Line level Isolation

Re: Line level Isolation

Any opinions on this: http://www.audiopile.net/products/Electronics/MST-103_mic_splitter/MST-103_cutsheet.shtml

I've used one to prevent hum when I am splitting my output to 2 amps on different circuits. It's cheap but seems OK, but I have to wonder if I am degrading my sound quality. Still, a little distortion, if even audible, is better than a hum, I guess. What do you think?

Neither is acceptable. Why use another piece of equipment that solves one problem and causes another? I like to use the right tool for the job.
 
Re: Line level Isolation

Seems like it's more appropriate for microphone level splitting than line level isolation. Big difference in the voltages used.

Yeah, that's what I was wondering. They say it can be used for "Sending mixed signals to multiple amp racks." Do you think the specs given are acceptable?

I can't say that I have heard any problem with using the unit, just looking for some opinions about potential problems. Anybody have experience with the Audiopile device?
 
Re: Line level Isolation

Yeah, that's what I was wondering. They say it can be used for "Sending mixed signals to multiple amp racks." Do you think the specs given are acceptable?

I can't say that I have heard any problem with using the unit, just looking for some opinions about potential problems. Anybody have experience with the Audiopile device?

Take a look at the THD specs, it's very telling that anything higher than mic level results in increased distortion. It will be even worse at peak console output levels (20+ dBv). It's obvious this is intended for mic level signals no matter how the "marketing department" tries to convince you otherwise!
 
Re: Line level Isolation

You can test for distortion with SMAART - just send in a sine wave and look at the RTA display. A year or two ago I got curious and went through most of the transformer boxes we had lying around. The only thing that was fairly clean at line level and 40Hz was a big box with big old Jensen iron that the owner had built back in the 70's. Even that Radial Twin-ISO didn't do much better than the Whirlwind mic splitters.
 
Re: Line level Isolation

The only thing that was fairly clean at line level and 40Hz was a big box with big old Jensen iron that the owner had built back in the 70's. Even that Radial Twin-ISO didn't do much better than the Whirlwind mic splitters.[/QUOTE said:
So, in reality it is as I said "a little distortion, if even audible, is better than a hum".
 
Re: Line level Isolation

So, in reality it is as I said "a little distortion, if even audible, is better than a hum".

Certainly neither should be heard! But if it comes to one or the other, obviously it's harder for the average person to detect a "little bit" of distortion. :)

It always comes down to context. It would be silly to spend $100 per channel on a Jensen for a weekend band that is lucky to make that in one night. But it would be equally silly to put a cheapie $30 transformer that distorts easily on the output of $50K mixing console for a gig worth thousands. Make wise choices, use an appropriate tool for the situation. A mic level transformer does not belong on the line output of a console. There are cheap line level rated isolation transformers out there that can work in a pinch. Obviously if it says "mic" on the outside of the box, that's a clue worth heeding.

That said, I made a $200 investment just a short while ago in my personal test kit to have a stereo Jensen Isomax box available whenever the gremlins should arise. The way I look at it is for the time in labour I've wasted over the years chasing after noise issues, had I had the Jensen back then, it would have paid for itself many times over in saved labour costs alone. Hindsight is always 20/20! :p
 
Re: Line level Isolation

So, is the Whirlwind ISO essentially the old Sescom IL19? My IL19s were barrel but did not have the bulge in the center.

The IL19's worked pretty good but a little inconsistent- you needed to test before putting into play (specifically for Frequency Response). I have one that has a slight roll off from 100Hz and below. The roll off is no more than a dB from 100 to 20Hz, but it's helpful to know what it's doing. I liked them mostly because of their size and ability to temporarily fix the problem.

I would love to upgrade myself, but I actually haven't used them since I went digital, although I'm still using the analog outs on the console. What getting better? Newer house consoles?
 
Re: Line level Isolation

I'm not sure! I found what looked like a new version of the Sescom IL19 on page labelled as a Whirlwind device. Thought maybe they were putting their name on a Sescom product. In a world of mergers and acquisitions it takes some like yourself that can keep it straight for us. By the way thanks for your work on this forum.
 
Re: Line level Isolation

I recently talked to Whirlwind tech support on the phone and if I understood correctly, they have replaced the Sescom unit with an improved version of their own design.
 
Re: Line level Isolation

Implied specs are very handy for the manufacturer.

Mac[/QUOTE

I'm not sure what you are implying, but it was just a phone converstation and Whirlwind is a company I trust more than many others to give the straight poop about their products..
 
Re: Line level Isolation

I don't think that he was implying anything- just making a pun on "specific". I don't think it was anything personal to you or Whirlwind. I'd bet you won't find anybody here that doesn't respect the products that Whirlwind makes available to it's end users at the various price point levels.
 
Re: Line level Isolation

Implied specs are very handy for the manufacturer.

Mac[/QUOTE

I'm not sure what you are implying, but it was just a phone converstation and Whirlwind is a company I trust more than many others to give the straight poop about their products..

Mac is saying that taking a manufacturer's word regarding a particular level of performance and a customer's acceptance of same is all very convenient. It's also easier than publishing a specification.

Like you, I hold Al K and his crew in high regard, but I'd like to see a spec sheet... I want to know where the edge of the Earth is, I hear beyond there be dragons or distortion or such things.
 
Re: Line level Isolation

Implied specs are very handy for the manufacturer.

Mac[/QUOTE

I'm not sure what you are implying, but it was just a phone converstation and Whirlwind is a company I trust more than many others to give the straight poop about their products..
Warning: I am not making a specific comment about company or this actual product, just speaking in general from a distance.
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Verbal communication is imprecise.

Not every representative from a given company has a full understanding of performance considerations and engineering tradeoffs made.

Written spec sheets ASSuming they are comprehensive and accurate, are not (should not be) subject to interpretation or misunderstanding.

I've overheard and/or been sucked into enough conversations between customers and service people or sales types, to know that even with the best of intentions misinformation can and does get spoken. Not with malicious intent but it is not human nature to understate the benefits of a product you represent. Most redesigns of mid line products are done to reduce cost, or perhaps deal with obsolete components. Few companies invest fresh tooling capital and incur supply disruption just to make a working product a little better. A good engineer will try to both improve and reduce cost when tasked with tooling up a replacement. Sometimes we win sometimes not so much.

It is possible to improve the performance of a transformer stuffed inside a small XLR barrel if it uses an improved core material, or if the old transformer it replaces sucked even worse than it had to for the limited core size constraint.

JR
 
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Re: Line level Isolation

got this note back from Whirlwind comparing their products:
Hello from Whirlwind,


The ISOXL does have a smaller transformer and its frequency response will not be as low as the larger TRSP600L used in the larger box type ISOs. The frequency response spec at 100 Hz, 0 dBu is -0.13 dBu. That's not bad as long as you don't drive it really hard.

The spec on the TRSP600L @ is 20 - 20k Hz, +/- 0.57 dBu but at +20 dBu.

So the ISOXL becomes a handy and relatively inexpensive problem solver. In fact, they're used all the time to isolate mixers from amplifiers in PA systems.

The ISO1 uses the same TRSP600L transformer as the Line Balancer but only has the single channel of isolation without the splitting capability but it's a bit less expensive.