Robin W.

Hello, I'm just in the planning stages of designing and building an SQ line driver. Some of the design will come from what I've learned from building headphone amplifiers because there is no masking noise or distortion when using very efficient 100-115db @ 1 milliwatt drivers that are next to your ears. I would prefer to design and build a single product that includes or has the option to include all of the required features.

I envision this as the product that gets mounted near/behind the deck in the front of the vehicle. And feeds processors or amps in the back.
How many channels? 2/4/6? If 4 or 6 does it need the option to run all 4/6 off of a single pair?
Single ended output? Balanced output? Both?
If balanced does there need to be a balanced line receiver? Or are there any balanced input amplifiers still made?
Any built in processing?
This will NOT be an OEM interface, but that may come in the future as I need one of those myself.
Any features that I didn't mention?
Any that I mentioned that should be left out?
My designs are typically as simple as possible, I don't include anything that isn't absolutely necessary.
The power supply will be tightly regulated, and the op-amps will most likely be LME49720HA (metal can) which has a clean natural sound, it's expensive but I find it well worth the price?

What do you guys think?

goalie 35

high quality op amps and output transistors..

Robin W.

Hi goalie 35, thanks for the tip.
I will of course do listening tests, but I will most likely be using the LME49710HA or LME49720HA. (board mounted no adapters like the attached picture) Both are amazing, as for the output it may or may not use a discrete (transistor) buffer, I will have to do some testing with long (10-20') cables to see what sounds better.

My question is more about the format of the line driver, number of channels etc. The electrical design is already in the works and will be the cleanest/best sounding that I can build. How that translates into number of inputs/outputs is still up in the air.

Newb

iTrader: (4)

I would love to see a 8 or 10 channel line driver. 10 would be epic IMO.

Robin W.

I assume 10 output channels? how many inputs? gain control on the inputs or outputs? Can you give me a rough system description of how this would be used? I'd be happy to "include more" so that the line driver covers anyone who would use it. Same idea as my SPL version, 24 mono outputs but not all of them have to be used.

JohnVroom

... why not go for the fence

try a Nelson Pass single ended driver with a dedicated battery power supply (low noise but it would probably prevent any ground loop) a single solid state output device per channel

Tubeamp

That would look so cool in an install... imagine the size of heat sink for 10 channels!

Tubeamp

Sounds like fun. Why not make it match your SPL version, 24?

Would love to see the final product!

The Tube Doctor

I'd like to see remote input and output level adjustments, perhaps USB, that could be accessed via a panel-mounted port. With the number of channels that other board members are suggesting, ease of adjustment would be of equal importance to the audio performance. Being able to easily access the levels would make it easier to take advantage of the maximum performance available from the line-driver.

FWIW, my favorite line-driver to date, is made by a small Japanese manufacturer (MCS) and uses two 5751 (similar to 12AX7) tubes. I modified one a few years ago, with copper-foil, paper-in-oil caps, high quality electrolytics & silver wiring. Sounded like pure magic.
NOS vintage Mullard tubes didn't hurt either, but were (and remain) terrifyingly expensive.

fozzz

iTrader: (1)

Add an analog master volume control.