AudioCircle
Industry Circles => Audio by Van Alstine => Topic started by: Wayner on 11 Aug 2010, 08:02 pm
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Perhaps this should be in the vinyl circle, but that would restrict some of my comments (pro AVA stuff), so it is better suited to Frank's circle. Others from the vinyl circle and other ilks may join, but understand you are in an owner's thread.
To start, let me say that in the last month or so, with my newly created turntable ARCom, I have never enjoyed vinyl with such excitement. Perhaps it's the synergy between the components, like the Insight+ EC preamp with the optional phono board, or the Ultravalve amplifier or even the Dynaco modded A25XL's, the fact is, there is some superb vinyl being played at this house.
There is an indescribable thrill listening to vinyl, and have the end of the song fade to black. Of course, a clean record helps, but so does a clean signal. When you have everything right, the system lets you know as it vanishes, letting the music be the center of attention, rather then the equipment.
One of those evil little mood destroyers is that dreaded hummmmm, that every vinyl guy/gal fears. It ruins the music, and leaves the listener watching TV. Where does the hum come from? Is there more then once source of hum? Can I have more then one cause?
I hope some of you jump in with some of your stories. Hopefully you can post a cause and a solution, and if you have a problem, perhaps the minds here can help you find a solution.
As I was finishing ARCom, I had a slight hum problem. The hum wasn't really in the normal playing level, but, like most of you, I jack the volume up when I'm not playing a record, just to see what the background is like. Well at about 11:30 position, the hum would start to show up. It took me 2 days to figure out that it was the ungrounded mounting base for my AR ES-1 tonearm that was the cause.
Lesson learned. If it's a metal part connected to the tonearm in any way shape or form, it's an antenna element. Unless it's grounded, it's a case for being a hum producer. Sure the body of the tonearm is grounded, but the ground thru the pivot is weak. It's a moving pivot that doesn't sometimes offer the best path for grounding, so the enemy was the metal base. An attachment wire to the ground screw was the fix.
I'm sure there are other stories out there.
Wayner
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Wayner,
Because it doesn't know the words! :lol:
Ron
P.S. I couldn't resist. That's one of Frank's comebacks!
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I thought it would take a couple of posts for this one to come up, but Ron wins! You beat Frank to the punch. Sweet.
Wayner :D
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I've been lucky thus far as I've never had a hum problem with my turntable. I used to have a real low level hum (even before adding a table) which I assumed was due to the DHT in my Supratek preamp. It didn't interfere with the music and I just kinda figured it would always be there. I then picked up a BPT 3.5 which has now made the hum almost non-existent. I say almost because I really have to crank it up, put my ear next to the speaker, and listen for the hum. I bet whenever I sell my house, my next place will probably have all manner of ground loops and hum problems just to punish me for all the years of silence I've enjoyed.
Kevin T
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I learned on the Galibier forum that those guys have a ground harness. Tonearm mount, bearing, chassis, etc. The harness has bullet connectors so you can try grounding different parts together. I've not had much of an issue until I started using a step up transformer now the rig got a touch more finnicky.
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Wayner I have an old Pro-ject 1.2 that I have a problem with Hum when I turn my omegastar (pat 5) up to 11:30 do you think adding a wire to the base of the tonearm would help this? the cart I'm using is audio-technica ML a
Ps wayner Just love your new turntable and would like to build one like it.
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Are you using the AT440MLa? There was a recall on these cartridges because they had a shielding problem and the cartridges hummed like no tomorrow. If you bought yours about a year and 1/2 ago, it might be a bad one. It certainly is not the fault of the AVA preamp or it's phono board.
Thanks for the comments on ARCom. It was a very successful project and I want to build another one based on the RB300 tonearm, using the same platter, bearing, but need to go with a different motor.
Wayner :D
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Install shorting RCA plugs into the phono inputs of your preamp and carefully crank up the volume and see how the noise level compares to when the TT is connected.
This will give you an idea as to how much noise is originating in the preamp and how much from the TT system.
Note that several years ago we did make a running change in the grounding of our solid state phono boards that really helped reduce residual hum levels. The ground wire (black wire running to the power supply board ground) should be connected near the bottom middle of the phono board, not near the top. Check this out please on your unit.
Regards,
Frank Van Alstine
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Are you using the AT440MLa? There was a recall on these cartridges because they had a shielding problem and the cartridges hummed like no tomorrow. If you bought yours about a year and 1/2 ago, it might be a bad one. It certainly is not the fault of the AVA preamp or it's phono board.
Thanks for the comments on ARCom. It was a very successful project and I want to build another one based on the RB300 tonearm, using the same platter, bearing, but need to go with a different motor.
