TFM-45

[mrjazz1959]

Just a couple of questions about this amp

1 Just purchased my second Carver this one a TFM-45 said to be in mint condition, seller gave it a 9/10 because of age not cosmetics , was $515.00 a good price said to be fully functional ? http://app.audiogon.com/listings/carver ... sting=true

2 I read somewhere that all TFM45's have some problem that requires a critical dampening adjustment be made if they have never been serviced is this true ?

3 I have also read that the TFM 45 has the best sound stage of all the TFM series , is that just a matter of opinion or is there factual documentation to support this claim.

4 Are all TFM 45's made overseas ?

[jjptkd]

1. Yes

2. Yes

3. Opinion. Very subjective and dependent on associated equipment, room etc. but nice amp all the same.

4. Yes, Japan

[elgrau]

1 Just purchased my second Carver this one a TFM-45 said to be in mint condition, seller gave it a 9/10 because of age not cosmetics , was $515.00 a good price said to be fully functional ?
I'd have to say for that amount I'd want a recently re-furbed TFM-45.

2 I read somewhere that all TFM45's have some problem that requires a critical dampening adjustment be made if they have never been serviced is this true ?
Yes, pretty much true IF the SN is such that it does not have the "drift fix" in place. The "break point" for these SN's is listed somewhere here in a thread (as well as the complete instructions for doing the damping adjustment and all the other service adjustments). Do a creative search to find these posts (use key words like "TFM-45", "damping", "drift", "number", etc.).
ADD: Found the SB # TFM-45-4 ("To eliminate damping pot drift"). It says this SB applies to TFM-45's with SN's below 02760 and TFM-42's below 01200. It does not mention M4.0's which I believe also share this same circuit.

3 I have also read that the TFM 45 has the best sound stage of all the TFM series , is that just a matter of opinion or is there factual documentation to support this claim.
All such claims re ANY amp are a matter of someone's opinion. But yes, some do say that the TFM-45/42 has the most "tube like" sound built into its transfer function and some also say that the Bob Father himself has stated this (even tho he of course loves ALL his amps...lol).

4 Are all TFM 45's made overseas ?
Mine says "Made in Lynnwood, WA, USA" on its back panel (as does my TFM-42).

[helicopterpilotdoug]

Mine says "Made in Lynnwood, WA, USA" on its back panel

Mine too.

[jjptkd]

Mine says "Made in Lynnwood, WA, USA" on its back panel

Mine too.

They all do.

[mrjazz1959]

Thanks

I imagine these carver amps vary in price greatly from year to year because $515.00 for this amp in such great cosmetic condition and fully working seems to be the going rate and I found what was said to be blue book 500-600 but i do not know if that is with or without out servicing. I guess if you approach it from the prospective that a new amp could be purchased at that price it may seem over priced.

[elgrau]

Yep....if the damping adjustment is properly set, this is one of best sounding "tube like" amps you'll ever hear. If not, it's average at best and can sound very flat and "ass like" at worse. Hence the Service Bulletin fix to this problem (highly recommended to have this done to ensure that once adjusted it will STAY adjusted for a very long time..). If there is any difference in the right-left volumn, the amp almost certainly is out of adjustment. Get it checked (or DIY...see thread here). If you do try and DIY, be very careful: the adjustment is VERY sensitive and tiny changes to the adjustment pot make a big change in the output volts... Good luck....perfect adjustment here is very much rewarded!

[TNRabbit]

Just looked at the pics; HOLY CRAP that is a HELLA clean amp---Looks new!

[elgrau]

Yeah, Gary, that might be true (LOOKS like a new amp). I got an m1.0t that looks new as well. But I also know that it has 20+ year old caps/components that will need replacing one day soon (and that manifest as that "turn off thump"). I'd still much rather have a less cosmetic amp that's been re-furbed to REALLY sound like new....my $0.02

[jjptkd]

I'd still much rather have a less cosmetic amp that's been re-furbed to REALLY sound like new....my $0.02

I most certainly agree with you myself but knowing the audio crowd out there through my eBay sales where I've sold many refurbed amps with slight cosmetic damage and mint amps that haven't been serviced I can tell you that we are the minority. Most people are willing to pay WAY more for a mint condition item and anything with cosmetic flaws will sell for well under market value no matter whats been done to it. Every once in awhile there's an exception but that's how it usually plays out.

[mrjazz1959]

Sound logic , Flawless 9/10 + $300.00 to refurbish is what the calculation works out to be + shipping both ways.So the original $515.00 quickly becomes $900.00 .

Thanks for the advice , point well taken

[mrjazz1959]

Found some info on damping:

Source 1 says:

Loudspeakers with piston cones will continue to move in the direction they are pushed from cone inertia when the drive signal has stopped. The idea of electrical damping is to use the output circuit of the amp which connects to the voice coil to act like a low impedance short circuit to the voice coil after the drive signal is gone. This makes the voice coil, working now like an electrical generator under heavy load to come to a faster halt, reducing its tendancy to ring or overshoot. The sound of percussive events like kick drums will sound mushy if the loudspeaker is underdamped.

You can demonstrate this for yourself by taking a woofer and carefully pushing/pulling the cone from the edges with your fingers. It will move fairly easily within the limits set by the spider and surround. Now take a wire and short circuit the speaker terminals and repeat the test. Now it will be noticeably more difficult to move the cone in and out. You have turned the driver into a generator and it is convcerting the work you are inputing with your fingers into electrical energy that is being converted into small amounts of heat in the shorting wire.

Solid state power amps typically have high damping factors whereas vacuum tube amps have rather low damping factors.

One way to increase the damping factor of any amp is to add negative feedback. Solid state amps mostly employ huge amounts of negative FB which in part explains their high damping factor. If a tube amp manufacturer places a user adjustable negative FB control on the amp they could conceivably label it "Loudspeaker Damping Control". Best to set this control while listening to music with good percussion and set this control for most pleasing, tight reproduction with whatever speakers you are using.
Some speakers are highly damped by the air against the cone, especially the case in horns. This explains why horns can sound so good producing tight 'fast' sound with tube amplifiers despite the generic lack of good damping in tube amps. My number one speaker recommendation for use with a low damping factor amplifier? Large full-range horns!
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Source 2 says:

Damping in the proaudio world is lowering certain frequencies. So high damping is lowering the higher frequencies, which will give a less detailed, bassier sound. Low damping will remove the low frequencies, giving you an edgier, more trebley sound. It's often found on reverb or modulation units.

[elgrau]

Sorry, dude, but someone just ain't gettin it. This adjustment MUST be very carefully set using a signal generator, "dummy" speaker load (high wattage resistors), and a digital volt meter to exactly set the spec values (input and output). It's so very sensitive that to try and do it "by ear" is just total folly...and most likely will lead to something getting ruined... It's not at all a "by ear" adjustment nor related in any way to any particular speaker. Just a technical adjustment: when it's spot on, the amp will sound best for ALL speakers, when "off", the amp will sound very flat and "non-musical". Not at all about "sound preference". But do whatever you want. Forewarned!

Do yourself a huge favor and download the service manual for this amp....here or at the other Carver site, I believe.