The 2BA-221 from Summit Audio is a microphone/line preamplifier featuring continuously variable microphone impedance. The preamp utilizes separate and individually controlled solid state input controls to mix a microphone input with a Hi-Z or line input into a variable vacuum tube output. Using both the variable impedance and variable solid state and tube stages provides a high level of sonic control.

But this is only half the story. Along with the required I/O, the unit features an insert before the tube stage, a variable 20Hz to 200Hz high-pass filter, 20dB pad, 48V phantom and polarity reverse. The 2BA-221 also features a stackable input design allowing multiple 2BA-221's to be linked together to form a modular mixing device with individual outs, inserts per channel and a final vacuum tube gain stage.

The unit's versatility is further extended with the use of the multiple outputs. By plugging in a 1/4" cable into the insert jack and using the "stack output," the 2BA-221 can provide a total of four high quality outputs from one source. For example, the microphone source can be sent to a recorder from the +4dB balanced tube out, with a backup to another track from the -10dB tube output to avoid any "overs" and send the solid state '"stack" output to a compressor and then to yet another track.

On the input side one could plug an acoustic electric guitar into the Hi-Z input and place a microphone in front of it and use the separate line and microphone input controls to mix the signals into the one, perfect blend.

All of this functionality is packed into a very compact 1U half rack chassis with an internal power supply. The tube output utilizes a high voltage plate, not the starved plate compromises of lower cost units, but is still delivered at an exceeding favorable price considering the myriad features provided, along with the traditional sonic quality of a Summit Audio product.

Single channel microphone/line preamp with variable input impedance from 100Ω to 10kΩ

Hi-Z instrument, line and microphone level input

Microphone and Hi-Z input available simultaneously with separate gain controls

Three variable, independent gain stages

Separate solid state and tube outputs

Variable high-pass filter, 20dB pad and polarity reverse switch

Insert jack for inputting an external processor

Stackable with more 2BA-221's to form a modular mixing device with individual outs, inserts per channel and a final vacuum tube gain stage

Related Questions and Answers

Q: 1. Does the unit have optional manual iris control or is it auto iris only?

A: This camera doesn't have a dedicated button with 'A', 'S', and 'P' settings, but each of those modes can still be set; it's just a bit fiddly.Summary:To put the camera into 'A' (aperture-preferred mode), you will put the camera into all-manual mode, then set the shutter to auto, then set the gain to auto. This will leave you with manual control of the iris.Details:1. Put the camera in full-auto mode by pushing the FULL/AUTO button. Then push the same button again; this will clear everything, puttin all functions into full manual mode (except for focus, which is handled separately).2. Adjust the IRIS to your desired setting. Keep in mind that this may change as you zoom, because the maximum aperture is f1.2 only in the wide-angle range; it decreases to f3.5 pretty quickly as you zoom the lens, dropping to f2.0 about midway through the zoom range.3. Press and hold the SHUTTER button on the side of the camera; this puts the shutter into AUTO mode. The shutter speed indicator will disappear from the LCD screen.4. Set the GAIN to AUTO mode (AGC). This is the fiddly part. You must first set default values for the GAIN switch's L, M, and H positions. The camera default is L=0, M=3, and H=6, but I changed those to L=0, M=6, and H=AGC. So, flipping the external switch to 'H' then sets the gain to AUTO. I also put these settings into my FAVORITES menu for easy access.You can also set the upper limit for the gain. I've set mine to 18db, because anything above that is really noisy. So, in AGC mode, my camera won't go above 18db. If you're desperate to record that evening campfire scene, there's always the LOLUX button, which sets the gain to 30db.5. Exposure compensation. You can tweak the exposure settings by pressing and holding the AE LEVEL button until a white box appears on the LCD screen (AE +/-), then adjusting exposure up or down with the little arrow buttons located on the lower-left side of the camera, nearest the battery. Note that, in low light, this may not have any effect if your camera has already reduced the shutter speed to 1/30 and set the AGC to its maximum.If there's an easier way, I haven't found it. The key points are A) to set the defaults for GAIN, and B) to remember to turn FULL AUTO on and then off at the start. Also note that you can use this same approach to put the camera into 'S' (shutter-preferred) mode.

Q: 2. Will the 24x Dynamic zoom work while shooting 4k?

A: According to JVC, Dynamic Zoom in HD mode combines optical zoom and pixelmapping to create seamless and lossless 24x zoom. So HD only for 24x Dynamic Zoom.

Q: 3. Can the center column split for use as a short column? There is a seam in the column but I can’t separate them.

A: The center column on the Fotopro Sherpa Summit Carbon Fiber Travel Tripod with FPH-63Q Arca-Type Ball Head and Monopod (Black) cannot be split. The center column can be removed, and the legs spread out wide for low-perspective shooting from a height of just 9.8".

Q: 4. Does the GY-HM170ua use the same batteries as the GY-LS300? I have the ls300 and extra batteries and it would be great if I could use those batteries on the HM170.

A: The GY-HM170UA does not use the same batteries as the GY-LS300. Consider the GY-HM200 instead, which is essentially the same camera as the GY-HM170UA, but uses the same battery as the GY-LS300 instead.

Q: 5. How does the aperture scale as you zoom in? So at what focal length does it become f1.4, f1.8, etc?

A: That is a bit difficult to tell, since the actual focal length is not displayed. What is displayed is either a bar graph or a number between 0 and 99 (when digital zoom is turned off. The aperture does appear to close linearlly with zoom, not reaching F3.5 until its almost fully zoomed. Based on the 0 to 99 numeric zoom indicator, its: 0 - F1.2; 18 - F1.4; 31 - F1.6; 41 - F1.8; 51 - F2.0; 58 - F2.2; 70 - F2.5; 77 - F2.8; 90 - F3.2; 99 - F3.5. Also, when zoomed to double the widest angle, judging by the image magnified 2X, the aperture is F1.8.

Q: 6. Has anyone used the JVC GY-HM170 for performance work? What are your thoughts?

A: I used it for filming part of a movie 8 Ball Clown and am planning to use it as primary camera for 8 Ball Clown II - I like the quality, not a low light camera, the manual operation takes a bit to get used to but then again all of them do. I bought 2 extra batteries and 128G cards, so I should be able to film quite a bit without stopping. The onboard sound is pretty good - I'm probably adding wireless mics, but its good. I use Bose headphones so I can get better sound and adjust volume. note most of the movie was filmed on a canon t2i - because I just wasn't ready to switch because I had not touched the camera - but I'm more comfortable with it and will practice to get used to it. I did some minor filming for commercials in 4k and that went well - but that was outside in bright light. I will always use a dslr in low low light.I edit in Final Cut - so the video output is easy to bring in and edit - one of the reasons I went with this camera.

Q: 7. Has the JVC GY-HM170 got a wireless remote control?

A: No

Q: 8. Is the Standard Def format in 4: or 16:9?

A: 16:9

Q: 9. Has the camera the ability to take stills direct to SD card?

A: I am sorry but this camcorder cannot take stills. One work around is to download the video to your editing software and extract a single frame of video. We can suggest the Canon XC10. It is meant for photojournalism so you can shoot full on stills or if you wish, you can extract a single frame of video but in still photo MP size if not quite quality.

Q: 10. I am trying to install the hood using the lines marked on the hood and the camera but when I rotate the hood is not straight. I can't seem to get the hood to rotate enough so that it sits correctly. What could be the problem?

A: Page 16 of the user manual goes over how to attach and detach the hood. It may just be a bit tricky at first to pick up. https://www.bhphotovideo.com/lit_files/118754.pdf