Re: LP1 tech question

[Charles Zwicky <cazwicky@earthlink.net>]

Title: Re: LP1 tech question

There seems to be a bit of confusion regarding impedance here...

The output impedance of the DM1000 omni outputs is stated as less than 75?. An "ideal" output source has an output impedance of zero ohms, which means that it can drive any input without loading.  The LP1 should have at least a 10k?  input impedance, so the DM1000 will have no problems driving the LP1.

If the DM1000 has non floating balanced outputs, then wiring the XLR outputs to the LP-1  will simply require connecting XLR pin 2 to the 1/4" connector "tip" and XLR pin 1 to the 1/4" "sleeve".

 This unbalancing will reduce the signal level by 6dB simply by virtue of the fact that you're not using the opposing polarity signal on pin 3 of the XLR.

If the LP-1 cannot accept a line level signal, then it's a simple matter to build an attenuator into the unbalancing adaptor cable I described above.

If you connect a 10k? resistor to the output XLR (f) pin 2 connector and wire the other side of that resistor to (1) the "tip" of the 1/4" plug AND (2) to a 1k? resistor whose other end is connected to XLR (f) pin 1 you will have  20dB less signal at the 1/4" plug.

When returning the LP-1 to the DM simply make a cable that connects the "tip" of the 1/4" plug to pin 2 of the XLR (m) plug and tie pins 1&3 of the XLR (m) plug to the 1/4" "sleeve".  Grounding pin 3 will give you as much as 6dB more gain, depending on the design of the input at the DM1000.

-Chuck Zwicky

> > if the aux sends and returns are
> > balanced, then you will get a low level in and out of the lp-1,
> > because it has unbalanced ins and outs.
>
> True that... unless the DM1000 has
> impedance control on its AUX output buss.  (Or conversly, the LP1
> on its unbalanced input... but I kind of doubt that LP1 would have
> this feature-- its more common to large scale digital
> mixers)
>
> A less than attractive alternative would
> be impedance line conversion adaptor on the send into
> LP-1
>
>
> D

if the aux sends and returns are balanced, then you will get a low level in and out of the lp-1, because it has unbalanced ins and outs.

sim

On Thu, Jun 16, 2011 at 5:41 PM, Charles Zwicky <cazwicky@earthlink.net> wrote:

The first thing I'd recommend is that you check  the signal levels using the DM1000 tone generator, sent to the LP1 via the Omni out you've selected on the DM1000.  If the LP is an "instrument level only" device, then you might need to trim he output by 30dB or more.  Check the LP1 docs to see if there is a line level option...

All my gear is hooked up to the DM1000 with DI where necessary. I am playing chapman stick with separate preamps and amps. Signal goes from DM1000 input to balanced AUX SEND. If  I stay well within the boundaries of what the LP1 INPUT will tolerate, my OUTPUT signal is very weak. You are saying I should boost the return signal from the LP1. Am I reading you properly? Would I be better off using a mixer with unbalanced OUTPUTS?

ANtony Hequet

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From: andy butler <akbutler@tiscali.co.uk>
To: Loopers-Delight@loopers-delight.com
Sent: Thu, June 16, 2011 5:48:27 PM
Subject: Re: LP1 tech question

First suggestion would be give full details about how you're
connecting things up, where the signal is too weak, and where it distorts.

The LP1 won't match pro studio gear for headroom so you'll have to
go easy on the signal strength that you send to it and boost
the Lp1 outputs somewhat more than you'd expect with the mixer.

The Lp1 has a low noise floor, so apart from being awkward
there's no disadvantage to this.

andy

antonyhequet@yahoo.com wrote:
> I am having problems interfacing my LP1 with new Yamaha DM1000 mixer. I used to take a unbalanced signal OUT from a Multiface and everything went smooth. Now I am using a balanced signal from the AUX OUT of the Yamaha. The signal is either too weak or immediately distorting heavily. Never managed to work it out... Any suggestions?

>
> Antony Hequet

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