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Carver M-4.0 ...A/C Hum

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DuncanAudio

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Joined: Sat Oct 01, 2011 2:19 pm

Post Sat Oct 01, 2011 2:56 pm

Carver M-4.0 ...A/C Hum

Hello... Carver fans... I'm new to this site , but a owner of many Carver components... Trying to figure out the source of a "Nasty" ...A/C hum issue w/ an Carver M-4.0 Amp. This amp is a recent Ebay Gamble.. Ha! I'm an Ebayer! [ DuncanAudio777 ]

What I have tried: When I Isolate the amp w/ a pair of speakers... a loud & horrendous A/C growl... from L & R channels comes forth. When hooked up to the system.. the hum drops considerably ! ?? It is a bit strange that the noise level lowers as much as it does, but it is still present... I know this is NOT normal. My first inclination is power supply caps? One can spend as much $$ on all the caps ... than I paid for the amp, so I do not want to just start replacing 9000 uf caps @ $ 60.00+ each. The unit is in great cosmetic condition so I'm willing to upgrade as needed... May even upgrade signal path caps w/ audiophile grade caps... Any input would be great....[/b][/size]
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treitz3

User avatar

"Julian"
"Julian"

Posts: 7746

Joined: Mon Oct 16, 2006 5:39 pm

Location: The tube lair in Charlotte, NC

Post Sat Oct 01, 2011 3:14 pm

Hello and welcome to the carver forum. Do you have any fluorescent lights, solid state dimmer switches or SS IR controls for a fan on the same circuit? You may try to flip the plug 180 degrees on the amplifier itself [where it actually plugs into the wall] and get back to us to see if that works.
In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence.

The best way to enjoy digital music reproduction is to never listen to a good analogue reproduction.

Robert R. - "Did you see my North Korea analogy? I should have named it Carversite.kim"
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DuncanAudio

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Posts: 3

Joined: Sat Oct 01, 2011 2:19 pm

Post Sat Oct 01, 2011 4:51 pm

Re: Carver M-4.0 ...A/C Hum

Hi Julin... thx for welcome & reply... I have tried all of the simple issues... it is not a " ground loop" problem.

"Do you have any fluorescent lights, solid state dimmer switches or SS IR controls for a fan on the same circuit?" ....Nope.

The thing that puzzles me is ... amp w / a speaker load isolated... the hum is more like a... ROAR , which begins to harm one's ears ??? I hooked up a ...Carver PM 175 to same circuit & speakers .... DEAD Quiet... as it should be.
No visible signs of leakage or stress on 4.0 PS caps, but I realize they are aging....

PS... a bit later.. Just finished re-checking....amp w/ a pr. of speakers isolated... using an extension cord , ..went about the house trying other outlets... same exact results & rage.
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jjptkd

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SILVER-7 TUBE AMP

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Location: Snohomish, WA

Post Sat Oct 01, 2011 9:35 pm

Re: Carver M-4.0 ...A/C Hum

I've experienced the same thing with an M-4.0t that I had awhile back. If you plugged in the amp to speakers without RCAs hooked up, a very loud hum came through the speakers. I think I discovered it when I was attempting to do an A/B comparison with a different amplifier. The hum wasn't present in the amp at all until I disconnected the RCAs then HHHMMMMMM!! Scared the crap right out of me!! I asked Rita (Carver's old tech) if that was normal and she just asked me why I'd have it hooked up that way in the first place. That amp was refurbished with all new caps and it still did it. Now I unplug everything before I attempt to make changes in my system, something I know I should of been doing anyway but for awhile there it was multiple amplifiers just about every day and I got lazy. :lol: Anyway, Welcome!! =D>
Sunfire TGP-III
Sunfire 405x5
PS Audio DL-III DAC
(2 Pairs) Klipsch Chorus II's
Klipsch RSW 15
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engtaz

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"TAZ"

Posts: 5208

Joined: Sat Jun 30, 2007 1:43 pm

Location: Tampa, FL

Post Sun Oct 02, 2011 1:28 am

Re: Carver M-4.0 ...A/C Hum

Welcome DuncanAudio
engtaz


Carver M4.0T in front channels to Caver AL VI's in SACD & 2 Channel setup
C 16, PT 2400, Slim Device, Carver TX-8, 490T and Rega TT w Grado Gold cart in the 2 channel setup
Bogen SRB20 is computer amp
Carver PM-350 donated for youth church use
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frenchguy

SILVER-7t

Posts: 1649

Joined: Fri May 14, 2010 11:53 pm

Location: wisconsin,home of the Green Bay Packers!

Post Sun Oct 02, 2011 4:02 am

Re: Carver M-4.0 ...A/C Hum

So tom, would you like us to start calling you Julian from now on ??? LOL
Carver M-4.0t & Rollandized tfm42, ct-6 & ct-17, sda390t, jolida jd 100A & JBL L96,s Modified JBL 4401,s W/Ribbon Tweeters, Carverfest vacuum tube amp & Dared SL-2000A tube preamp, Carver AL3 amazing speakers in natural oak & Douglas connection cables
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treitz3

User avatar

"Julian"
"Julian"

Posts: 7746

Joined: Mon Oct 16, 2006 5:39 pm

Location: The tube lair in Charlotte, NC

Post Sun Oct 02, 2011 8:15 am

Sure. You wouldn't mind me calling you TFM-6cb, would you? :D It's all good. Folks can call me whatever they would like.



