Hum hunter. Audio Isolator.

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Hubaxe
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Re: Hum hunter. Audio Isolator.

Post by Hubaxe » Mon Jun 24, 2019 6:05 am

Reply my own post. Did a lot of attempts and little things to get rid of this loud hum and buzz.
It may help some forum-mates, here is the list of actions.

1) RFI/EMI filter. I went for the cheap solution (no furmann), a schaffner FN filter housed in a small box with a in and out plug.
Used as main plug (amp, multi-effect, pedal board) it works fine and helps a lot. Make sure to get a Schaffner model with enough Amp capacity.
2) Change FX loop ECC81 and Inverter ECC83 driver valve. I took these selected valve from Tube Amp Doctor. Not cheap, but works fine.
3) Check V1 in preamp. Swapped valves, and I found one that was quieter than the others.
4) Put an audio isolator transfomer on the effect loop return (and turn up accordingly the multieffect output). As it's a lot quieter even without the audio isolator, I may use that trick only in recording situation.

Now even playing on Hi gain, the amp is quiet.
Image

Les Paul Lover
Duke of Orange
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Location: Derby, England

Re: Hum hunter. Audio Isolator.

Post by Les Paul Lover » Mon Jun 24, 2019 5:22 pm

Hubaxe wrote:
Mon Jun 24, 2019 6:05 am
Reply my own post. Did a lot of attempts and little things to get rid of this loud hum and buzz.
It may help some forum-mates, here is the list of actions.

1) RFI/EMI filter. I went for the cheap solution (no furmann), a schaffner FN filter housed in a small box with a in and out plug.
Used as main plug (amp, multi-effect, pedal board) it works fine and helps a lot. Make sure to get a Schaffner model with enough Amp capacity.
2) Change FX loop ECC81 and Inverter ECC83 driver valve. I took these selected valve from Tube Amp Doctor. Not cheap, but works fine.
3) Check V1 in preamp. Swapped valves, and I found one that was quieter than the others.
4) Put an audio isolator transfomer on the effect loop return (and turn up accordingly the multieffect output). As it's a lot quieter even without the audio isolator, I may use that trick only in recording situation.

Now even playing on Hi gain, the amp is quiet.
Funny that 2 out of your 4 points are valve related.

I've found some affordable NOS ECC83 and ECC81 and out them in all my amps.
All my EL84 amps have NOS 6P14P EV power valves, my R30 has NOS RFT EL34 too.

Beside the extremely noticeable improvement in tone, the biggest surprise has been how silent these amps are now.

Incredibly quiet, regardless of volume and gain. Pretty remarkable.
Ant

Orange Gear: RV50 MKI, R30, AD15, AD5, PPC212
Past Orange: Orange AD30TC Combo, Tiny Terror

Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute

Hubaxe
Orange Expert
Posts: 824
Joined: Fri Jan 11, 2013 2:21 pm
Location: France
Contact:

Re: Hum hunter. Audio Isolator.

Post by Hubaxe » Tue Jun 25, 2019 6:42 am

Agree.
Looks like the TH100 is not gentle with the ECC83. I need to get a batch of various preamp valves to play with.

The main improvement came from the EMI RF1 filter, and other stuff improved on top.
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