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Post subject: "Hum" control on DRRI/68CDR?
Posted: Tue Jan 13, 2015 1:37 pm
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I believe I once saw a schematic and/or drawing that should a "hum" adjustment on the DRRI amp.
Is there such an adjustment or am I having false memories? :)

I have a 68 CDR and am wondering if it to has a hum adjust.


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Tue Jan 13, 2015 3:27 pm
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No hum adjustment on either amp.

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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Tue Jan 13, 2015 3:29 pm
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shimmilou wrote:
No hum adjustment on either amp.



+1


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Tue Jan 13, 2015 3:53 pm
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shimmilou wrote:
No hum adjustment on either amp.


Man those college years took a toll on my mind and memory all those many year ago. :)


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Fri Jan 16, 2015 2:27 am
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My 68CDR has a hum too, not tried it at rehearsal or gig levels yet as I've only had it a couple of weeks.
I'm not too impressed with that tick/thump sound i get when i engage the Vibrato :-/


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Fri Jan 16, 2015 2:48 am
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BGG wrote:
My 68CDR has a hum too, not tried it at rehearsal or gig levels yet as I've only had it a couple of weeks.
I'm not too impressed with that tick/thump sound i get when i engage the Vibrato :-/



Humm or hisss ? Check tubes with know good one .

Waranty ? Return to the store :(


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Fri Jan 16, 2015 2:51 am
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I bought it used :(


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Fri Jan 16, 2015 2:55 am
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BGG wrote:
I bought it used :(



1-Did you hear hum with no guitar ?
2-Volume to "0" hum or not ?
3- Is it hum or hisss ?


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Sat Jan 17, 2015 1:03 am
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stratele52 wrote:
BGG wrote:
I bought it used :(



1-Did you hear hum with no guitar ?
2-Volume to "0" hum or not ?
3- Is it hum or hisss ?


On mine there is very little hiss plugged in or not, even with volume up this hiss is not bad pretty normal.
The hum is there plugged in or not, volume doesn't make much difference, but increasing reverb level increases the hum.

Rolling verb send and return tubes does alter the hum level but even with around 10 different tubes of 12at7, 12ax7, and 5751 the hum never goes away.
It's not crazy loud but when recording it's there on quiet playing or not playing but turned up.

I've got it about as good and quiet as I can now and honestly it's not crazy loud hum, it's just that it's the loudest hum I've heard in the 15 tubes amp w/verb that I've had.
Not bad enough to get me to give up the tone though. :)

The 68 CVR also has a bit of verb hum but quieter.
Overall the CVR is quieter.

I took out the verb and bag to check things out.
The interconnect RCA cables are pretty good quality.
I added some foam strips to the bottom of the tank, the part that sits on the foil covered cardboard and reinstalled. Visually the unit looks good.
I don't think it's coming from the tank.

The other odd thing I get is when I turn standby off.
I hear faint sound that has a bit of verb in it as the power and volume come up and on.
Wish I knew more about electronics to trace where it might be coming from.
And I do feel some transformer hum on both the CDR and CVR.
I can feel it in the chassis and it comes through lightly through the outside of the cab.
Is that something to bring to a Fender tech's attention?


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Sat Jan 17, 2015 1:54 am
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Can you post a sound clip of the offending noise. With and without EFX (reverb and vibrato).


Thanks! :D


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Sat Jan 17, 2015 2:29 am
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Rverb wrote:
stratele52 wrote:
BGG wrote:
I bought it used :(



1-Did you hear hum with no guitar ?
2-Volume to "0" hum or not ?
3- Is it hum or hisss ?


On mine there is very little hiss plugged in or not, even with volume up this hiss is not bad pretty normal.
The hum is there plugged in or not, volume doesn't make much difference, but increasing reverb level increases the hum.

Rolling verb send and return tubes does alter the hum level but even with around 10 different tubes of 12at7, 12ax7, and 5751 the hum never goes away. Output tubes ?

Remove tube on by one listen

It's not crazy loud but when recording it's there on quiet playing or not playing but turned up.

I've got it about as good and quiet as I can now and honestly it's not crazy loud hum, it's just that it's the loudest hum I've heard in the 15 tubes amp w/verb that I've had.
Not bad enough to get me to give up the tone though. :)

The 68 CVR also has a bit of verb hum but quieter.
Overall the CVR is quieter.

I took out the verb and bag to check things out.
The interconnect RCA cables are pretty good quality.
I added some foam strips to the bottom of the tank, the part that sits on the foil covered cardboard and reinstalled. Visually the unit looks good.
I don't think it's coming from the tank.

The other odd thing I get is when I turn standby off.
I hear faint sound that has a bit of verb in it as the power and volume come up and on.
Wish I knew more about electronics to trace where it might be coming from.
And I do feel some transformer hum on both the CDR and CVR.
I can feel it in the chassis and it comes through lightly through the outside of the cab.
Is that something to bring to a Fender tech's attention?


Post some good picture from inside the chassis to see how is the wiring


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Sat Jan 17, 2015 10:06 pm
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stratele52 wrote:
Post some good picture from inside the chassis to see how is the wiring


I'll try to get some.

As for the verb send and return tubes, yes I changed them one by one, one at a time.
None of the tubes I used eliminated the hum, just either increased or decreased the level.

I'm not to bothered by the hum though, it's not that bad.
I just posted a new thread about a different issue with both of my Fender amps, it's a "ticking" sound.
Now that does kinda bother me.
Take a look at that thread if you will.


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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Sun Jan 18, 2015 1:57 am
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Rverb wrote:
[
As for the verb send and return tubes, yes I changed them one by one, one at a time.

If 2 tubes are weak ?

Try to remove tube one by one and listen .
1- Remove V1 first tube at left from the rear of the amp ; hum or not ?
2- Remove V2 second " " "
3-
4-


Take a look at that thread if you will.
I see it



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Post subject: Re: "Hum" control on DRRI/68CDR?
Posted: Sun Jan 18, 2015 11:14 pm
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stratele52 wrote:
Rverb wrote:
[
As for the verb send and return tubes, yes I changed them one by one, one at a time.

If 2 tubes are weak ?

Try to remove tube one by one and listen .
1- Remove V1 first tube at left from the rear of the amp ; hum or not ?
2- Remove V2 second " " "
3-
4-


Take a look at that thread if you will.
I see it



I'll take closer notice doing one tube at a time.

Will a weak tube cause more hum?

I'm using new 5751's in the send and return right now.
One is a new JJ's and the other is new NOS.
This combo seems to be the quietest, but maybe because they are both low gain tubes compared to the OEM
12at7 send and 12ax7 return.


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