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TFM-45 Bias,offset,damping adjustment procedure

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mbskeam

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SILVER-7t

Posts: 1830

Joined: Mon Jan 25, 2010 2:32 am

Location: Woodinville Wa

Post Tue Mar 23, 2010 8:44 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

HOLLY PICTURES BATMAN....LOL

thanks,
but ....
Adjust RP2 on each amp board until you get 1v across the 8ohm load resistor at each output


so do I put the leads on each side of the load resistor?

this is new to me also, so any help, thanks.....
Mbskeam


#1 BLACK BEAUTY's made by the man, the myth, the legend Bob Carver
CARVER: TFM-75, TFM-45(3), SD/A-490T
SUNFIRE: Tube pre
2 sets of ALS'3, set of SILVERS, set of PLATS
AUDIOCONTROL: phase coupled activator
KENWOOD: BASIC M2a (2)

“Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.”
― Aristophanes

The only thing I'll feel......will be the RECOIL
Necronomicon Ex-Mortis....... Klaatu Barada Nikkto
"We should seek the greatest value of our action"
<<

elgrau

SILVER-7 TUBE AMP

Posts: 2858

Joined: Wed May 31, 2006 9:33 pm

Post Tue Mar 23, 2010 9:37 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

Yep
Family room: 400 disk changer with PS Audio Digital Link III DAC; Technics SL-1100A TT. QED Quenx1 IC's from DAC & TT to Adcom GTP-602 preamp/Tuner. AudioQuest King Cobra IC's from preamp to M1.0t mk-II opt2. QED Silver Spirals 4M wires to EPI 1000’s.
Living room: AudioQuest Black Mamba 8M IC's from family room preamp to Barcus-Berry 2002R Sonic Maximizer to GlowPower Zyxt IC's to Sunfire 300x2 to Nordost 6M bi-source wires to AOS 28" MDF spherical speakers using six 8" woofers and eight 1" dome tweeters symm. arranged around the surface.
SS system: CX-995V DVD to AV-705x 5 channel amp (center/rears) & M1.0t mk-II opt2(fronts).
Garage: TLM-3600 CDP to MXR150 Receiver (pre) to TFM-42 to EPI 400 speakers.
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gunner64

Newbie

Posts: 44

Joined: Sun Mar 14, 2010 11:57 am

Location: Dubuque,Iowa

Post Tue Mar 23, 2010 9:43 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

Just make sure you're on the same board as the output you're testing.

Yea,I know freaking trainwreck of a post.sorry for that!I tried to make the pics smaller but like I mentioned,I'm more or less not computer friendly,so my efforts to decrease the size were futile.Again accept my apologies,for I've made a huge mess!But hey, if you take it down to 50% or less you can see were the adjustments are in the amp.Hey I tried.........And any suggestions you can give me as to how I can post normal size photos without looking like an idiot would be appreciated.Not that I won't look like an idiot,just an idiot with normal sized pics.

Robert
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mbskeam

User avatar

SILVER-7t

Posts: 1830

Joined: Mon Jan 25, 2010 2:32 am

Location: Woodinville Wa

Post Wed Mar 24, 2010 12:14 am

Re: TFM-45 Bias,offset,damping adjustment procedure

try this, very easy to load and use
works real nice.....

http://bluefive.pair.com/pixresizer.htm

this is a small stand alone program that you open when needed, and close when done, unlike some of the crap that likes to run all the time and worms it way into places they dont need to be.....
Mbskeam


#1 BLACK BEAUTY's made by the man, the myth, the legend Bob Carver
CARVER: TFM-75, TFM-45(3), SD/A-490T
SUNFIRE: Tube pre
2 sets of ALS'3, set of SILVERS, set of PLATS
AUDIOCONTROL: phase coupled activator
KENWOOD: BASIC M2a (2)

“Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.”
― Aristophanes

The only thing I'll feel......will be the RECOIL
Necronomicon Ex-Mortis....... Klaatu Barada Nikkto
"We should seek the greatest value of our action"
<<

elgrau

SILVER-7 TUBE AMP

Posts: 2858

Joined: Wed May 31, 2006 9:33 pm

Post Wed Mar 24, 2010 11:46 am

Re: TFM-45 Bias,offset,damping adjustment procedure

That (previous) program will most likely work fine for what you need, Gunner; but if not, I bought ($29 or such) a commercial one called Jpegsizer (google it if interested). Works great!
Family room: 400 disk changer with PS Audio Digital Link III DAC; Technics SL-1100A TT. QED Quenx1 IC's from DAC & TT to Adcom GTP-602 preamp/Tuner. AudioQuest King Cobra IC's from preamp to M1.0t mk-II opt2. QED Silver Spirals 4M wires to EPI 1000’s.
Living room: AudioQuest Black Mamba 8M IC's from family room preamp to Barcus-Berry 2002R Sonic Maximizer to GlowPower Zyxt IC's to Sunfire 300x2 to Nordost 6M bi-source wires to AOS 28" MDF spherical speakers using six 8" woofers and eight 1" dome tweeters symm. arranged around the surface.
SS system: CX-995V DVD to AV-705x 5 channel amp (center/rears) & M1.0t mk-II opt2(fronts).
Garage: TLM-3600 CDP to MXR150 Receiver (pre) to TFM-42 to EPI 400 speakers.
<<

gunner64

Newbie

Posts: 44

Joined: Sun Mar 14, 2010 11:57 am

Location: Dubuque,Iowa

Post Wed Mar 24, 2010 12:15 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

Thanks guys,I'll give the first one a try.I couldn't do any worse,thats for sure.

Robert
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gary_wong5

Newbie 50+

Posts: 70

Joined: Fri May 16, 2008 8:17 pm

Post Wed Apr 21, 2010 9:29 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

gunner64 wrote: 3.Set Damping.Attach an 8 ohm dummy load to both outputs.I used 2, 20w 8 ohm resistors from radio shack.The amp will be only outputting 1v,so the 20watters will be o.k. for this adjustment.Insert a 2khz 36mv signal to the inputs of the amplifier.Use the signal generator from Higherfi.com and your preamp to get the proper signal if you don't have a dedicated signal generator.Once I got a 2khz signal I adjusted the volume on the preamp for 36mv at the pre-outs.Adjust RP2 on each amp board until you get 1v across the 8ohm load resistor at each output.Keep in mind your pots here may look dif. than mine,as mine have been replaced per damping drift fix at back of service manual.]


Hi gunner64, I have bought digital multitester. Please put some pictures on how you feed 2kHz signal. How is signal generator looks like? :?
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gunner64

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Posts: 44

Joined: Sun Mar 14, 2010 11:57 am

Location: Dubuque,Iowa

Post Fri Apr 23, 2010 6:30 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

you need to go to the higherfi.com and download the test bench.one of the options on the test bench is a signal generator.just follow the instructions I posted earlier(with pics)you'll need a y cable with l/r rca plugs on one end and a corresponding jack from your computers audio out on the other.I used the headphone jack on my laptop.
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gary_wong5

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Posts: 70

Joined: Fri May 16, 2008 8:17 pm

Post Sun Apr 25, 2010 9:55 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

It is no way to get 20W8ohm resistor locally unless get from internet. There are two nearest spec., viz. 10W8.2ohm and 25W10ohm. Can I use or modified to use either of these?
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gary_wong5

Newbie 50+

Posts: 70

Joined: Fri May 16, 2008 8:17 pm

Post Wed May 12, 2010 7:14 am

Re: TFM-45 Bias,offset,damping adjustment procedure

gary_wong5 wrote:It is no way to get 20W8ohm resistor locally unless get from internet. There are two nearest spec., viz. 10W8.2ohm and 25W10ohm. Can I use or modified to use either of these?


There is no shipment to Malaysia for 20W8ohm from both Parts Express or Amazon, can anyone here advise where to get the right 20W8ohm resistors? Thanks!
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BillD

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(pair of) SILVER-7 TUBE AMPs

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Joined: Wed Jun 06, 2007 8:29 pm

Location: The west's most mid-western town, Scottsdale, Arizona

Post Wed May 12, 2010 11:05 am

Re: TFM-45 Bias,offset,damping adjustment procedure

I did a little look at Mouser and Digi-Key. Here's the cheapest I could find (I went up to 50 Watts because they are cheaper than 20W).
http://www.mouser.com/ProductDetail/Arcol/HS50-8R0-1/?qs=sGAEpiMZZMuQ5%2fsBR7SoApeYXA2q7aZRcfiEEp0lbLA%3d
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
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Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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mbskeam

