04 Mar Testing 1, 2, 3 (Marshall “Boost” Test)
Okay, here we go:
[Video missing, sorry.]
Please note: at about the end of the video clip, clip will turn black while audio is still working. Canon camera heated up and turned off automatically. The audio will continue for a few more seconds.
Used the 1987 for this one, as the 1959 was heating way too much (I put new tubes yesterday, but didn’t BIAS: I will have to put the old ones back in if I want to avoid foolish damage) . And also, as I wanted to concentrate a bit on solo’s (though I played quite a bit rhythm, too) I gave it a go.
The chance was good to remind myself that even this reissue – though modified – Marshall 50W head is pretty good. Judge for yourself, but I like it much.
Consider that I used only one setting for the amp (Presence 0, Bass 8, Middle 5, Treble 5, Volume 6: now it makes sense to use the volume at 6 as Angus stated in many interviews… of couse, with a BOOST!!!) and only setting for the microphones equalization (Sonnox Plugins, Professional Equalizer for ProTools). Didn’t change it across the whole video/audio session.
The boost unit is a custom made, by hand, unit made by “Cloe Guitars” (my Luthiers/PLEK shop).
Still, I think you can now “recognize” a decent studio tone.
I am only scratching the surface.
We just started today, imagine what “we” can deliver tomorrow, once we know better which boost works wonders and which one is instead to be avoided. The proper amp settings (the above ones are standard, though excellent ones), the proper boost settings. We’ll have the CETEC Vega opened up, debunked and copied.
I mean boys, a “bright” future awaits us.
I am very proud of all this. I think that only in a few months, we found out things, discussed them over, learned a hefty hunk of stuff. I’m loving it, and I really do hope you do too.
Yours,
Fil 🙂
PS
The bottom line of this video is, that I think that Angus used extensively his Vega boost system, even for rhythm in the studio. I believe it has been an integral part of his sound since (and including) Let There Be Rock.
cwildes
Posted at 08:03h, 23 JulyAfter comparing this to something with the SVDS, this sounds less like a clean boost to my ears. It’s close, but it sounds like the amp’s being given some artificial saturation. But the essense of the sound is still there.
ghostwriter
Posted at 18:25h, 08 MarchSoloDallas,
You mentioned you changed tubes without changing the bias. Do you know what your bias settings are on your different amps? It makes a critical difference and you really should know all of the bias settings for each amp and what the voltage number of the tubes are, especially if you like how the amp sounds. Check what the amp bias is and what the number of the tubes are (written on the tube box) before you blow tubes or you may never get the same tone back when you do change the tubes.
This is so important to the amps sound and I’ve never seen it mentioned on this site.
If you do know what your bias settings for each amp are and what the tube numbers are please post them. It would be very helpful to everyone.
Examples from a few of my amps; my David Bray 1987x Marshall has Electro-Harmonix tubes #37 with the amp biased to 35.
But, my 1976 JMP 50 watt master volume sounds best with Svetlana #25 tubes and the amp biased to 40. My Fender Deluxe Reverb biased to 22. Change the bias to any of those amps and they sound completely different.
This is a discussion us amp tone junkies should be having.
ar2619Rob
Posted at 18:29h, 08 MarchHi, do you bias yourself?
Do you know of a good write up on how to do it?
ghostwriter
Posted at 20:32h, 08 MarchYes, I bias all my amps myself, it’s very easy. As long as you are careful you can safely bias your own amps.
You will need to purchase a bias probe tester. I own the QuadStage BiasPro from Asharpfretworks.com (it’s metered and easy to use), but a search for “Bias Probe” on Ebay will get you several options to choose from. For a Marshall be sure to select the 8 pin cable option (you will need two of them and they come with the tester, but you have to tell them you want 8 pin when ordering).
