Phono preamp with adjustable impedance and capacitance?

Honestly? You people are frying my ocd brain a bit. I thought I had settled on a phono preamp until I read up more on impedance and capacitance and the effect on the sound. I saw an ear324 that did this for $6000. Dont know anything else about it. Dont want to spend that much. am I sweating over details that aren't important? My current tt has an ortofon 2m blue if that matters.

 

For a 2M Blue you certainly don't need to spend anywhere near $6,000. If you like your Mani - keep it, it's adequate. If not, see if you can find a used Parks Budgie for a reasonable price. Should run about $500.

 

That’s way too much money for me. I can spend that on other things

Luckily, the input selector on my preamps include a choice of impedances and capacitances for MC/MM.

 

I agree. Too much money. I'm a state employee. suggestions for phono preamps? I was planning on the gold note ph10, but I read too much and it made me question that.

 

Stop reading and listen. Go visit a local dealer or two and find something that you like. Call ahead and they may be able to work that out for you... even now.
-Bill

 

Am I getting lost in the audio weeds? I agree that I dont need to spend that. Just wondering what all I need to look for or what not to worry about. I thought that I was intelligent and educated

 

The Ortofon 2M Blue is an MM cartridge, so the impedance is standardized at 47K Ohms. So if you have a 2M Blue Ortofon specifies the following: Recommended load capacitance - 150-300 pF. As long as you stay within these capacitance range with your phono pre-amp selection, you're fine. Once you get into MC cartridges, the extremely low voltage that can vary between models and brands, the capability to change these the characteristics drastically. The circuitry and wiring through the preamp on your amplifier affect MC signals. So adjusting these settings with MC carts is more important. Not so much with MM cartridges.

 

Others will chime in with phono preamp suggestions. I’ve never researched them nor looked for any since I have too much gear already and some of my preamps (and integrated pre/power amp) have decent phono stages. My Yamaha C-2x is said to have a quite good phono preamp, or so I’ve read. I’m not one that has been able to set up good experimental setups to quantitatively compare “A” to “B”.

One thing I’ve learned not too long ago is that as long as I’m happy with how the music (recording) sounds, I’m content. However, the more I read about how much better it can be with a better this or a better that, the more I wonder if I should “invest” in the change.

Cheers,
John

 

I knew I liked the mm cartridges for a reason. thank you all

 

Hagerman Technology LLC: Cartridge Loading

Load the Magnets!!! - [English]

^Read those articles if you want to understand loading. Both MM/MI and MC cartridges need to be loaded correctly in order to achieve optimum performance.

If you have a phono preamp that lacks adjustments, resistance can be lowered by the use of parallel resistive loading plugs. Likewise, capacitance can be increased by adding loading plugs with capacitors in them, or sometimes by using different RCA cables that have higher capacitance. Note: using cabling to increase capacitance only works where the TT RCA cables are not hardwired internally.

It is not very easy to take capacitance away without surgery on a piece of equipment, which is why I recommend choosing a phono preamp that has input capacitance at 100pf or below or something that has adjustable capacitance built in.

I wouldn't buy any phono preamp with fixed 220pf + capacitance, personally. With tonearm wiring and RCA cabling that could easily put you at ~320pf total. While that might be okay for some Ortofon carts, if you switch brands/models to something that requires a lower value (e.g. 100-200pf total) you will NEVER hear what that cartridge is supposed to sound like when properly loaded.

Loading MM/MI carts properly is something that isn't talked about in detail anymore and you can thank the cork-sniffer brigade for that as well as manufacturers that think it's okay to leave out critical specs on equipment (very common with big brand built-in phono sections). I often see threads on various boards where people complain about the sound of a particular cartridge, and then it turns out they have it loaded wrong. This is because they never bothered to read the spec sheet or manual that came with the cartridge, then compare that to the specs of their phono preamp or built in phono section.

 

Does dialing in the correct capacitance give the same order of magnitude change in sound as different speakers and cartridges, or is it more like a change in speaker cable and power cord thing, (if you know what I mean)?

 

The latter, in most cases. We used to test the adjustable capacitance on a preamp by feeding in a 20K signal through a resistance and watching the signal level go down on an oscilloscope as the capacitance increased. My ears have always been far from golden, but I have never heard a difference at home when playing music with conventional MM cartridges like the Ortofons I have always used.

 

From what I've seen measurements wise, keeping within Ortofon spec of 300pf and less keeps you flat as intended by design. Going up to something like 500pf will cause a 2db rise in the upper treble frequencies.

 

So, does this imply that the today's mass marketed receivers and AVR's with 400pf phono inputs should sound bright with many cartridges?

 

I think so.

 

Yes, and the phono preamps in them are generally $10 throw in junk anyway.

 

The difference can be quite dramatic depending on the specific cartridge and its electrical measurements. Look up "tank circuit" and read the articles I linked upthread.

