Usually the overload margin is inversely related to phono gain. I read the spec sheet too and it’s ambiguous Anyway the real problem is using a 1:20 SUT. in the first place.
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rdk, where did you get the 50mV spec for phono overload? Since the Steelhead has both MC and MM inputs, and since MM inputs generally tolerate much higher signal voltages than MC inputs, there ought to be two different specs for phono overload, one for MC inputs and one for MM. The output from any SUT ought to be connected to MM inputs, and the gain set for the minimum 50db.
By the way , using a 0.5mV cartridge with a SUT that has a 1:20 gain factor into an MM stage that provides 50db gain is way overkill so far as total phono gain. Most MM stages proved 38 to 45db gain, typically 40db. 1:10 ought to be more than sufficient, with that cartridge into the Steelhead’s MM stage.
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In all cases, at all settings, my Steelhead is very quiet. So (Snackey), I am wondering whence comes the noise you say was bothersome when you set gain at 65db via the MM inputs. Try reducing the gain setting in 5-db increments until you get to a point where noise is not a problem but gain is still sufficient. Was the volume control over past the 12 o'clock position? If so, that might suggest you won't have luck reducing the gain setting, as I just suggested. I cannot recall ever having the volume control past 1 o'clock, even with very low output cartridges, but that speaks to the input sensitivity of my amplifiers. Also, try listening to a variety of LPs, to be sure that the noise you heard did not emanate from a dirty or particularly noisy LP. Before this turns into a SUT symposium. If you do hear noise, listen to determine whether it is in both channels or just one. If in one channel, that might indicate a faulty tube,
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I am quite sure that some other company makes or made the Koetsu SUT for Koetsu, and then slapped the Koetsu name on the product. Just like the Koetsu tonearm was made for them by Jelco. Audio Note (Japan or UK) is a fairly wide ranging enterprise (cartridges, preamplifiers, amplifiers, etc), so i am willing to believe they make AN SUTs. My short list of Denon and Ortofon was by no means meant to be complete.
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Maybe because designing and especially building a SUT is a vastly different enterprise from designing and building an MC cartridge for a small company like MSL. You’ll notice that among cartridge makers only the big guys also make SUTs, like Denon and Ortofon, and even Ortofon only makes SUTs specifically for its own cartridges.
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Sometimes it's a matter of semantics, but many do speak of SUTs as if they have an impedance of their own. This is not the case, so I am sensitized to that implication. As I know you know, any transformer merely converts current to voltage (if you think primary to secondary), and the impedance seen by the cartridge is simply a function of the impedance present on the secondaries. The SUT adds no impedance. (This is in a perfect world; in reality there is a tiny effect that can be disregarded for loading a cartridge.) It's obvious that you have a handle on it, so I apologize for my pedantry in correcting your original statement. I just know some others might have been led astray and was trying to prevent that.
For one thing, if you have a cartridge with a high-ish internal resistance, like a Denon or some Benz cartridges, such that it is not an easy match for a SUT, there is no reason you can't replace the 47K resistor at the MM input with a 100K resistor or even higher, to make the cartridge happy with the final impedance it has to drive.
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The SUT doesn’t present a load. The load seen by the cartridge is dependent on that 47K resistor in the phono stage and the square of the turns ratio of the SUT. There is absolutely no reason to believe that you have to fine-tune the turns ratio of the SUT in order to end up with an exact tenfold ratio between the cartridge internal resistance and the input impedance as seen through the SUT. Any ratio greater or equal to 10 works fine. And I would say you can go below 10 as well. Play it by ear.
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Dear Snackey, Your response, "Matching the gain setting on the SUT or preamp with cartridge output rating.", is not quite the way to think about it. The cartridge has a certain signal output, expressed in mV in relation to stylus velocity. The standard stylus velocity is either 3.54cm/sec for older cartridges or 5cm/sec for modern cartridges. So that number in mV is the output at that velocity and is just a guideline for thinking about phono gain. Since the typical MM cartridge makes about 5mV at standard velocity, and since a SUT is connected to MM inputs, the paradigm is to choose a SUT with a step-up ratio equal to whatever it would take to raise the voltage output to about 5mV (give or take). So you need to know the turns ratio of the SUT. The limiting factor is the effect that the SUT has on the impedance seen by the cartridge. The input impedance of the phono stage is reduced by the square of the turns ratio. So for a SUT with a 1:10 turns ratio, placing it between the MM inputs and the cartridge output will reduce the impedance of the phono stage as seen by the cartridge by a factor of 100, etc. The convention is that the phono input impedance ought best to be about 10X higher than the internal R of the cartridge for best signal transfer (although there is no danger in using a lower ratio, but as you go below 10X, there is loss of cartridge output to ground and possible high frequency roll off due to capacitance). So, in choosing a SUT you want to have enough boost to result in a about a 5mV output at the MM phono inputs without violating that 10X rule of thumb. But with a high gain MC phono stage or with an outboard active voltage booster stage (see Hagerman Piccolo for example), you don't have to think about any of that. You just need enough total gain ahead of the amplifier to drive the amplifier. (Typically, that requires about 1V more or less.) There is no need to worry about "matching". To make this more confusing, most SUTs are labelled for the internal R of the cartridge that works best, e.g., a "3 ohm" SUT is intended for LOMCs with a very low internal resistance but it doesn't have to be exactly 3 ohms. A 40 ohm SUT is for those LOMCs with a rather high internal resistance (Denon typically), but it doesn't have to be exactly 40 ohms. You need to do some digging to discover the turns ratio of such SUTs. What I am trying to get across is that a SUT is just a tool, not necessarily an embellishment to SQ.
