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PostPosted: Sun Apr 09, 2017 11:17 am 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 267
This is about my MarkV - I see people struggeling to get a heavy saturated musical tone from it the same I did - this will help!

I bought my MarkV back in 2010 on a holiday trip to cali and since then, I had to learn how to set it up - before, I played a dual recto 3CH which could never meet the tone I was expecting and I hated to use any pedals. The MarkV on the other hand came much clother to the tone I heared in my head, but there where always some fizzy or cold treble frequencies that I couldn't dial out.
The amps FX loop section is bright and adds brightness to everything you play. In the meantime I understand the reason and know how to get rid of that. This is what I want to share with you.

The ice pick or fizz issue is always there, mainly in CH3. The simple cause, that makes it nearly impossible to dial out is that it is generated late in the signal chain, at the end of the preamp. To disable the FX loop makes it better, but I didn't want to lose the solo function and the FX loop. The only thing you can do with standard tube configuration is to keep the chanel master low (I wrote about that secret tone control in another threat), but there is a far better solution:

There is one preamp tube that is golden and perfect to me - back in the days, it cured all troubles I had with my laney, peavey or orange and it cures my MarkV trouble as well. It is the Jan Philips 12AT7. And on the MarkV it belongs on V6, the last stage just before the PI. One triode of V6 contains the last gain stage of ch3, the other triode is the fx loop/solo stage. Compared to 12AX7 it sounds big, fat and nothing but sweet in the higher frequencies and never harsh or cold. It has only 60 percent of gain - and that is maybe the main reason why it will not generate any further treble distortion or ice pic - it just fatens up the tone and lets you dial in more usable sustaining gain that you could think of. It simply cuts out all the harshness.
The funny thing is that you can still dial in more high frequencies than you would ever need. Just use the EQ. The missing level can easily be compensated by turning up the send level (mine went from 10:30 to 02:00).
With the 12AT7 in V6, the highs are not longer dominant. The consequence is that you can dial in more gain, which adds so much sustain and brutality to the sound. The MarkIV mode as well as the MarkII mode can deliver heavier tones then before.

Here is a video I shot just half an hour before my bandmates arrived to rehearsal - random noodeling, so please be patient with my playing :)

Unfortunately, I don't have any high quality recording equiptment at my rehearsal space, but when you listen to the video I think you get the idea of the tone.

https://pl.vc/1ksxbg setting

https://www.youtube.com/watch?v=PbTDvYfRMwI video

Mesa MarkV (2010) - Mark IV Mode // 90 Watt // Full Power
Preamp: V1-V5: EH12AX7 // V6: Jan Philips 12AT7 // V7: Sovtek 12AX7LPS
Poweramp: TAD 6L6GC-STR // JJ GZ34 (for a heavy 10 Watt Mode)
Mesa 412 std slant & Mesa 112 Thile EV Speaker [Clone]
Ibanez RG Prestige 3620 (Mahagoni with DiMarzio D-Sonic) thru Sommer Spirit XXL Cables

Tell me what you think - greetings from bavaria!


Last edited by APEMAN on Sun Apr 09, 2017 11:44 pm, edited 1 time in total.

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PostPosted: Sun Apr 09, 2017 3:55 pm 
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Mark III

Joined: Sun Sep 27, 2015 2:50 pm
Posts: 279
Location: Good ole England
Hi,

That's very interesting. The ice pick highs are the nemesis of all Mark V owners I reckon. Especially in iic+ mode I find. I've tried all sorts of things to eliminate it, different combinations of channel and Master volumes, presence and EQ setting etc. I even tried a bigger coupling cap soldered in place of the small one for iic+ mode after the EQ to try get some more beef out of the mode. Didn't seem to make any noticeable difference unfortunately. However, I was at home with a baby asleep upstairs so didn't get the chance to get it up to any decent level of volume. Had a gig the next day so put the original back incase something could possibly go bang. Maybe I'll try it again and see if it does help the beef of that mode at reasonable volume, it should do I would think. Anyway, I digress, I too have heard many times of substituting the 12AT7 in various other amps for similar reasons. Can't believe I hadn't thought of this before. Definitely gonna scour eBay for one after next payday and check it out.

Thanks for the inspiration.

Great video by the way. Proper chunky tone you got there.

