Hi all.

I have a piece of consumer gear (-10dB) plugged into a pro-amp (+4dB) via an Ebtech Line Level Shifter.

This all seems to work just fine.

However, I am now confused.

a) Would a DI-Box have worked instead?
b) What is the lay difference between a passive DI-Box and a LLS?

Thanks in advance.

b) What is the lay difference between a passive DI-Box and a LLS?

Probably none - if they're passive all they'll contain is transformers. Watch out with the Ebtech device though. It works okay, and is not terrible, but the transformers are cheap and not the highest quality. I used to have one of their 8-channel Hum Eliminator devices and the degradation was slight but definitely audible. Not banging too hard on Ebtech because good transformers are very expensive. Like $50 to $100 each - and up!

--Ethan

Probably none - if they're passive all they'll contain is transformers. Watch out with the Ebtech device though. It works okay, and is not terrible, but the transformers are cheap and not the highest quality. I used to have one of their 8-channel Hum Eliminator devices and the degradation was slight but definitely audible. Not banging too hard on Ebtech because good transformers are very expensive. Like $50 to $100 each - and up!

--Ethan


Thanks. This is actually going between my SW output on a consumer receiver and a pro-amp powering 1800W of subwoofer goodness. I'm hoping the degredation isn't going to make my bass sound bad :(

They did rate this at 10Hz-20kHz w/ +/-1dB attenuation and max .01% THD...

It is a little late, but which brands would you recommend as having "high quality" transformers for my intended use?

They did rate this at 10Hz-20kHz w/ +/-1dB attenuation and max .01% THD...

Again, I had their Hum Eliminator, not the LL shifter, but I believe they're similar products. The problem with specs like that is the signal level is not mentioned. Assuming the LL Shifter does use transformers, the specs are always worse at high levels even if they're acceptable at low levels.

It is a little late, but which brands would you recommend as having "high quality" transformers for my intended use?

Jensen makes excellent transformers but they're pricey. I paid about $110 for one isolation transformer. But do you even need that at all? A consumer receiver should be able to drive a consumer subwoofer amplifier directly.

--Ethan

Again, I had their Hum Eliminator, not the LL shifter, but I believe they're similar products. The problem with specs like that is the signal level is not mentioned. Assuming the LL Shifter does use transformers, the specs are always worse at high levels even if they're acceptable at low levels.



Jensen makes excellent transformers but they're pricey. I paid about $110 for one isolation transformer. But do you even need that at all? A consumer receiver should be able to drive a consumer subwoofer amplifier directly.

--Ethan

I have a consumer receiver driving a Crown XTI-2000 pro amp (not a consumer amp). This is supplying the power to my home built, 4x15 IB Subwoofer. I think I am going to set my receiver SW gain to something like -5dB, use the Ebtech to get it shifted into the +4V range, then simply up the gain on the Crown to compensate for the -5dB loss on the input signal.

If all that fails, I'll take a look at the Jensen (I only need one transformer).

Thanks!

I have a consumer receiver driving a Crown XTI-2000 pro amp

Now you're talking my kind of power amp. I have a pair of Crown PowerBase amps driving huge JBL 4430 speakers bi-amped in my home studio.

I bet that amp has enough gain to accept a consumer level signal. Have you tried simply raising the input level?

--Ethan

I agree Ethan I do not think he needs any sort of line driver it should work AOK without one.

I'm using the LLS-8 to drive a set of 30-60 foot XLR runs. It works pretty well. Certainly better than the Behringer I listened to before.

No, a DI box would not have worked, because the gain is different. A DI box will typically give you a gain of 20 dB or more; the LLS gives you a gain of about 10 dB (note that the -10 dBV is measured relative to a 1.0V reference, and +4 dBu is measured relative to a 0.775V reference, so the difference is not 14 dB).

If you need the XLR conversion, or the extra gain, then an active line level shifter/XLR generator might work for you, and color the signal less (but probably introduce more of a noise floor).

Here is what seems to work for me:

Receiver set to +12dB on the SW out channel.
Ebtech LLS-2 -10dBV -> +4dBU

My issue is not that the amp doesn't have enough gain (it is only at about 60% on the gain knob). The issue is that the amp disregards signals that are too weak (the signal light turns off, and the amp amplifies nothing). This is not a problem when listening at reference levels, but if we are watching a movie quietly (3 kids in the house!) then I want the sub to give me my 10-30Hz still, even at lower SPLs.

I guess a DI box would have done better, as I can push the gain up on the interconnect as much as possible and then just use the amp gain knob to fine tune.

Here is what seems to work for me:

Receiver set to +12dB on the SW out channel.
Ebtech LLS-2 -10dBV -> +4dBU

My issue is not that the amp doesn't have enough gain (it is only at about 60% on the gain knob). The issue is that the amp disregards signals that are too weak (the signal light turns off, and the amp amplifies nothing). .



The signal light can be off that is ok, it is when the Ready light is off that a issue is going on.

The signal light is not a good indicator. Load system architect on your pc and connect it to the amp. Then you can really see what is going on in the amp.

BTW, To prevent the chance of "your brother-in-law" from turning up the amp and burning out speakers or knocking down the ceiling, we always set the front knobs to max and adjust the levels from within the software. Then lock out the front controls.