How important is ext. adj. for cartridge loading


Hello Folks,

A New Phono Preamplifier will soon be introduced - MSRP around $1750 - $2000

A small "focus group" questionnaire - On a Phono Preamplifier how important is it to you that MC cartridge loading is adjustable from the front panel of the amplifier? How often do you "fiddle" around with loading ? Enough to warrant the cost increase, probably about $200 for the additional switches faceplate machining etc. pricing the preamp towards the higher end of projected price?

Same goes for MM/MC switching Would external selection be preferable to a internal Jumper setting ?

Is a MUTE function desirable on the front panel as well?

MC loading is at 100, 220, 330, 500 Ohms and 47K Ohms, do you think these are OK or would you like other values?

We have designed the unit so it can be used as a fully differential unit as well with one balanced input and one balanced output, you'd need two of them for stereo, do you find this desirable? Would you prefer this mode of operation to be selectable from the outside (switch on back) or would internal jumper selection be enough?

Thanks in advance for your thought on these questions

Peter
128x128pbnaudio
You seem to have covered all requests and indicated what they would cost. IMHO the real question is your last one stated i.e. the pocket book vote. Going back to your original high quality sound minimal extras may actually target a buying segment better than catering to all wishes. Possible RCA plug loading options for the back, MM/MC switch, and internal capacitance or a set single capacitance and just focus on the sound. The sound quality is what will be talked about and shared, leading ultimately to us parting with what is in our pocket books.
If the preamp included all the features mentioned in you last post, then, yes, I would seriously consider buying it. Sounds too good to be true, yet I'd want a 75K impedance setting.
05-11-10: Pbnaudio
Hello Folks

Seems like a LOT of features are wanted, so if we made the Phono Preamp with 5 adjustments/ selectors on the front panel as follows

1. Mute / Operate / Mono

2. Impedance 25, 50, 100, 500, 1K, 10K, 22K, 33K, 47K, 100KOhms

3. Capacitive Load 0, 50, 100, 150, 220, 330pF

4. Gain 40, 44, 48, 60, 64, 68dB

5. Input 1 / 2

Would that meet most folks requirements - and would a $2500 price point make you vote for it with your pocket book too ?


Man did I ever get ripped off!! My phono stage cost more than twice your suggested price and the only front panel selector/adjustment is a stinkin' Mute/Operate button.......DAMN!!!

Seriously though, it does sound intriguing, good luck Peter.

Cheers,
John
This is a great post. Thanks to Pbnaudio for coming to the forum to ask.
Above and beyond everything is sound. Not too long ago I switched to a 30yr old headamp and phono stage where the mfr moved heaven and earth to reduce EMI within the circuitry with exotic materials and manufacturing techniques used (call it super-tweaking). The results are blatantly obvious. That is what I want in a stage. The rest is something I'll deal with somehow. But, as that stage/headamp combo has 1, 2, 3, 4 on the list, the only one I am missing is multiple inputs. I wish I had that.

My commentary would be as follows:

1. Mute/Operate/Mono
Mono good, but then it begs the question if it is real mono or faked mono of a stereo cart. If real mono, it might be better placed in #5 (i.e. Input1, Input2, InputMono). I don't need a mute on a phono stage. If it is 'fake mono', this could be a button/switch next to your input selector (out/in (or up/down) = stereo/mono).

2. Impedance. Lots of choice is great but with so many choices, you'd need a bigger knob. Don't ignore the low end of impedance. I have a couple of carts with <2ohm internal impedance and one cart I lust after has internal impedance below 1ohm.

3. Capacitive Load
My gut is you don't need that granularity but if it costs nothing to get it, go for it.

4. Gain
Everyone will have a volume knob so no need to go overboard. I would think 2 should be fine, 3 would be a luxury, 6 choices is overboard.

5. Input 1 / 2
My preference would be for 3 inputs plus a mono input (real mono).

6/7 If you do real mono, I would suggest doing turnover/rolloff points to provide equalization curves. Maybe that is a special version with a different faceplate and you charge an extra amount for real mono with different equalization curves - if layout was designed right, it would not be a difficult add-in I expect so could be upgraded later, or be added in as a 'module' when building it, tacking on a different, more expensive faceplate. Some would want it, some would not. Those who would want it don't have many commercially available choices at the high end.

The real problem with all of this is that it means lots of switches/connections in the circuit. An input switch is probably the worst offender so has to be the best quality.

As to price... as long as it is the quietest thing on the road, there would be plenty of buyers at that price.
If you have a mono cart with a single RCA output on the leads and you run this into one channel of the input then select the 'Mono' switch that sums the signal and sends it to both channels gain stages...isn't that 'real mono'?

I guess I want fake mono for my stereo cart, but seems like that is compatible with a true mono cart.

At the $2500 level for a phono stage I want something that will grow with me through different, having all the flexibility to make it work in different systems would help justify the cost.