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Phillip Holmes tweaks the $639 Jasmine LP2.0 SE phono preamp

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When I wrote the review of the Jasmine LP2.0 SE phono stage, I suggested that it might lend itself to tweaking. I didn’t mean to denigrate the parts quality, and still don’t, because you’ll see these parts in products costing more. Considering the rather low price, the outboard power supply, and the nice metal work, I wouldn’t have been surprised to see cheaper parts. I was happy enough with the quality, both in build and sound, that I purchased the review sample. Both Fernando Cruze (US Importer for Jasmine) and I, nearly simultaneously, launched into modifications of the LP2.0 SE. The simple circuit and the design of the board lends itself to tweaking. During the process, we didn’t really trade ideas, and we took different directions.

I’ve been modifying and tweaking classic gear for years. If you think that today’s fanciest products are way more advanced than something from forty years ago, think again. Everything old is new again. Today’s single-ended amps and horns are refined products based on eighty-year-old technologies. I’ve heard a 30-year-old Japanese direct-drive beat a contemporary $40,000 turntable. The cult following of Garrard, Thorens and EMT is based on solid engineering and quality craftsmanship. You won’t see a Garrard or Thorens in a stock plinth though—they can only shine when mated to plinths and tonearms of the highest quality. If you don’t have the money for the state-of-the-art equipment reviewed here and elsewhere, don’t despair. Your purchase of an entry-level high-end product, like this Jasmine phono stage, can serve as the starting point for even better sound (other products like RB300 come to mind). If you can’t solder, then start learning. I wasn’t born with a soldering iron in my hand, but after years of practice, I’m doing quite well. The good thing with the Jasmine is that it’s easy to modify.

My starting point with most preamp modifications is with the power supply. Much is made of coupling caps, and I can’t argue with those who put their money there first. But, in my experience, the rather lame electrolytic caps that find their way into many of our audio products are more of a limitation to performance than a decent, metalized polypropylene coupling cap. After hearing transistor products that used servos instead of coupling caps, and after upgrading the god-awful sounding tantalum caps in other transistor amps, I decided that electrolytic caps are a bad idea in general. Most have ESR values that change with frequency. They age and change value. They change value with different temperatures. They fail catastrophically and usually without warning. Yuck! Phooey!

With the Jasmine, it’s actually a lot better than that. The coupling caps are metalized polypropylene and the power supply electrolytics are generously uprated in voltage and capacitance. Still, the designer left areas on the board to try larger coupling caps and places to add more power supply capacitance. This is good.

I asked for some suggestions and received not real consensus from the answers. I’d tried Black Gates in the past, but didn’t notice a proportional bang for the buck I spent. I used Silmic and Muse for coupling caps and they were pretty good, so I looked at those values. Also, several people spoke highly of the Panasonic caps. I decided on Panasonic FM 1000uF at 50VDC, Nichicon FW 2200uF at 63VDC and Nichicon Muse ES 220uF at 50VDC; the Muse ES might be the best available since it is bipolar, but it is also much larger than other caps, limiting where you can put it. I chose the caps based on two criteria: adding more microfarads, and lowering ESR. All things being equal, more capacitance should give better bass and dynamics. All things being equal, the lower ESR should make for quieter backgrounds, prettier highs and more dimensional sound—always does for me. The Nichicon FW 2200uf cap should add grunt; the Muse ES should help musicality; and the Panasonic was thrown in for good measure. Just for the sake of overkill, and since I had them, I piggybacked five (per channel) 1uf at 100VDC TRW polyester film caps made in the ‘80s. They are hard to find, but are excellent in transistor power supplies.

I wanted to go retro with the coupling caps so I experimented with several NOS PIO caps. John Semrad, maker of fine panzerholz turntable plinths, supplied me with some interesting varieties to try out and I wound up settling on some military spec polycarbonate and tin-foil-in-oil 1uF at 100VDC. I had also tried some Vitamin Q that didn’t sound like I expected. I found out that they were metalized mylar in oil. They were quiet and very dynamic, but the sound was slightly phasey with a woolen sounding midbass.

