Hi everybody,
I haven't been here since a long time ( I was playing mainly acoustics...)
I bought a Blackstar Artisan 15 combo about 6 months ago. Great dynamic response of the amp, what I miss is a warmer tone. So I tried a lot: changing preamp tubes which gave more mids but spoiled the tone so I put back the originals, I tried different speakers (came originally with a Celestion G12M 15W), I tried a vintage 30 which gives a fatter tone but a little too aggressive, Greenback 25W is what I use now.
Is there any experience out there with this amp? To my ears the amp is to harsh and trebly sounding (clean and overdriven mode), this can be heard on various youtube videos (not the company's video). I had even contacted the manufacturer but the answer I got was to roll down the treble pot on my strat, any further discussions were not possible. Any experience about the power tubes - maybe too cold biased? (The amp has fixed bias)
Any suggestions are welcome.
Bernd
If you were trying different speakers could it be you are finding the 12 to beamy you could look at the weber beam blockers to help diffuse the highs or just use gaff on the inside of the baffle?
Otherwise you would have to venture inside the amp and possibly lower some cap values that effect treble depending on the circuit.
I suspect those amps have a tight bass response to ensure the power stage doesn’t fart out when driven hard.
This ends up making the amp more “thrusting” at lower settings
See if you can get hold of a schematic, that would make figuring out any mods easier.
Or get us some high resolution shots to see what’s inside…
Please post a picture of the control panel or a link to its user manual and tell us your settings.
A schematic would be even better.
Thank you guys for your thoughts,
I don't have the schematics of this amp, I once opened the amp to see the main things but it is hard to follow by eye all those wires inside.
Yes, the amp has a tight bass response. I forgot to mention that I connect my guitars always directly to the amp,no effects in between.
I made another test and played the amp through my old 4x12 Marshall Greenbacks cab from 1969 and suddenly there was a real sweet tone coming out. I have the impression that this amp is simply too new it should be 40 years older to sound great ;-)
I just looked at he Weber beam blocker - this is a nice idea, I will try something like this or will try to get a real old speaker.
Bernd
Let's see -- 2xEL84 output, EF86 channel, Celestion Blue... I'm guessing they used the AC15 as a starting point for this amp, which will give a tight and bright sound. From their description, the Tone control sounds like more than just a treble-cut. Maybe it's more like a Big Muff control, where it will actually roll off low end as you turn it up -- that could be the source of your discontent.
Plugging into a closed-back cab will definitely give a darker, thumpier sound. I've got an old 2x15" Bassman 70 cab that is too inefficient and underpowered to work for bass, but guitar amps instantly take on more of a Marshall vibe when plugged in.
At any rate, I know I wouldn't be able to hold myself back from tinkering if I bought one of these amps. With that turretboard construction, it practically begs for it!
- Scott
Hi Guys,
New poster here. Like the OP I also have the Artisan 15 combo and am experiencing the exact same problem.. I really want to like this amp because it has all the qualities of a great amp. It is very dynamic/ touch sensitive, responds great to pick attack, cleans up nice, and its built like a tank. It has everything it needs to be a classic imo but it is just so darn bright!!!
Mine has the UK made Celestion G12M speaker and even with the tone knob of the amp on 0 it still seems bright if I am using the bridge pickup on my Les Paul. I roll the tone knob of my guitar way down as well but if I lower it too much it starts to become muddy and I loose definition. Here is a link to a bigger image of the tag board but its not close enough to tell the values.
http://www.performing-musician.com/p...15tagboard.jpg
I have owned a couple of 18 watt Marshalls and in many ways this is a very similar amp, except for the extreme brightness. Anyway, I would like to keep the amp but if I cant find a way to warm it up then I will probably have to get rid of it and that will be a shame because I really want to like it.
Well it would be easy enough to add some bass to this amp, but too much bass is not a good thing on these types of amps as they fart out quickly when cranked,
Would you do the job yourself, if so crack it open and get the actual values used. Otherwise find an amp tech that is prepared to work on it for you.
It might be that the volume control has a big bright capacitor across is or that the coupling cap off the first stage is dumping loads of bass, but we don’t know because we don’t have the components values or schematic
To pick up on the beamblocker idea.Originally Posted by beano4ever
Two stripes of gaffa tape side by side on the grille cloth in front of the speaker cone can soften the highs like a beam blocker.
