Tube amp users! Switch those output taps!

organ

I'm sure most of you are using the 8 Ohms output taps on your amp. Looks like the best way to connect them to the proper taps is to find out how low the impedance dip is. If your speakers reach 4 Ohms, connect them to the 4 Ohms output taps. Even if they're 8 Ohms nominal.

I just switched to 4 Ohms and let me tell you, there's no way I'm going back to 8.

Here's a link to the discussion... http://forums.klipsch.com/idealbb/view.asp?topicID=61547&sessionID={62FD5B8E-D7E7-467D-8854-E5598C0344EF}

Maurice

RuSsMaN

Ed Zachry Maurice.

I use the 4ohm taps for 4/8 speakers, 8ohm taps for 16ohm. I usually have the 16 ohm taps (if present), tied back in with a resistor.

Cheers,
Russ

organ

Russ,
Can't believe I waited until now to try this. The difference is night and day. No joke.

What happens when you tie the 16 Ohms tap with a resistor? Should I do this even though I don't use the 16? What wattage and resistance value should I be looking for in a resistor?

Maurice

madmax

If you had 6 ohm speakers and wired them to the 8 ohm outputs you would be trying to pull more power out of your amplifier than if you hooked them to the 4 ohm taps. I think I got that right.

I notice differences in sound between the two. I go both ways. I'll have to check and see which I decided on.

madmax

dcarlson

I tried the 4ohm taps and I was getting a wierd sound that really wasn't right at all out of one of the channels so I had to switch back to the 8ohm taps. My ST-70 needs a rebuilding badly.

BlueMDPicker

Originally posted by organ
I just switched to 4 Ohms and let me tell you, there's no way I'm going back to 8.

Hi Maurice,

The only thing I've driven with the ST-70 is a pair of SDA 2A's (which are 5 or 6 ohm nominal, I forget), so I've not used the other taps (8/16.) The Manley 75+75 is "balanced for 8 ohm loads" and has one pair of binding posts.

Are yo going to try Russ's resistor trick on your amp?

Mike

RuSsMaN

It's not my trick, it's something my tech has done on occasion for me. That, and I'll ask exactly what is done, as I could be talking out of my **** on this one.

organ

Madmax,
You're right, I believe the higher output taps put out more power.

Derick,
Have you had a look under the hood. Could be a lose solder joint on the output terminal. I'm almost done rebuilding mine. Just need to re-wire the guts and buy a replacement 7199 board or the upgrade board. Changing tube sockets was a real pain in the ****.

Mike,
Not sure how to perform the resistor tweak or what it does exactly. I'm going to need more info first.

Russ,
That would be cool. I also noticed that there's a feedback wire to the 16 ohm taps on my amp.

Maurice

boogie02130

Hi all,

New to the forum with a dumb question. I've been reading this thread with some interest. I have a 1982 set of Polk Monitor 11's that I'm driving with a 1962(?) Pilot 746 Tube powered (4-RCA 7591's) stereo. My turntable (Numark TT-1) and other stuff is running thru an Onkyo P-304 SS Pre-amp into the Tape Rec input on the Pilot. I see that the nominal impedance on the 11's is 6 ohms. I've been running them off the 8 ohm taps and just switched them to the 4 ohm taps. They seem to be airier with a more pronounced bass. Seem to lack a little mid range depth though. I know that the choice is really up to my ears on which tap makes most sense, but just soliciting opinions. Also if anyone has any ideas on how to get a schematic/manual for the Pilot amp please let me know. I've tried most of the usual sources.

Thanks,
Dr. Hepcat

Dennis Gardner

Originally posted by madmax
I go both ways.

Sorry, I just couldn't resist.:D

boogie02130

After a couple of days of listening. I finally switched back to the 8 ohm taps. Seems like a more full range solution.

DRx. Hepcat

Originally posted by boogie02130
Hi all,

New to the forum with a dumb question. I've been reading this thread with some interest. I have a 1982 set of Polk Monitor 11's that I'm driving with a 1962(?) Pilot 746 Tube powered (4-RCA 7591's) stereo. My turntable (Numark TT-1) and other stuff is running thru an Onkyo P-304 SS Pre-amp into the Tape Rec input on the Pilot. I see that the nominal impedance on the 11's is 6 ohms. I've been running them off the 8 ohm taps and just switched them to the 4 ohm taps. They seem to be airier with a more pronounced bass. Seem to lack a little mid range depth though. I know that the choice is really up to my ears on which tap makes most sense, but just soliciting opinions. Also if anyone has any ideas on how to get a schematic/manual for the Pilot amp please let me know. I've tried most of the usual sources.

Thanks,
Dr. Hepcat