_________________
Her highness the Veenus
(Mark V/V4 AT7 Combo)

2 x 12 Vertical Cab
GSP-1101

Gibson LP Studio with alnico ii pro
Schecter C1-XXX with emg 81/85
Jackson Dinky XL with Duncan designed???
Sigma DNC-1STE


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PostPosted: Sun Apr 09, 2017 9:51 pm 
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Mark III

Joined: Sun Feb 02, 2014 11:51 am
Posts: 165
Hi Apeman,

Thanks for the tube advice, it sounds interesting. Do you know if it makes a difference if it is the Jan Philips Grey or Black 12AT7WC tube? I see online that both versions are offered.

Thanks!

Mace


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PostPosted: Sun Apr 09, 2017 11:28 pm 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 267
I dont know the difference between the black and the gray, I fell in love with the gray tube and bought a bunch of them and they sound almost identical to me.

Cant wait for you guys to hear it for yourselves :D


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PostPosted: Mon Apr 10, 2017 1:36 pm 
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Mark II

Joined: Tue Jun 25, 2013 1:53 pm
Posts: 53
This makes sense. There is definitely a frequency there that is pretty much gone when its disabled. I've been using with the loop off for a while.


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PostPosted: Wed Apr 12, 2017 4:48 am 
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Triple Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 3031
Location: North Carolina
Good call there....

I have actually done this before. I also loaded V4 and V5 with the Jan/phillips 12AT7 and that changed everything. Gave the amp a more vintage tone which was nice for a change. I will have to give one of the Jan/Phillips 12AT7 another go but in V6 and leave everything else as is. Also have a JAN/GE 5751 to try there as well. I will have to check my inventory, may even have an RFT 12AT7 available as I bought the 12AT7 for replacements in my RA100's.

I have not given up on the Mark V yet.

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Current amps: TC-100, TC-50, JP-2C, MK V, Roadster, RA100


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PostPosted: Wed Apr 12, 2017 11:47 am 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 267
bandit2013 wrote:
I have not given up on the Mark V yet.

Good to hear that - the amps potential is unbelievable. I changed the tube about 3 weeks ago. Yesterday, was my 3rd rehearsal and it sounded stellar in the mix as well.

I did a lot of tube rolling (12AX7) over the years, but I always came back to the EHX, which is the tube the MarkIV was designed for back in the days. To my ears the recto trick (tung sol as V1) sounded terrible and made my troubles even worse. Sry Boogie, but my best decision was to get rid of your original JJs, since they left my amp the mid spike (wah-like) frequency is gone.

The good thing with the V6 is that the preamp stays untouched, because V1-V5 make 99% of the tone. With the 12AT7, you just remove that annoying ice pick and get a tamed high end, nothing else. The overall effect is a more prominent mid range as well as bigger low end. And in my amp there is a magic spot on the gain pot in ch3, somewhere between 2:15 and 2:45 where you get that thick crunchy saturated tone, and it feels like the amp plays itself. (With the std tube config, you would never reach that spot without the ice pick effect.) I never wanted more from a high gain amp.


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PostPosted: Thu Apr 13, 2017 6:04 am 
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Triple Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 3031
Location: North Carolina
I will agree with this and will do the acid test this weekend. I had started my tube rolling with all EH tubes, sounded good for a while but once they had a few hours on them I could not get rid of the low frequency hum on the clean channel. If I got past the noise level and just played the amp I did not notice the idle noise. Same applied to the Tung Sol, Loaded the amp with those and it sounded good for a while. Seems that tubes with coiled heater elements tend to add power supply noises (especially the tube positions that use the AC sourced heaters). Old Mesa 12ax7 tubes from the 90's (Chinese tubes with foil square getter) were the best overall in noise reduction. Gain characteristic was more compression on CH3. Also did the mix and match as well but never found ideal tubes to make the amp sound like I wanted it too. Main reason why I bought the JP-2C which ended my tone quest. After that, I lost my interest in the Mark V, and that carpet weight is beginning to collect dust which I find disturbing to the point if I do not use it, it must go mentality. Still if and when it is operating optimally it is a great amp to play though and make use of. The love/hate thing has to stop sometime....right?

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Current amps: TC-100, TC-50, JP-2C, MK V, Roadster, RA100


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PostPosted: Thu Apr 13, 2017 8:11 am 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 267
As long as the love hate thing goes on, you will not find your peace. I hope you find it.

