Haven´t really poked around too much. still waiting for the two 100 ohm resistors, so I can make the virtual center tap. But yes, the hum is louder when volume is turned up. But theres also hum, when both volumes are turned down. Havent tried removing the preamptubes, but will give it at try and see if it changes anything.
Best bet is to wait until you get the resistors(or pot) otherwise you will just be chasing ghosts.
On all of my 5E3's I found that isolating the inputs from the chassis helps a great deal. I used the Marshall style Cliff Jacks for this.
No sense in isolating the output jack though, it MUST be grounded to the chassis at all times.
Another point where I found/reduced a bit of hum has to do with grounding in the power supply. The original layout used back in the 50's had a hint of hum that was basically not an issue as much as today.
If I can find my updated layout drawing I'll forward it over.
Notice/Check on the Re-issue drawing I sent you how they moved the jumper between the negative side of the filter caps.
The pre-amp filter is on its own ground unlike the original 50's unit.
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I never suggested isolating the output jack, he did in a previous post.
Sorry, we're at cross purposes 😀
I was asking why you said that you MUST NOT isolate the speaker jack.
OHHhhh , haha
Several of the current 5E3 transformers have been shipping with the negative lead soldered to the transformer frame. So the output jack ground would need to be connected to the chassis.
http://www.classictone.net/40-18022.pdf
THat's NASTY!
Well, maybe, but it sure is era correct for that part. Several others have the same setup.
Well. I have just enjoyed the crystal,clear and LOUD sound of my 5e3 build(this iamp is way louder than I thought it would be).
Best af all. it´s absolutely hum free🙂 and biased to 11,47 watts pr tube
Well not absolutely? Only as long as there is a cable inserted in the input jack?
This also means that if I would like to turn up the volume of the unused channel, it starts to hum, cause there is no cable in there?
Is this maybe because the jacks aren´t isolated from the chassis (an easy fix, and yet another 3 days of waiting for parts?)
Thanks for all the help you guys. I´m absolutely confident that this thing is going to work
Best af all. it´s absolutely hum free🙂 and biased to 11,47 watts pr tube
Well not absolutely? Only as long as there is a cable inserted in the input jack?
This also means that if I would like to turn up the volume of the unused channel, it starts to hum, cause there is no cable in there?
Is this maybe because the jacks aren´t isolated from the chassis (an easy fix, and yet another 3 days of waiting for parts?)
Thanks for all the help you guys. I´m absolutely confident that this thing is going to work
You do have the correct shorting jacks installed?
Typically there is very little hum on the stock setup with the switchcraft 12A jacks.
On mine I can turn up both volumes without any hum at all with the isolated jacks.
When I had the original style jacks there was a detectable but very mild low level hum when the amp was at 100% volume. It was really not loud or anything, I just wanted it completely inaudible.
Do you have an EH 12AY7 in V1?
No, I guess I don´t have shorting jacks installed? Embarrassed to say I don´t even know what those are.
I just used normal switctcraft mono jacks for the two inputs with the 1m resistors. Thought it was fine, because the layout showed that the sleeve was wired to the ring anyways)
Then I used stereo switctcraft jacks for the other two inputs.
I just used normal switctcraft mono jacks for the two inputs with the 1m resistors. Thought it was fine, because the layout showed that the sleeve was wired to the ring anyways)
Then I used stereo switctcraft jacks for the other two inputs.
By the way, the v1 is a 12ay7 from tubeampdoctor
12AY7/6072A TAD Premium Selected - TAD Vorstufenröhren SELECTED
Should be fine..
12AY7/6072A TAD Premium Selected - TAD Vorstufenröhren SELECTED
Should be fine..
Nope, they are shorting jacks, they short to ground when no plug is in the hole.
Here is a good way to wire the jacks Fender style, scroll down to the Hi Lo inputs picture.
http://www.el34world.com/charts/CommonHookups.htm
That Tad 12AY7 sure looks like a re-labeled EH 12AY7 in the picture.
My experience with the EH is they tend to hum right out of the box. I found that you really need the shields on the sockets with these, it does indeed reduce the hum.
I have no idea why those tubes do this, but it has been very common of them to have the problem.
Get a nice NOS GE, or even an RCA 5751 for V1, you will never regret it.
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Thanks again.
I sure hope it isn´t just a re-labeled eh. They sell the eh12ay7 as well, but much cheaper
I sure hope it isn´t just a re-labeled eh. They sell the eh12ay7 as well, but much cheaper
Installed the cliff jacks today, as recommended, and now the amp is hum free 🙂
I put a jensen p12r reissue in. Read a few bad reviews and a few good ones as well. Thought it was kinda cheap, being an alnico speaker and all?
It sounds sweet. The cleans on the amp are absolutely wonderfull. I like the overdriven tones as well. When I turn the volume to 12, it kinda farts out? This does not happen at all at around 11,5, only when it´s dimed.
I read about a few guys that experienced the same, and they agreed taht this was normal in this cirquit?
Should I accept this? or should I troubleshoot/debug again?
Would prefer it to be perfect, but if it is normal, then I won´t bother. Then I would rather just play the thing🙂
Thanks again, for all the help
I put a jensen p12r reissue in. Read a few bad reviews and a few good ones as well. Thought it was kinda cheap, being an alnico speaker and all?
It sounds sweet. The cleans on the amp are absolutely wonderfull. I like the overdriven tones as well. When I turn the volume to 12, it kinda farts out? This does not happen at all at around 11,5, only when it´s dimed.
I read about a few guys that experienced the same, and they agreed taht this was normal in this cirquit?
Should I accept this? or should I troubleshoot/debug again?
Would prefer it to be perfect, but if it is normal, then I won´t bother. Then I would rather just play the thing🙂
Thanks again, for all the help
Most likely you are ahead of the curve on the farting out. Likely because your B+ is a tad higher & stiffer.
Me personally, I am not fond of alnico speakers in the 5E3. The P12R is a 25W speaker, to clean up some of the farting I would use a stronger speaker.
I have personally used C12N(ceramic) , Neo 12/100, Tornado Neo 12/100, Jensen Falcon & the Electric Lightning(ceramic).
My favorite is the Electric Lightning for big full bodied tone and minimal flabbiness.
The cleanest was the 12/100 neo, but it just seemed to lack soul, kind of neutral and lack luster.
tastes vary, but that was my take with my 5E3.
BTW, Avoid the Celestion Blue, in my 5E3 I blew one in under 30 minutes. Guys swear by that speaker in a 5E3 but its only rated for 15W? That is just asking for trouble in my opinion.
I have an old celestion 75 watt speaker ( the ones you find in marshall cabinets)
You´re right. The fartiness is gone, and it handles the distortion completely different. Also makes the amps clean sound much louder. But the magnet is too big. The speaker does not fit in my cabinet. guess I´ll try another speaker with a smaller magnet.
You´re right. The fartiness is gone, and it handles the distortion completely different. Also makes the amps clean sound much louder. But the magnet is too big. The speaker does not fit in my cabinet. guess I´ll try another speaker with a smaller magnet.
Front to rear distance to big?
Many of the Celestions are fairly deep frame speakers. The Electric Lightning in my cab has about 3/4 (.750)inch clearance.
The 12/100 neo had about 5/8ths (.625)
Electric Lightning measures 129mm 0r 5.1 inches
Measure the speaker on a flat surface front to rear.
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