled inputs - so the phono cartridge can plug into one set, and the customer can make up his/her own sets of loading resistors built into RCA plugs, and plug them into the other set of (paralleled inputs). These options cost betweenand

Finally; there is the question of “better” parts. One has to do with the single input capacitor in the signal chain; one per channel. In the "stock" pre's I use high quality polypro Sideral NOS units that I still have a few of. These units sound very nice and most customers are happy with them. I have supplied both the "best" Mundorfs (Gold/Silver/Oil) - they do seem slightly better to my ears, and Duelands - which I couldn't detect an improvement over the Mundorfs. The Mundorfs are a option which is basically my cost. Don't know what Duelands cost these days but it is SIGNIFICANTLY more! Also the Duelands are much larger and I can't fit them into certain chasses - like the "Cello box". Then there is the question of “boutique” connectors. I use high quality, gold plated RCA jacks but certain customers have asked for the better Furutec Rhodium-plated RCA and IEC power connectors. These are also available at my cost which is around .

I do not keep any "stock" of finished units, so each one is "built to order" with a usual build time of 6 to 8 weeks. I spend the better part of “final assembly” with at least 2 to 3 days of just burn-in - playing a sweep signal thru the unit - then listening for a few days to compare it against my "serial #1".

Finally, per some customer requests, I have built an accessory "VU METER PANEL" in an enclosure identical to the pre and power supply. It plugs into the preamp from which it derives both power and tape signal. The front panel has a 6 position "METER SENSITIVITY" switch, and a 3 position input select switch for TAPE/OFF/AUXILIARY - with the auxiliary inputs from a separate set of RCA's on the back panel. You can monitor any signal from the rest of your system by plugging in an RCA cable from it to these jacks. This Accessory Panel costs in the "Blue Box and for the Cello Box.

These prices do not include shipping. I do keep you informed throughout the build process with Emails and pictures. I've attached a few images showing most of the various options.

Looking forward to hearing from you - with any questions that you may have. Or call me if you’d like at

Thank You

 

[amadeus]

yesterday received back my King Cello tape repro from Charles King, the original builder, after some modifications. the basic repro circuit is a Tom Coangelo design from the Cello years, and Charles added his own power supply. i've had it since 2008. back then i had Charles add a 50 ohm 'zeel' output interface to allow it to be optimized into my darTZeel preamp......which allows me to have my -3- big Studer A-820 decks reside on the opposite side of my room without any sonic penalty for that 20' + distance.

the original King Cello was pretty basic, and did not lend itself to any adjusting to particular heads or tapes. i was using it for both my 1/4" Studer and my 1/2" Studer with the same basic set-up.......a compromise for sure. yet i loved the sound of the King Cello with my tapes. however; recently there have been a number of Tape Repro preamps come to market and so i was considering making a change as these newer ones all came with the ability to adjust the frequency response to particular heads and tapes.

but before i go down that road i figured i would see what the King Cello could do if it had the flexibility to be adjustable. so i contacted Charles and we came up with a plan to add pots and meters, also added was a second input so i would not need to plug and unplug the direct out's from the 1/4" and 1/2" decks. and while he was at it i had him add a Furutech FI-09 NCF IEC inlet to optimize my NCF plugged power cords. the meters required a 3rd box, and the preamp box had to have new front and rear panels.

i'm very happy about how it all looks and i did hook it up and using the Pot adjustments that Charles recommended i listened last night zero noise or hum of any kind and to my ears it's a little better even after it's cross country trip. either today or later this week a local friend will come over and walk me through the process of adjustment. Charles did send some guides for me but i'll wait for some hand holding.

View attachment 57777View attachment 57778

What beutifull few!

 

[Foxbat]

I would like to express my gratitude to Charles for his contribution to the industry - it is sad to see him leaving, but I hope he finds plenty of good stuff to do in his retirement! His contribution has been tremendous!

My personal love affair with tape recorders goes back about 60 years, but it's been on the back burner for decades. So I thank Charles for keeping the torch burning, for bringing people like me back to this hobby. We do not make commercial product in that market segment (and I doubt we will), but I have built units for my personal use - I have three of them in my system at this time... and Charles is largely responsible for that large hole in our family budget.

So my best wishes to Charles, and I hope we keep hearing from him!

Victor Khomenko
Balanced Audio Technology