Framus Cobra Tube Replacement

[Oriphen]

Hello everyone, thank you in advance.

Lets say i know nothing about amplifiers.

I've had my Framus Cobra for about 2ish years now, always hated both crunch and lead channels.
Never a fan of parallel loop.

Kind of sounds like it's out of phase when in the crunch or lead.
I've been using pure digital effects through the clean channel the whole time simply because to me it sounds better than the other channels. Although infinitely more harsh and I cant get definition out of chords when playing heavy gain.
(Always a problem with digital)

As with any tube amp it does sound better with the volume up but even excessively loud moments are just too harsh and I cant apply effects through the loop correctly due to the phasing issue.

It currently has some very low rumbling when idle and soft crackling as well.

I thought I should get the stock tubes out since lots of people say they aren't very good. Mine could be faulty at this point too.

http://www.rig-talk.com/forum/viewtopic.php?f=3&t=98491

I've been using this thread as a guide.
However some of the tubes they talk about I cant seem to find via eBay and I want to verify that these tubes are still currently good selections and any alternatives that are roughly the same if I cant obtain them.

Thanks again.

 

[benduncan]

Stock tubes usually suck, at least in my experience. Go to the Valve Queen, she's been good at helping me, with my lack of knowledge, get what I want. She was out of commission for a bit, I'm not sure if shes back. GET IT BIASED!

 

[benduncan]

http://www.valvequeen.com/

Shes on RT too

 

[RJF]

Supposedly, the clean channel never shuts off on a Cobra. It's actually on in the background when on the crunch and lead channels. It's what you are likely hearing as "phasing."

If you feel it's too fizzy, make sure you have the channel volumes dimed, and a set of KT77's will help kill some of the fuzz. It's what I have in mine, and it helps clean up the dirty channels just a hair.


But honestly, if I had an amp that I hated the gain channels, FX loop, and was using some digital thing to get a decent sound I like, I'd just get rid of the amp and get something else.

 

[Oriphen]

Thanks all.

I had regretted buying a new amp. Because this one was already pricey and it seemed like it should have done everything I wanted it too.

But compared to my friends alternative brands of amps. It cant get as good and it lacks saturation. Too much raw high end EQ and very harsh on the ears.

I want to believe its a great amp so I would like to check everything out, and tubes aren't expensive.

I already biased it quite hot and if I go any higher its going to kill something.

I will try said volume on clean channel.

thanks.

http://store.valvequeen.com/tubes/sovtek-12ax7-lps

Would this be suitable for my phase invertor?

 

[the4thlast1]

I think you can get it more to your liking on the crunch and lead channels.

Please tell us what your settings are on the crunch channel lets start there.

Tubes are normally a preference thing but the go to set for the Cobra would be chinese 9th type preamp tubes..Penta Ruby Sino Shungang .....Power amp tubes go to set for that amp would be Ruby EL34s
JJ EL34s also sound good to me in it and will yield a smoother tone than the Rubys. The Rubys will have more grind. Kt77s will be the tightest but also scoop the mids they weren't my favorite in the Cobra but some would love it

 

[Oriphen]

I think you can get it more to your liking on the crunch and lead channels.

Please tell us what your settings are on the crunch channel lets start there.

Tubes are normally a preference thing but the go to set for the Cobra would be chinese 9th type preamp tubes..Penta Ruby Sino Shungang .....Power amp tubes go to set for that amp would be Ruby EL34s
JJ EL34s also sound good to me in it and will yield a smoother tone than the Rubys. The Rubys will have more grind. Kt77s will be the tightest but also scoop the mids they weren't my favorite in the Cobra but some would love it

Forgive my late reply.

The crunch channel I would primarily use.
I have about 5-6/10 gain, 7/10 volume, 4/10 bass, 7/10 mid, 5/10 high.
Notch is down.
I have patched the effects loop but with or without the patch there's little difference just small amount of saturation.
Effect mix is 5/10
Deep is 3/10
Master volume channel 1 is at lowest 2/10 but gigs is more like 7, 8. or 9.
Master volume channel 2 has less highs than 1, no idea why, and i use the same described volumes

The phasing is still there even with no clean volume.

The gain is pathetic at low house volume obviously, it sounds like I'm trying to squeeze out some blues.
I'm getting an attenuator soon to solve that.

Even at very high volumes its very harsh and phasing. all my high notes for solos etc sound rubbish.
Not so bad with the power chords and any tremolo.

I've tried using my effects through the loop but I don't get a choice of order and i still get phasing issues.
Not a fan of the parallel loop.

What do you suggest?

 

[the4thlast1]

There are some Cobras out there that sound off for some reason. I've owned three Cobras and somehow all the ones Ive had were good. Some of them do have a weird phasing issue.....Your settings sound fine except I would run the highs and presence very low like 3/10 depending on the speakers being used and how the guitar sounds but in general I set them booth no higher than 5/10.

