Hello, I'm looking to get a lomc cartridge with about .2v output. In the phono stage manual, it shows the H5500 (The H1201/H1202/H5500 all have the same gain settings) has +22, 26, 28 and 32db (with MC it's +62, 66, 68 and 72db). Each of these selections has a different impedance setting which is 27ohms, 117, 69 and 29. I have two questions with this: 1. I've heard that with a 0.2v output, the gain should be about +64db. With this unit, +66db is the closest without going under. Does the gain need to be exact, or is +2db okay? 2. With that being said, would the ohm/impedance settings with higher gain such as +68db with 69 ohms or +72 with 29 ohms be better than the +66db with 117 ohms? Thank you all in advance for helping me understand these relationships better.
The input impedance is just the value reflected to the cartridge due to the transformer winding ratio. So on the +22dB setting, the transformer has a 1:13 step up ratio, and the impedance value reflected from the 47000 ohm load on the secondary is 47000/13² = 278 ohms. The other higher winding ratios will result in a lower value of reflected impedance, as you note, with the highest 32dB (1:40) setting 47000/40² = 29 ohms. That's the relationship, but very hard to anticipate which setting may sound best to you with whichever cartridge you select. Typically we just shoot for around 5mV at the MM phono stage input to simulate a normal MM cartridge output, and the load is what it is. So your 0.2mV cartridge example would use an "extra" gain of 25, which is 28dB (but actual output voltage from transformer would depend some on the cartridge coil impedance). The MM section is 40dB, so total gain would be around 68dB. But not critical, a phono stage like this is very flexible with regard to gain settings due to low noise and high overload margin, so any of the settings would work OK, though you may prefer one.
I try to use the least amount of gain I can get away with, but sometimes need to boost it a bit depending on the record. Don't want to overload what ever you're putting the signal into. What is better is up to your ears. Nice phono stage!
Ahh cool. Always like an Allnic RIAA phono thread. I own the H7000 and its load dials are the same. I guess you could say it’s limited but it really does cover the most demanding cartridges that need 470 ohms. Even the lyra atlas SL (which is .25mv). I dont like the way it works but it works and you sort of just go by ear sometimes. im definitely NOT getting rid of mine anytime soon. I suppose you could also get more by changing the cables impedance to go above 470. currently, for my Hyperion I do 70k setting and 62db gain which is 440ohms (so they say). ive not ever had to go above lowest gain
The 5500 doesn't have the impedance control like on your 7000, it only has the transformer gain controls, so is fixed at 47k load on the transformers.
Thanks for the math, that helps with understanding the "x40" markings. I will try it out by ear, but I read the cartridge's suggested impedance would be at least 100 ohms, so I think the 66db and 117 ohms systematically might work out the best.
That looks like an amazing phono stage. As Davey said, it seems yours goes higher for ohms. The highest ohms for the H5500 is 117.
Just keep in mind, the suggested cartridge load in the specs is typically with reference to a resistor terminated active gain stage, not a transformer. It's often just specified at about 10x the coil impedance to prevent reducing the voltage output below specification. Transformer loading can really open up and expand the conversation, some prefer to treat it as a power transformer and give the cartridge a load equal to the coil impedance, while others suggest 3x the coil impedance, not much agreement. And nowadays, transimpedance (current input) phono stages have gotten more popular, with near zero ohm loading, and have traits similar to some types of transformer loading. Best to just experiment and keep an open mind ... and ears
Thanks for the extra details. It's a lot to unpack at once for myself currently. I'll look more into what you're saying. I'll use my ears too, thanks for the reminder, since it's easy to get caught up in details. I also don't want to potentially mess anything up. Would +72db overload and cause problems?
I remember reading up some on the 5500. Guess I didn’t read as much on it. Maybe im confusing with 6500
All good. It's still a nice sounding phono preamp. I do enjoy that clean 3D'ish sound it gives. Cheers!
I ended up getting an Audio Technica AT-ART9xa MC. It says the minimum load impedance (when head amplifier is connected) should be at least 100 ohms. I have found the best sound in my situation is at +72db with 29 0hms (adjusting volume with each change in db and ohm switches). It has the widest soundstage and better linear frequency detail. +68 had too much low end and less top and +66 had more top end and slightly less soundstage or some sort of closed in sound that wasn't as good as the +72 setting. The manual on the H5500 says the input impedance has a maximum of 278 ohms for MC, so with reading 29 ohms for this setting and the highest setting being 117 ohms, I'm lost. Maybe I'm missing something with making the numbers work for both the MC cartridge and the H5500... However, this cartridge and setup is sounding nice with only around 7 hours in. It's very detailed, articulate and open. There is some hardness/less smooth highs right now, but I've read that is typical for at least 10 hours. Thanks everyone for your help! Much appreciated.
