elvis
Well-known member
If you're worried that it's a wild goose chase, hunt down a couple more F-series amps in your area and try them out to see if they're the same.
Love my F30 but...
- Thread starter Cole
- Start date
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I was just looking at an image of the F30 chassis on Mesa's site and noticed that the 3 blue battery looking things (sorry for my simpleton descriptions) are all in a neat row whereas mine are stacked, one on top of two. I was curious how the glue goop was pretty sloppy in mine. In some cases covering contact points. Mesa's image shows neatly wrapped/tied wire runs and that's not the case in mine. Maybe somebody has previously worked on it or it was first thing Monday morning at Mesa when the amp was assembled.
elvis
Well-known member
Actually, that's a very apt description. The 3 blue cylinders are the high voltage supply capacitors. Your chassis should look pretty much exactly like the on in the photo. Every Mesa amp I've opened is super neat inside. Cable ties, minimal goop, etc.
It's possible yours was damaged at some point, and the supply caps were replaced. They're not old enough to warrant changing for maintenance purposes. One other possibility is that the exact capacitors shown in the photo were not available when your amp was built, so a slightly larger version was substituted, forcing the tech to stack them.
But if it's not all neat inside, it may have been gone through or modded by a less competent tech. I doubt Mesa does sloppy work, even on Mondays.
It's possible yours was damaged at some point, and the supply caps were replaced. They're not old enough to warrant changing for maintenance purposes. One other possibility is that the exact capacitors shown in the photo were not available when your amp was built, so a slightly larger version was substituted, forcing the tech to stack them.
But if it's not all neat inside, it may have been gone through or modded by a less competent tech. I doubt Mesa does sloppy work, even on Mondays.
elvis
Well-known member
Thought about this some more. The amp may have always been noisy, and some tech thought replacing the caps might help, after failing to find any other cause. It's a common desperation move. Then the owner probably gave up and sold the amp. To you.
I'm getting the amp to guy in Orlando who is confident he knows what is going on. The way I got this amp is the most embarrassing and immature musical equipment trade I ever made. So bad that it will go to the grave with me. Live and learn...
elvis
Well-known member
If everything went according to plan, what stories would we have to tell?
Hello,
I have exactly the same problem with my combo F30. A lot of white hiss on the clean channel at higher gain and volume. That hiss is louder than the hiss on the dirty channel. Anyway I'm playing with them and I 've already managed to record on studio by eliminating the noise but If I can reduce it without loosing some power I take any advice.
My F30 is stock equipped.
I have exactly the same problem with my combo F30. A lot of white hiss on the clean channel at higher gain and volume. That hiss is louder than the hiss on the dirty channel. Anyway I'm playing with them and I 've already managed to record on studio by eliminating the noise but If I can reduce it without loosing some power I take any advice.
My F30 is stock equipped.
Hey there, Graon! Glad to hear I'm not the only one with this issue. Mine is stock as well except for some new tubes. Due to other financial priorities, I had to cancel an appt with a local amp tech who indicated he had a good idea what was going on. I wish I had a definitive answer but hopefully I will w/in a few weeks when a little extra $ rolls in. Even with the noise, it's a great amp, don't you think?
Hi Cole,
Be sure we are not the only ones! Of course I like it, this little magic black box is a killer. I am going to bring my amp to a quite good and known technician next to me and he will tell me what's going on with that noise. Moreover I gonna change all the tubes and what I know is that he absolutely advised me against JJ tubes as power tubes. He recommends Mullard ones. For the preamp tubes we gonna see.
I gonna review it on 10th november.
So see you soon.
Be sure we are not the only ones! Of course I like it, this little magic black box is a killer. I am going to bring my amp to a quite good and known technician next to me and he will tell me what's going on with that noise. Moreover I gonna change all the tubes and what I know is that he absolutely advised me against JJ tubes as power tubes. He recommends Mullard ones. For the preamp tubes we gonna see.