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SILVER-7t

Posts: 1830

Joined: Mon Jan 25, 2010 2:32 am

Location: Woodinville Wa

Post Wed May 12, 2010 2:47 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

this weekend as I was digging into my wire box, I find a set of resistors.
I set these out thinking I may need these....... :-s
then I read that you cant find the resitors you need, so I look and they are the size you need.
you can borrow them if ya need to, let me know.......
got these years ago at an autoparts store.....napa I think
Mbskeam


#1 BLACK BEAUTY's made by the man, the myth, the legend Bob Carver
CARVER: TFM-75, TFM-45(3), SD/A-490T
SUNFIRE: Tube pre
2 sets of ALS'3, set of SILVERS, set of PLATS
AUDIOCONTROL: phase coupled activator
KENWOOD: BASIC M2a (2)

“Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.”
― Aristophanes

The only thing I'll feel......will be the RECOIL
Necronomicon Ex-Mortis....... Klaatu Barada Nikkto
"We should seek the greatest value of our action"
<<

gary_wong5

Newbie 50+

Posts: 70

Joined: Fri May 16, 2008 8:17 pm

Post Fri May 14, 2010 10:26 am

Re: TFM-45 Bias,offset,damping adjustment procedure

BillD wrote:I did a little look at Mouser and Digi-Key. Here's the cheapest I could find (I went up to 50 Watts because they are cheaper than 20W).
http://www.mouser.com/ProductDetail/Arcol/HS50-8R0-1/?qs=sGAEpiMZZMuQ5%2fsBR7SoApeYXA2q7aZRcfiEEp0lbLA%3d


Hi BillD, USD3.26 x 2= USD6.52 plus courier charge USD40.00, total USD46.52 sounds too heavy to buy #-o
<<

BigBadWally

Newbie

Posts: 7

Joined: Wed Aug 24, 2005 8:31 pm

Post Fri May 21, 2010 10:45 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

gunner64 wrote: 3.Set Damping.Attach an 8 ohm dummy load to both outputs.I used 2, 20w 8 ohm resistors from radio shack.The amp will be only outputting 1v,so the 20watters will be o.k. for this adjustment.


Thanks much for the descriptions and the pics. I'll be recapping and adjusting my TFM-45 soon and this info will definitely come in handy. I have a question, though. Why use such high wattage load resistors? You mentioned that while adjusting the damping the amp will output 1V. If this is the case, since power is equal to voltage squared divided by the resistance, the the power dissipated is (1 * 1) / 8 = 1/8th watt. Double that to 1/4 watt for some margin and you're good to go. Mouser sells an 8 ohm 1/4 watt metal film resistor (1% tolerance) for around a buck. Or am I missing something?
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elgrau

SILVER-7 TUBE AMP

Posts: 2858

Joined: Wed May 31, 2006 9:33 pm

Post Fri May 21, 2010 11:38 pm

Re: TFM-45 Bias,offset,damping adjustment procedure

It's a VERY sensitive adjustment and if you adjust it too much in the "wrong" direction (evidently) the voltage can go up a lot. I did this with mine and the resistors heated up REAL fast (and smelly!).
Family room: 400 disk changer with PS Audio Digital Link III DAC; Technics SL-1100A TT. QED Quenx1 IC's from DAC & TT to Adcom GTP-602 preamp/Tuner. AudioQuest King Cobra IC's from preamp to M1.0t mk-II opt2. QED Silver Spirals 4M wires to EPI 1000’s.
Living room: AudioQuest Black Mamba 8M IC's from family room preamp to Barcus-Berry 2002R Sonic Maximizer to GlowPower Zyxt IC's to Sunfire 300x2 to Nordost 6M bi-source wires to AOS 28" MDF spherical speakers using six 8" woofers and eight 1" dome tweeters symm. arranged around the surface.
SS system: CX-995V DVD to AV-705x 5 channel amp (center/rears) & M1.0t mk-II opt2(fronts).
Garage: TLM-3600 CDP to MXR150 Receiver (pre) to TFM-42 to EPI 400 speakers.
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