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Snackey, what do you mean by “optimize the gain”?
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Snackey, I don’t recall whether I mentioned this before, but you can have up to 65db of gain via the MM inputs, which bypass the autoformers. You might try that if you haven’t done it already, before resorting to a SUT.
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..."the unit sounded a little spare, lean..." In my experience, that sonic character is very often associated with marginal phono gain, and when higher gain is provided, the coloration is ameliorated. But if you are saying it sounded lean even after you inserted the Lamm, then all bets are off, except maybe you were hearing the Lamm, which after all is another device in the pathway that could potentially introduce its own sonic character. On the other hand, I am in no way saying the Steelhead is flawless. However, it sounds a whole lot better post-modification. I am now thinking of upgrading the attenuator, but I hate to give up the luxury of the remote volume control.
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I still don't know what is a Veloce in terms of audio functionality. If it uses 6H30, I assume it is a linestage which you used to replace the Lamm. Yes? I have a strong bias against the utility of spending huge bucks (like $22K and up for Lamm) on a linestage, but that's just me.
I found a blurb I once wrote about upgrading the Manley Steelhead v2.0. I saved it on my computer, because so many people asked me about it, and I got tired of re-writing the idea for each inquiry. I don't know whether earlier versions of the Steelhead are built the same way or whether the Chinook is also comparable. But here you go:
"I could not get a schematic; Manley does not provide a schematic even for professional repair shops. But if you read an interview with Evanna Manley, several years ago in 6 Moons, she describes the output stage. I won't reiterate her summary (please google it; look for the Steelhead review in 6Moons) but suffice to say that the output of the phono stage, which either drives the volume control if you use it as a full preamplifier or the outboard linestage, if you use it as a phono stage only, uses a 47-ohm resistor in series with the signal followed by a 30uF output coupling capacitor, which in my opinion is mediocre in quality, at best. This capacitor and what follows are holding back the performance of the Steelhead, IMO. I removed the 47-ohm resistor entirely; it's not needed, and I replaced the 30uF coupling cap with a much higher quality 10uF capacitor. (Choose whatever you like but spend the $$$ for a very good one.) You need 10uF, I guesstimate, because the volume control seems to have a 5K ohm input impedance (very low). (10uF driving a 5K ohm load will give you a very low bass cut-off; 30uF is way overkill.) If used as a full function preamplifier, the output capacitor drives the attenuator as noted, and the attenuator drives the linestage. The linestage itself is nothing but a White cathode follower; it adds no gain to the signal from the phono section, but it provides a very low impedance output to drive any amplifier. The output from the linestage section (after its White cathode follower) uses yet another 47 ohm resistor in series with yet another 30uF capacitor of the same type and brand. That connects to the linestage output jacks. I removed that 47R resistor and replaced THAT capacitor with a 4uF film cap that I like very much. Since my amplifier has a 50K input impedance, 4uF is more than adequate to get good bass. Those two coupling capacitors, from phono stage output to attenuator and from attenuator to linestage output have everything to do with the SQ of the Steelhead. There is a lot of room inside the chassis to use just about any film capacitor you might want, but I would recommend the 10uF Dynamicap E (for “Electronic”) for the output of the phono section that drives the attenuator, and for example a 4uF Dynamicap E for the output of the linestage. Dynamicaps can be purchased from Michael Percy. Other choices are up to you."
Big difference to ditch the two OEM 30uF capacitors and those 47-ohm resistors. Manley chose those odd values, and the odd idea to insert that resistor at all, apparently to enable the Steelhead to drive high capacitance cables, like VERY high capacitance cables, like higher than I could ever imagine anyone using in the home. It's no wonder to me that some owners prefer to use the unit as a phono only stage; that at least gets one of those two (mediocre is a diplomatic choice of adjective IMO) 30uF capacitors out of the way of the signal. It's actually a wonder that the thing sounds as good as it does.
Whart, If you heard an improvement after adding the Lamm, it could be because the Lamm Reference linestage adds about 9db of gain. Could be your phono gain (60 or 65db in the original Steelhead?) was a bit marginal for those very low output cartridges you were using. Just guessing.
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Whart, what’s a Veloce? I own a 59 Alfa Romeo Giulietta Spider Veloce, but it only plays music on an open country road with top down. Later today I’ll dig up my recipe for upgrading the Steelhead and post it here. Also, I own v2.0 with remote. I think it’s a bit different from the original that you owned.
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in my opinion, this is an idea, for sure, but not what you would call a good idea. If you just want to know what a step up transformer can do for you, sure, go ahead and try it. But if you expect a SUT to change the sonic character of the steelhead in some particular way, perhaps it would help if you would say what it is you want to change. As someone else noted, the steelhead on its MC inputs already uses autoformers, but from what I can tell, and Manleyare fairly mysterious about this, the autoformers are not used purely for gain, as in the case of using a SUT. I say this because you can dial gain up to 65 db using the MM inputs which bypasses the autoformers entirely. And that is what you would have to do with an external SUT. Connect it to the MM inputs, and set gain to the minimum of 50 db. it doesn’t make any sense to me, but if you want to do it, you will not be hurting anything except your pocketbook. If you want to tweak the Steelhead, upgrade the output coupling capacitors, which are mediocre at best. And way higher in value than necessary. My next thought, not yet done, is to upgrade the attenuator. ( I use mine as a full function preamp.)
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