The latest TapeOP magazine has a “Behind The Gear” article on Dan Lavry and the AD10 A/D converter. It caught my eye because it has ability to color sound from “clear” to “tube”, “transformer”, or “complex” (both). That sounded like something I’d like to have in my arsenal (not to mention the creator's resume seemed impressive). So, I promptly went to the company website to check this thing out, only to find out that it runs on AC.
I decided to email the company to see if they might ever release this item in something that was more friendly for recording in the field, and possibly with pres built in. Dan Lavry emailed back and said he would consider it. At his direction, I’m posting here, as he wishes to “post some comments regarding some of the issues and compromises that take place when designing portable gear.”
Dan, the stage is all yours.
Mods, I apologize if this discussion is more suited for the “retail” section. Since, the product I inquired about doesn’t actually exist, and I have no relation to the vendor, I thought posting here would be okay.
Hi Michael and all,
Michael Lindsey wanted to know if the LavryBlack AD converter “AD10 will ever be released as a unit that can be used in the field on battery power”. The other question was about including a built in microphone amplifier (micpre) with the capability of supplying phantom power for condenser mics.
A as a designer, I am aware of the commonly encountered tradeoffs associated with battery powered gear. As a rule, when designing equipment to be powered by AC line energy, a few more watts is not much of an issue. The limiting factor for power level is most often heat, but given large enough physical size, one can get top notch performance without overheating. The AD10 is ½ rack wide, and it runs relatively cool.
But designing portable battery operated equipment calls for a serious focus regarding the usage of power. The power consideration gets magnified when small size is desirable, because a while given amount of power may not heat up a large chassis, the same amount of power can cause very high temperatures in a small case. In addition, when using battery operated gear, some of the space is reserved for the battery itself, leaving less space for the electronics.
It is not wise to lump all battery operated gear together. Laptop technology is pretty impressive, enabling a few hours of operation at power levels of tenth of watts. Achieving such high performance is a result of much technological evolution for a true mass production product line. Progress in battery technology is still being made, to provide more power for longer operation. But the focus of such progress is towards mass production laptops, hybrid cars and alike.
High end portable audio recording is not a mass production market. Most often, the designs relay less on increasing battery capability, and more on reducing the power required to operate the gear. There is a whole “family” of semiconductors designed specifically for low power applications, for portable equipment. In most cases, such portable components are made to work at very low voltages (such as single 3V-5V range) and draw as little power as possible. Such devices is what makes the major portion of portable recording gear. Much of the portable recording market is driven by mass production low cost device, where performance is not the driving consideration.
For those interested in technology, digital has been going to lower and lower voltages (the currents are still high for high performance) and that is the best path for digital. But analog for audio is “being dragged down” by the mass production computer, cell phone and similar technology. Lower voltage and high performance audio are opposite…
When using circuits and devices with low power and low voltage, one compromises performance. Say my goal is to have 120dB dynamic range, with a 3V supply. The electron motion inside a single 3.5KOhm resistor at room temperature generates noise at 120dB below a 3V signal… While some of the technological limitations may be temporary, there are a number of fundamental physical principles at play, that are here to stay. That is why the highest end gear ends up using higher power (higher voltage and higher currents).
When it comes to low power operation, the big question is the level of compromise in performance vs. the amount of power. In most cases, small, light, long battery life (or time between charges) and product price seems to outweigh the quality and performance.
Portability and low power and not exactly the same thing. One can “settle for” a heavier, bigger device (with a battery) that performs much better.
Clearly, I can make a version of the AD10 that is more portable. I can go for a different, less power consuming display and do what can be done to reduce power, which was not much of a consideration fro the present AD10. But at some point, one faces the decision of performance and quality vs. portability. Say you want 48V phantom stereo power. There goes a watt… Much portable gear offers lower phantom voltage, say 12V or even less. That is an example of compromise. Then come the monitoring question. Do you want to be able to listen to the OUTPUT through your choice of quality headphones? That would call for a quality DA plus heavy duty headphone driver – more power…
My very new AD10 is gaining much respect at music production facilities, a market that I am familiar with. At this point, I do not know how much need there is for the performance level of my products in the portable market. Clearly I am not going to recommend that people carry a 12V car battery with 115V 60Hz inverter to the field. I can alter the product to yield similar performance with increased portability. I can not make an AD10 fit in a pocket, but I can make it portable enough. I just do not know how many people with portable recording applications have a requirement for the highest sound quality.
Regards
Dan Lavry
www.lavryengineering.com 
