Great feedback on the SUT and crossover. I understand about a third of it but that is o.k. I've got some homework to do. Thanks all.
Will Step Up Transformer Improve the Sound Quality?
I'm wondering whether a step-up transformer would improve my analog signal path. I have a VPI Prime Signature with a Dynavector 17D3 Karat cart. My phono stage is a Parasound JC3+. The rest of the path is a PS Audio BHK Signature Preamp and a Pass Labs X-150.8 amp into Spatial Audio M3 Turbo S speakers and dual REL S/3 SHO subwoofers using Audience cables. I am looking for advice as to whether adding a SUT would markedly improve the sound. I am also looking for recommendations as to which SUT's would work well in this system.
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I love my SUT's and have a small collection of 6, but certain cartridges pose a challenging electrical match for a SUT when your MM stage is fixed at 47K loading. One example is the Benz Ruby / Gullwing / LPS. These have an output of only 0.34 mV to a (relatively quite high) coil impedance of 38 ohms. And your DV Karat is spec'd very close to that: 0.3mV at 32 ohms. An ideal SUT ratio for 0.3mV is the range of 15x - 20x step-up. Let's take 20x gain - into 47K, which makes a reflected load of 118 ohms back to your cartridge. Most "rules of thumb" will say you want at least 10x load-to-coil ratio. In this case, 118 ohms / 32 ohms is only a ratio of 3.7x. You're going to be throwing away 2.0dB of cartridge signal in this scenario from Ohm's Law (and hence the noise floor creeps in that much more), and also probably introduce other sonic aberrations that the cartridge designer didn't intend. I've successfully used as low as 6x load-to-coil ratio, but it's still not optimal and some cartridges will object to that more than others (Koetsus seem relatively well behaved as low as 6x). Below 5x is really asking for bad sound. BTW I've also tied the Benz LPS into a SUT and it just will be nowhere near its potential at 47K loading, no matter the SUT ratio (I have several to try). Now if you had phono stage that could run higher than 47K load in MM mode, then you could "fix" this problem. A load of 100K with a 20x SUT reflects back 375 ohms. 375 / 32 = 11.7x. That's OK! The Rogue Ares Magnum is one example of a phono stage that allows loading well above 47K in MM mode, but unfortunately this feature isn't nearly as common as I'd like it to be. So in short, I'm normally one who encourages SUT experimentation (even after college), but not with certain cartridges without the right MM loading options. In your case, I'd pass on the SUT. |
@pg62 , REL does what most of the subwoofer manufacturers do. For reasons of cost and complexity REL designs it's subwoofer to be integrated in under the bass of the main speakers. There is no high pass filter at all on the main speakers. This is problematic for many reasons but the single most important reason that this is a bad way to go about it is that you are missing out on the tweak of a lifetime. Your speakers have coaxially mounted compression drivers which your 15" mid/bass drivers cross over to at a high 800 Hz. Low bass requires even a 15 " driver to make long excursions. This wastes power but more importantly adds very significant amounts of Doppler and IM distortion to everything else the woofer is carrying and in your case it is carrying a lot! If you get a proper two way crossover and cross to your subs somewhere around 100 Hz your system will improve so much that your wife will notice it. Seriously, women are very sensitive to distortion. The best analog crossover is probably the JL Audio which is pricey but here is an excellent 4th order Linkwitz Riley cross over for $190 https://www.parts-express.com/ART-CX310-2-Way-3-Way-Crossover-245-880?gclid=CjwKCAiAyc2BBhAaEiwA44-w... you will also require one more set of interconnects. There is one even less expensive way to to it and that is to use the crossover in the RELs for the subs and get the appropriate sized capacitor and put it in series with the input of your amplifier channels. In order to do this correctly you need to know the exact input impedance of your amplifier. The equation is Fc = 1/2piRC. Fc is cutoff frequency or 3 dB down point, R = resistance(impedance), C = capacitance in Farads. Turning this around C = 1/ 2piRFc. Lets say we want a crossover at 100 hz and the input impedance of the amp is 20 Kohms. C= 1/ 2pi20,000 x 100 = 1/12,566,400 = 0.00000008 Farad or 0.08 microfarad. That would be one of these. https://www.digikey.com/en/products/detail/panasonic-electronic-components/ECW-HC3B803JA/7567997 That will cost you $3.00 for two of them. Putting them in the amplifier is no big deal if you know how to use a soldering iron. You identify the wire going to the positive post of the input jack. Heat it up and lightly tug on it and it should come right off. Connect one lead of the cap to that post and the wire you just took off to the other lead of the cap. Make sure nothing can short out before you close up. Done. It might take me 20 minutes to do an amp. I'd be happy to work through it with you if you want to give it a try. You can always return the amp to stock configuration. The electronic crossover would more than likely sound better because it will roll your speakers off faster 24dB/oct vs 6dB/oct for the input capacitor but I think the capacitor will make a decent improvement. When I first started with subwoofers back in 1978 we were all stuffing capacitors into our amps. The very first subwoofer crossover the Dahlquist LP 1 came with a package of 30 or so assorted capacitors that you could put either in the LP1 or in your amp, made no difference. |
