Phono Preamp. With transformer or fully active
Dear @mglik :
Dear @mglik : I have no doubt that you love the Zesto unit that's a tube phono stage design. Why LP analog alternative needs a phono stage? mainly to apply the inverse RIAA curve eq. and in second place to amplify the cartridge signal. The inverse RIAA curve eq. should mimic the RIAA curve eq. for we can achieve a flat frequency response. This means with no frequency deviations. The RIAA eq. is a heavy equalization process that goes from 20hz to 20khz and the eq. from around +,- 20dbs ! ! where any single deviation on that curve affects almost two octaves during the inverse eq. phono stage second process. From some time now a good phono stage design normally comes with an inverse RIAA deviation of: +,- 0.1db but the Zesto comes with higher frequency response deviation: 0.5db that means it has a swing of 1db that's is to high and that puts additional colorations/distortions to the already inherent colorations/distortions generated by tubes. The inverse RIAA eq. curve is critical to achieve or to stay nearer to the recording. Normally with tubes is extremely hard task to be " there ". Yes, tube alternative is an option to the SS alternative. R. |
With one SUT you can't use all MC cartridges, such phono stage is not universal for all MC. It will work for some of them nicely, but if your cartridge impedance is very low (2 Ohm) or very high (40 Ohm) you can't use one SUT for both of them.This statement is false. The use of an SUT depends heavily on how its loaded at its output. This in turn is dependent on the source impedance of the cartridge. Transformers transform impedance and this goes both ways. So you can indeed use a transformer with a 2 ohm or 40 ohm cartridge, but the loading at the output of the transformer will be quite different! And its important that this is done correctly otherwise the SUT will not sound right to say the very least. Most SUTs made for a specific cartridge are designed to be loaded at 47K by the phono preamp, with that specific cartridge as the input. That's why they appear to be 'Use specific'. But if you loaded that SUT correctly at its output you could use it with any cartridge. This is why Jensen Transformers (some of the very best made anywhere) can be used with any cartridge, and they have a chart that shows what the loading on the output should be with that cartridge. I prefer no transformer at all; I find that even the best SUTs seem to take something away from the detail, even if they have plenty of bandwidth (which most do). Since I run an all-tube phono preamp, this requires that I use low noise tubes. Its a simple fact that if you have a phono section with direct-in capability, whether it is solid state or tube the active devices have been hand-picked. I've noticed with our preamps that people think they can just buy a premium tube off the shelf and expect it to work. While that is sometime true its really a craps-shoot; even a premium tube might not be as low noise as you might expect. With any high performance audio equipment you have to hand pick the devices. But the result is great transparency. |
Using an outboard SUT not only requires an extra pair of (expensive) ICs, it also entails passing the delicate low level signal from the cartridge through an extra pair of RCA connections (or two extra pairs, in the extreme case). The RCA plug and jack is a commercial standard but hardly a choice one would make for optimum signal transfer. What one can do to at least partially ameliorate this problem is to hard wire the input side of the SUT to the tonearm wires. Phono stages with built-in SUTs at least eliminate this issue. |
Dear @frozentundra : "
As a general rule...." I own 5-6 SUTs and owned some others in the past. The ones I own are hard wired to not disturb the cartridge signal through the input/output connectors and are hard wired with 0.5m good IC cables. My Phonolinepreamp is an active high gain design with separated/dedicated MC and MM circuit boards. Yes, the MC stage is better than the MM+SUT and how much better depends on the SUT I use. My favorite SUT is this vintage one by Denon and note its really wide band windth frequency response that even today SUTs can't approach in the other side note that it's a really heavy unit with 12kg.: https://www.denon.jp/ja-jp/museum/products/au1000.html performs excellent and as a fact it's installed rigth now in my system. Normally a phono stage with internal SUT are less expensive than a good SS active high gain phono stage that at the same time performs better too. I could think that this today SUT by Audio Technica can works really fine in a good MM phono stage design: https://www.audio-technica.com/cms/accessories/1211e0cd29d5d0aa/index.html With SUTs as these ones that " softening " is really at minimum and we can't avoid it in a SUT. These kind of SUTs asks for top LOMC cartridge models. But more important than if passive or active high gain phono stage is the quality of its design with main focus in the inverse RIAA eq. curve. Everything is important in any design but exist different priority levels in the design characteristics. R. |