I don't have an issue with hum, but I run an AC filter in front of the amps power line. Hum is always very subjective. I would say my amp is 'dead quiet' on CH1 - can you hear any in my video? My tung sol troubled me since beginning, it pumped even more highs into the amp, which was not the right cure to me.


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PostPosted: Thu Apr 13, 2017 7:29 pm 
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Triple Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 3031
Location: North Carolina
I use Mesa SPAX7 in V1 as I found this seems too roll of the top end, at least in this amp of mine. Ran though two 12AT7 tubes (RFT and JAN/GE, selected the ones with the least amount of tarnish, not sure if the black is due to silver content or nickel). Was not a fix for me.... These tubes work great in my RA100 since the design uses them on the FXloop send and return. I could have tried the current Mesa 12AT7 as I have a few of those as well but opted out. The Stock 12AX7 tube seems to work great so what I had installed I will stick with at the moment. Mullard long plate RI 12AX7 also do a great job from V4 though V6. Those will roll off the top end. I found that tubes I install into V3 will be the culprit for the hum if they have the coiled heaters (heater wire is actually coiled like a light bulb filament) which are supposed to reduce noise but not introduce it. Typically a non-coiled heater element works better in that position and does not seem to contribute to the hum. Preamp tube positions that use the 6V AC heater circuit: V3, V4, V6, and V7. The tubes that use a 12VDC heater circuit are V1, V2 and V5.

I was looking at the schematic again....
CH3 signal path is: V1A -->CH3 tone stack--> V1B -->CH3 Gain control -->V5A-->V4b-->V3A-->(send return reverb CH3) -->V6A --> EQ Sliders--> FXLoop send/return -->V6B (master/solo). Of course if you opt to bypass the FX loop the signal would just go to the PI circuit (V7).

Since V5 is more critical in the gain chain than V6 I found the 12AT7 to be more effective there but at the time I was experimenting I did not have the schematic. The effect was Darker tone and less gain. V5 may be a better position for a tube with better top end roll off to eliminate the higher harmonics in the distortion (will provide softer clipping on the signal waveform). Would have to borrow the scope and frequency generator for a stable waveform to verify. More rounded corners and perhaps a dip in the center of the square wave would reveal high frequency roll off effects. A signal analyzer would also help to determine the harmonic content based on a single test frequency. This brings back memories some 24 years ago when I had access to such equipment in college. I used my Mark III as a test subject to determine frequency content and gain characteristics during my Senior year project.

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Current amps: TC-100, TC-50, JP-2C, MK V, Roadster, RA100


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PostPosted: Tue Apr 18, 2017 2:20 am 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 267
...I hope you all had great holidays. Yes, scope and frequency generator would be the good ol' way to go. I can remember those days when this type of designing has been done without spice. :roll:
For this threat, I only wanted to offer a very simple non-solder solution to get the ice pick down and the gain up. And what could be easier then changing one preamp tube. I chose the V6 position because I had issues with channel master leveling - the higher you set it, the more highs you get and at a certain point it starts to add distortion. I wanted to get rid of this postprocessed clip while maintaining the amps original character.


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PostPosted: Fri Apr 28, 2017 3:42 pm 
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Mark III

Joined: Sun Sep 27, 2015 2:50 pm
Posts: 279
Location: Good ole England
Holy sh!t balls batman. Apeman is spot on.

Only had half hour and had to be quiet not to disturb baby but still...

Just received a couple JAN GE 12at7 from eBay today, popped one in V6 and wow, everything Apeman said is right. The top end is warmer, even at low volume. Much closer to how the amp sounds with loop bypassed. Can now dial in more gain without getting screech. Chuffed as punch as I find the solo feature extremely useful with the band and now it sounds as good as without as far as I can tell at low volume. Can't wait to get the chance to crank her up and really get her purring.

Also after reading through some of the other threads on tube rolling from bandit and Co I've hopefully got a couple 5751's winding their way over. Gonna have a swap around with them to see what I end up with.