Dear @pg62 : Well, your speakers crossover at 800hz and evev that looks that those drivers/woofers are a good design you can achieve even better quality performance levels from your room/system if you lower the inherent IMD ( Intermodulation Distortion. ) on that woofer. Tha's mean to use your subs haddled frequencies below 80hz-90hz and at the same time that the Spatial speakers runs the frequency from 80hz-90hz and up. You will note an improvement all over the system frequency range and you can do that with an external active crossover as this one: http://old.bryston.com/products/other/10B-SUB.html It's worth by its high rewards to do it and you have nothing to lost. It's a very good learning audio/MUSIC experience. Here you can read about those advantages when we add to our system subs as you already own but that you are using in different way: https://forum.audiogon.com/discussions/do-you-think-you-need-a-subwoofer/post?postid=310058#310058 R. |
I have various SUTs, special Headamps, High Gaing MC phono stages (with adjustable gain), MC phono stage with built-in SUT is the quietest of them all ... What is really special is Current-Injection type of MC phono which I also have (for low impedance MC). I like simplicity, less wires, I would like to use just one box instead of two. But if you like different flavors you must try what you like in your system! Don’t ask others what you will like. If you want to try a SUT there are so many top quality SUTs from the Japanese manufacturers, inexpensive classics from the 70’s, 80’s. If your cart is low impedance, try Current-Injection type of the MC phono stage instead of a SUTs |
I have various SUTs, special Headamps, High Gaing MC phono stages (with adjustable gain), MC phono stage with built-in SUT is the quietest of them all ... What is really special is Current-Injection type of MC phono which I also have (for low impedance MC). I like simplicity, less wires, I would like to use just one box instead of two. But if you like different flavors you must try what you like in your system! Don’t ask others what you will like. If you want to try a SUT there are so many top quality SUTs from the Japanese manufacturers, inexpensive classics from the 70’s, 80’s. If your cart is low impedance try Current-Injection type of the MC phono stage instead of the SUTs |
To build in SUT inside isn't the good one idea. It will catch more noise so SN ratio will be inferior compared with external one. Friend of mine builds tube phono stages so customers usually wants SUT inside as it makes less space and less wiring for it. Although the same external SUT performs better. Mostly for SUT he uses Lundahl various types. And they are really good ones but nothing spectacular. But from the price point Lundahl is the best, IMO. If to hear spectacular you have to look for artisan designs some of them are really good ones. Then you'll find your favorite you'll forget active gain stages, head amps etc. |
Like everything else, it depends. First thing is how your phono stage is made. Some have lots of gain built in, and are nevertheless quiet - when I DIYed my phono/pre, I built in lots of gain, and spent time and money to make it quiet. Dead quiet. I also built in a very fine SUT, the top silver Lundahl, because I have a Miyajima mono cartridge, and it hums unless isolated by a transformer. I marginally prefer the electronic amplification to the Lundahl SUT (which, by the way, is the best I've ever heard, including a 10K unit) because it's just a touch clearer and just a touch more dynamic. But that's with dual unobtanium input devices in parallel to reduce noise. Otherwise I would definitely prefer the Lundahl. YMMV |
Again, thank you. I appreciate the expertise here. rauliruegas , I agree that the JC3+ is a fine phono stage. As for the REL's they are utilized for the lows below 32hz which is the bottom end for the Spatial Audio M3 Turbo S. It provides a great bass foundation. You can really hear the difference when they are off. The bass is tight and fast with no bloat. |
Dear @pg62 : That J.Curl design is way better performer that its price can says. You own a very good phono stage that no single SUT can improve in no way against its active MC stage in the JC3+. Stay calm and with out SUT. No need to add to the delicated and very sensitive cartridge signal additional " links " that only degrades that beloved MUSIC signal. https://www.theabsolutesound.com/articles/parasound-jc-3-phono-preamp Btw and in reference of what @mijostyn posted about your Rel subs: are you running your speakers in full range way with the Rels added only as a low bass reinforcement? Regards and enjoy the MUSIC NOT DISTORTIONS, R. |
