TX 103: 1:10 or 1:20

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efm2

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TX 103: 1:10 or 1:20
« on: 6 Sep 2006, 01:00 am »
Hi John,

Slight dilema here. I would like to upgrade my Morchoff step-up to the TX-103. I just don't know which is the better option. A fixed 26db gain or the one with the toggle switch. This is my current set-up:

Source : Linn Sondek LP12
            Arm - Morch DP-6
            Cart - 47labs McBee O.I. 0.3 mV

Phono pre - Precision Fidelity C7-A

Amps : Quicksilver Mini-mites 25wpc PP but I'm changing into an Art Audio Carissa soon.

Interconnects : Silver Audio Silver Bullet 4.0 from step-up to phono-pre
                     Silver Audio Hyacinth - Phono-pre to amps

Speaker Cable: Guerilla audio silver

Speakers: Swans Speaker 2-way 96db sensitivity (old model)

I am not intending to change my cart in the near future but for flexibility I am leaning more to the unit with a toggle switch. Or am I better off with the fixed 26db gain?

One more question. I know this is unfair because you haven't heard my system but in the remote possibility that you have an inkling as to how it sounds, what can you recommend? Copper or silver?

Best,

Edwin

John Chapman

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Re: TX 103: 1:10 or 1:20
« Reply #1 on: 6 Sep 2006, 01:22 am »
Hello!

First a few important specs to considder:

Cart specs - 0.3mV / 5 Ohms internal Impedance / recomended load >30 ohms

Phono Stage Gain = ??? got stuck here! I searched for specs but could not find any. If you could let me know the ratio of the step-up used now and how the levels are that will let us do a better job of homing in on the ideal setup.

The cart you have now (with it's nice low internal impedance) would be fine driving the 26db mode. Some carts are not as happy loaded down low and that is why it is more common to use the 1:10 ratio - it opens up a nice wide window for loading. I have a thing against putting extra contacts and connections in the signal path so I have tended to avoid the gain switch a bit but I can't say I hear it's effect at all so it is certainly not doing much to the sonics when it is included.

For copper vs silver it'd be best to discuss that on the phone - please call if you a chance or e-mail me a number and a good time to give you a call.


A general rule I am using now for copper vs silver (not factoring the cost into it!) is kinda like this:

If your system just gets by in the low end (ie if it is at all lean) or if it can tend to be a bit aggressive in the top end then go for copper.

If your system tends to be very full in the low end and the top is nice and well behaved then go for silver.

Again these general comments don't take the rather large price jump for silvers into account...... If neither of those answers the question then we can discuss your system in detail and make the call.





Thansk!

John



efm2

  • Jr. Member
  • Posts: 10
Re: TX 103: 1:10 or 1:20
« Reply #2 on: 6 Sep 2006, 03:23 am »
Hi John,

Here are the specs for the Phono-pre:

Frequency Respnse:
        20 Hz to 20 KHz  +/- 0.5db

Maximum Output:
        Greater than15 Volts

THD:
        Less than 0.1%

IHF IM Distortion:
        Less than 0.1%

MM Phono Sensitivity per IHF A-202 for
0.5V Output at 1 KHz:
        0.25mV

MM Phono Overload:
        400mV @ 1000 Hz

High Level Sensitivity:
        Unity gain

Phono Input Capacitances:
        50pF

Phono Input Impedance:
        47K Ohms

Can't comment on the sound characteristics yet as I still have to take delivery of my new amps in a month. I'm from the Philippines BTW and as most audio shops here have limited inventories most of the time we end up buying without the benefit of an audition. This is the reason why sometimes I need to ask a lot of questions before I buy :)

I hope the above specs are adequate enough. Thanks for the quick reply.

Edwin

John Chapman

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Re: TX 103: 1:10 or 1:20
« Reply #3 on: 6 Sep 2006, 01:07 pm »
Hello!

Specs were great - the one we needed was:

MM Phono Sensitivity per IHF A-202 for 0.5V Output at 1 KHz: 0.25mV

This tells us the phono stage has a decent amount of gain - more than would be typical for an MM phono stage. Converts to a gain level of 66db - more like a lowish gain MC stage. You may even be able to run the cart direct if the rest of your system has a decent amount of gain in it and if your system is really quiet. Even 1:10 mode should give a high gain level in your system. If you think you'll likely play with other cartridges and/or phono stages in the future the switched version would be a way to go. If you think you want a fixed unit then I would go 1:10 - it'll allow a bit more of a window to play with loading and should suit a wider range of carts if you do change cartridges later on.

If you are not in a hurry the thing to do is to get the stage running with the cart going direct first. I am a bit leary that the "0.25mV" spec above might really be "2.5mV". This would be a more typical gain for an MM phono stage - 46. If this really is the case then there is more of a case to go with the 1:10 / 1:20 switched unit. I still think right now with your efficient speakers, etc that 1:10 would do just fine but the 1:20 mode might come in handy of you make a system change like keeping the phono stage and cart but replacing the speakers with a less efficient pair.

Hope that helps a bit!

Thansk!

John



PS-

I tend to analyse these things a bit much sometimes. The truth is that 1:10 mode and 1:20 mode are not extemely different in level. The 6 db difference translates to 3 steps on a typical stepped level knob - an easily audible change but not a giant leap in levels. Most of the time the 1:10 ratio gives a level about like a typical cd player or dac would.


efm2

  • Jr. Member
  • Posts: 10
Re: TX 103: 1:10 or 1:20
« Reply #4 on: 6 Sep 2006, 01:40 pm »
Hi John,

Thanks for taking the time to reply. Changing speakers to a little less sensitive one has been playing in my mind for quite sometime now. Depending on how my system sounds with the new amp I might audition and probably go with the Coincident speakers. Might get the Partial Eclipse or the Triumph Signature Extreme/mini subs. I will experiment and enjoy my system for a while as per your suggestion. I will report in a month how everything goes. Our exchanges was very informative.

Best,

Edwin