I gonna review it on 10th november.
So see you soon.
Anthony50Cal+
Member
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Dude,
I have an F 30 that has the identical problem. I just changed ALL tubes today but the problem persists. If I crank the "Clean" or "Drive" MASTER past 10 o'clock, the HISS is very obvious. I'm almost certain that it is a ground issue. I intend to take the amp to the shop in the next couple of weeks. I will update to this board with the results.
Anthony 50Cal+
I have an F 30 that has the identical problem. I just changed ALL tubes today but the problem persists. If I crank the "Clean" or "Drive" MASTER past 10 o'clock, the HISS is very obvious. I'm almost certain that it is a ground issue. I intend to take the amp to the shop in the next couple of weeks. I will update to this board with the results.
Anthony 50Cal+
A-50cal+...
Thanks for the heads up. Mine is with a tech as I write. I REALLY hope he can fix this issue. I also asked him to provide me with the details of the "hopeful" fix so I can post it here. I was told I'll have it back next Friday. Until then...
Thanks for the heads up. Mine is with a tech as I write. I REALLY hope he can fix this issue. I also asked him to provide me with the details of the "hopeful" fix so I can post it here. I was told I'll have it back next Friday. Until then...
Well, got the amp back yesterday. I'm confident the tech is competent. I can't get technical but he gave it a very through going over which included beefing up some components but was unable to cure the noise issue. In his own words, he was "dismayed" he couldn't get it done. He's been an amp tech for a long time has worked on a lot of Mesa's and indicated it was one of the highest gain amps he has ever experienced. So, it's time to put this issue to bed. I'll hang on to it and keep my eyes peeled for another Mesa that is quieter. I'd really like to get a head in the same wattage or slightly higher. Thanks for all the great advice and if you have some suggestions re: a suitable replacement, I'm all eyes.
I should have brought my F30 to the technician two weeks ago for a complete review and tubes replacement but he was busy. I'm going to bring it tomorrow and take my amp back next thursday.
I gonna make a review about the noise reduction especially as soon as possible.
I gonna make a review about the noise reduction especially as soon as possible.
Ok, here we go for the review:
Yesterday I took back my F30 after a complete review and tubes replacement by the technician. Now, with the new setup the sound is much fuller and there is almost no hiss
!
Tubes changes :
Power tubes : 2x EH EL84 paired (checked) with a customized BIAS (add/change of 3 resistances)
Preamp tubes :
V1: Tung-Sol 12AT7W
V2: JJ ECC81/12AT7
V3 & V4: 2x EH 12AX7-EH
Yesterday I took back my F30 after a complete review and tubes replacement by the technician. Now, with the new setup the sound is much fuller and there is almost no hiss
!Tubes changes :
Power tubes : 2x EH EL84 paired (checked) with a customized BIAS (add/change of 3 resistances)
Preamp tubes :
V1: Tung-Sol 12AT7W
V2: JJ ECC81/12AT7
V3 & V4: 2x EH 12AX7-EH
i would like to inquire from experts here how can i "tame" a bit the gain of the drive / contour channel?
i was advised to use a 12AT7 preamp tube...is there another brand that i should be using to attain this tone? or just use a mesa boogie 12AT7 tube?
also, which preamp tube socket should i place the 12AT7?
thanks in advance...
i was advised to use a 12AT7 preamp tube...is there another brand that i should be using to attain this tone? or just use a mesa boogie 12AT7 tube?
also, which preamp tube socket should i place the 12AT7?
thanks in advance...
old thread and late reply BUT I have solved the hiss problem :!:
The Mesa F series as well as the Studio 22, Maverick , Blue Angel, Dual Caliber and Express series all suffer from very high background hiss because they all use a 2 resistor and two capacitor filter right at the first tube stage input - the hiss is caused by the thermal noise of these resistors being amplified by the first tube stage. The resistors also cause an 8db to 11db signal reduction further reducing the signal to noise ratio of the critical input stage. Why did Mesa put these resistors and capacitors here then ? I believe Randall Smith was trying to increase the amplifier's headroom and give a gradually sloping from 2Khz 3db shelving boost to 100Hz and below, which subjectively gives the amplifier a more "punchy" bottom end response. The unfortunate trade off is an obnoxious rise in background noise or hiss. Changing tubes has a very negligible effect on reducing this hiss. The filter is comprised of a 1M5 resistor paralleled by a180p capacitor in series with the first tube stage input. There is also a 1M resistor paralleled by a 470p capacitor from the tube input to ground.