SRV did so with his MusicMan amps.
It might help.
Last edited by txstrat; 01-24-2011 at 02:30 PM.
Or you might go "beyond" the problem, bypass it.
What you seem to find objectionable is "the beam" , which really does exist; it's a huge peak in highs typical of all guitar speakers, caused not by an increase in efficiency at those frequencies (far from it) but because all power concentrates in a narrow ... beam (duh!).
One aftermarket solution is to put sound absorbing materials just in front of the speaker center dome, in the path of said beam.
Good, it works, sort of.
You are not *really* making the speaker mellower, just less harsh (which is not exactly the same).
1) Why don't you jump the fence and go for a speaker which does not have such peak?
I suggest you try your amp with a flatter, PA type speaker, such as Eminence "Greek letter" series (Alphas/Betas/Gammas/etc.)
They are loved by many Jazz players because they are *warm* from the beginning.
Search and pick the highest efficiency one you can afford; after all you are not in a Jazz band.
2) The "trivial solution": if still
which are harsh words (no pun intended) , consider trying other amps you may like better.To my ears the amp is to harsh and trebly sounding (clean and overdriven mode),
Anyway you choose, good luck.
Thanks a lot for the the ideas guys. I wish I could get my hands on the schematics and post them but for whatever reason Blackstar doesn't or wont release schematics of their amps. I think I will start with the trying the gaffa tape and or one of these beam blockers and then work from there. If that isn't working then I will try the eminence speaker suggestion and I have a local tech here that can open it up and change some caps if need be.
I also will try to maybe find some darker sounding tubes. I have a couple old Mullard EL84s that may warm it up and I have read that RFT pre amp tubes sound a bit darker. It has EH tubes in it now,which is what came from the factory.
Again thanks a lot for the suggestions guys.
Hi Beano,
one of the keys is the speaker in my opinion. I feel that the G12M 15W is the worst sounding speaker in this amp - please see my comments in my first posting regarding the different speakers. I don't want to say that this is speaker is generally bad - I once connected my old 50W Marshall to it and it sounded great - but not with the Blackstar. So changing a speaker is a very easy thing. Changing power tubes needs rebiasing and this amp has a fixed bias setting which does not make things easier. I also noticed a slightly smoother tone by using a longer speaker cord.
There may be a capacitor enhancing the highs, this might be one point to start as it was already said. I also thought of putting the 2 channels in series and see what comes out - one day when I have the time to do it.
Bernd
Yea I agree that a speaker swap would be the easiest and most direct solution and after doing a bit of research I have decided to get a Eminance Cannibis Rex. Everyone seems to be in agreement that this is a great speaker to use for taming an overly bright amps and its not expensive either. I am pretty sure that the artisan is a cathode based amp so it wouldnt need rebiasing but regardless tube swaps can be hit or miss. I think this speaker change should do the trick.
Hi Beano,
by the way, what is your opinion about the Marshall 18W reissue compared to the Blackstar Artsian 15? So far I had no opportunity to try this amp.
Bernd
In comparing the two I would say the Artisan has much better and usable cleans. Granted it doesnt have a lot of headroom but on the 12ax7 side their is decent amount but on either channel the cleans sound good to me. On the other hand the Marshall doesnt really clean up well at all. For the little amount of cleans it does have it sounds okay. When overdriven, the Marsall sounds sweeter and warmer to my ears. As you know the high end on the Artisan can be bright and a bit harsh. Even though its bright, it never sounds thin. Its fat and bright and will rip your head off if your not careful, but not so with the Marshall. It retains its warmth and smoothness.
To sumerise I would say the Artisan is the more flexible out of the 2. It has the 2 channels of 12ax7 & ef86 which can also be jumped and mixed, has the 5/15 watt push pull/ single ended mode and has some very usuable cleans. The OD tones also sound pretty good and if I can just get the brightness/harshness issue worked out with the speaker swap then it should be great.
The Marshall has the tremolo channel but I never used it, has marginal cleans, but a very sweet and great sounding OD right out of the box, no mods needed.
Thank you for your descrition.
I have just started to draw the schematics of the Artisan 15. As far as I have drawn now I can see that the design is not the usual vintage amp design. It will take a few more days until I have finished the job.
Does anyone know how to publish the schematics for discussion in this forum?
Bernd
How to post your own schematics
Hi Bernd.
To begin with, how are you drawing?
