Headamps - Grass Greener?

[alphaGT]

All electronics hiss - it's a fundamental part of the universe. When LOMCs first appeared it was pretty much impossible to get a good signal-to-noise ratio without using a step-up transformer, so step-up transformers were obligatory. When transistors came along it didn't make much difference - you still needed a step-up transformer unless you were prepared to tolerate a certain amount of audible hiss. With modern solid state electronics it is now possible to get very low levels of hiss, but still not quite as low as you can get with a step-up transformer. The down-side of SUTs is that they're prone to hum pick-up.
Still, noise issues aside, there are plenty of people who believe that the sound quality you get with a SUT cannot be beaten.
As for "extra boxes", audiophiles seem to love using more and more boxes. Phonostage in one box? Why not pay more money and have it two?

I’ll buy that. It all sounds logical to me, and I’ve never actually used an SUT, but can see that a transformer could preserve the original waveform better than an amp. My Phonomena is a two box affair, one box has two battery packs. And an ingenious circuit that charges one while it runs off the other, once it gets below a certain level it swaps them, runs off the other while it charges the low one. So, the preamp runs on DC current the whole time. And I promise, the hum is so negligible it is nearly non existent. Many times I go to drop the needle and am shocked at how loud the volume is, it makes no noise at all that I can hear, setting at about 60db of gain. Maybe if I cranked it up to 75db I may hear something? But it is quite remarkable compared to any other phono pre I’ve ever heard in my system, as far as noise is concerned. I know battery power is nothing new, Sutherland makes several rather expensive pre’s that use batteries. Perhaps a stand alone battery power supply like I’ve got would make a great product to sell? To power any brand of pre? Or DAC?
Russell

[montesquieu]

Still, noise issues aside, there are plenty of people who believe that the sound quality you get with a SUT cannot be beaten.

This. I’ve tried some very good head amps (not yet the Paul H one) but I don’t think it’s possible to beat a really top end SUT (can be v expensive though ). A good place for one is inside the phono stage if steps are taken to minimise potential hun.

[Wakefield Turntables]

All sounds good fun! I'm still experimenting with the best setup for my valve setup. Next week or so will involve using my Ortofon SUT with my Silver Meister SPU through the EAR clone.

[montesquieu]

There are several ways that hum can infest a signal and power supply ripple is only one of them. Actually, op-amps are relatively immune to power supply ripple and ripple isn't that hard to eliminate anyway, so there's no real need for a battery PSU to get low hum. The bigger problem with mains power is the magnetic field from the transformer rather than PSU ripple. Getting the transformer well away from the circuit - maybe in a separate box - is the answer to that.


I make a phonostage with step-up transformers built-in, located only millimeters from the next stage of amplification. A review is due to appear in an up-coming edition of Hi-Fi Critic.
http://www.rothwellaudioproducts.co....honostage.html

That looks very nice. Be interesting to read the review.

[alphaGT]

There are several ways that hum can infest a signal and power supply ripple is only one of them. Actually, op-amps are relatively immune to power supply ripple and ripple isn't that hard to eliminate anyway, so there's no real need for a battery PSU to get low hum. The bigger problem with mains power is the magnetic field from the transformer rather than PSU ripple. Getting the transformer well away from the circuit - maybe in a separate box - is the answer to that.


I make a phonostage with step-up transformers built-in, located only millimeters from the next stage of amplification. A review is due to appear in an up-coming edition of Hi-Fi Critic.
http://www.rothwellaudioproducts.co....honostage.html

Wow that is a nice unit! I would love to have one for US voltages. But it’ll probably be forever before one is found on the used market? Not that it’s too expensive, a competitive price I’m sure.

I think your idea of incorporating the transformer right into the circuit is genius. I can see why transformers offer more accurate reproduction. The input is creating the output as the signal cuts across the secondary windings, so a nearly exact copy. As you were saying, hum has many causes, and a lot of it is not just because of the super small input signal, but that signal has to travel a very long way to be amplified. I’m sure my tuner starts with a super small signal too, but it is located right on the same low voltage circuit board where it gets amplified. While a cartridge output must travel up the tonearm, up the interconnects, into multiple stages of amplification, gives hum so many places to start. Congratulations on producing a top notch product! I hope I get to hear it one day soon!

Russell

[Marco]

This. I’ve tried some very good head amps (not yet the Paul H one) but I don’t think it’s possible to beat a really top end SUT (can be v expensive though ).

It's an interesting one, and always has been for me (and no doubt you) who've experimented at length in this area over many years. There's no doubt in my mind that when *true* synergy (both sonic and electrical) has been achieved between a top-notch SUT and its partnering low-output MC cartridge, it results in a level of sheer musical magic that simply can't be replicated by actively amplifying the signal, via an MC head amp.

However... To do it RIGHT, as you say (and as Andrew has designed in what looks to be a superb unit), the chosen SUTs must be hardwired into the circuit of the partnering phono stage, to avoid the sonically detrimental effect of raised capacitance, when SUTs are employed externally inside a separate box, via the use of interconnecting cables, especially when those cables are any longer than 0.5m - and even at such short lengths, it markedly alters the sound for the worse.

Also, if the SUTs employed are correctly located within the circuit of the partnering phono stage, any hum will be minimal and well below the threshold of audibility, when a music signal is present. Undoubtedly, it's a rather elegant and effective way of amplifying that signal.

