Author Topic: Tube Preamp humming (Read 3002 times)

threadlock · « **on:** Jun 17, 2008 at 11:45 AM »

Is it normal for tube preamp to cause humming?
This is actually paired with a SS poweramp and im sure it's not the poweramp since I already isolated and tested the poweramp with another preamp/processor and it's not the one causing the hum.
I've checked all the connections and even tried a few times disconnecting and reconnecting and the hum is still there. All interconnects and wires used are brand-new.

Previously, I thought it was because I placed the preamp on top of the power amp. But I also tried spacing the two 2 feet away but the hum is still there.

The hum is constant at all volume levels, and it's coming from the two speakers.
Both the tube pre and the poweramp is connected to a Panther powerstrip which is connected to a house outlet.
Except for the annoying hum, the tube-pre+ss poweramp combo actually sounds great and is better than my Denon AVR.

dana · « **Reply #1 on:** Jun 17, 2008 at 12:19 PM »

what is your preamp & the tubes in it?
first time to use this pre amp in your system?
could be inherent in the design/internal wiring/grounding...?

you can try the ffg:
try reversing the ac plug connection of your preamp to ac outlet.
try also different tubes (spares, if you have).
try shielding the preamp transformer with aluminum foil and ground it in the chassis (ingat lan not to contact the B+ supply of your preamp...)
try putting tube metal shields.

threadlock · « **Reply #2 on:** Jun 17, 2008 at 12:29 PM »

yes, first time user of tube preamp.
preamp is tono violin, tubes are 2 x JAN CHY 5692, RCA ECC8 rectifier. Currently I have no spare tubes as I just recently bought it from another forum.
Thanks sir, I'll try some of your advises.

JojoD818 · « **Reply #3 on:** Jun 17, 2008 at 12:40 PM »

first of all, how loud is the hum?

tube gears have small amount of acceptable hum that should only be heard when you put your ears right next to the speaker cones. if the hum is not noticeable about 1 foot away then it's just about normal.

dana · « **Reply #4 on:** Jun 17, 2008 at 12:57 PM »

yes, agree.baka sobrang hina lang naman, unless you put your ear near the speaker.
just the same, try mo rin baka mag improve pa level...

Jagner · « **Reply #5 on:** Jun 17, 2008 at 01:05 PM »

Did you try earth grounding

threadlock · « **Reply #6 on:** Jun 17, 2008 at 01:15 PM »

Quote from: JojoD818 on Jun 17, 2008 at 12:40 PM

first of all, how loud is the hum?

tube gears have small amount of acceptable hum that should only be heard when you put your ears right next to the speaker cones. if the hum is not noticeable about 1 foot away then it's just about normal.

The hum is quite acceptable naman especially in the listening position when there is already music playing. Im just actually thinking if it can be lowered in levels since in my room it's really VERY QUITE I can hear even the ticks of my wall clock 2 meters away when no music is playing. Im just annoyed when I hear the hum during silent passages in music or during silence in between tracks.
My room is acoustically treated with Panel Resonator basstraps and broadband absorbers, so the noise floor is very small it's almost dead quite, especially at night. My listening volume is about 75dB for jazz, classical, chamber music, female vocals, upping it to 85dB is already very loud.

Maybe, I'll try the grounding, thanks for all the suggestions.

JojoD818 · « **Reply #7 on:** Jun 17, 2008 at 01:37 PM »

Quote from: threadlock on Jun 17, 2008 at 01:15 PM

The hum is quite acceptable naman especially in the listening position when there is already music playing. Im just actually thinking if it can be lowered in levels since in my room it's really VERY QUITE I can hear even the ticks of my wall clock 2 meters away when no music is playing. Im just annoyed when I hear the hum during silent passages in music or during silence in between tracks.
My room is acoustically treated with Panel Resonator basstraps and broadband absorbers, so the noise floor is very small it's almost dead quite, especially at night. My listening volume is about 75dB for jazz, classical, chamber music, female vocals, upping it to 85dB is already very loud.

Maybe, I'll try the grounding, thanks for all the suggestions.

If you can hear the hum when you are seated at your listening position then it's not acceptable at all. Better check all connections and see if hum disappears, or try the preamp with another amp and if hum persists, have your unit checked. Loosely seated tubes can also cause hum problems.

alexg · « **Reply #8 on:** Jun 18, 2008 at 09:44 AM »

Quote from: threadlock on Jun 17, 2008 at 01:15 PM

The hum is quite acceptable naman especially in the listening position when there is already music playing. Im just actually thinking if it can be lowered in levels since in my room it's really VERY QUITE I can hear even the ticks of my wall clock 2 meters away when no music is playing. Im just annoyed when I hear the hum during silent passages in music or during silence in between tracks.
My room is acoustically treated with Panel Resonator basstraps and broadband absorbers, so the noise floor is very small it's almost dead quite, especially at night. My listening volume is about 75dB for jazz, classical, chamber music, female vocals, upping it to 85dB is already very loud.

Maybe, I'll try the grounding, thanks for all the suggestions.

Why don't you ask the Tono boys at wiredstate.com for help, they should be happy to help you out.

For me, an acceptable hum should not be heard at your listening position. I am not even happy with hum with my ears a foot away from my speakers.