The biggest gains were with the power supply caps. It took a bit of cramming, but the added capacitance and higher quality caps improved every aspect of sound. If I were more patient, I would have done one cap at a time, but life is too short and that wasn’t going to happen. At the output stage, I had the Panasonic FM and Nichicon Muse ES stacked, one cap at a right angle to the legs of the other cap, with stacked mylar film caps on the bottom of the board attached to the legs of the Panasonic that I left about ½ cm longer than needed. Mylar has a slightly higher dielectric constant than polypropylene, but its very low ESR makes it a good power supply choice. It wasn’t pretty, but with the space I had, it was the only arrangement I could get to work. The input stage got the Nichicon FW 2200uf cap.

There is plenty of room on the board for experimenting with the output stage coupling caps. Unfortunately, the space for the coupling caps after the first stage, which amounts to a headamp, I think, is much tighter. I left it as-is. The cartridges I was using were high output, and if I were using a low output cartridge at the time, then I might have tackled the other coupling caps (they are Wima, which are good).

After these mods, the Jasmine had a better tonal balance. Compared to the best phono stages I’ve heard, it had a slight rolling-off in the bass and a hint of forwardness in the midrange. Please don’t think that I’m saying the Jasmine was “forward sounding” or aggressive in stock form. It wasn’t. I’ve heard several orders of magnitude more aggressive midrange from some 6dj8 phono stages. I’ve heard several 12ax7 phono stages with little or no bass. After the mods, the Jasmine’s bass was deeper, with much better impact. There was less overhang with the mods, making bass lines speedier, and more propulsive. Rhythms were easier to follow.

On top, highs were sweeter with more authentic textures. Differences between cymbals were more audible. Top to bottom, the sound was cleaner, faster and more transparent.

The only thing that didn’t improve was dimensionality. A trusted friend felt that I should try different coupling caps. I have to agree. I only used two different NOS oil caps that I had access to. All the improvements I heard could be from the power supply mods. A note for users of older gear: electrolytic caps age, losing their ability to supply current when needed, and to filter out noise. As they age, their ESR goes up and capacitance goes down. It’s better to classify power supply caps as a normal service item, like having your transmission or differential fluid changed at 100,000 miles (or whatever your auto maker recommends). Fernando Cruze, Jasmine’s U.S. importer, took a slightly different approach, upgrading the wiring, phono jacks and changing the coupling caps to Mundorf. This reinforces my original point that the Jasmine is a very “tweakable” preamp; none of us messed with resistors. That exponentially adds to the choices you could make: metal film, metal foil, wire wound, tantalum, carbon film or carbon comp (for the classic sound).

I’ve lost none of my enthusiasm for the stock Jasmine LP2se. It’s a flexible phono stage at a very attractive price. Jasmine made very good decisions on circuit design, parts choice and build quality. You could enjoy this phono stage for many years, upgrading its parts as time and money permit. If I do more experimentation or get other feedback, I will keep the readers informed. Now more recommended than the first time I recommended it.

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6 Responses to Phillip Holmes tweaks the $639 Jasmine LP2.0 SE phono preamp


  1. Bill Kilbourne says:

    Philip – I recently picked up a Jasmine LP2.0 MKII after a fair amount of research, reading reviews (including yours of the LP2.0 SE model). I am using a modest high output Denon DL-160 mounted on a Oracle Alexandria TT. Preamp is a Parasound P3 paired to a Parasound A23 amp. My goal in getting the Jasmine was to improve the gain lacking in my P3 Phone section, and have the flexibility to move to a LOMC down the road. Unfortunately my initial testing of the LP2.0 MKII has been less than pleasing on one of my reference LPs (Sheffield Amanda McBroom “Growing Up In Hollywood”). I agree with you comment “I… got the impression that most records sounded a bit too bright and a little light weight. The combination slightly emphasized groove grunge, sounded a bit forward and didn’t have enough bass depth and macrodynamic slam.” For me, the highs were over extended, and the recorded lacked the warmth fullness I experienced in the past. The Jasmine revealed far too much of the upper frequencies, and certain vocal passages were a bit harsh.

    So I’m hoping you could shed some light on the benefits of the modifications you did and if you think it is worth going down this path, vs. selling the unit and going with a different product.

    Thanks,
    Billl Kilbourne

  2. Phillip Holmes says:

    Bill,

    On a phono stage like this, you’re better off with a low output moving coil or something like a Shure M97. The high output moving coils have a resonance frequency that is in the audible range and exacerbates any issues with brightness.

