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Post by mcirish on Sept 12, 2022 10:22:26 GMT -6
I just got an older 1073MPA and I'm curios about the DI impedance. I've seen some schematics of Neve 1073 circuits and it has a transformer on the DI input, which would mean that the impedance would not be great with a passive guitar pickup. Is the Stam the same way? 10k? 100k? 500K?
I took a look on the Stam site but there are no manuals and the specs don't list the impedance of the DI.
Thanks for the help.
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Post by Vincent R. on Sept 12, 2022 11:02:33 GMT -6
stam perhaps you can help?
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Post by phantom on Sept 12, 2022 12:46:59 GMT -6
I have the MPA and the EQ version, and both the DI sounds really bad, with no top end at all.
It's an impedance problem for sure, but I don't know how to solve it and it makes the DI unusable.
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Post by mcirish on Sept 12, 2022 14:26:59 GMT -6
I have the MPA and the EQ version, and both the DI sounds really bad, with no top end at all. It's an impedance problem for sure, but I don't know how to solve it and it makes the DI unusable. Thanks for that. I guess they used the same circuit and transformer as Neve did. That means the impedance is way too low for a passive guitar. I'm sure it will sound good on a keyboard or other active output source. That's really the only reason I keep a Presonus MP20 in the rack. The input impedance is 1Meg, so it works very well with DI guitars. I have a Daking preamp as well. Their DI is around 450K. I don't like the sound of that either on passive instruments like bass. Sounds very good on an active bass though. |
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Post by matt@IAA on Sept 12, 2022 15:29:26 GMT -6
There’s only one input transformer in that box (mic level). I don’t think the DI goes through that transformer.
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Post by sirthought on Sept 12, 2022 15:48:38 GMT -6
No knowledge about this D.I. but I've known a handful of D.I.s to just work better with my Strat if there was some kind of preamp pedal or clean boost pushing the signal. Seems kind of odd when plugging into a preamp box like a 1073, but I have no clue what's going on in there.
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Post by the other mark williams on Sept 12, 2022 17:18:10 GMT -6
There’s only one input transformer in that box (mic level). I don’t think the DI goes through that transformer. This is my memory, as well. I have that box, and really like it. But I don’t use the DIs. |
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Post by notneeson on Sept 12, 2022 19:07:50 GMT -6
The DI thing I’ve seen is the “bootsy” mod which adds a Jensen transformer. I don’t think anyone other than BAE markets that option.
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Post by mcirish on Sept 13, 2022 7:28:13 GMT -6
It would be good to get some confirmation on what they are doing with the DI. A schematic would be even better. I could mod it to have a FET front end to get the impedance ready for a guitar. A small daughter board with a few components might be all that's needed to make it usable. But, do I really need a couple more "ok" DI's? Nah, but it's fun to tinker when I have the time.
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Post by yewtreemagic on Sept 13, 2022 7:39:12 GMT -6
Well I've just found a manual for the Stam 1073 EQ, and that lists line input impedance of 10K, and DI input impedance of 150K. SOmehow I doubt that the 1073MPA will be a lot different. EDIT: Just found this fascinating 1073 preamp comparison page (including the Stam 1073MPA) - still no indication of its DI input impedance, but it's interesting that the Heritage Audio HA-73X2 Elite 2-channel preamp states 'JFET based DI', which suggests that it's a special feature to that clone and not general: www.braingasmlab.com/braingasmblog/2019/1/4/the-massive-1073-clones-shootout |
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Post by mcirish on Sept 13, 2022 8:14:59 GMT -6
I could test the impedance with a pot when I get a chance. Put a pot inline with the input and lower the level. When the level is 50% of what it was without the pot in series, measure the pot and that's the input impedance. I've already racked up the Stam so it may be a while before I can get around to it. My guess would also be 10K. That's fine for keyboards or active circuitry but not good for passive instruments. No big deal. I bought it for the mic preamps. I'm looking forward to dong some comparisons to the Hardy M1 and Daking preamps I have.
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Post by mcirish on Oct 4, 2022 8:04:35 GMT -6
I got this response from Stam. Hi Tom! My name is Vicente and I’m the engineer in charge of the Stam Audio technical support. Regarding your question, the input impedance for the DI input of the 1073MPA is 1MOhm. Best regards, Vicente Cruz Vásquez www.stamaudio.comI will have to test it out 1M should be great for passive instruments. |
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Post by mcirish on Oct 4, 2022 8:08:40 GMT -6
BTW,
I did get a chance to do some A/B with the 1073MPA and my Hardy M1. Both sound great. The 1073MPA, as expected, had just a touch more low-mid girth and a little gentler top end. For vocals, we ended up picking the 1073MPA. Not a gigantic difference but it was there. The Hardy was faster and picked up more detail in the vocal. It was perfectly fine. The 1073MPA was just a touch smoother on those particular vocals.
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Post by yewtreemagic on Oct 4, 2022 11:36:22 GMT -6
I got this response from Stam. Hi Tom! My name is Vicente and I’m the engineer in charge of the Stam Audio technical support. Regarding your question, the input impedance for the DI input of the 1073MPA is 1MOhm. Best regards, Vicente Cruz Vásquez www.stamaudio.comI will have to test it out 1M should be great for passive instruments. Well that is good news for piezo-based transducers everywhere! It's also a good sign that manufacturers are starting to make their DI inputs suitable for acoustic/electic instruments, as well as more basic line-level stuff like synths. |
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