ART TUBE MP mods/improvements?

[travelin travis]

a friend just moved away and gave me one of his old art tube mp preamps. i have always wondered what one of these things sounded like. well it makes some kind of static sound when i di my bass through it, mainly when i hit the lower notes but it fattens it up and adds some kind of cool effect. (dimension?) same for guitar. i plugged my cad m179 into it and tried singing and playing acoustic guitar through it. it sounded decent as long as i did'nt crank up the gain. as far as just sitting and playing in front of a mic, i prefer its sound over my yamaha mg mixer.

i know i have read some where about improving the sound of the mp by changing the tube and some components but I can't remember where. does anyone know of any mods or reccommended tube to try? i think the tube may be pretty old due to the static sound on bass/guitar.

[edwardiii]

The recommended mod is to replace the stock 12AX7 tube with a 12AU7. I've heard you shouldn't put a vintage tube in a modern unit hoping to get a nice vintage sound - you're better off getting a recently produced tube than pay out for a 60s cleartop RCA if you're just going to stick it in something made 3 years ago.

Take my advice with a grain of salt, though, since I've never actually swapped out tubes on these units...

[mshilarious]

I just bought a batch of old 12AX7s off eBay, it was like $35 for 7 of 'em. I tried 'em all until I found the best, and I resold the rest Very cheap way to get a good tube.

There are other mods too, check this thread:

http://www.homerecording.com/bbs/sho...d.php?t=143763


PS If you're getting 'static', that's because you're pushing the tube too far into overdrive. Cut back on the tube gain.

[travelin travis]

thanks for the info. i get the static sound even when the gain is very low. does this sound like a bad tube?

[gemsbok]

i dont think the u7 tube is the same gain wise as the ax7. i put erotubes in mine and swapped the 5532 op amp for a 2134. it sounds sweet and quiet . probably better than a vtb-1 and blue tuber.

[mshilarious]

Not sure about your problem then.

Also the MP doesn't have stock 5532s, if it did it wouldn't be worth changing. It has TL072s.

[travelin travis]

mshilarious: i hope the static sound is an old tube or maybe something with the bass. i will borrow another bass and find out.

gemsbok: is mshilarious right about the op amp?

is changing the op amp pretty simple? I don't know much about electronics but I can solder and remove/replace components (i think i can anyway). specifically, what would be a good tube and op amp to try and where would they be available? thanks guys.

[taperocket]

mshalarious, that's not necesarily true, the tube mps with OPL have 1 tl072 and 1 5532. And I think they're both worth switching to burr brown 2604 or 2134's. I switched both out in mine and noticed a much thicker and clearer sound. I also replaced the stock chinese tube with an old telefunken which I think made the sound a little more open. The tube mp will never sound like an avalon but it does sound better after these basic mods.

[travelin travis]

I have one the the original tube mp's, no opl. what would mine have in it and what would make good replacements? i have never changed an op amp before. would it be easy to remove? i have a cheap radio shack soldering station, solder, and some de-soldering wick. would i need anything else? about the only things i have soldered are instrument cables, some capacitors for my guitar, and inputs on a couple of guitar amps. where can i find the burr brown op amps?

oh, my friend said that if i decide to open up the mp, to be very careful because the circuit board is pretty fragile. is there anything else i should look out for?

I don't expect it to sound like an avalon, but I'm willing to drop a few bucks into this thing to get a noticeably better sound. i could see using it for a bass di and maybe for some acoustic guitar/singing solo stuff.

[mshilarious]

Originally Posted by taperocket

mshalarious, that's not necesarily true, the tube mps with OPL have 1 tl072 and 1 5532. And I think they're both worth switching to burr brown 2604 or 2134's. I switched both out in mine and noticed a much thicker and clearer sound. I also replaced the stock chinese tube with an old telefunken which I think made the sound a little more open. The tube mp will never sound like an avalon but it does sound better after these basic mods.

That's interesting. Swapping out 5532s is not always straightforward, and it's a decent enough opamp given the rest of the circuit. I tend to leave 5532s alone. But if yours is OK I guess that works.

Anyway the plain MP will have 072s, change for 2134s. You can request free samples from TI's website. The circuit board doesn't seem that fragile to me; the holes are plated through so desoldering is a pain, but they take that abuse OK.

[gemsbok]

i have a early version tube mp and it had two of the 5532-s. the opl has a 072 and a 5532. i also burned the units in for quiet a few hours and they got very hot. if youve never soldered its kinda tricky but not too bad . what i did was take the thing completely apart and buy a tiny snipper to cut all the legs off the op amps then i desoldered the legs being careful not to heat things up too much. i then went to radio shack and got removable sockets and ordered op amps from digi key. i got a euro tube 12ax7 and a better wall wart power supply. it sounds much better. a word of caution about the plastic wire harnesses inside. its easy to wear them off the circuit board if you get rough with them and move the harness back and forth too much while taking the unit apart. the way i look at it is a tube mp is under 50$ and for myself worth tinkering with. i feel it sounds more like a mid level pre .

[travelin travis]

why did you put in the sockets? it this for being able to swap op amps quickly for comparison or are the sockets needed in order for the new op amps to fit? thanks for the info.

what are some characteristics of different tube types that I could try?

[gemsbok]

i put the socket in for easy swap and since my soldering skills arent the best .the heat wont get to the op amp this way. i swapped the tube for a euro tube . it was also suggested to look for old amperex bugle boys and telefunken 12ax7-s. i dont know much about the tube characteristics but i think a good tube helps smooth out the sound. a different tube might help but i believe only slightly with the tube mp. i think the op amp is where its at. it was just a fun project that i feel made a nice difference.

[travelin travis]

thanks for explaining gemsbrook.