@millercarbon In general though I think unless it is a very low output cartridge then the odds are about equal to screw it up as make it better. it was great to listen with you Friday night, enjoyed meeting your wife. just FYI, everything you heard was through my pair of EMIA silver 1:10 SUT’s. http://myemia.com/SUT.html i really like the performance; i believe it equals or surpasses most any active phono preamps unless you get north of $50k. my viewpoint is that i’m able to add 2 more top level phono channels by adding 2 reasonably priced SUT’s (list price $4250 each for silver wound, copper wound $2750) to my CS Port phono which while not cheap, plays way above it’s $17k list price. since the CS Port has 2 MM inputs in addition to it’s single MC input. and the only extra cable i need is two simple 18" sets of RCA’s. they were a few hundred dollars each. my viewpoint is no way could i get this level of performance for the $$$ from three inputs without using SUT’s, and i think that scales to lower price points too if you are careful and buy smart. and if SUT’s make your eyes roll back in your head because the math and the science is beyond you on how to choose an SUT, i’m with you. Dave Slagle of EMIA held my hand, sent me a set of SUT’s to try, and helped me figure out exactly what SUT’s i needed. so not understanding SUT’s does not need to be a problem. i still don't know crap about SUT's but i enjoy their goodness every day. |
This MM/MC Phono seems very versatile https://www.ebay.com/itm/Pro-Ject-Tube-Box-DS-MM-MC-Tube-Phono-Preamplifier-Black/224349939634 think of it as an internal variable SUT |
SUTs have their own problems. They add distortions, though different from active stages. They can also pick up hum. This in addition to extra cables and connections mentioned above. They also must be matched properly to the cartridge, not only for gain but for primary impedance (load that the cartridge sees). I have a Supex cartridge and a matching sdt-722 transformer that sounded better than the active stage I had at the time, but the same transformer did not sound as good as the active stage with similarly spec'd Audioquest and Lyra cartridges. YMMV |
Thank you for the great feedback. I did not perceive an issue with the sound of my system. I just wanted to get this forum's opinion on whether this was a worthwhile enhancement. mijostyn thanks for the other insights on my system. I am content with the bass but what is your advice on the REL's - is it a tweak or are you saying that the crossover issue is inherent with the REL's. |
A SUT adds an extra interconnect, and extra connections, into the most sensitive signal path in all of audio. That's not to say it can't be an improvement. Some guys swear by them. Some even go so far as to say all cartridges benefit from a step up. In general though I think unless it is a very low output cartridge then the odds are about equal to screw it up as make it better. Your cart at 0.3mV is a little on the low side for me personally, but nowhere near to where a SUT starts to feel real necessary. Even if it is, consider the big picture. Spend a grand on a SUT, another $500 or so on a good interconnect, for what? To make a $1350 cartridge sound a little better? Maybe? For $60 you could buy a sheet of fO.q tape, guaranteed to make it sound better. Synergistic PHT, Townshend Pods, stuff like that costs a little more but still way less than the SUT and way more likely to make a satisfyingly big improvement. Way more. Look at it this way. I have never in my life messed with a SUT- and if you heard my rig your jaw would drop. So I rather doubt a SUT is the way to go. For future reference, I find it a whole lot easier to avoid low output cartridges. Just like it makes life a whole lot easier to avoid low sensitivity speakers. Medium output cart, lots and lots of great phono stages. No problem. Down below .3mV, choices rapidly disappear, while price tags rapidly escalate. I prefer to not make things harder than they need to be. |
pg62, the JC3+ is a solid performer, you are just as likely to take a step backwards. What are you looking for in your system? Do you perceive a problem? There are two weaknesses in your system I would confront. If you are using VPI's unipivot arm I would consider moving over the their gimbal pivot arm. Your bass should improve. Next is Rel's crossover. The best subwoofer/system performance is always achieved with a full two way crossover rolling off the bass to the main speakers. This decreases the distortion in them by an order of magnitude and can give you an additional 6dB of head room. It is like getting an amplifier 4 times the size! Other than those two issues you have a fine system. If there is a problem it may have to do with the room. |
