Altec 1689A Preamlifer Mixer

**Audio_by_Goodwill** · November 9th, 2010, 09:55 PM

A few of these have shown up on Ebay pretty cheap. Would this work well for me, to run a DVD player through my 9444A? Currently, I have my DVD player connected directly to the amp, and it works okay, but I'd rather have a pre-amp. This is used for DVD and CD use in my living room.

**tomt** · November 9th, 2010, 10:33 PM

most likely.

**Audio_by_Goodwill** · November 10th, 2010, 12:11 AM

Here is the only copy of the spec sheet I could find online.

Altec Lansing Professional Amplifiers Microphone Specification List 1689A Mixer Preamplifier page 1

**Audio_by_Goodwill** · November 10th, 2010, 02:10 AM

Hmmm, after careful reading, I think I'd need two of them, not one like I first assumed.

What is a "pre-amplified" signal called? ...... in other words the output from a pre-amp ready for a power amp.

**bowtie427ss** · November 10th, 2010, 10:18 AM

Originally Posted by Audio_by_Goodwill

Hmmm, after careful reading, I think I'd need two of them, not one like I first assumed.

What is a "pre-amplified" signal called? ...... in other words the output from a pre-amp ready for a power amp.

You're correct, single channel(mono) out.

"Mains send" or "Mains out" IMO is probably the most accurate term for your pre out signal, "send" sometimes implies the output of a loop, and "mains" is sometimes assumed to mean AC mains. So, i think you have to be careful about calling it anything other that what it is "preamp out" unless you're in familiar company.

**whitebroncoii** · November 10th, 2010, 10:34 AM

The 1689A is a two-channel mixer. It has very good transformers on both inputs and a transformer on the main out (mono). There is an unbalanced line output for each input. I have successfully used these for stereo applications.

The bass and treble circuits are in the mono main output and will not affect the line outs.
The mic/line switch bypasses the input transformer.
Throughput gain can be as much as 54dB (selected with internal switches).

Maximum output is 18dB. Good gain structure through a 9444A would be with the amplifier's volume controls around 2 o'clock.

**Audio_by_Goodwill** · November 10th, 2010, 01:29 PM

Originally Posted by bowtie427ss

You're correct, single channel(mono) out.

"Mains send" or "Mains out" IMO is probably the most accurate term for your pre out signal, "send" sometimes implies the output of a loop, and "mains" is sometimes assumed to mean AC mains. So, i think you have to be careful about calling it anything other that what it is "preamp out" unless you're in familiar company.

I was thinking mainly about what equipment manuals might call it. Last night, reading the spec sheet I trying to evaluate exactly what the output connections where. I'll explain more in my response to whitebroncoii.

**Audio_by_Goodwill** · November 10th, 2010, 01:47 PM

Originally Posted by whitebroncoii

The 1689A is a two-channel mixer. It has very good transformers on both inputs and a transformer on the main out (mono).

That's good to know. I had read one thread from another forum that said it was a well made low end unit........ while I certainly like well made, the low end part didn't get me too excited.

There is an unbalanced line output for each input. I have successfully used these for stereo applications.

I saw that, but after realizing it was designed for a signal channel and figured that these unbalanced outputs were simply a pass through. Are you saying they do get amplified?

Maximum output is 18dB. Good gain structure through a 9444A would be with the amplifier's volume controls around 2 o'clock.

Could you (or someone) translate that to English?

I'm using the gain controls as volume controls currently.......... what's the differance between volume and gain?

**Audio_by_Goodwill** · November 11th, 2010, 12:26 AM

Maybe it's the "links" that are just pass through connections.

**whitebroncoii** · November 11th, 2010, 11:12 AM

Originally Posted by Audio_by_Goodwill

That's good to know. I had read one thread from another forum that said it was a well made low end unit........ while I certainly like well made, the low end part didn't get me too excited.

I saw that, but after realizing it was designed for a signal channel and figured that these unbalanced outputs were simply a pass through. Are you saying they do get amplified?

Could you (or someone) translate that to English?

I'm using the gain controls as volume controls currently.......... what's the differance between volume and gain?

First, the 1689A was a high-end mixer when sold new. It would still be high-end today. 'Line Out' on any professional mixer is after the mic/line pre-amp (gain stage) and that is how the 1689A is configured. The 'Link Outs' are a line level, unbalanced version of the main out (mono). Gain and volume are two different things, although many of us will use gain as a volume control.

In the simplest terms; gain will boost the original signal and a volume control attenuates an already hot signal.

The 1689A inputs offer a significant amount of gain. In any sound system the goal is to raise the signal level (gain) well above the noise floor. However, the final absolute level can exceed the input needed for the next stage (power amplifier). Good gain structure boosts the signal above the noise floor at one point and then attenuates the entire signal, including the noise floor, at the power amplifier using the volume knob. You will get the same power out of the amplifier by putting in an extra 10 - 15dB and then attenuating 10 - 15dB with the amp's volume knob.