Post by stumbler on Jan 22, 2015 12:06:05 GMT -7
Hello Z Experts,
I have a Z28 2x10 which has developed a subtle, yet nonetheless extremely frustrating, sound that I am hoping you may be able to provide insight on.
It's best described as a high frequency ringing sound. It follows just a moment after a note or chord is played and remains with the sound as it decays. Whether playing at lower volumes or cranked, the sound is present. However it doesn't get louder or more intense if the amp is cranked.
The amp was recently serviced and came back sounding absolutely fantastic. The tech could hear the sound and figured he'd remedied it. But it was still there. If you will indulge me I'm including the details of the work done. The only additional item I will include is that the 6v6s were replaced with a new pair of EHs.
'I managed to isolate the problem to a combination of tube deficiencies primarily the EF86 tube ergo the ringing.
As the EF86 has an approximate amplification mu factor of 200 ( as opposed to the 12AX7s 100 mu) this tube needs to be spot-on)
In the case of the EF86 a problematic tube at the best of times the stock tube showed significant sag under load and as it is extremely sensitive to input amplification and out of spec tube makes the pre-amp stage have to run far to hard. I have replaced the Russkie tube with a NOS 1960s medical grade Valvo (Telefunken made) EF86. One of the best ever made. As we discussed before your 5AR4 was gassy and needed to be replaced. I have installed an authentic NOS Amperex Bugle Boy 5AR4 as an amp of this quality IMO should have a rectifier with a proven record of durability, stability and quality.'
I've moved the amp to different locations just to ensure the sound wasn't from a vibration in the room, frequency bouncing of a wall. I don't hear it with my other amp that's in the same location. I say again, this is a really subtle sound. It doesn't present like a problematic tube, which is a sound i am quite familiar with. And to be honest, not everyone can hear it. Especially if they aren't a guitar player. But I can hear it - all the time. And it's very distracting.
In advance, i truly appreciate any and all advice and info.
Best,
Stumber
I have a Z28 2x10 which has developed a subtle, yet nonetheless extremely frustrating, sound that I am hoping you may be able to provide insight on.
It's best described as a high frequency ringing sound. It follows just a moment after a note or chord is played and remains with the sound as it decays. Whether playing at lower volumes or cranked, the sound is present. However it doesn't get louder or more intense if the amp is cranked.
The amp was recently serviced and came back sounding absolutely fantastic. The tech could hear the sound and figured he'd remedied it. But it was still there. If you will indulge me I'm including the details of the work done. The only additional item I will include is that the 6v6s were replaced with a new pair of EHs.
'I managed to isolate the problem to a combination of tube deficiencies primarily the EF86 tube ergo the ringing.
As the EF86 has an approximate amplification mu factor of 200 ( as opposed to the 12AX7s 100 mu) this tube needs to be spot-on)
In the case of the EF86 a problematic tube at the best of times the stock tube showed significant sag under load and as it is extremely sensitive to input amplification and out of spec tube makes the pre-amp stage have to run far to hard. I have replaced the Russkie tube with a NOS 1960s medical grade Valvo (Telefunken made) EF86. One of the best ever made. As we discussed before your 5AR4 was gassy and needed to be replaced. I have installed an authentic NOS Amperex Bugle Boy 5AR4 as an amp of this quality IMO should have a rectifier with a proven record of durability, stability and quality.'
I've moved the amp to different locations just to ensure the sound wasn't from a vibration in the room, frequency bouncing of a wall. I don't hear it with my other amp that's in the same location. I say again, this is a really subtle sound. It doesn't present like a problematic tube, which is a sound i am quite familiar with. And to be honest, not everyone can hear it. Especially if they aren't a guitar player. But I can hear it - all the time. And it's very distracting.
In advance, i truly appreciate any and all advice and info.
Best,
Stumber