HTH

Philjonc · « **Reply #9 on:** Jun 19, 2008 at 05:03 PM »

Quote from: JojoD818 on Jun 17, 2008 at 12:40 PM

first of all, how loud is the hum?

tube gears have small amount of acceptable hum that should only be heard when you put your ears right next to the speaker cones. if the hum is not noticeable about 1 foot away then it's just about normal.

yes this is true, i use a tono violin 6sn7 tube preamp it may be the EH or the 5692, yes i hear hum(normal in tube gears) but only when i put my ears about 3 inches from the speaker cone. i used this with high powered amp and low powered amp but the same level of hum sound.
didnt you hear any hum when you auditioned it?

skee6 · « **Reply #10 on:** Jun 26, 2008 at 07:59 PM »

Suggest bring it to Mang Rod.tel 5221696. He can easily solve your hum problem while you wait.

threadlock · « **Reply #11 on:** Jul 07, 2008 at 11:51 AM »

I brought it to Mang Rod and he was really great! He was able to fix the problem by modifying the power supply
and as an added bonus I also got another pre-outs. There is still humming but can only be heard when you stick your ear a few inches from the speaker cone, it is no longer heard in the listening position.
I thought I would just sell the preamp but now it's for the keeps.

tuscany · « **Reply #12 on:** Jul 07, 2008 at 05:35 PM »

Hi Threadlock, would you mind sharing how much you paid for the repair and the mods and how long it took.

threadlock · « **Reply #13 on:** Jul 07, 2008 at 06:07 PM »

Medyo mahal sir, pero yung cost ng 2nd hand tono violin + the mod will not reach the price of preamp when bought brand-new. Medyo sulit na rin kasi the preamp had a good tube(CBS 5692 brown base) and mundorf silver/gold and I like how it sounds, especially when the humming was minimized.
The mod/repair took only one day but I picked it up only after one week because kapos kasi yung pera ko.
Also sent you a pm.

Jagner · « **Reply #14 on:** Jul 07, 2008 at 06:25 PM »

Quote from: threadlock on Jul 07, 2008 at 11:51 AM

I brought it to Mang Rod and he was really great! He was able to fix the problem by modifying the power supply
and as an added bonus I also got another pre-outs. There is still humming but can only be heard when you stick your ear a few inches from the speaker cone, it is no longer heard in the listening position.
I thought I would just sell the preamp but now it's for the keeps.

Try to earthground the pre-amp

It'll help in further minimizing the hum.

Philjonc · « **Reply #15 on:** Jul 08, 2008 at 09:16 AM »

Quote from: threadlock on Jul 07, 2008 at 11:51 AM

I brought it to Mang Rod and he was really great! He was able to fix the problem by modifying the power supply
and as an added bonus I also got another pre-outs. There is still humming but can only be heard when you stick your ear a few inches from the speaker cone, it is no longer heard in the listening position.
I thought I would just sell the preamp but now it's for the keeps.

congrats noel!

oweidah · « **Reply #16 on:** Oct 30, 2008 at 11:29 AM »

Quote from: Jagner on Jul 07, 2008 at 06:25 PM

Try to earthground the pre-amp It'll help in further minimizing the hum.

very helpful to read pdvd gurus' posts. my 12au7preamp's hum problem solved by grounding it to yammy avrs ground terminal (used for phono input

)

choit · « **Reply #17 on:** Jan 14, 2009 at 09:43 PM »

I have the same humming on a recently purchased AMX preamp. Humming is noticeable 1 ft away from cone. I don't think I have any ground on my wall outlets. Pano ko kaya ma minimize pa yung hum?

Jagner · « **Reply #18 on:** Jan 19, 2009 at 04:53 PM »

Quote from: choit on Jan 14, 2009 at 09:43 PM

I have the same humming on a recently purchased AMX preamp. Humming is noticeable 1 ft away from cone. I don't think I have any ground on my wall outlets. Pano ko kaya ma minimize pa yung hum?

Best is still to earth gound your equipment

macks75 · « **Reply #19 on:** Apr 19, 2009 at 10:06 AM »

saan po yung location ni Mang Rod ?

threadlock · « **Reply #20 on:** Apr 20, 2009 at 05:13 PM »

bro you can find MR at conchu st. cor Zobel Roxas ave
tel# 522-16-96

louiesia · « **Reply #21 on:** Apr 21, 2009 at 10:32 PM »

better get a Automatic Voltage Regulator with Line Conditioner. Meron sa ACE Hardware 1,990.00 only

bass_nut · « **Reply #22 on:** Apr 22, 2009 at 12:36 AM »

Quote from: threadlock on Jul 07, 2008 at 11:51 AM

I brought it to Mang Rod and he was really great! He was able to fix the problem by modifying the power supply
and as an added bonus I also got another pre-outs. There is still humming but can only be heard when you stick your ear a few inches from the speaker cone, it is no longer heard in the listening position.
I thought I would just sell the preamp but now it's for the keeps.

congratulations sir threadlock !!!

thanks kuya skee for chiming in... will keep your sound advise in mind po in case humming will be an issue on my system

louiesia · « **Reply #23 on:** Apr 23, 2009 at 06:24 PM »

I have not experienced humming in my cayin tube amp.