Replacing a 12ax7, Hartke LH 1000

morewattsplease · #1 03-08-2013, 04:22 PM

trust me I've been doing some reading of old threads and such but I haven't found an answer to this particular question:

I have a Hartke LH series amp...and I love it. Any complaints I have are minimal considering the $408 out the door for 1000 watts of good amp.

Complaints: Little bit of noise (could be my house wiring)
Could use a more drammatic EQ, its a stackable EQ apparently, and its a learning experience that I may cheat on and just get a graphic eq from source audio, ashdown, boss etc...

(my actual question here) Preamp has a "sound" built in to it which is very pleasurable, kinda swr like, a scoop to it. Very warm, crisp highs, smooth low, punchy etc.
HOWEVER the mid is really really tame. The "Mids" knob is not broken, but there just isn't that availability of mids that I', used to.

Don't get me wrong, I love the sound. All my basses sound great through it, the preamp and power stage has an excellent vintage vibe mixed with hartke punch.

What I'm wondering is if I replace the stock tube with something else, will a different tube possibly have a more dramatic mid response.

The other amp i have is a Warwick quadVI. Its got more knobs, more buttons, more tubes, and probably dif. tubes and well, its a warwick product so its got mids and more built in control to achieve them.. The mids on that thing will punch you in the stomach from the next room. I'm not looking to recreate that, I like the difference between the two amps, its just that I want a little more of an option for the mids.

To anyone who happened upon this thread looking for Hartke LH info, I feel the need to reiterate that this problem is barely a problem for me. these amps don't pretend to have a million knobs. They do great vintage tone with the capability to be more aggressive and just sound awesome. and when you add in that they are cheap...well I bought this because it was cheap and I wanted something simple and that I didn't care so much about if it got spilled on or dropped. I now care about it as much as I do my wick amp.

To clarify what I'm hoping for in responses is recommendations on tubes and or equalizer pedals (maybe racks) that are some of your favorites and if you are feeling nice, say why.

Mr. Foxen · #2 03-08-2013, 04:26 PM

VAlve change will do very little to the mid response. Its all in the circuit, and its a Fender style tone stack so stuck with a mid cut, max mids, min treble and bass is closer to flat, useful if you plan on external EQ.

morewattsplease · #3 03-08-2013, 04:36 PM

thanks mr. foxen, I had a sneaking suspicion that this is the case but I figured I'd ask, I still might try a few dif tube replacements in both my amps just for the experience.

Floyd Eye · #4 03-08-2013, 08:12 PM

The amp has one 12AX7 in the pre. Other than tube longevity, there will be no discernable difference with another tube.

JimmyM · #5 03-08-2013, 09:34 PM

Some amps with one tube do respond to tube rolling. But it's a really small difference usually, and most of the time I don't hear any difference whatsoever, though there are times I have heard one...mostly with high dollar new old stock tubes from the 60's and 70's vs cheap JJ's or Sovteks. It also depends on whether the tube was wired to use some actual plate voltage or starved plate...the starved plate designs are only slightly better than regular solid state most of the time...glory tubes, mostly. You can throw any old tube in them. But I don't know how Hartke wires up their tubes so you'd have to find out to see if it'll matter.

Or you can buy a $150 Mullard from 1962 and a $10 Sovtek and see if it makes a difference and find out that way

OTOH, it could be broken...wouldn't hurt to have a spare or two anyway.

NYCbassist · #6 03-08-2013, 09:57 PM

It's got a Sovtec in it now at least mine does. I have some 35+/- year old NOS Penta USA 12AX7's that I could try & report back. I don't think it's going to make much difference though.

JimmyM · #7 03-08-2013, 10:48 PM

Sounds like fun, although if the sound doesn't change, that doesn't necessarily mean it's starved plate but that you have two similar tubes. I like Sovteks. I think people give them a bad rap but I've had good luck with them in other amps.

**mjac28** · #8 03-08-2013, 10:56 PM

Quote:

Originally Posted by JimmyM

Some amps with one tube do respond to tube rolling. But it's a really small difference usually, and most of the time I don't hear any difference whatsoever, though there are times I have heard one...mostly with high dollar new old stock tubes from the 60's and 70's vs cheap JJ's or Sovteks. It also depends on whether the tube was wired to use some actual plate voltage or starved plate...the starved plate designs are only slightly better than regular solid state most of the time...glory tubes, mostly. You can throw any old tube in them. But I don't know how Hartke wires up their tubes so you'd have to find out to see if it'll matter.

Or you can buy a $150 Mullard from 1962 and a $10 Sovtek and see if it makes a difference and find out that way

OTOH, it could be broken...wouldn't hurt to have a spare or two anyway.

+1 save your money I am into tube rolling and I can tell you first hand it won't make that much of a difference. I put a NOS 60's RCA Black Plate in my Mesa it sounds a little better but I think it's because I spent so much on a set of those tubes that I want to "believe" it does. I recently got a 59' Raytheon Long Plate that I put in my Swell Pedal and that made a huge difference in the sound but a single 12ax7 in a solid state amp does little.