Current V1 - V7:

V1 - Tungsol
V2 - JJ stock mesa
V3 - Sylvania 12AX7 long grey plate
V4 - Sylvania 12AX7 long grey plate
V5 - JJ stock mesa
V6 - JAN GE 12AT7
V7 - Sovtek LPS

V8 - 10 JJ EL34ii

Still have the stock 6L6's so will have to try them again too.

First thing will be to try a 5751in V1 and move the Tungsol to V2 and see how channels 2 and 3 respond. More on that soon hopefully if anyone's interested.

Apeman thank you again, still can't believe I hadn't considered the 12AT7 before. Sorry if I've hijacked your thread.

This amp always had balls, now it has cojones :P

_________________
Her highness the Veenus
(Mark V/V4 AT7 Combo)

2 x 12 Vertical Cab
GSP-1101

Gibson LP Studio with alnico ii pro
Schecter C1-XXX with emg 81/85
Jackson Dinky XL with Duncan designed???
Sigma DNC-1STE


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PostPosted: Tue May 02, 2017 2:13 am 
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Mark III

Joined: Tue Nov 08, 2011 10:48 am
Posts: 267
Hey Wayno, I'm glad it worked out for you as well. Another big step to a BIG lead tone was the TAD 6L6GC. Before, I used the standard Mesa 6L6s for a long time and just tried other 6L6s by accident... the difference is day and night.


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PostPosted: Tue May 02, 2017 3:10 am 
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Mark III

Joined: Sun Sep 27, 2015 2:50 pm
Posts: 279
Location: Good ole England
Hi apeman,

Yeah worked great thanks.

Had another spare hour over the weekend and tried my second 12at7 in there as well.

Revised;
Current V1 - V7:

V1 - Tungsol
V2 - JJ stock mesa
V3 - Sylvania 12AX7 long grey plate
V4 - Sylvania 12AX7 long grey plate
V5 - JAN GE 12AT7
V6 - JAN GE 12AT7
V7 - Sovtek LPS

V8 - 10 JJ EL34ii

Sounds better still, like bandit stated before, has a more vintage feel to it. Really digging it :-) and no noticeable gain drop.

Can't stretch to new 6L6's at the moment as have littluns first birthday coming up but hopefully will get the chance to get the amp out in the garage soon so I can can crank her up a bit and try the stock 6L6's. Preferred the EL34ii's with the original 12AX7'S but got a feeling they might feel better now the highs are tamed a bit.

Got to admit I have been twitching after the JP2C for a while as much as I love the Mark V but this has put that itch well and truly to bed.

I am one happy chappy!

_________________
Her highness the Veenus
(Mark V/V4 AT7 Combo)

2 x 12 Vertical Cab
GSP-1101

Gibson LP Studio with alnico ii pro
Schecter C1-XXX with emg 81/85
Jackson Dinky XL with Duncan designed???
Sigma DNC-1STE


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PostPosted: Wed May 03, 2017 6:50 am 
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Mark III

Joined: Sun Feb 02, 2014 11:51 am
Posts: 165
Hi,

I also tried the AT7 in V6 to see if it could reduce a bit of ice pick at higher volumes/gain. I was running the Mark V through a Thiele with EVM 1x12 (the older 300W Thiele cabinet). I must say, it seemed my listening position made more of a difference in the tone (on axis or off axis). On axis listening was more harsh on the ears than off axis. This seemed to have a larger effect than the tube V6 tube swap. This was at about 100 dB sound volume.

I'll do a bit more testing with the rectifier 2x12 (stock V30s).

I guess my main point is for those suffering from ice pickiness, listening position and/or cab placement can make a huge difference. Also, just how loud in dB are you experiencing this?

Is it like 90, 100, 110 dB? The human ear can only take so much volume before it also "clips". The perceived frequency response of the human ear is dependent on sound volume. The louder it gets, the more the mids fill in. So, a deep scoped tone at low volume sounds good, but doesn't to me at higher volumes (too much treble and bass). I have some CD's which sound flat and muffled at lower volumes, like 70-80 dB, but when cranked up to 95-100 dB listening level they just come alived, no muffled or soft tones (my tube amp stereo has no tone controls). Guitar tone as similar well. Mesa's are critized for being "muffled" and "under a blanket" or "too thick" and that may be true at home or at low volumes (to some degree). But, when gigging, and turning it up in a big room, the tone balances to the human hearing EQ very, very nicely.

sorry for the ramble...

Mace


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