o-scope

[Beatin' 10+ year member]

what's a cheap azz little o-scope I can get for less than $100?

or do they not exist?

I just want something simple where you can choose an ohm load on the device then put the test leads on the output terminals of an amp and turn the gain up until we see clipping.

Click to read more...

 

[gckless 5,000+ posts]

DSO nano

 

[momofx 10+ year member]

Yes DSO Nano works pretty well.

This is the one I have and its fantastic with color LCD and built in Multimeter as well (although I still prefer my Fluke for DMM use //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif) :

Owon HDS1021M 20 MHz Handheld Digital Storage Oscilloscope - on sale at Test Equipment Depot

 

[Beatin' 10+ year member]

how accurate is the dso nano? how much wattage can it handle?

also, do you have to create a homemade dummy load or is there a feature on the nano?

I would like the device to be able to show THD before the voltage rail of the amp is exceeded. Like in that thread about audiopipes, somebody was able to show how the amp distorted a signal well before clipping. But he said that a non-reactive load must first be presented to the amp. So I'm wondering if you must create that load using resistors or does the dso nano have something internally that can present a load to the amp?

 

[Team Ampere 10+ year member]

I know tfade uses one that was like 65 or 70 bucks. He swears by it and tbh man, there are a lot of people that have purchased ampos based on his gtesting. If the testing is being done with a 65 dolar scope, I would imagine its as reliable as it can be.

Look around for the nano, it can be had for cheap. I know tfade says that the easiest one to use is the first version. It has a little arrow keyboard on it so you can find the "wave"

 

[TaylorFade 10+ year member]

Yep. I use the little DSO Nano v.1. I got it from eBay from a US seller for like $70 shipped or something. It's worth it's weight in gold to me.

Not sure what you're talking about with the dummy load thing. I scope them unloaded first to get a reference voltage. Then I test them loaded down with subs. A "Dummy" load would be nice, but you're talking about several thousand watts worth of fixed resistors now. And that's some money.

Fiixed resistance is the money when testing amp output. Because there's no rise and the voltage and amperage are in phase. You also aren't waking the dead or tearing up subs trying to set/scope/clamp the amp while it's playing full tilt.

As for it's limits... mine has a 10x probe. The scope itself is only good for ~ 80vpp (volts peak to peak). That would only be good for amps up to about 3k or so. But there's a little "10x" switch on the probe that multiplies that voltage. I have no problem setting my 10k amp with it.

Also... right this second... I am developing a product to set gains that allows you to HEAR the clipping/distortion. No scope, no DD-1, nothin. It's a pair of headphones that you put on, play a tone and adjust the gain. You won't hear anything when it's clean. As soon as the amp starts clipping, you will actually hear the distortion. Pretty neat. And cheap.

 

[TaylorFade 10+ year member]

P.S. - your sig is actually a key to how my headphones work //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[gckless 5,000+ posts]

Yep. I use the little DSO Nano v.1. I got it from eBay from a US seller for like $70 shipped or something. It's worth it's weight in gold to me.
Not sure what you're talking about with the dummy load thing. I scope them unloaded first to get a reference voltage. Then I test them loaded down with subs. A "Dummy" load would be nice, but you're talking about several thousand watts worth of fixed resistors now. And that's some money.

Fiixed resistance is the money when testing amp output. Because there's no rise and the voltage and amperage are in phase. You also aren't waking the dead or tearing up subs trying to set/scope/clamp the amp while it's playing full tilt.

As for it's limits... mine has a 10x probe. The scope itself is only good for ~ 80vpp (volts peak to peak). That would only be good for amps up to about 3k or so. But there's a little "10x" switch on the probe that multiplies that voltage. I have no problem setting my 10k amp with it.

Also... right this second... I am developing a product to set gains that allows you to HEAR the clipping/distortion. No scope, no DD-1, nothin. It's a pair of headphones that you put on, play a tone and adjust the gain. You won't hear anything when it's clean. As soon as the amp starts clipping, you will actually hear the distortion. Pretty neat. And cheap.

You ever used the V.2?

What do you use for fixed resistance?

You putting those out yourself or working with/through Murphy?

 

[TaylorFade 10+ year member]

You ever used the V.2?
What do you use for fixed resistance?

You putting those out yourself or working with/through Murphy?

I've tried to use Muprh's v.2. I can't figure the sum'bish out.

Wire wound or braking resistors. I mean... if you need that sort of thing. You'd have to test as many amps as I do to make them worth having, IMO.

Working with Murph. He's going to handle assembly and orders and shipping and.... basically everything.

 

[chefzane]

So about these headphones? Update?

 

[calebkhill 10+ year member]

voltage and amperage are in phase.

Can you explain what you mean?

So about these headphones? Update?

Same question here.

 

[chefzane]

P.S. - your sig is actually a key to how my headphones work //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Bump for update

 

[clickclickw00t 10+ year member]

Bump for update

same here

 

[TaylorFade 10+ year member]

So about these headphones? Update?

Can you explain what you mean?

Same question here.

When clamping a reactive load (like a subwoofer), the voltage and amperage are out of phase. Instead of one single wave, it's two seperate ones. The degree of their seperation determines the inaccuracy of the clamp.

Say you clamp 1,000w. But the voltage and amperage are 30* out of phase. Cosine of 30* is .87. That means that our clamp is 13% higher than "real" power. The 1,000w is what's known as "apparent power". To figure real power you have to account for this phase angle. With fixed resistance, you don't because the voltage and amperage will be in phase. This is why the numbers from the AD-1 amp dyno will usually be lower than a traditional clamp. Because it uses fixed resistance. It's also why some amps will do way more than their ratings.

Clamping isn't perfect. But it's all we have.

Bump for update

same here

Did none of you see my T-Fade-o -phones video? Lol.

Headphones that can hear distortion. - YouTube

[Edit: before anyone says anything about the DD-1 in this video, I spoke with D'Amore engineering and apparently i have a busted DD-1. It's apparently a common issue with the earlier runs. Something about a two step voltage doomahickey or some shit.]

 

[Oraclem19]

When clamping a reactive load (like a subwoofer), the voltage and amperage are out of phase. Instead of one single wave, it's two seperate ones. The degree of their seperation determines the inaccuracy of the clamp.
Say you clamp 1,000w. But the voltage and amperage are 30* out of phase. Cosine of 30* is .87. That means that our clamp is 13% higher than "real" power. The 1,000w is what's known as "apparent power". To figure real power you have to account for this phase angle. With fixed resistance, you don't because the voltage and amperage will be in phase. This is why the numbers from the AD-1 amp dyno will usually be lower than a traditional clamp. Because it uses fixed resistance. It's also why some amps will do way more than their ratings.

Clamping isn't perfect. But it's all we have.

Did none of you see my T-Fade-o -phones video? Lol.

Headphones that can hear distortion. - YouTube

[Edit: before anyone says anything about the DD-1 in this video, I spoke with D'Amore engineering and apparently i have a busted DD-1. It's apparently a common issue with the earlier runs. Something about a two step voltage doomahickey or some shit.]

Very interest.

No chance there' a possible time window on this? OOR maybe tester sets?