Duncan, the hum while the RCA's are disconnected does not surprise me. As jjptkd has mentioned, this happens even on newly refurbed units as well. It wasn't until he mentioned this that I was reminded that this is normal [Mine did the same thing after refurb when I powered up and forgot the RCA input connection on a recently refurbished M4.0t].

Let me ask you this.....when you changed out the 4.0t with the PM amp, is there anything else that changed? I mean anything beyond the PC, L&R SC's and the L&R RCA's?
In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence.

The best way to enjoy digital music reproduction is to never listen to a good analogue reproduction.

Robert R. - "Did you see my North Korea analogy? I should have named it Carversite.kim"
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frenchguy

SILVER-7t

Posts: 1649

Joined: Fri May 14, 2010 11:53 pm

Location: wisconsin,home of the Green Bay Packers!

Post Sun Oct 02, 2011 8:31 am

Re: Carver M-4.0 ...A/C Hum

you need to remove the hair on that avatar tom!!! :lol:
Carver M-4.0t & Rollandized tfm42, ct-6 & ct-17, sda390t, jolida jd 100A & JBL L96,s Modified JBL 4401,s W/Ribbon Tweeters, Carverfest vacuum tube amp & Dared SL-2000A tube preamp, Carver AL3 amazing speakers in natural oak & Douglas connection cables
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DuncanAudio

Newbie

Posts: 3

Joined: Sat Oct 01, 2011 2:19 pm

Post Sun Oct 02, 2011 7:46 pm

Re: Carver M-4.0 ...A/C Hum

TOM ... sorry about that lol

THX ...Everyone ... ALL comments are right on target ! AS ...we all know ... Rita's Comment is true. Why ?
I was swapping out amps while testing the M - 4.0... first noticed a hum while no music was playing. Not... the typical high power hiss. I use multiple amps & speakers @ the same time. Anyway..the , M-4.0 was the only one w/ any A/C noise . I pulled the amp out ..hooked a small set of test drivers to amp ... W/ ..No RCA ..In put. Why? To put a load on the amp & listen to see if the power tranny is humming OR ... hum from speakers only. As stated ... When this girl warmed up! ...she started.. P M S _ing !
I have owned many Carver amps .... still have my 15cb. NEVER... have I heard such a ROAR...from a SS amp. I own & tinker w/ tube amps, have had this happen w/ a tube amp w/ bad caps. Anyway, Having read many blogs & Carver posts... I'm finding out that this is... " normal " ??? However.... Read the Service Notes in the TFM 42/45 - M-4.0 manual last night... Found some great repair/ changes that address the excessive " buzzing " issues of these models.... SO GLAD I READ this info... as stated by others, Changing caps do NOT fix ..ALL ..Hum/buzz issues. There are several changes { by Carver } to power supply & lowering the input ohms... to lower noise ... I plan to try these "factory Fixes"
My personal add on.... Adding some shielding around Power Tranny & down the side of the Right Channel Rail

Really like the sound of the M-4.0.... I'm a Tube Lover , but my Power Hungry... JBL L'7s needed more juice than most tubed amps can deliver...
BTW/. Really like the sound of the TFM's ... Hate the A Series Amps that C. Corp. made. Sound harsh & horrible to me. Bet they would perform better w/ Higher Grade caps... I wanted to hear the M-4.0 ... due to the " tube modded sound" .... Later! D` I "m glad to be a part of this forum.... I do NOT need a $30,000 dollar SNOB Amp.... Give me a Carver..... then trick it out w/ Audiophile Grade caps ....I will let ya know how it turns out!
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treitz3

User avatar

"Julian"
"Julian"

Posts: 7746

Joined: Mon Oct 16, 2006 5:39 pm

Location: The tube lair in Charlotte, NC

Post Sun Oct 02, 2011 8:03 pm

Duncan, you remind me a lot about LB. Forgive me if you do not know who he is.

Let me ask you this.....when you changed out the 4.0t with the PM amp, is there anything else that changed? I mean anything beyond the PC, L&R SC's and the L&R RCA's?


Could you please answer this one question for us?
In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence.

The best way to enjoy digital music reproduction is to never listen to a good analogue reproduction.

Robert R. - "Did you see my North Korea analogy? I should have named it Carversite.kim"
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Mr. M-500t

(pair of) SILVER-7 TUBE AMPs

Posts: 6211

Joined: Fri Mar 17, 2006 10:00 pm

Post Sun Oct 02, 2011 8:06 pm

Re: Carver M-4.0 ...A/C Hum

You should really give an M-500t a listen. They sound great with JBL's.

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