Step Up Transformers

I had no idea what these were or what purpose they served until a few months ago. I asked @purrin in the TC-750 thread if he had planned to mod the TC-760 (MM and MC cart compatible) if he decided to move to a MC cartridge. He said no because it had an opamp in it and wasn't discrete like the TC-750, and he would just use a Jensen transformer and continue with the TC-750.

I was curious how this was possible, so I began digging through search engines and reading up on the subject. I came across Bob's Devices ($800+) and Parks Audio "Budgie " ($350+) step up transformers, but there were tons of pictures and looked fairly simple to put together. More digging and research produced a few fairly simple DIY solutions.

I ended up calling David Geren at Cinemag and asking what they had in stock. They were out of the 3440AH $75 each (blue print) I was after, but had a pair of 3440A $51 each (red print and slightly higher distortion) that would be just fine for my first DIY step up transformer. I bought a Hammond 1590A enclosure (Amazon), 4 Rean RCA jacks and a grounding post (Markertek has free shipping on any order), all for $130 shipped.

They're several different ways to wire the grounds of the unit, and I'm trying the Bob's Devices schematic first, minus the switches.

http://www.lencoheaven.net/forum/index.php?topic=18338.0

I'll try the Cinemag schematic sometime in the future...

http://cinemag.biz/mic_input/PDF/CMQEE-3440A-Moving-Coil.pdf

Here's a link to a Japanese blog that has a sound sample comparing the 3440A vs 3440AH. 24/96 files are near the bottom of the post.

https://translate.googleusercontent...130317&usg=ALkJrhi3O968pQuqtO_hIchZeV01kNScXg

I tried the 37ohm tap with my Denon DL-103 cart, and everything sounded on the thin and strained side. The 150ohm tap is much nicer with this cart. Fuller, richer and musical.

 

You mentioned that you were unfamiliar with step up transformers until recently, but I still don't quite understand what they do. Is this similar to the Jensen CI-2RR? Trying to isolate noise caused by the RCA cables?

 

Basically if you have a phono pre amp that only does MM cartridges, it won't have enough gain to handle the lower output MC carts. A step up transformer will boost the signal from th eturntable before it gets to the phono pre amp so that the signal is at a similar level.

For example the Ortofon Blue 2M cart I had on my Project turntable output was 5 milli volts, my current Denon DL-103 output is only 0.3 milli volts. My step up transformer is set at a 1:18 ratio currently, so 18x.0.3 milli volts = 5.4 milli volts.

There's more to it than that, but that's the jist of it.

 

Thank you, this was very helpful!

 

Don't get a MC cart for your Project TT unless you have an acrylic platter. The cart will get sucked to the platter, Project uses ferrous (magnetic) platters.

 

I do have the acrylic platter, but no immediate cart upgrades. I am just curious and trying to learn what does what and why with turntables. Ridiculous build. Looks proper and those cinemags sticking out the top are sweet. Congrats

 

Man, that turned out really nice. Good first job dude

 

Did you use a drill press for those perfect holes you made in the chassis?

 

Nope, I measured the center's and drew lines with a pencil, then measured equal distances between the relevant holes, and also used this pdf from Cinemag http://cinemag.biz/mic_input/PDF/CMQEE-3440A.pdf to get a ballpark idea of spacing. Cinemag recommends a certain size of screw (easily found at a Hardware store) to mount the transformer, other wise I suspect damage can be done to the internal winding's by going into deep.

When I had everything marked with pencil, I center punched where I wanted each hole and then drilled pilot holes with a small bit and my 12V Dewalt hand drill. Then went up a to the bit size I needed for the larger holes. I used a 3/8" bit for the RCA terminals and holes to run the transformer wires into the chassis. I erased all the pencil lines when finished. All the holes are not exactly spaced, but just bit a little bit larger than necessary to provide room for adjustment. All together it took me roughly 3 hours from start to end. Remember... measure twice, you can only cut/drill once.

 

Finally got around to assembling the the Cinemag 1254 SUT, and geez... it sounds nice, very nice, but a lot more $$$ than the 3440A ($52ea vs $175ea.)

So far I've only listened to a few songs, it sounds like a layer of haze has been lifted compared to my 3440A SUT. Vocals and instruments are crisper, more defined, and have a nice lively quality.

There is however, a touch more humm than my 3440A SUT (all RCA outer rings are grounded to chassis, and are almost dead quiet). Cinemag recommends that the 1254 RCA outer rings NOT be grounded to the chassis, but I'll try grounding them later and listen to the result.

Overall I'm really impressed with the 1254 SUT !!! My 3440A will probably be put up for sale for the cost of parts and shipping.

UPDATE: I tried grounding the RCA outer rings with my fingers (pointer and middle fingers on the RCA's and thumb grounded to chassis). The input outer rings are now grounded, and humm is gone, I'm stoked... Daft Punk's TRON OST here I come !!!

http://cinemag.biz/phono/PDF/CM-1254 Hookup.pdf

 

With all the relevant chatter in the used deals thread, it seems like a fine time to resurrect this thread.

I've got a DIY 3440 box at home, but I just picked up a Sound-Smith Sussuro Paua and may want to incorporate some at least slightly higher end SUT into the VTA PH-16 build I'm working on.

Have any of you tried both the Cinemag 1254 and the Lundahl 1931? Or is there yet another recommendation?

 

I found a deal for you guys

https://www.head-fi.org/threads/fs-tribute-moving-coil-sut-nanocrystalline-toroid-1-10-20.870072/

 

So basic question, why use a transformer instead of another gain stage? If you have a Schiit Mani would it sound better to use 40db gain with a transformer as opposed to 60db gain without a transformer?

 

Generally, SUTs are used for tube designs with low output cartridges. I think 60db is just too difficult to attain with tubes alone.

Many solid state designs don’t use SUTs. It is unnecessary when you aren’t limited by noise characteristics of tubes.

There are some that argue transformers have a more pleasing sound, however that is really up to the end listener.

 

For tube phono applications 60db+ of all tube gain is too noisy so designers stick a SUT or SS (usually FET/JFET) first gain stage in front of a MM tube.

 

Thanks. It probably doesn't hurt that transformers are completely passive and don't add additional noise. Curious what an ECP phono would look like since Doug likes using transformers.