McIntosh newbie questions

[mungkiman]

I am new to McIntosh equipment, and if any of you can help me, I would be grateful. I just got a C28 preamp and MC2505 solid state amplifier, but no manuals. I would appreciate a reference or a copy of the appropriate manuals.

In the meantime, I would like to hook up the speakers, and need some guidance. On the rear of the amp, the speaker wire terminals are marked: C 4 8 16. Which side of the speaker wire goes to the "C"? If it is backwards, will they be out of phase? Please explain.

I will probably be driving a pair of '59 Shorthorn 15's with the amp rather than my La Scalas, as the amp is not high powered. The La Scalas are listed on the Klipsch site as having 8 ohm impedence, but nothing is listed for the Shorthorns. How do I determine which terminal to choose?

Any help with these questions and a resource for manuals would be appreciated. Thanks.

[WMcD]

Wow. You have good taste in equipment.

The amplifiers have output transformers. You'll seem them as big black blocks on the amp.

The terminals are the output taps from the output transformers.

You should take the "c" or common as ground. They will go to the black terminal on the speaker.

I suggest you use the "4" or 4 ohm output terminal to connect to the red side of the speaker.

This is a good choice for a couple of reasons. First, this output terminal gives the least voltage and most current. Therefore any noise from the amp is reduced.

Second, some speakers go down to 4 ohms in input impedance. I can't say that Shorthorns do (perhaps not), but it works for a lot of other speakers.

Regarding out of phase. As long as there is consistency from left to right speakers, they are in phase.

Another issue, and one which you're close to asking about is overall polarity. We'd like to make sure that there is no switch in polarity in the entire string from recording microphone, to studio mixer, to recording, to playback of the recording, to amp, to speaker.

I suppose we'd like a positive pulse at the mike become a positive pulse out of the speaker. There is much debate whether that can be heard. And in any event we can't control what is going on at the recording end. Or even know what is going on. Some blocks of the amplifer circuits can invert.

In any event, it makes sense to keep the (+) red of the speaker to the 4, 8, or 16 of the amp.

My visit with Dave brings to the fore the issue of how we handle the markings on speaker wire. Not that it makes a difference as long as we get the right result. Almost all wire pair have some marking. Strations or lettering. We were hunting for a potential problem with phase. He is a careful fellow and everything looked good.

I use red nail polish to mark a plus wire on both ends. This obviates the problem that I can't recall, with any consistency, whether I'm using striated side as hot (red, plus) or as ground.

Gil

[WMcD]

Also, look for "Audio Classics" on the web. They're located in upstate New York and is the leading dealer in Mac equipment.

They may be able to help you with a manual.

Gil