Unless I have the tape machine modified. How difficult is it ?@inna It might not be that hard. I think the big problem to vercome is not input impedance, but the overall gain. But if the input impedance is dealt with, then no need for a transformer- so you might have enough gain at that point (a line transformer steps down, so reduces gain). That might be the easiest solution, and changing the input impedance should not be difficult. A look at a schematic will tell a lot. |
Who else makes tube preamps with excellent phono that could compete with Ralph's design ?@inna The problem you have is driving the input of the tape machine. If you are going to use a stand-alone phono section, it will undoubtedly have to use a matching transformer in order for you to do that. |
I would think that 55db gain is way too high for most or all MM and MI cartridges. Usually it’s around 40db ? But maybe Ralph’s preamps can be customized to change the gain.The phono section has an unusually high overload margin so you can run a MM direct, but we also offer a jumper plug that replaces a tube in the phono section; this knocks the gain down to a more manageable level for high output cartridges. MP3 preamp into Gryphon Diablo integrated. Diablo has passive preamp. Why would I want it ? Well, if I decided to have, temporarily or permanently, solid state power amp my choice would be Gryphon, but I wouldn't be able to afford Gryphon power amp even used. So basically I would want just the power amp section of the Diablo, or older Callisto and Atilla. I took a look, Gryphon's input impedance is 10 kohm RCA and 40 kohm XLR. FWIW the MP-3 has no worries driving a 10K input impedance. The output can also be configured to drive single-ended. |
It appears that pro tape machines were not quite designed to take the signal from phono. Well then I would have to use a transformer, what else can I do ?Pro audio tape machines tend to have lower impedance inputs, and often needing some voltage at the same time. +4dbm is common. This is because they are usually driven by a mixer rather than a consumer line source like a tuner or phono preamp. Such sources are usually run through the mixer in a recording studio. The reason for all this is so that the interconnect cables don't play some sort of sonic havoc with the signal. Its not just that its balanced- its also low impedance. However, since we (Atma-Sphere) started this whole balanced operation thing in high end audio, we didn't think that we could get away with making a balanced product that didn't support that balanced standards used in the studio, so we supported it. So one way to use what ever phono section you want is with one of our line sections. Or you can have our phono section added to that line stage. Otherwise you're going to find that a line transformer that can go from a higher impedance down to 600 ohms is mandatory- and since you are going to be stepping down, the output voltage will be reduced. But you might have enough gain that the latter isn't a problem- you'll have to try it and see. When I was first designing our preamps, I had an Ampex 351-2 tape machine in my living room and I found that I either had to modify the tape electronics or use my preamp line section to drive the line level inputs for recording. That's how my Otari and my Studer behave also. Your plan B is to run the output of the phono section into the microphone inputs, but as you can imagine that's not ideal either. Mic inputs are often lower impedance than line inputs (my Neumann microphones are set up to drive 150 ohms). But some machines can handle a 'high impedance' microphone input, although usually you see that sort of thing on consumer decks, not pro audio. So this might still require a transformer, but it would solve the potential gain issue caused by the step-down of the transformer. |
By the way, XLR ouput would be a plus because I am going to make recordings to reel to reel tape deck, and the good ones come only with XLR ins/outs. @inna If you are going to drive your tape machine XLR inputs, you are going to need more guts! There isn't a single 'high end audio' phono preamp that can drive them directly (without bass loss and increased distortion)! You'll need a line stage that is designed to support the balanced standard or at the very least, a line transformer to go from the phono stage to the line level of the XLR input. We did solve the transformer issue some years ago BTW... |
