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SM450 Help
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radiouser View Drop Down
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Joined: 22 April 2010
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Points: 49 		Post Options Post Options   Thanks (0) Thanks(0)   Quote radiouser Quote  Post ReplyReply Direct Link To This Post Topic: SM450 Help
    Posted: 15 January 2012 at 3:10pm
Hi All,
I wonder if anyone can help me out with the above mixer.I have had it from new and was only used a couple of times and then put away and forgotten.Recently i got it out again and decided to put it back in service but alas i could find the PSU.Does anyone know the correct voltage and current needed for the mixer +/- 15v springs to mind but not 100% on that.I also want to convert the turntable inputs to line level so if anyone has a circuit diagram or details on how to do it i would be very grateful.I would imagine that there are far better op amps out there now which could be used so if anyone has tuned-up one of these please let me know.
Many thanks all.
 
Derek.
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Mhamplification View Drop Down
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Points: 541 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mhamplification Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2012 at 8:34pm
The power supply is + - 15 volts you need about 300ma to power the SM450 but if you are building a psu i would make one about an amp either side so it runs cooler   The Citronic ones in the plastic cases do get quite warm
I have tried different ways to reduce the cart input to line level and found the best is a 220ohm resistor from the input to ground on each channel
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radiouser View Drop Down
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Points: 49 		Post Options Post Options   Thanks (0) Thanks(0)   Quote radiouser Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2012 at 8:55pm
Hi,
Many thanks for the info,i had an idea it was +/- 15 most op's tend to use that figure.I have some 7815/7915 series 1.5A regs which i will make up into a supply,i already have a suitable transformer
and rec so ill order up some caps from rapid tonight.Thanks for the info on the cart input,ill try that and see what it sounds like.
Yes i had a proper PSU for it but i must have dumped it and i cant find it anywhere,mind you its been stored in the wardrobe for about 18years!! but i do remember it did get very warm. hi hi
Thanks again,
Derek.
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bobcat View Drop Down
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Points: 92 		Post Options Post Options   Thanks (0) Thanks(0)   Quote bobcat Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2012 at 9:43pm
if your'e thinking about using the magnetic cart inputs on line level, you will need a reverse ria filter a circuit is available and its easy to build, as for the psu use an 15 0 15 tx and after rectifier & smoothing this will give you around 21.5 v per rail, and a pair of lm317/377 regs adjusted to 15 v + - wil give you a good stable supply with good noise rejection.
B.t.w the v regs will need a heatsink
Tim

   
Cheers And Thanks For comin!
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radiouser View Drop Down
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Points: 49 		Post Options Post Options   Thanks (0) Thanks(0)   Quote radiouser Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2012 at 10:33pm
Thanks for the info Tim,I have made up a supply but i used 7815/7915 fixed voltage regs and it seems to work ok,but i do have a cicuit for the 317/377 adj regs and it will probably give lower
ripple as well.The trannie i used is 18 0 18 which i had to hand and although a bit high i just put a larger heatsink on the two regs.I will get a 15 0 15 doughtnut trannie and built another PSU using the 317/377 regs.
On the disc input i did try initially a inverse RIAA but it tended to sound very different from the other line level inputs and lacked bass,that is why i asked for a circuit so i could compare the line and disc input amps.
I like the sound of the mixer but might try to upgrade the op amps if i can find a suitable eqiv.
Many thanks again for the info.
 
Derek.
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radiouser View Drop Down
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Points: 49 		Post Options Post Options   Thanks (0) Thanks(0)   Quote radiouser Quote  Post ReplyReply Direct Link To This Post Posted: 02 March 2012 at 4:00pm
Hi
Thanks for the comments on the PSU for SM450,i have now got it going ok and have replaced
the opamps with some OPA2134's which sound great.I have left the NE5532 IC24 in place for the mic circuit.I have also converted the PU inputs to line only and if anyone needs the info for doing this i have the circuit diagrams for the 450,if anyone wants them i will pm a msg to them and append the circuits.Or if there is a place on the forum for circuits etc,i will post them there for all.
 
Many thanks all.
Derek.
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Mhamplification View Drop Down
Young Croc
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Points: 541 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mhamplification Quote  Post ReplyReply Direct Link To This Post Posted: 02 March 2012 at 5:11pm
Hi Derek
Pleased you got the 450 going 
I would like a copy of the circuit daigram if possible


I will send a message with my email address on it
Were the op amps direct replacements for the 553`s ?
thanks
Martin


Edited by Mhamplification - 02 March 2012 at 5:17pm
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mostyn View Drop Down
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Points: 186 		Post Options Post Options   Thanks (1) Thanks(1)   Quote mostyn Quote  Post ReplyReply Direct Link To This Post Posted: 25 March 2012 at 9:59am
if it helps i've got copies of the circuit diagrams for the sm440 and sm450 kindly sent to me from the melksham days
mozza
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radiouser View Drop Down
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Points: 49 		Post Options Post Options   Thanks (1) Thanks(1)   Quote radiouser Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2012 at 5:02pm
Originally posted by mostyn mostyn wrote:

if it helps i've got copies of the circuit diagrams for the sm440 and sm450 kindly sent to me from the melksham days
mozza
Many thanks,have sent PM.
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AGUS R View Drop Down
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Joined: 03 April 2018
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Points: 1 		Post Options Post Options   Thanks (0) Thanks(0)   Quote AGUS R Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2018 at 9:30pm
Hi all,
Could you mail me the schematic diagram for the mixer Citronic SM 450...
I have problem this mixer, VU level LED one chanel is off.

Many thanks all
Agus R
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Ripcurler View Drop Down
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Joined: 18 February 2019
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Points: 2 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ripcurler Quote  Post ReplyReply Direct Link To This Post Posted: 18 February 2019 at 9:06pm
Can anyone help me with a schematic for my pristine Citronic SM-440. I put this back into regular service after cleaning the faders and replacing the trimmers. It sounded excellent but there was a bit of underlying noise that bugged me after a wwhile. Chasing this through I pulled the ztx108 transistors that sit in the cue select and other places replaced them with bc549 but now the cue select doesn't work. The LEDs  light but the logic is stuck on the main output.

A schematic would help me enormously.

Thanks Ripcurler
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Points: 4125 		Post Options Post Options   Thanks (0) Thanks(0)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 18 February 2019 at 9:49pm
Here's the 440 schematic
Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB
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