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Post by bluegrassdan on May 14, 2020 22:33:00 GMT -6
I am in the middle of a new tube preamp/channel strip design that is really exciting. The topology is quite a bit different from my previous two-tube design. It is a three-bottle design, somewhat overbuilt, and results in a completely linear frequency response at all gain stages from 6 Hz to 40 kHz (+/- 1.0 dB at the extreme edges). It is all open loop gain WITHOUT negative feedback. It is also not a recreation of any historic or currently available design. Been working on this for a couple years now.
Dave at Cinemag has a custom "never-before-seen" input transformer that he is sending me for trial. It could be that there are a couple of transformer options depending on whether someone wants clean vs colored.
I'm indecisive about the feature set, so I thought I'd throw this poll out there. I would appreciate knowing what you all tend to look for in the gear you use.
Thanks in advance.
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Post by bluegrassdan on May 14, 2020 22:36:55 GMT -6
Here is a little PCB teaser of the preamp card.  |
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Post by bluegrassdan on May 15, 2020 2:17:40 GMT -6
Here are some actual test sweeps of the EQ. Two knobs: one "Lo" one "Hi". Rotary switches with 2 dB increments. Counterclockwise on the "Lo" knob is a stepped high pass filter (70Hz, 100Hz, 150Hz, 200Hz, and 300Hz). "Lo" boost is 60Hz. "Hi" boost and cuts are at 10kHz. Very gentle tone shaping. Still some tweaking to do, but you get the idea.  |
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Post by Ward on May 15, 2020 11:58:57 GMT -6
EQ please. At least one variable midrange band. +/- 12db variable between 250hz and 3KHz. Even selectable frequencies like 250 350 400 500 600 800 1.2 2 2.4 and 3K would be ones I would find really useful.
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Post by bluegrassdan on May 15, 2020 13:05:39 GMT -6
At one point the design was headed in this direction. The EQ included a MID band with selectable 210Hz, 340Hz, 700Hz, 1.6kHz, 3.2kHz, 4.8kHz, and 7.2kHz.  |
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Post by Ward on May 15, 2020 15:28:33 GMT -6
At one point the design was headed in this direction. The EQ included a MID band with selectable 210Hz, 340Hz, 700Hz, 1.6kHz, 3.2kHz, 4.8kHz, and 7.2kHz. View AttachmentIf the street price is right, you've got one more customer in me. |
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Post by bluegrassdan on May 15, 2020 15:41:42 GMT -6
Based on suggestions and thinking about it, I'm starting to narrow down to two separate pieces:
A two-channel preamp with three-band EQ (selectable mid frequencies).
A one-channel strip with opto compressor and three-band EQ. Also line input option.
OR, I could throw them into one gargantuan unit and have three channels as described. The perfect home studio setup. One great vocal channel and two stereo instrument channels. We could even use an ultra-fast transformer in the stereo channel and something with more "beef" in the strip.
Now that is a combo that NO ONE would want (or try to afford).
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Post by Blackdawg on May 15, 2020 17:32:16 GMT -6
At one point the design was headed in this direction. The EQ included a MID band with selectable 210Hz, 340Hz, 700Hz, 1.6kHz, 3.2kHz, 4.8kHz, and 7.2kHz. That looks awesome! |
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Post by Johnkenn on May 16, 2020 13:55:56 GMT -6
Are the other designs out of production?
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Post by lpedrum on May 16, 2020 15:29:27 GMT -6
Maybe I'm in the minority, but I love mute buttons on pres. Many of us record at least some tracks in the same room, switching back and forth from headphones to monitors. Being able to lean over and mute the pre is really helpful.
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Post by bluegrassdan on May 16, 2020 16:16:10 GMT -6
Are the other designs out of production? Right now, I've got the earlier two-channel on hiatus. It is a wonderfully great and smooth sounding pre, and may see the light of day again. But I'm really stoked about this new circuit and the Cinemag transformers. I'm thinking there will be three iterations of the new one: - Two-channel preamp with three-band EQ
- One-channel preamp with three-band EQ and opto compressor
- One-channel "economy" preamp. Pot instead of rotary switch, PSU inside the same box.
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