You will need to remove the 4 screws on the bottom of your Marshall and slide the chassis out the back to get to the bias adjustment on the underneath side of the chassis. WARNING: Even unplugged, parts in an amplifier can hold enough voltage to kill you. Keep one hand behind you and wear proper gloves when adjusting the bias and you will be fine. Just don’t be stupid and there is nothing to be scared of. I’m only putting this warning up so someone doesn’t get the bright idea to do this after a few beers 🙂
Directions:
1. Turn off your amp, pull the AC cable out and allow the output tubes to cool.
2. Pull the output tubes out and insert the tester probe sockets into the amp’s tube sockets. (The tester sockets get inserted between your amp and the tubes and have a cable coming from them that attaches to the testing meter).
3. Insert the output tubes into the tester sockets (which are now inserted into your amp).
4. Make sure your amp is connected to a speaker and then power up your amp and let it warm up for at least 5 minutes
5. Read the numbers on the test meter screen (switch between tubes on the tester and always use the higher number). This is what your amp is currently biased to with the tubes you have in it. Write down this number and the number of your tubes for reference (if you like the tone) 🙂 If you have done this reference test previously and are biasing new tubes, then skip this step.
6. Read the numbers on the meter with your new tubes installed. The bias setting will most likely be off from your reference numbers you took from the original tubes. Insert a screw driver into the bias level adjustment potentiometer on your amp (Located on the underside of most amp chassis, usually a little box or round pot sitting sideways or facing up with a screw driver slot, please search the web instead of assuming you have found it). Adjusting this clockwise raises the bias, counter-clockwise decreases. Adjust the bias control on the amp until the test meter shows the value of your reference test (or new bias setting if you are experimenting with different number tubes or raising the bias to increase distortion or lowering it to clean it up, but that’s for another discussion, Search the web to learn about how larger numbers on your tubes increase headroom, smaller numbers distort quicker, etc…).
7. Power down the amp, pull AC cable, let tubes cool down. Remove tubes from tester sockets, remove tester sockets from amp’s tube sockets. Now put the tubes back in the amp’s tube sockets and you are done.
ar2619Rob
Posted at 21:12h, 08 MarchThanks for the time taken to write this reply. I am an electrician so will be ok with the procedure, this is however my first tube amp. I have found suitable testers on eBay and will get one. I don’t need new tubes yet but would like to be ready when the time comes, especially as I’ve just started using an attenuator.
Have read lots of good write ups but none of them clearly identify the pot as R? or RV?, they just say to adjust the bias. Will have to remove my amp and see if its obvious(ish).
ghostwriter
Posted at 21:26h, 08 MarchGo to this link and look at the first photo. http://vintageamps.com/plexiboard/viewtopic.php?f=1&t=90957
On the right side you will see 3 black parts, one of them is round and turned sideways. That is what many of the Marshall bias pots look like, although some will be all metal. Some will have a box with the screw driver adjustment facing up. But, this pic will give you an idea odf what you are looking for.
ar2619Rob
Posted at 21:57h, 08 MarchYes got it, the variable resistor to the left of the two caps. I thought there would be one pot for each tube but some of the videos I’ve watched have implied just the one.
thanks again.
SoloDallas
Posted at 21:59h, 08 MarchGhost, need to thank you about this terrific write up. I am learning more and more. Gee. I am being submerged with learning lol. Ghost, would you like to contribute yourself with an article about this subject, even just copying and pasting what you have just described? I am sure the whole place would benefit, and it wouldn’t get lost in comments. Not that the comments get lost or deleted, but just for easier access. We can make you “contributor” and you can write your own articles when you want. You are right, BIASing is very important. I realize I have blown two amps trying to change tubes in one. Now the one I had taken tubes off, isn’t sounding anymore. Turns on sound but no sound. Same as my 2204. I will have to have them checked both now. Foolish of me.
banane
Posted at 22:07h, 08 MarchMy thoughts too, this information needs to be filed in an article.
ghostwriter
Posted at 22:49h, 08 MarchI would be glad to be a “Contributor”. What do I need to do? Please let me know and then I will post the How To Bias and other tidbits of fun.
