A phono amp that beats the MFA Magus's phono?

I have a Magus also so I have a few questions for you to consider before you get another pre-amp.

1) You are using a MC cartridge (I assume - I don't know the Koetsu Black). Have you used resistors to match its output impedance (plug in types)? If not that could be your problem.

2) Have you played with the phono and output stage tubes in the Magus? Perhaps all you need is something warm in the line stage tube - try a cheap new JJ 6dj8 for example, and or some Mullard 12AX7's in the phono stage. That would warm it up in the highs and fill out the bass.

3) Have you optimized VTA on your turntable? That could be also be a cause or solution to your problem.

That Magus is a nice little pre-amp...........:-) BTW, you say you want a dedicated phono stage. What will you use for a pre-amp to drive your amps?

First thing to do is get the impedance load between the cartridge and the pre-amp matched. The Magus has a nominal impedance of 47K which is fine for most MM cartridges but not for most MC cartridges which run best somewhere between 500 and 100 ohms.

Find out what the manufacturer recommends for the load of the cartridge. Then find a techie who will make a couple of male RCA plugs with resistors with the load values - then plug them in. You'll note the proper female RCA's on the back of the Magus right next to the Phono RCA's. That what they are for and that alone could solve your entire problem (well most of it anyway). And it is highly recommended in any event. Either that or get a MM cartridge. A MC cartridge with a 47K load will more often than not sound bright and thin.

Re tubes - I'm not enthused by EH 12AX7's at all and warm they are not. Unfortunately the tubes I use are practically unobtainable now. NOS Mullards should/could work well but are spendy. Before you go that far I'd buy some new production JJ's for all tube positions and see if that tone would work for you. If so at least you have a benchmark for further exploration if you want to fine tune it further. And these four tubes would cost less than $60 total.

Re VTA, save that for last unless you can find out what exactly that cartridge likes. Some cartridges like to be set up so that the rear of the arm is a degree or so lower than the cartridge. Another fine tuning thing - but don't get to anxious about it, as different records will sound different depending on their thickness, and how they were initially cut. Also the shape of the stylus plays a big role in the sensitivity of it to VTA as well.

BTW, I know some will disagree, but using a phono pre with a volume control is similar to using a standard phono pre with a passive volume control. Even though using a phono pre w/VC may avoid a couple of issues of the latter you still loose the dynamics that an active pre-amp will add.

As I mentioned before, this little Magus is a fine unit! Just learn how to use it. Getting vinyl right ain't a Sunday walk in the park :-)

Hope that helps a little bit.

Allen, How ironic. That JLTi phono stage is advertised for sale today on the 'Gon. Interesting that the manufacturer must have deviated from your design. It has provision for loading built in.

Actually, many other phono stage manufacturers incorporate that provision. Are they doing this just to accommodate a bunch of deaf, dumb, or lazy audiophiles?

Perhaps you just have problems with the 100 to 500 ohm comments. Would something between 500 and 10K ohms be a better match considering the actual cartridge and the voicing of the pre-amp being used by the OP? Or is your advise generic?

Hi Clio, I've been fortunate (or cursed perhaps) with an old ARC SP10 which allows loading on the fly. Obviously I've had many cartridges, TT's, etc to play thru it. That is where I'm coming from.

IMHO a system is successful only when you have found synergy from source to speaker. To me the speaker is the anchor and once you have identified a speaker that works for you you can address the other components. The problem, as I see it, with running a system with any cartridge arbitraily loaded at 47K, is that the result is not necessarily optimum depending on the rest of your system.

As you have noted, you prefer 75K and 100K. I have used 10K with some old Grado's, 2K with some Gliders, etc, even an old Accuphase and Grace and only the Grace sounded good at 47K. All have been chosen for tone and clarity using the pre-amp, amp and speakers on hand at the time they were used.

I would agree with anyone who believes that changing the load that a cartridge sees is more a tonal change and 'clarity' sets in somewhere between 'muddy' from loading down too much to 'excessively bright' by not loading it enuf, also subject to ones personal aural preferences.

The problem with Herron's, and probably Allen's, views on an absolute load of 47K is that you are likely to have to change out other components every time you change your cartridge, or only buy cartridges designed to work optimally at 47K. (Of course if you have tubes everywhere you can probably just fiddle with those and get a pretty good result.

Now, the reason I post on this subject (other than my originals to the OP) should be obvious but I'll clarify. Look at the OP's problems and his first response as well.
Of all the solutions at hand the cheapest and easiest way to solve the problem (if it worked) was to load the cartridge. If it don't work you just pull the plugs. He could have several sets made at different loads to play around with as well. Cheap.

Or he could have changed some tubes in his pre-amp. This is also very cheap UNTIL he identifies a tone he likes and tries to duplicate it by getting some high quality NOS with a similar tone.

Lastly he could buy Allen's designed phono pre on sale for 1650, buy a high quality line stage to match, probably at least 2000, and hope it works! Unless he is sonically clairvoyant I doubt that he'll get it right the first time out.

He mentioned the EAR phono stage with its passive VC, thinking that he could bypass the MFA Magus. While that phono stage is good enuf, and he can fiddle with loads and tubes, a nice combo I think, and if he were to get it modded it would be even better (so I'm told) it would still be passive and miss out on the dynamics a good active line stage adds, which I think is essential to enjoying vinyl sound. Because of the cost and uncertainty attendant to getting new electronics I though he might satisfied HIS needs in an easy and economical way by exploring loading and tube changes. Was I wrong?

Frankly I'd be interested in seeing more possible and practical solutions for the OP's dilemma, than just Allens promoting his own design and overbroad dis'ing cartridge loading without any specificity.

A PS. A new revelation that aught to really impress Allenwright. Another phono pre of his design was just advertised for $925 (not mine) and it comes with 100 and 470 ohm loads!. Go figure. :-)