    The two big issues are the power supply capacitors and coupling capacitors. It’s a low voltage transistor design, but they used polypropylene coupling capacitors instead of the “normal” electrolytics. There’s a formula designers use to calculate the -3dB low frequency cut off. For a given volume, the capacitance of a film capacitor is MUCH lower than an electrolytic. The film capacitor is a much better coupling capacitor, but it requires a huge volume to give you the same amount of capacitance. It’s possible that the designer chose the 2uF (IIRC) coupling capacitor to introduce a subsonic roll-off (built in rumble filter). I’ve seen several phono stages designed that way.

    I would upgrade the power supply filtering capacitors, which are very mediocre. That makes a tremendous difference. I would replace the coupling capacitors with Mundorf Supreme, which tend to be warm. The circuit and the active devices are good. The construction of the case is good. They saved money on some passive components that they paid pennies for. The good stuff costs 20-50 times as much, so instead of it costing $150 to build, it would be $250-300.

    Regards,
    Phillip

  3. Bill Kilbourne says:

    Hi Phillip – Thanks for your reply. OK, I have only a basic understanding of how capacitors work, but will need to clarify a few of your points. In your articles you stated “The coupling caps are metalized polypropylene and the power supply electrolytics are generously uprated in voltage and capacitance. Still, the designer left areas on the board to try larger coupling caps and places to add more power supply capacitance. This is good.”
    Could you give me suggestions of for the following?:
    – Products for the upgrade of the power supply filtering capacitors and values if different from the originals.
    – Regarding the coupling caps – go with the same values and just upgrade to the Mundorfs?

    Also, since I have the MKII version are you aware of any changes to this unit vs. the SE?

    FYI, I am in the process of upgrading some of the electrolytic caps in my vintage late 80’s DCM TimeFrame 1000 speakers. Unfortnately space on the PCB is very limited for the 47uF and 100uF caps, so I am using the Mundorf Electrolytics that I hope will improve their sound.

    Best regards,
    Bill

    • phillip holmes says:

      Bill,

      It’s been too long and the boards were changed since then. The two film capacitors should be larger, if possible. Just about any voltage will do for the coupling capacitors. 50V is high enough for a transistor design. Some of the Mundorfs are too dark in my opinion, so I don’t know which to recommend.

      When it comes to power supply capacitors, I recommend you use 2 or 3 different brands or types. I like the Silmic II best for an electrolytic coupling cap, and it should be very good for a filter cap. I like the Muze as well. I hear, but have not tried, that some of the Panasonic caps are first rate. You really need to take a small set of calipers to measure the distance between the mounting holes in the filter caps, then find the largest capacitor that will fit there, at the next highest voltage. Because these audio electrolytics are larger than the .05 cent ones, you won’t have enough room to get carried away. In my mod I found the extra room to mount another capacitor, and chose a different brand. The reason I recommend mixing electrolytic caps is that each type and subtype has different ESR versus frequency, so if you mix, you have a chance of getting a better balanced sound.

      Something extreme I did: I left the leads sticking through the PCB for the final filter capacitor (the one closest to the audio circuit), and “daisy chained” some 50V 10uF polyester film capacitors under the board. As a coupling capacitor, a TRW polyester capacitor sucks. As a filter capacitor, it does a much better job than most electrolytic products. It’s fast and filters off extremely high frequency noise that the electrolytics sometimes don’t filter. Also, the power supply charge is released from a film capacitor faster than an electrolytic, so your transients and “slam” are better.

      This whole thing can be a pain in the ass. I have an old board that came out of my first attempt that you can buy for parts. Cheap! I kept switching coupling capacitors to try different old-fashioned Vitamin Q types, and eventually destroyed a couple traces from all the solder/desolder action. The capacitors are good.

      Thanks,
      Phillip

  4. Bill Kilbourne says:

    Hi Phillip,

    I may be interested in the parts you have. I loaned the Jasmine units to a friend to try with his setup (VPI Classic TT w/ JMW tonearm and Van Den Hull LOMC cartridge). He liked the sound but also had issues matching the load and dealing with too much gain. So I see the potential is there but some tweaking is in order to fine tune. Can you send me an email to billk at techedge dot com?

    Thanks,
    Bill

  5. Richard Kalm says:

    Hello,
    Nice review and great info. Where can I pickup a this product or the MKII?
    thanks,
    can’t seem to find it available in the US

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