SoloDallas
Posted at 22:59h, 08 MarchYou didn’t need to do anything additionally, just “accept” my invitation. You are now contributor 😀 In your dashboard, you should be able to find the option of adding a “new post”. Please do so and take your time familiarizing with the interface. Franz, Rob and I (and anyone else who knows how to is welcome to) will gladly support you, but you’ll see, it’s simple and easy. Once you’re finished your article, you can “submit it”. An Administrator will publish it for you 🙂
ghostwriter
Posted at 23:29h, 08 MarchDone, I just submitted the “How To Bias”.
banane
Posted at 23:33h, 08 MarchAlright, you’re online. Thanks for writing! 🙂
SoloDallas
Posted at 23:34h, 08 MarchThanks ghost! And thanks to our super efficient Admin, Mr. Banane! 🙂
ar2619Rob
Posted at 14:07h, 08 MarchMy THD hotplate arrived this morning and I’ve given it a couple of hours use. I’m playing at similar room volume but with the hotplate on -16db can now use as much m.v as I like, around 6-7 is good . This means I’m using lower settings on the guitar volume and am more consistent with the tone :). I have a Zoom G2.1u multi effects unit which isn’t good for much but when I checked, halleluyah a boost, pedal control too!.
With just a bit of boost, what a difference to the drive (probably something to do with my weak pick-up) I’ve found a setting that is ok for rhythm (volume pot now 4-7) and lead (volume now 6-9) 9 is boardering on too much. I’ve also tried adding a bit of eq which is giving a touch more drive, nicer for the solo but (as with yours) a bit over done for the rhythm, happy days. 🙂
Gonna replace the ceramic tone caps with orange drops this afternoon and see how that goes.
What are you thinking now re: high output pick-ups vs a boost pedal?
banane
Posted at 15:20h, 08 MarchDid you notice any changes to the sound with the hotplate? My Weber MassLite produces a muffled sound when amp and cab are configured to 16 ohms. With 4 ohms its just fine.
For me, the boost is essential now,after I tried out a MXR equalizer pedal. It’s probably a bigger step to Angus’ tone than the right pickups, but maybe both is needed for the very last small differences.
ar2619Rob
Posted at 17:15h, 08 MarchAs you add more attenuation there is a slight change in tone but the deep and bright switches really work, small adj’s to the amp eq is all that’s req’d. I’m using it on -16db which also has a pot that will reduce the sound to zero, going down quieter than I want does have a negative effect but I’m still playing pretty loud anyway cos it just sounds better! I’m really pleased with it.
I changed the tone caps for orange drops same value .22mF, can’t say the difference is huge but I now have both pick-ups connected ‘old school’ and the tone is more linear rolling off.
I’ve had a really good day with the THD and the boost, with the m.v up around half and just a little bit of boost I’ve found my tone and drive balance that has been a short coming in my playing. I’m able to use the volume pot lower, in the area where I like the tone and get as much drive as I did at full throttle. I’ll probably splash out on an MXR M108 or similar to get more eq, my boost is only 3 band so I’m sure that when I record and listen to the play back I’ll hear the true sound is not as good as I’m thinking. But anyway, leaps and bounds 🙂
banane
Posted at 17:30h, 08 MarchHehe, there’s somebody having a lot of fun, great! 🙂
Ok, then your THD’s behaviour seems to be equal to my Weber on the 4 ohm setting. Fine 🙂
I’m still playing around with the MXR, didnt have found the best settings yet. But it’s really a nice one, and the boost at all is the finding of the year for me 🙂
ar2619Rob
Posted at 17:58h, 08 MarchI assumed you meant -4db not 4 ohms? maybe the Weber is different but I’m pretty sure you need to have the impedance matched to your amp and cab or the amp will blow. i.e. for 16ohm cab, amp output set to 16ohms and 16ohm attenuator. I know this is true for the THD and others. Excuse me if I’m wrong just thinking of your gear mate.
banane
Posted at 18:05h, 08 MarchYes, I meant 4 Ohms indeed 🙂 The Weber is impedance-independent, and it even doesn’t have a power supply. but I got the best sound when I switched amp and cabinet from16 to 4 ohms. Sounds funny, but is true. Maybe the old 6550 tubes I had in the JMP were the reason, don’t know.
