edward
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Post by edward on Dec 6, 2022 19:14:21 GMT
On my travels I picked up this custom MC SUT. Clearly a lot of thought was put into it. The 4 transformers are marked JE-642-90 1048 which google informs me are made by Jensen and Cinemag. Am hoping someone can decode for me how and when to use the various switches on the rear. Currently, for MC, I'm using an AT-F7 cart but an Ortofon SPU is on its way to me. [edit] just to clarify all the switches are 3-way switches. cheers     |
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Post by lurch on Dec 6, 2022 19:33:07 GMT
Hi Edward top left selects ratio and above or below horizontal tape selects loading.
Middle position on switch is off.
Select value, if above a switch then flick 1:10/1:20 ratio switch to up. ALL Other witches to OFF
Ignoring top left switch, rh column = L2 and lh column = L1.
All loadings off =470 for 1:10 & 117.5 for 1:20 as this is direct, so 47k of mm divided by the square of the selected ratio.
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edward
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Post by edward on Dec 6, 2022 19:50:46 GMT
Thanks John for the super fast response. You seem to have edited your post. I was just trying to get my head round your earlier post.
To be honest all this above my head. How do I determine what loading I need for specific carts?
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Post by lurch on Dec 6, 2022 19:58:20 GMT
Thanks John for the super fast response. You seem to have edited your post. I was just trying to get my head round your earlier post. To be honest all this above my head. How do I determine what loading I need for specific carts? Realised I'd misread the switches so readjusted and simplified the post. General rule of thumb is 10-12 times internal ohms of cart (on cart spec sheet). After that it's a question of your ears, sometimes the 10-12x can sound a bit constricted so simply go to a higher value until your ears are happy. Counter intuitive I know but the higher the load number the less the coils are (electrically) damped so the stylus can react faster. |
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edward
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Post by edward on Dec 6, 2022 21:07:06 GMT
Thanks John Still trying to get to grips with the settings. So the AT-F7 has (per spec sheet) recommended load impedance of Min 100Ω and the SPU recommended load impedance: > 10Ω So assuming I use line 2 on the SUT (right hand side) what should the switches be set to? What do all the numbers mean anyway? trust me - I'm a neophyte on these matters.  This is all for fun by the way. The TTs I have sound just fine using the stages I already use (an AT630 on one and WD on the other). Nice to play around with this custom jobby. Do you reckon it is any good (given the traffos in there)? cheers E |
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Post by lurch on Dec 6, 2022 21:19:59 GMT
Thanks John Still trying to get to grips with the settings. So the AT-F7 has (per spec sheet) recommended load impedance of Min 100Ω and the SPU recommended load impedance: > 10Ω So assuming I use line 2 on the SUT (right hand side) what should the switches be set to? What do all the numbers mean anyway? trust me - I'm a neophyte on these matters. This is all for fun by the way. The TTs I have sound just fine using the stages I already use (an AT630 on one and WD on the other). Nice to play around with this custom jobby. Do you reckon it is any good (given the traffos in there)? cheers E Just realised, bottom 2 switches are the 10/20 ratio for L1 & L2 You can't double load 1 sut, you have to use the sut and corresponding L that matches the value you want (it's intended for 2 arms/decks) so try the AT at 225 & SPU at 75 So L2 1:10 L1 1:20 then) L1 75 & L2 225 all other switches OFF. |
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edward
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Post by edward on Dec 6, 2022 21:39:27 GMT
Cheers John
Let me plumb it in and see how I get on.
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