The fix: Remove the 1M5/180p and replace with a shorting link, then remove the 470p and optionally replace the 1M resistor with a 10M resistor. okay that cures the hiss problem now how do we put the bass boost back in you may ask? I designed a replacement filter with only a 1db to 4db insertion loss and inserted it immediately before the third tube amplification stage. The filter I used consisted of a 1M5 paralleled by a 180p capacitor in series and then a 10M in parallel with a 120p capacitor from the tube grid input to ground. This worked well and restored the gradual bass boost and tone of the amplifier BUT without that awful hiss!
Alternative partial fix: Leave the input filter 1M5/180p in place but reduce the 470p to ground capacitor to 120p and replace the 1M resistor to ground with a 10M resistor. This should reduce the his by 7db but there will still be the thermal noise of the 1M5 in series with the input, however this may not be so noticeable now - worth trying first 8)
Cheers
bajaman
The Mesa F series as well as the Studio 22, Maverick , Blue Angel, Dual Caliber and Express series all suffer from very high background hiss because they all use a 2 resistor and two capacitor filter right at the first tube stage input - the hiss is caused by the thermal noise of these resistors being amplified by the first tube stage. The resistors also cause an 8db to 11db signal reduction further reducing the signal to noise ratio of the critical input stage. Why did Mesa put these resistors and capacitors here then ? I believe Randall Smith was trying to increase the amplifier's headroom and give a gradually sloping from 2Khz 3db shelving boost to 100Hz and below, which subjectively gives the amplifier a more "punchy" bottom end response. The unfortunate trade off is an obnoxious rise in background noise or hiss. Changing tubes has a very negligible effect on reducing this hiss. The filter is comprised of a 1M5 resistor paralleled by a180p capacitor in series with the first tube stage input. There is also a 1M resistor paralleled by a 470p capacitor from the tube input to ground.
The fix: Remove the 1M5/180p and replace with a shorting link, then remove the 470p and optionally replace the 1M resistor with a 10M resistor. okay that cures the hiss problem now how do we put the bass boost back in you may ask? I designed a replacement filter with only a 1db to 4db insertion loss and inserted it immediately before the third tube amplification stage. The filter I used consisted of a 1M5 paralleled by a 180p capacitor in series and then a 10M in parallel with a 120p capacitor from the tube grid input to ground. This worked well and restored the gradual bass boost and tone of the amplifier BUT without that awful hiss!
Alternative partial fix: Leave the input filter 1M5/180p in place but reduce the 470p to ground capacitor to 120p and replace the 1M resistor to ground with a 10M resistor. This should reduce the his by 7db but there will still be the thermal noise of the 1M5 in series with the input, however this may not be so noticeable now - worth trying first 8)
Cheers
bajaman
Hey bajaman, thanks for posting this!
I'm considering doing one of the mods to my express 5:25, and I have a couple of questions, if I may...
First, for either of the mods, is removal of the circuit board necessary?
Second, do either of these mods change the tonal characteristics of the clean channel? Apart from the hiss, the clean channel on this amp is gorgeous.
Thanks again!
I'm considering doing one of the mods to my express 5:25, and I have a couple of questions, if I may...
First, for either of the mods, is removal of the circuit board necessary?
Second, do either of these mods change the tonal characteristics of the clean channel? Apart from the hiss, the clean channel on this amp is gorgeous.
Thanks again!
