Step Up Transformers? Pros / Cons?

[levimax]

I recently made a DIY SUT using Jensen transformers following their recommendations along with some help from @SIY. It worked perfectly first try and cost about $250 all in. My understanding is that in addition to the MC coil being lower mass the lower impedance also interacts much less with the capacitance in the interconnects which makes it easier to get a flat FR. Attached are some measurements of a VM 540 ML and a Demon 103 R and SUT.... Everything the same except cart and SUT. I used a test record and peak, hold, continuous on the oscilloscope.... In this case the MC SUT has much flatter FR and to me subjectively sounds better (comparing needle drops).

 

[watchnerd]

I recently made a DIY SUT using Jensen transformers following their recommendations along with some help from @SIY. It worked perfectly first try and cost about $250 all in.

For $250, I'd be willing to try building / using one just for the learning experience, even if I ended up finding it no better than going straight to the active MC phono stage.

Do you mind sharing the instructions and what components you bought?

Do you have pics?

 

[watchnerd]

I recently made a DIY SUT using Jensen transformers following their recommendations along with some help from @SIY. It worked perfectly first try and cost about $250 all in. My understanding is that in addition to the MC coil being lower mass the lower impedance also interacts much less with the capacitance in the interconnects which makes it easier to get a flat FR. Attached are some measurements of a VM 540 ML and a Demon 103 R and SUT.... Everything the same except cart and SUT. I used a test record and peak, hold, continuous on the oscilloscope.... In this case the MC SUT has much flatter FR and to me subjectively sounds better (comparing needle drops).

Also, I'm curious what arm you're using with the Denon

 

[levimax]

For $250, I'd be willing to try building / using one just for the learning experience, even if I ended up finding it no better than going straight to the active MC phono stage.

Do you mind sharing the instructions and what components you bought?

Do you have pics?

I bought 2 Jt-44k-dx transformers and a hammond project box and RCA / balanced connectors and the resistors and caps shown in the "suggested" circuit, see attached sheet and picture of partial assembly. I have a Technics SL-1300 MKI which with the original arm and head shell. It is a little heavier than later head shells and according to the tables on the internet matches OK with the Denon. I did not need the extra counter weight.

 

[Sal1950]

Can you elaborate?

Well there is the ongoing debates over things like compliance-tracking force-tonearm mass-antiskating-groove wear- etc, etc, there's more.
I'll bow out of getting any further into these things. You know I personally feel this is a long obsolete technology and that I can't understand why anyone would put thousands of dollars into the pieces needed for decent playback, while a $100 DAC will make of monkey out of vinyl's SQ.?
Just doesn't make any sense.

 

[Frank Dernie]

So all this subjective stuff about improved spaciousness, imaging and 2nd order harmonic distortion (of SUTs) is overblown fantasies?

I would say so. By what mechanism could a transformer add any of these, apart from distortion?

 

[Frank Dernie]

As an interim experiment, if you have an unused recording interface, I'd feed the cartridge into a mic input and use 10-30 db gain. The input impedance is likely too high. You could easily place the proper value resistor across the RCA cables to load the cartridge properly. And of course you'll need an XLR to RCA adapter.

Metric Halo offered to customise the input impedance of their recording devices for anybody wanting to use them like this.
In fact I went for a Devialet instead, which has all the benefits of the recording interface in digitising and RIAA correction and loads of other things like adjustable gain and loading and a range of equalisation curves.
The OP already has this...

 

[Blumlein 88]

Metric Halo offered to customise the input impedance of their recording devices for anybody wanting to use them like this.
In fact I went for a Devialet instead, which has all the benefits of the recording interface in digitising and RIAA correction and loads of other things like adjustable gain and loading and a range of equalisation curves.
The OP already has this...

Thanks for pointing this out. I didn't read carefully and had in mind watchnerd was feeding a Devialet ADC. Which he is, however it has a phono stage already. Active amplification like a microphone or phono preamp are only going to ad 3 or 4 db to the inherent thermal noise of the resistances involved if they are well designed. I'd think the Devialet is well designed though hopefully they aren't just using a quiet DAC and boosting everything digitally. In that case a additional gain stage might work a little better depending upon particulars.

So is the hiss noise, heard at high volume very loud or barely audible? Usually at very loud levels even good phono stages have a bit of hiss. You can't get rid of it altogether. If the 20 db or so less gain of his MM stage gets rid of the hiss, a step up transformer that added no noise of its own, would still amplify hiss due to it stepping up voltage. So at best I'd doubt even 6 db noise reduction would be the result. This is assuming Devialet did a good job on their MC phono section.

https://jensen-transformers.com/wp-content/uploads/2014/09/Audio-Transformers-Chapter.pdf

On page 13 an estimate of xfmr noise is shown as an example. Less than 1.5 db, but not zero even if well designed.