Trouble with that is (as we live in an imperfect world), you lose the flexibility of trying different SUTs with your chosen cartridge, as you're stuck with whatever the manufacturer has fitted, and so whether or not those will be an ideal match sonically and/or electrically is largely a matter of luck, especially when it comes to the former. The latter can be achieved by matching them to the spec of the cartridge, but even then there is still an element of trial and error needed if one wishes to get the absolute best results.

One has to consider this lack of flexibility carefully, because I've found that the key to achieving true synergy between an SUT and its partnering cartridge, electrical parameters aside, is to successfully marry their respective sonic signatures, as experience has shown that all SUTs have their own unique 'sound', such is the nature of transformers, as indeed do all MC cartridges. Therefore, for said 'musical magic' to occur, one has to achieve the best balance of traits between both - and the only way to do that is to experiment! Something you can't do if the SUTs are fixed into a circuit...

And that is the conundrum of using SUTs:

Unless you've been able to experiment with different ones, in order to find that 'magical combo', and then hardwire the chosen SUTs into your existing phono stage, which is both difficult and likely impractical to do, you'll never know if there's some other SUTs out there (often rare vintage ones, originally used in microphones), which could add something really special to the reproduction of your favourite music.

With head amps (which fundamentally sound different from SUTs) there exists less variables, and therefore the likelihood of missing out on that 'magical combo' is lessened, although that's not to say that head amps don't sound different, they do, just not to the same degree (IME) as transformers. Therefore, if you like what they do, sonically, in comparison with SUTs and use a really good one, designed to match the electrical parameters of your chosen cartridge, the results can also be sublime.

This is especially true when used in conjunction with a top-notch valve MM phono stage, as to my ears, when the right combinations are achieved, there is a synergy between head amps and valves that is as musically beguiling (although in a different way), as when the same has been achieved with an MC cartridge and SUT - and which cannot be matched when head amps are combined with solid-state MM phono stages.

Furthermore (returning to SUTs), sometimes, depending on what cartridge is used, one can over-egg the pudding, in terms of the 'mellifluous effect' achieved when combining valves and SUTs, with everything sounding a trifle 'too nice'. This is far from automatic, of course, especially if the partnership is right, but I've heard it happen all too often, and I'm not into that sort of 'airy-fairy' sound, which ultimately lacks drive and 'punch', and only suits certain types of music.

If, like me, you have wide and varied tastes in music (and a sizeable collection of such on vinyl), and so one minute can be listening to AC/DC, and the next, some classical Sonatas or solo piano, that simply won't do, as you can start finding that the music you play is being dictated by what sounds best with your SUT...

That is why I use an FET-based head amp (as the sonic characteristics of FETs closely match those of valves, minus their negative aspects) from Paul Hynes (who really knows his stuff in that area) fitted with a massive off-board fully regulated PSU, in conjunction with the valve MM stage in my Croft preamp, which itself has been extensively modified with top-notch components, and fitted with some very nice sounding and rather rare NOS military-spec valves, from the 1940s and 50s, as I find that gives me the best of both worlds.

However, one day I intend to experiment again with SUTs (the best vintage ones) and attempt to find that 'magic combo' between those and my Denon DL-S1 or any of my 103s, and then hardwire them into the circuit of the Croft, as there's plenty of space inside the case to do so. Therefore, as they say, watch this space!

Marco.

[Jimbo]

Hi Marco, thanks for the well written post on SUTs and head amps. You capture the differences succinctly and also how I hear and perceive the two devices. I have experimented a fair bit myself now and have concluded I prefer a SUT to a headamp and appreciate that they are both viable devices especially when the magic partnership is found with whatever MC you are using. However I fall into the SUT camp. However if funds were sufficient I am sure eventually I could find a good headamp.

They do fundamentally work differently and I feel a SUT is more natural sounding especially when you acieve the perfect partnership.

Interesting you mention vintage SUTs as I have a friend who has a cupboard full collected over the last 35 years. He has evaluated them all and some of the golden oldies are very good indeed. We also evaluated the K&K against these and it came out very high in our preferences.

I feel that it would be ideal to have a selection of SUTs on hand In order to find the best suitable partner with any given MC.

[Yomanze]

I would be very tempted to build a Hiraga 'Prepre':

http://www.bonavolta.ch/hobby/en/audio/prepre.htm

[Jimbo]

Headamps may be technically more accurate but often they don't sound as good as an SUT.

[Marco]

Hi Marco, thanks for the well written post on SUTs and head amps. You capture the differences succinctly and also how I hear and perceive the two devices.

Interesting you mention vintage SUTs as I have a friend who has a cupboard full collected over the last 35 years. He has evaluated them all and some of the golden oldies are very good indeed. We also evaluated the K&K against these and it came out very high in our preferences.

No problem, Jim. I just thought I'd throw my thoughts out there, as it were, based on years of experimenting with these things, for anyone interested

Using vintage transformers (which suit your cartridge), for me, is where it's at with SUTs, as the best ones truly are something special and can imbue your favourite music with an extremely addictive magic all of their own, and not one which is 'wrongly coloured' either

Glad that the K&Ks (Lundahls) performed well in such exalted company! They are very good, but in my experience there are some vintage transformers out there with a sonic signature, which if they can successfully match your partnering cartridge, electrically, raise the bar further to a notable degree.

Marco.

P.S Good post, Andrew. I'm just popping out for a bit, so will reply to the points you've raised later.