Wayner :D
Yea Wayner It is a 440 ML a don't know why I didn't put that in the post, I'll check my records and see when I bought it But with that being said It doesn't hum in My AVA T-7 pre-amp.
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Install shorting RCA plugs into the phono inputs of your preamp and carefully crank up the volume and see how the noise level compares to when the TT is connected.
This will give you an idea as to how much noise is originating in the preamp and how much from the TT system.
Note that several years ago we did make a running change in the grounding of our solid state phono boards that really helped reduce residual hum levels. The ground wire (black wire running to the power supply board ground) should be connected near the bottom middle of the phono board, not near the top. Check this out please on your unit.
Regards,
Frank Van Alstine
Ok Frank will do and thanks
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r1seals,
If you have a volt/ohm meter, see if you get continuity from the tonearm base to the turntable ground. If not, that could be the source of the hum. Care must be taken when attaching an additional ground as it really should be done in the "star" configuration, as all ground attachments end up in one point, rather then a series jump from one part to another.
The AT sounds like it is OK, because it would hum with every phono input on any preamp.
Wayner
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Install shorting RCA plugs into the phono inputs of your preamp and carefully crank up the volume and see how the noise level compares to when the TT is connected.
This will give you an idea as to how much noise is originating in the preamp and how much from the TT system.
Note that several years ago we did make a running change in the grounding of our solid state phono boards that really helped reduce residual hum levels. The ground wire (black wire running to the power supply board ground) should be connected near the bottom middle of the phono board, not near the top. Check this out please on your unit.
Regards,
Frank Van Alstine
Frank I did remove the cover and the black wire is at the bottom like you said so guess that was done last time it was with you. I tried to send a picture with no luck. oh well I'll try later.
I don't have any shorting RCA plugs so didn't do that is there something else I can use?
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r1seals,
If you have a volt/ohm meter, see if you get continuity from the tonearm base to the turntable ground. If not, that could be the source of the hum. Care must be taken when attaching an additional ground as it really should be done in the "star" configuration, as all ground attachments end up in one point, rather then a series jump from one part to another.
The AT sounds like it is OK, because it would hum with every phono input on any preamp.
Wayner
Ok wayner I will do that to we have a rain day here so I will get to that today thanks
Russ
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I have a technics 1200, suddenly got a high hum when I turn the pre to mc even with the tt off.
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Remove your headshell and clean the contacts on the headshell and the arm. This is the first place I would start. Use some rubbing alcohol if you have nothing else like Caig's De-oxit 5 or in a pinch, a pencil erasure works good too.
I have also noticed that I can induce hum into the SL1200 by over-tightening the headshell nut. Not sure what's going on, but make it snug, not monkey wrenched on.
Wayner
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I did clean the contacts, still with the hum, even disconecting from wall, the only way is disconecting from the preamp. any advise?
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Any chance you have other things on the line like a dimmer switch? I read this with interest - I had a right channel hum in my phono line the other day and couldn't figure it out - changed the interconnects and it went away. Wished I knew why . . .
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I did clean the contacts, still with the hum, even disconecting from wall, the only way is disconecting from the preamp. any advise?
OK, next take your headshell off and rotate each clip on the cartridge pins, not physically moving them from one pin to another, but rather just moving them on the existing pin to scrape away any film that may have collected, especially the right ground (green wire). Lots of cartridge bodies use this pin to ground the cartridge body.
By the way, with the hum, do both channels still work?
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I did remove the headshell, the ac from the outlet and still with the hum,I can not change the IC from the TT. and yes both channels work well.
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Well, did your ground wire from the TT to the preamp get loose or fall off?
Wayner
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no, I double check.
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Now I suspect your phono preamp.
Wayner
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I changed the IC from mc to mm , and still with the hum ( in mm)
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Go to Radio Shack, get a set of shorting RCA plugs, and make the test I suggested earlier.
The easy way to isolate your hum issue.
Regards,
Frank Van Alstine
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ARCom problem got solved today. I had a very faint residual hum, entering the picture at about 2 o'clock on the volume control. Of course, my ego got in the way and I thought that everyone else was the problem. Today I moved ARCom to a different spot in the studio, plugged it into the preamp and advanced the volume control, to find that it was dead silent. I thought it must have been one of the amps magnetic fields, kind of thinking that the AR-ES1 tonearm has a slight shielding problem (which it still may have). However, after I connected the motor module, the hum came back. :duh: It's the motor! I replaced the switch make/break capacitor with a .022 mfd/600 volt cap that I got from an AR turntable. This knocked the noise down, but grounding the motor itself to the ground point to preamp completely (for all practical purposes) killed it.
Lessen learned, next motor assembly will have a 3-prong cord with a grounded motor. I think I'm my own worst enemy.
Now back to some serious vinyl.
Hope you all have a nice Friday nite.
Wayner