Are you using
1) a general purpose program as AutoCad or similar,
2) an electronics specific one such as Express Schematic (free and easy) or
3) good old hand drawing on a sheet of paper?
In any of three cases, you'll need to turn your work into some graphics file which can be posted.
1) usually you can save or export as .gif or .bmp , then convert to .gif .
Worst case you save into its native format .dxf ; then with some graphics program open the .dxf and save as grayscale .gif.
2) these usually save as as a proprietary .sch file, which only themselves can open; but some offer the possibility of saving or exporting as some general purpose graphics file , such as .bmp.
Excellent quality but *huge*
You can open these in some graphics package such as free and excellent IrfanView and save them as grayscale .gif.
Try to avoid .jpg which is optimized for color pictures, usually smears formerly clean and sharp schematics.
3) hand draw into an A4 sheet, then scan at 150 DPI and save as grayscale .gif .
If you don't own a scanner, usually some Cybercafe or graphics/photocopy shop will.
Worst case take a sharp clean closeup picture with a good camera, in 1600x1200 pixel resolution or the next higher one.
Sharpness and even illumination are essential; avoid flash , the best light source is outside (sunlight) on a cloudy day, or when a cloud covers it; steady your forearms with a chair, some books, etc, push slowly the trigger button, don't shake the camera.
In this case you can't avoid the .jpg.
Open your picture onscreen, check that small text is still readable.
4) in any of 3 cases, post your image into some photo-sharing site, such as Image Shack , they will give you a link to the full image.
Answer here, go advanced, click "insert image" , in the window that opens paste the link to your Image Shack picture, save, submit reply.
In your answer you'll see your schematic in its full glory.
Good luck.
I have finished the job now, it took me some evenings, longer than I thought. I had to remove the board to be able to follow all those wires. It is much easier on a printed circuit board. I will redraw it now by hand and scan it tomorrow.
I don't have any webspace on a photo sharing site - I thought that I could publish it directly on this site. So if someone could do the publishing for me it would be helpful. Pass me an email address and I will send you the files.
Bernd
ImageShack lets you publish without even registering.
Afterwards they give you 3 or 4 options ; copy the address that points directly to the image, click here "go advanced" and then within the reply, click "add image" and in the little window that opens paste the link they provided.
Just to be sure click "preview" to see what others will see.
If unsure about some step mail the schematic to juanmanuelfahey (at) gmail (dot) com and I'll post them for you.
wow, great effort Bernd, likewise I have accounts with photobucket and mediafire that I could upload it for you.
Thank you for your help guys. It's 2 gif files now. I tried the upload on image shack but something in my computer inhibits the upload.
JM Fahey- please check your e-mail, I have sent you the files, maybe you can do the upload better than me.
I have drawn about 90% of the amp, the complete signal path up to the power tubes.
Let's wait for the files to be uploaded and then let us start the discussion.
Bernd
Maybe I can attach the files:
Bernd
Hi Bernd.
Your attachmentt works fine, but to display these within the response, I posted on Imageshack too and linked them here.
I took the liberty of downsizing your .gifs to 1/4 original size, to better fit a normal screen
and
I guess both EL84 cathodes should be joined on the top side of the 100 r resistor "41"
So the volume control has a bright cap as well as the tone control bright cap? You haven’t put the bright cap value on the schematic; I assume it because it was not possible to see it.
There’s lots you can do here to change the “high end” response on this amp,
If it’s the very high frequencies that you are finding harsh then you could remove or lower the bright cap.
If it’s the high mids that are too punchy then you could change the tone control 1n cap to a 470p cap.
I appreciate you doing this Bernd. I know it was not that easy so thanks so much for taking the time to map and draw it out. Unfortunately I couldn't read a schematic to save my live so thanks for the suggestions on the bright cap guitarmike. I had been waiting to see what Bernd would find on the schematics before I changed anything on the amp so I will I believe I will just leave in the stock heritage g12m speaker and start by having a tech remove the volume bright cap and go from there. Removing the bright cap seems to be a pretty common / successful mod on various amps so I am hopeful that it will alleviate the problem.
To guitarmike:
The bright cap that bridges the vol. pot of ch. 1 is 1nF. I wrote this on the left side of the vol. pot, it may be hard too see. The drawing is a bit narrow in this area and I didn't want to squeeze the value between the pots so I wrote it outside.