Here you’ll find some pictures, also from inside the Weber, its my (german) blog: http://www.banane.at/blog/archives/678-Ne-Spur-leiser-ein-Weber-Attenuator.html
ar2619Rob
Posted at 18:14h, 08 Marchah, I see, I didn’t know you could switch your cabinet to 4 ohms, learn something everyday!
banane
Posted at 18:36h, 08 MarchYou can do this with the modern 1960A cabs, see here: http://www.banane.at/blog/uploads/DSC04190.JPG
Maybe I better stay with this, otherwise I have to buy a new attenuator and a new cab.
06AngusSG
Posted at 19:27h, 08 MarchFranz’s cab has the switchable varsion of what I wired up on My 2×12. (pics in my post)
I found that switching from stereo to mono does have a significant change in how my cab sounds.
Here is a link to what explains the how different ohm ratings will affect your sound.
http://colomar.com/Shavano/ohms_law.html
Cab wiring diagrams:
http://www.soundcitysite.com/sc_webpages/wire_diags.htm
This one is from Celestion(under Dr. Decible Secrets.)
http://professional.celestion.com/guitar/features/drdecibel/index.asp
The only bummer, as Franz sort of stated, most attenuators I’ve heard of are only good for one ohm setting. So if you switch your cab rating the att. does no good.
banane
Posted at 21:17h, 08 MarchYeah, I can use mono with 4 or 16 ohms and stereo with 8 ohms with this cab.
Thanks for the links, will take a deeper read now.
Well, I understand now that the speakers get less power with the 16 ohm setting. Ok, but they were as loud as they are now with the 4 ohm setting. Maybe I had to pull up the volume a bit more back then. But how did this change the sound itself, mainly cutting the highs out?
For the Weber attenuator, see here:
http://www.tedweber.com/atten.htm
Mine is similar to this one: https://taweber.powweb.com/weber/masslite.htm
It’s an older model I got from ebay.
06AngusSG
Posted at 21:30h, 08 MarchI’m not very good at describing “sounds” but the best way I can think to say it, is my cab has a much fuller sound in mono (16ohm) vs stereo (4ohm)
I think what amp, speakers, cab design, ect… on has will affect the sound difference vs impeadence.
For me it boils down to what my ears hear. 🙂
I don’t use an attenuator. My amp has the Bray master vol. mod. I do get a little tone loss at super low volume but I like the freedom of switching my impeadence.
banane
Posted at 21:41h, 08 MarchYeah, same for me. I just wasn’t satisfied with the tone and remembered what I read in an article from some musician using the Weber attenunator and saying “it sounded best with 8 ohms”. So I tried 4 ohms then and was happy instantly 🙂
My 2204 also has a master volume, but I need the tubes kicked just a bit. I guess your MV mod is a bit different?
06AngusSG
Posted at 21:52h, 08 MarchYah. Bray insinuates that it’s more like an attenuator. Saying there is minimal to no tone loss. Which he’s right in the minimal. Mine only looses some tone in the lower 1/8 to 1/4 of the knob sweep. But not much.
Here’s his mod page. Look at his description of the “output control”
http://davidbrayamps.com/pleximod.html
I’m trying to find time to do my sound test. As soon as I have it I’ll post a “Soundcloud” link. (I’m not a video myself guy)
banane
Posted at 22:14h, 08 MarchThanks for the link, even more nice information to read 🙂
Yeah, I’m also not really a video myself guy, but on the other side it would be nice to see you. I also managed to make at least one video 🙂 But getting a sound test would be fine too, of course 🙂
06AngusSG
Posted at 23:06h, 09 MarchO.K. Franz. You win. 🙂
Got the test done.
Here’s the Soundcloud Link. Video is in the User Performance Section.
http://soundcloud.com/06angussg/ysmanl-test
banane
Posted at 08:36h, 10 MarchHehe, like it a lot! See comment there.
pit
Posted at 07:56h, 08 Marchhi,
been following you around your journy with tone/guitars/amps etc. and it’s been a blast.
i have a comment i would like to share with you.
i have a 2204 early model and i think it nails angus ‘s tone. Now with the boost added to the equation is it really needed in case of a master volume amp? i think those added harmonics you are talking about are there with the master volume 2204…
maybe i am wrong
banane
Posted at 08:12h, 08 MarchHi Pit, well, I also have a 2204, but a late 70s model and while it has a really great tone, there’s still something missing to Angus’ tone. Good example to compare is the “You shook me all night long” intro.