Invalid test. You need a full frequency sweep off a broadcast grade test record. A 20Khz signal won't do jack in many cases, because the peak of most MM/MI cartridges will occur below that. Further, unless you are 12 years old with perfect hearing, the odds of you hearing out to 20khz are pretty much nil. People lose the top frequencies of their hearing range as they get older - it's a fact of life with humans. My hearing tops out at 17khz-18khz and I am in my late 30s. People that are older may not hear much above, say 12-13khz (or worse), depending on exactly how old they are and their exposure to noise over their lifetime. The only way to know for sure about hearing is to go get tested by an audiologist.

 

Huh? Sorry, couldn't hear you

 

The 20K test was a perfectly valid test, because the 20K signal (which came from an oscillator in a manufacturing setting) was predictably reduced as the capacitance load was increased. But all that was under test in that case was whether or not the switch had been assembled correctly with the parts at the correct value. If it was, the measured difference was repeatable. I'm not claiming my anecdotal listening tests proved anything, other than that I with my admittedly unspecial hearing never heard a difference when playing music.

 

Again, on most MM/MI cartridges the rise to peak will occur before 20k. Testing only 20K is like looking at 1/20th of a painting and saying you know what the entire thing looks like. Actually in your case it's like covering both of your eyes and looking at a painting, because the odds of you hearing out to 20khz at that point in time (assuming you weren't 12 years old or whatever) is nil.

 

The problem is that test with the oscillator at 20K doesn't account for the cartridge inductance. What you're looking at with a phono cart isn't so much an RC low pass filter as it is an RLC harmonic oscillator which will have a resonant peak at a particular frequency and a steep roll off of frequencies above the resonant frequency. The amount of capacitance will tune the resonant frequency -- more capacitance will tune the frequency lower, less capacitance will tune the frequency higher. Varying the resistance will variable damp or damp less the amplitude of the peak.

With a typical MM cart and phono set up, the RLC peak is always going to be in the audible range. The OP's cart has a 700 mH inductance. With a 47 kOhm load resistance an 300 pF of capacitance, the resonant frequency is going to occur up at nearly 11kHz. There's not a lot of musical energy up there and the top octave above that you'll be rolling off might not have a lot of musical energy on an LP either. But go to 500 pF of capacitance and the resonant frequency moves to 8.5 kHz. If you effectively have a boost around there and a roll off after that, you might have a little big more of a harder, in your face sound but with less air. Go down to 100 pF of capacitance and the peak frequency is 19 kHz. With that kind of capacitance and sufficient resistance damping you'd be pretty much flat out to the top of the audible range.

 

That cart has a 700 mH inductance. My guess is that with 300 pF or less of total capacitance (cable capacitance plus load capacitance), and proper resistance loading, you won't hear much difference and you'll have pretty good response up to 11kHz or higher. More than 300 pF of capacitance and you'll probably notice tonal changes. How much you notice and what you like will be a personal matter. I note that Ortofon recommends 150 - 300 pF of capacitance for that cart. I'd go as close to 150 PF as I could get personally. Like, look for a phono stage with an input capacitance of 50 or 75 pF.

 

It's good to understand the basic math behind this. However, it's worth pointing out that the cantilever resonates like a tuning fork and the formulas do not perfectly simulate real world conditions. For example, if you have a cartridge with 500mh inductance where the peak is around 16khz as calculated by this math, the actual peak could be further down into the audible band, more like ~12khz. This was discussed on another forum recently. Certainly in my own measurements I have noticed that where the peak occurs is often a little different. All the more reason to load your MM/MI cartridges correctly.

 

Regarding loss of hearing sensitivity over time (age), a couple of my experiences. A number of years ago I got hold of a used, professional 32-band graphic equalizer and thought that the upper bands were defective, lol. No, it was just that my hearing was unable to detect the changes. I found an audio test online and used headphones and realized that, yup, my ears don’t work “up there.” Googled and found graphs of typical loss of high frequency sensitivity over age and the falloff is precipitous. I posted my findings on AK and there was not one reply. I found that even more interesting.

I distinctly remember that over 45 years ago or so, a friend brought over aV15 and the difference in high frequency response over my cheapie was eye opening. Now I still like nicer MM, MC, TT’s, preamps, etc. But what I’m able to hear is pretty different than what my sons can.

I’ve recently quit chasing h/w and am trying to just enjoy the s/w (music). The phono stages in my preamps/integrateds are good enough for me. Likely not so for most and that’s OK.

 

It'll probably cause a rise circa 8kHz, but a roll off of the highest frequencies. The more capacitance you add the lower into the frequency range a roll off of the highest frequencies will begin, but also the lower down in the audible range a peak in the mid treble will occur -- so you can have the experience of less output in the highest frequencies, but something that sound subjectively brighter