TFM 45 Questions

Guys,
Just got 2 TFM 45's from eBay and had a couple questions...

-When you bridge the 45 to run mono, does just one meter work? In my TFM 35, both meters go when bridged, but this is a very different amplifier, so not sure. Also, the manual is confusing as it says the RIGHT RED is POS and the RIGHT LEFT is NEG, but the picture they show, shows the absolute opposite, so can someone help me out here?

-Is it safe to run a 4 ohm center speaker (PSB 6c) mono on the tfm 45. I know you are never supposed to run mono on 4 ohms, but with a center does it matter. Would there be any negative to just running one channel and not the other? I know it will NEVER use all 375 watts on a center speaker in a normal sized room.

Anyone who has worked on these amps, please email me, Would love to replace the caps, set bias, etc, but not sure how...

gjm76@cox.net


Thanks!

Nice looking amps!! I think only one meter is supposed to work in bridged mode as it seems I've had the same experiance. I'm sure others here will chime in and help out, good luck!

I bridged a 55 and both meters worked???? Rainman is the forum expert on the 45...Mikey????

Thanks for that info, Does anyone else know much about the 45? Hoping to get more info about working on them...

Main thing (IMO) about the 45 (assuming it's working) is to make sure that the service "damping adjustment" on both channels is properly set. Otherwise this amp can sound like ass, instead of its intended very musical, very clear "tubelike" sound... Is a post here (somewhere) that details how to do this adjustment (which requires a signal generator and these instructions include how to download the Virtual Testbench software version of a signal generator and how to use it for this adjustment...). Especially important if your 45's don't have the service bulletin "fix" that prevents these adjustments from "drifting" off their proper values.

I have never bridged the 45 and would not want to so I can't answer your question from personal experience. I will look in the service and owners manuals for the 45 and see if the answer is in either manual. I do have a question for you.. Why in the world would you want to run two 45's bridged?

Rainman

[quote="Rainman"][color=#0000FF] I have never bridged the 45 and would not want to so I can't answer your question from personal experience. I will look in the service and owners manuals for the 45 and see if the answer is in either manual. I do have a question for you.. Why in the world would you want to run two 45's bridged? Rainman quote]




Mike I'm surprised that you with your background in auto racing would ask such a question.

Obviously the answer is:


MORE POWER !

I've never bridged a 45 but I did bridge a 42 (same thing, different meters) and it seems to me only the left meter worked but that was a long time ago. I had bought an SW-15 Klipsch subwoofer and the amp plate didn't work so I wired in a bypass so I could power it with an external amplifier. At first I tried powering it with only one channel (375 watts) thinking that should've been enough power but I was pretty disappointed. Then I bridged it (1,000 watts) and look out! It was a whole new animal. Suddenly I had too much power at my finger tips and had to be very careful not to blow the thing up, it was great.

Since bridging has been the topic there is something which has not been mentioned... When bridging for more power there is a penalty for power gained which is paid as a sound quality loss. The amount of sound quality lost varies greatly depending on the amplifier being bridged. With an amplifier such as the tfm 45 the personality of the amplifier can also change. The change can range from barely noticeable to highly annoying depending on what the amp is running as well as the other components in the system such as how revealing your speakers may or may not be. Personally I would not run a bridged amplifier in our home gear for these reasons. I also have a rule (not a guideline) when it comes to car audio which is- I will only run bridged amps to subs, try to avoid it when possible on mid bass, and never to mids/highs. This is one of those things that is done or not done by each persons needs and personal choice. With some peoples systems any penalty paid for power gained may not even be audible so it may work for them, whereas other systems will show you the penalty in a big way.... And by the way Frankie, more power can be a good thing as long as your more powerful engine will live for the entire race distance...

Rainman

^^^^What he said--

As I said ^^^^^^

As they said <-------

Hell, I don't even understand what they said , but ^^^^^^^^^^ I agree.