 

[watchnerd]

So is the hiss noise, heard at high volume very loud or barely audible? Usually at very loud levels even good phono stages have a bit of hiss. You can't get rid of it altogether. If the 20 db or so less gain of his MM stage gets rid of the hiss, a step up transformer that added no noise of its own, would still amplify hiss due to it stepping up voltage. So at best I'd doubt even 6 db noise reduction would be the result. This is assuming Devialet did a good job on their MC phono section.

https://jensen-transformers.com/wp-content/uploads/2014/09/Audio-Transformers-Chapter.pdf

On page 13 an estimate of xfmr noise is shown as an example. Less than 1.5 db, but not zero even if well designed.

At 0 dB (pretty loud, I'm guessing 96+ dB at the listening position 17 feet from the speakers), the hiss is blantaly audible from a standingin the ar plane of the speakers...no need to have ear to tweeters.

Uder those conditions, I can't hear it when music is playing.

 

[sergeauckland]

Well there is the ongoing debates over things like compliance-tracking force-tonearm mass-antiskating-groove wear- etc, etc, there's more.
I'll bow out of getting any further into these things. You know I personally feel this is a long obsolete technology and that I can't understand why anyone would put thousands of dollars into the pieces needed for decent playback, while a $100 DAC will make of monkey out of vinyl's SQ.?
Just doesn't make any sense.

To me, it makes the same sense as running a 1936 MGTC or 1950s Corvette, using a mechanical wrist-watch, using a Leica film camera or any other hobby using what is now obsolete technology. It can be fun.

In the case of turntables, apart from the 'hobby' element as mentioned above, there's also the musical content from long deleted LPs or those never available digitally.

S.

 

[Blumlein 88]

At 0 dB (pretty loud, I'm guessing 96+ dB at the listening position 17 feet from the speakers), the hiss is blantaly audible from a standingin the ar plane of the speakers...no need to have ear to tweeters.

Uder those conditions, I can't hear it when music is playing.

Well you can do better than that obviously. Not sure where the breakdown is.

Here is a PPA-2 unit similar to what Sal mentioned.
https://www.usaudiomart.com/details/649521624-marcof-ppa2-battery-driven-headamp/

You also might look at the Emotiva XPS-1 ($199) or Cambridge Duo ($299) that Amir reviewed here. Feed them into a line input. I know someone with the Emotiva that feeds it into an ADC. It is very clean with his moving coil.

https://www.audiosciencereview.com/...measurements-of-emotiva-xps-1-phono-amp.7568/

https://www.audiosciencereview.com/...nts-of-cambridge-audio-duo-phono-preamp.6901/

 

[Frank Dernie]

This is assuming Devialet did a good job on their MC phono section.

The original Devialet D-Premier had a stellar phono stage. Flat frequency response and no audible noise.
I met the designer who told me it had very high quality low noise expensive parts in the loading, everything else is digital anyway.
I had the firm impression that when I had my D-Premier updated the phonostage in the new boards was noisier, I could be mistaken but that is when I put my Ortofon T3000 transformer back between my Jubilee cartridge and the Devialet, I had been contentedly using the Jubilee directly into the D-Premier for years.
It is something I saw as a big plus when I first bought the Devialet but which many owners of the newer models complain about
I will be seeing the designer later this month, I will try to remember to ask him, though if they downgraded the phono input on the update it is not something they are likely to publicise.

 

[Panelhead]

I also have not been using a phono. But built many step up devises using transformers. First was a 10:1 Sowter. Ended up with UK Audio Note.
I think I would use Jensen or Cinemag if building a new one.
They can be hum magnets. I have rewired the last few tonearms to use balanced cabling. The phono cartridge is a balanced source. The ground wire connects to the tonearm tube.
The transformers can be wired balanced in and single ended out. VTL used to build a preamp that had XLR and RCA phono inputs. It was balanced tube.
I believe things like this is why all the LP’s sit unplayed.

 

[anmpr1]

I ran the Marcof PPA-1 for quite a while. Very quiet using 2 9v batteries, it would run a very long time on them as long as I remembered to turn it off when not in use. It's main failing was a lack of any loading adjustments.

There were several iterations of this device. Marshall Leach claimed that it was essentially a commercial take off of his Audio magazine 'do-it-yourself' project. You can find his comments, here:

https://leachlegacy.ece.gatech.edu/headamp/

The 'designer' of the Marcof pre-preamp had this to say in one of the forums:

"...when I read the original Audio mag article I recognized it being very similar to and old push-pull grounded grid ham amp design that I did in high school. I originally set out only to fix its problems. It was very much a blend of the work that I had already done. The resistors in the emitters of the transistors were added for degenerative feedback (although they did somewhat control bias stability) the bias circuit was a re-designed to control thermal drift and control offset in bandwith and stability (prevent parasitic oscillation).