SoloDallas
Posted at 09:32h, 08 MarchThanks Pit.
Well, all the JMP-era amps are accurate to “this period in time” that we are studying, i.e., early 1976 to 1980 and maybe a little beyond (1985).
MVs and non MVs boosted JMPs, that is.
However, there is no doubt at all that the Vega unit was used constantly from 1977 onward, and to me, there has always been “something” that I couldn’t replicate in Angus sound of those years, specifically.
You must understand that my ears and brain – though corrupted lol – are now extremely sophisticated, I really go for frequencies, attack, etc. So while the 2204 is indeed terrific and superb, something was still missing. I think that to get the sound closer in fact, the 2204 may be using with master at 7-8, pre-amp at relatively low volume and the boost added. This could/should complete the tone search.
Thundersnook
Posted at 14:32h, 07 MarchHope you didn’t get me wrong Fil, but my favorite Part was the broken string! xD Love such little incidents, and what cool way to solve this problem: Lets grab a new guitar! LOL! xD Love it!^^
And what should I say to the sound … with every video I think its not possible to get close, but damn you’re able to get closer with every video, outstanding!
Hugs and Greetings!
Felix =)
SoloDallas
Posted at 14:37h, 07 MarchGet you wrong? How could I. I left that bit in it JUST to create this sort of enjoyment, and you’re the ONLY one who’s picked it up! 😉
Felix – (means happy) – I haven’t forgotten about our collab. A little concentrated on this boost thing, but I’ll revert soon to “normal” behavior 😉
Thundersnook
Posted at 14:50h, 07 MarchThanks Fil! And no haste of course! =) Glad you didn’t forget it, so don’t worry about if its done in some week or months 😉 I’m here and I’m ready^^ (With some luck I could shoot with a new EOS 500D … safed some money to get more into one of my other hobbies =) … little bit jealous about your fine L lens in front of your DSLR 😉
All the best from the happy-one! xD
SoloDallas
Posted at 09:34h, 08 MarchLet me know when you get the Canon. I am now an expert in that field, ready to help you 🙂 Keep in mind that Canon cameras have a software called “EOS Utility” that connected to the computer will open a monitor window to let you control the camera remotely, just like I do. You place the camera on a tripod and control it from the computer. Neat 😉
Thundersnook
Posted at 09:46h, 08 MarchThats exactly what I plan to do after reading and viewing thousands of reviews^^ Cant wait to get that nice Cam in my hands =) What do you have by the way? 7D or maybe full-frame-body? And whats that L-Lens? On one photo it looks like the 17-40 L in the mirror, but I’m wrong for sure^^
All the best and keep shooting! xD
SoloDallas
Posted at 10:00h, 08 MarchYou’re never wrong. This proof that both you and I have something in common: we DO study things! Every detail counts for us. Yes, it is a 17-40L. I must use this one (on the wide angle side) in here (lab). I also have two 24-105L, a 70-200, a f/1.2 (THIS is my holy grail of lenses) 50L (LOVE IT) and a few more. Cameras I have a 1DmkIV and a 5DmkII. I use mostly the 1D, as it can produce directly 1280×720, while the 5D only shoots larger files. Too heavy to process in short times.
Thundersnook
Posted at 12:14h, 08 MarchDamn that’s a kickass collection! two full-frame bodies with such a nice collection of glases! =) very cool and for sure so much fun to use!(And you proved that you can use it perfectly in terms of video and photo!) Can absolutly understand why you love the 50mm prime! with 1.2 you have such a small DOF that you can compose pictures in a way you can do hardly with other lenses =) Very nic Fil, very nice! =)
Greetings! =)
banane
Posted at 10:03h, 08 MarchThere are also some cool Linux programs for the same purpose. Seems to be a really nice piece of hardware.
Timvo
Posted at 21:53h, 06 MarchHighway To Hell same tone exactly