I could imagine that putting some resistors in series could tame the overall response.
Bernd
Bernd
Ok I can see that now, I plotted the frequency response of the stack earlier, but dont have the file at home to change the bright cap value to see how much it affect it, but the with the tone up full you have a 2n volume bypass cap, I would start by removing the bright cap, but would probably end up putting a 100pf cap or so back in its place. .
AFAICR the Marshall 18watt doesnt have the bright cap at all and the top tone cap is 470p. the bottom tone cap is different too. usefull as a reference anyway
Neds a bit of experimenting anyhow, a decent tech will get it closer to what you want anyway.
Edit: Neds should be needs, wasnt meant to be a reference to my fellow countrymen
http://en.wikipedia.org/wiki/Ned_(Scottish)
I'd like to have some changes on ch. 2 which has no bright cap across the vol. pot but feels the same as ch. 1. Any suggestions to "marshallize" this channel without completely rebuilding it?
Bernd
The only Marshall amp I know with a single tone control is the 1974 and derivatives
If you look at the schematics you can see the 18watt trem channel uses the same layout, but different cap values, you if you change the cap values you will get closer to the 18watt Marshall response.
Your C5/C6 and C23/C24 are the caps to change.
For a more “Marshall” tone C5 and C23 could be changed to ~470pf., C6 and C24 could be changed to 4.7n, but it wont change the tone as much as changing C5/C23 so I would just leave it
Another option would be to change the caps to Matchless/Vox type tone controls, for that you need to change the C5 or C23 cap to ~180pf
If you don’t mind drilling the front panel you could put all three options on three way toggle switch and switch between them depending on what you feel like.
I have plotted the response of the different controls discussed here to get a visual of what they sound like. The key area is the 1 – 2 khz area, I think our ears are quite sensitive in this range, normally when its boosted like this the guitar has a great thrusted sound, but may be over bearing too, as you can see the blackstar tone controls boost in this area, I think this may be what you are complaining about, along the with the brightness of the vintage 30 speaker in the back.
http://www.mediafire.com/file/xuqm1p...e-Controls.pdf
If this was my amp build I would add a switch, or have each channel set up differently.
Hope this helps
Last edited by guitarmike2107; 02-14-2011 at 10:35 AM.
oops.. I made an error on the last blackstar plot, I have updated the file now, I had 1n instead on 10n for C6 and C24. from the new plots you can see that those caps affect the low mid roll off point. I would still leave it at 10n.
http://www.mediafire.com/file/xuqm1p...e-Controls.pdf
Well, to put an end to this thread:
Finally I have changed nothing except the speaker which I had done before.
My settings that I find usable (guitar plugged directly into amp) :
channel I, low input at mid volume for fender amp style tones, ch. II, high input at full volume 15W and a marshall powerbrake to reduce the volume a little. In this way the sound is warmer and not so bad, mainly my drummer likes it. It could be a little more creamy to my taste.
Bernd
Hi Guys,
I'm new here. I arrived here looking for an answer about the type of biasing in the Artisan 15. I have read everything I could Google up and got four answers. The problem is that they are all different. This is without a doubt the most knoweldgable group so far, so, Is the A-15 cathode biased, fixed or adjustable?
Thanks for being here, and my tech will love the schematic.
BTW, I replaced the tubes with new production Tung-sol Gold pins in the pre amp and new production mullards in the power section and it lost some of the bright edge that it had when I bought it. I had a cabinet made for it and loaded it with a G12H30 and a Blue Alnico.
The thing sounds amazing, warm rich and creamy.
Answer it yourself.
With amp on, no signal, what DC voltage do you read on power tube cathodes?
And on grids?
If grids negative, cathodes grounded: fixed bias.
If grids grounded and cathode positive: cathode bias.
We expect voltages consistent with tube types; we are talking on the order of 20V, not millivolts.
Hope it helps.
My Apologies,
I must have wandered into the wrong place here. I have zero background in electronics. I can replace my tubes, fuses, and speakers, but once the chassis is open, I'm lost.
I was just hoping someone would be kind enough tell me what kind of biasing this amp uses so I would know weather or not I need to take it to a tech everytime I replace the tubes.
Thanks
Its cathode biased. You can replace the valves yourself but check them to ensure they are not red plating or screens glowing
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
LinkBack URL
About LinkBacks
Reply With Quote
Bookmarks