Other things like bias regulation (to prevent the amp gain from changing as the voltage of the battery changed and the cap bias circuit that eliminated most of the warm up sound qualities after the amp had been turned off for awhile. In my mind the Leach circuit was a natural evolution (allowed the NPN/PNP transistors) from the 3 transistor circuits used as microphone balanced preamps used everywhere."

There were at least three 'major' versions of the device, with (I believe) several incremental minor changes within versions. The first was the standard low output version (27 dB), in a blue metal box. Next came a second low output version, in a black metal box. A higher output box (35dB gain) was sold as the PPA-1H. Finally, Marcof came out with a switchable low to high version, also allowing impedance adjustment, the PPA-2. I owned both a low and high PPA-1, and still have the high output box. It is susceptible to stray hum, but with proper placement it's OK.

 

[anmpr1]

I've used a few active devices. A good one being the Roger Modjeski RM4 tube head amp. It used 6DJ8s and you did need good quiet examples of that tube. Not always easy to find even back then.

I lived with a 6DJ8 pre preamp for a month or so. Counterpoint SA-2. A longish term dealer loan. At the time I was using a Counterpoint tube preamp, but I could never get the preamp/pre preamp combination to work well. Too noisey. The dealer gave me the little Marcof battery pre preamp to try, and that was much better than the tube unit. Eventually I settled on Acoustat TNP preamp, which had MC gain built in.

After Counterpoint went south, the designer of the SA-2 had an operation where he'd fix and upgrade his Counterpoint designs. Not warranty work, but fee based. Even that is long gone, now. In one of his blog posts he stated that attempting to amplify a MC cartridge with a tube was wrongheaded, and he'd never do it again. I think his new designs were transformer based, but I don't remember since it's been years, and his Web site is no longer up.

 

[LTig]

I thought HOMC sort of defeated the purpose of LOMC, namely lower moving mass.

If higher output is the answer, why not just go MM and avoid the whole issue?

Probably I didn't make myself clear. I recommend a cartridge with a higher output level like the 0.65 mV of my MC1s, not a high output cartridge with 2.5 mV.

 

[LTig]

So all this subjective stuff about improved spaciousness, imaging and 2nd order harmonic distortion (of SUTs) is overblown fantasies?

Not necessarily. Depending on the whole system match (cartridge -. SUT - preamp) it's possible to get a non flat frequency response with a bit more mid bass and some peaking in the highs. Looks like a bit like a loudness correction and of course this results in fuller sound.

Add to this a low feedback valve power amp with high output impedance (> 1 Ohm) and a typical 2 way box loudspeaker and you get anougher inherent loudness curve, making the sound even fuller. A solid state power amp with very low output imedance creates a flat FR and must lose against the valce amp when level matched at 1 kHz. To level the field measure the output impedance of the valve amp and add a resistor of the same value to the output of the solid state amp ...

 

[LTig]

Well there is the ongoing debates over things like compliance-tracking force-tonearm mass-antiskating-groove wear- etc, etc, there's more.
I'll bow out of getting any further into these things. You know I personally feel this is a long obsolete technology and that I can't understand why anyone would put thousands of dollars into the pieces needed for decent playback, while a $100 DAC will make of monkey out of vinyl's SQ.?
Just doesn't make any sense.

It makes sense when there are 1300+ vinyl records in your listening room.

But I agree that it does not make much sense to start with vinyl when you have no records at all. OTOH just today I spoke with a young man who hat bought a used TT because he hoped that vinyl is not so much overcompressed like digital.

 

[orangejello]

I would direct you to K&K Audio. You can get a good Luhndahl-based box from Kevin. His prices are more than fair for these. There are two selectable gain settings on most of the implementations, so you can accommodate the output of most MC cartridges. There are also two sockets into which you can insert impedance matching resistors. You don't really need to solder them in, so you can experiment with what they sound like easily. Kevin has data sheets for all of the variants that he makes. These sheets include a table of resistor values to use to achieve the desired load. He would probably even throw in a set of resistor pairs that correspond to your needs based on the cartridge and the input impedance of the MM preamp. Further, there are several different options for grounding - one of which will be suitable if hum is an issue.

I have tried several different active head amps in the past and never liked any as much as a SUT with proper loading. You get noiseless gain with SUTs.

Finally, you can read all about this stuff and look up the recommended load for cartridges in the database at Vinyl Engine

 

[Sal1950]

I spoke with a young man who hat bought a used TT because he hoped that vinyl is not so much overcompressed like digital.

Did you explain to him that once you subtract the loss of DR due to surface noise, clicks & pops, and all the rest of vinyls technical failings, the extra compression being applied to the CD's master then doesn't matter? LOL