Welcome • User Guide
ToS • Privacy • Canary
Donate • Bugs • License

©2024 Poal.co

900

I know active high and low pass filters are very accurate and generally didn't need a zobel circuit but would a passive high and low pass with a zobel circuit provide a more nature sound than actives or actives the only way to go?

Also for you tube heads I getting into circuitry mainly audio filters, power stabilization and pondering getting into diy amplifier building. I am wondering are there any tube pre amps that can convert high level input to low level output and what type of distortion would be seen at say 6v output Max on the low level line. I ask cause I thought I read around tubes produce distortion regardless a and if the case can it be lower.

Also I was reading about class a/d amplifiers but can locate one or a circuit diagram to compare with a class a and class d to see the implementation of hybrid setup

I know active high and low pass filters are very accurate and generally didn't need a zobel circuit but would a passive high and low pass with a zobel circuit provide a more nature sound than actives or actives the only way to go? Also for you tube heads I getting into circuitry mainly audio filters, power stabilization and pondering getting into diy amplifier building. I am wondering are there any tube pre amps that can convert high level input to low level output and what type of distortion would be seen at say 6v output Max on the low level line. I ask cause I thought I read around tubes produce distortion regardless a and if the case can it be lower. Also I was reading about class a/d amplifiers but can locate one or a circuit diagram to compare with a class a and class d to see the implementation of hybrid setup
You are currently inside a comment thread.
Click here to see all the comments (21).
[–] • 0 pt

I have no idea what that article is talking about. Speakers are low impedance - typically 1 to 8 ohms, with more exotic speakers being used in direct drive systems that have an impedance between 8 and 100 ohms. You usually only find that in pocket radios from the past, cars typically ran 3.2 or 4 ohms for their speakers.

Speakers are high-LEVEL, as in lots of power. If you're using a transformer, you're going to need to run an output transformer in reverse because you want to match the output impedance of your device. These types of transformers tend to only be a few watts, with bigger ones being unobtanium or very expensive. Just slapping transformer in there without considering what you're talking to is recipe for disaster.

On RCA things - RCA refers to the jack type, not the signal present therein. Yes, in audio, RCA jacks tend to refer to line level I/O, but you can find a lot of things on those, including video and low-level RF. It's best to describe the signal level you want as opposed to the jack type.

If your vehicle's electrical system is providing almost 15 volts, stop. You have a problem.

6SL7GT tubes can be upwards of $50 per, check tubesandmore.com. Bob @ hamtubes.com sells them for less if he has any. The *SL7 is a hi-mu (gain) tube, and may be too hot for what you're trying to do. The *SN7 is probably a better choice here, being a medium mu device. High mu is typically more for phono level inputs, you may find you have too much gain. Remember that you don't need massive amounts of gain if all you need is 1Vp/p input on your device. Don't try and drive it to the max, keep it fully within it's linear range and everyone will sound happy. All of those are octal tubes, and take up space, and have limited shielding options. You're better off using the decent russian 12AX7 tubes here, as you can get shielded sockets with spring-loaded clamps for miniature tubes. Also remember that tubes don't just "take line and give more out," you need to specify your inputs as well. The 6SL7 needs a decent voltage drive to operate, somewhere in the order of 3V peak.

If you're already at line level, you don't need to boost anything. This is what you want for your next amp. You want a voltage follower (buffer amp) at this point providing 1:1 output.

You don't just give them voltage and they work - there's a lot of calculations that you're going to need to do, or other parts needed to properly bias the tubes. A tube uses a resistor on the plate and the cathode to develop the voltage you want during amplification. Tubes are purely a voltage device, and without some biasing it's not going to do anything because you can't get that voltage change without something to cause that change. Yes, op-amps are a perfect choice for break-out amplifiers, but you can get ulta-clean instrumentation amps. Why stick a noisy, dirty, nasty vibraty microphonic tube in there to ruin the sound? Get some OPA1637, they have a THD in the dirt. Adding transformers in here and other conversion devices is going to pop your harmonic distortion up to measurable ranges. Transformers suck, it's why we don't use them for audio anymore.

The rest of the crap is black-box nonsense. It's technically correct, but it's like sending you to the hardware store to get a lightbulb. Which one, they have hundreds.

You're going to get a lot better, more accurate sound by using audio op-amps (or transistors if you're a masochist) for your system. It will absolve you of all of the crap a tube needs to run, and all you'll need is a simple negative voltage converter for the rails on the op-amps.