The Cobra sounded best to me on the crunch channel boosted with a maxon 808...Do you use a boost at all ?.... I dont want to scare you cause your amp might be fine and a retube will get it closer to where you want it but in general the tone of the Cobra's crunch channel is pissed off in your face type tone for modern metal rhythm, It does that awesome in a open and bright kinda way , leads tones are just ok.... Clean channel is great.

 

[benduncan]

Man, my reply was pretty simplistic. Maybe I should have read more of your post

 

[Oriphen]

There are some Cobras out there that sound off for some reason. I've owned three Cobras and somehow all the ones Ive had were good. Some of them do have a weird phasing issue.....Your settings sound fine except I would run the highs and presence very low like 3/10 depending on the speakers being used and how the guitar sounds but in general I set them booth no higher than 5/10.

The Cobra sounded best to me on the crunch channel boosted with a maxon 808...Do you use a boost at all ?.... I dont want to scare you cause your amp might be fine and a retube will get it closer to where you want it but in general the tone of the Cobra's crunch channel is pissed off in your face type tone for modern metal rhythm, It does that awesome in a open and bright kinda way , leads tones are just ok.... Clean channel is great.

I haven't been running boost.

I wanted to get a decent sound before I ran a boost.

I have an Ibanez TS808 which I wanted to boost it with but I couldn't get over the bad sound.

Ill try again with lower presence and highs.

I'll be replacing the tubes anyway to a more cookie-cut build just to eliminate any form of issue that might be held with the stock tubes.

Now I would like to know how many of each tube i'd need in each section.

What do you recommend:

V1:

V2:

V3:

V4:

V5 (Phase

As I've explained I know next to nothing about this stuff, like location of each section and how many tubes are in V1 as opposed to V2? My figure is 2 each, is that right?

 

[Oriphen]

Man, my reply was pretty simplistic. Maybe I should have read more of your post

I'll use your reference as a guide for purchasing required tubes.

Thanks for your help.

 

[Stone Heavy Sound]

I think Cobra is one of the best high gain amps out there, so something is wrong with your setup. First off, crackling usually indicates bad power tubes. You should change those first. DO NOT bias "hot" that reduces headroom and will wear your power tubes out faster, and clip your output tone as you turn the amp up. I would recommend having a a tech correctly bias your power tubes. With regards to preamp tubes, the stock EH tubes sound very decent, changing them may change the tone but it's subjective to say better or worse, you would have to tinker for yourself, but the stock EH tubes don't sound bad at all.

Regarding phasing and gain problems, my money is on the switching circuit. Contact Framus and ask about their switching circuit, but I'll bet you it uses optical switch circuits, I've had those crap out on Mesa and Splawn amps, and it messes up the gain structure and causes channels to bleed really bad, essentially rendering the amp unusable. That will require a replacement of the channel switching circuit, usually a board, Framus would be kind to replace that, Scott at Splawn replaced my Nitro switching board at no charge since it's not a consumable item like tubes.

 

[jd267]

I have owned three cobras over the years and always sell them for other amps and alway end up buying another lol. They really are great amps once you learn how to dial them in. I run ruby el34bht power tubes biased at about 34ma I bealeave I set the bias at . Cobras have about 510 plate voltage with out power tubes in it. For pre amp tubes I ended up with all square getter china 12ax7 tubes . They are kind of pricey but well worth it if you ask me at $25 each. I run bass at about 2oc mid at about 9oc highs at about 12oc, pres at about 10oc, depth at about 3 to 4oc on lead chan with maxon od808 as clean boost out of a mesa 4x12 and my tone is to die for. Can nail KSG tones all day. The stock jj power tubes suck and so do the EH pre amp tubes . This is my third cobra and I have tried like every tube combo possible and I liked what I posted the best. The cobra sounds good at about 32ma to 34ma and under if you don't want a lot of compression

The mid pot on these amps act as a mid bass adjustment . Kind of weird . I find keeping it low really thickens up the amp a ton. My tone slays

 

[the4thlast1]

There are some Cobras out there that sound off for some reason. I've owned three Cobras and somehow all the ones Ive had were good. Some of them do have a weird phasing issue.....Your settings sound fine except I would run the highs and presence very low like 3/10 depending on the speakers being used and how the guitar sounds but in general I set them booth no higher than 5/10.

The Cobra sounded best to me on the crunch channel boosted with a maxon 808...Do you use a boost at all ?.... I dont want to scare you cause your amp might be fine and a retube will get it closer to where you want it but in general the tone of the Cobra's crunch channel is pissed off in your face type tone for modern metal rhythm, It does that awesome in a open and bright kinda way , leads tones are just ok.... Clean channel is great.

I haven't been running boost.

I wanted to get a decent sound before I ran a boost.

I have an Ibanez TS808 which I wanted to boost it with but I couldn't get over the bad sound.

Ill try again with lower presence and highs.

I'll be replacing the tubes anyway to a more cookie-cut build just to eliminate any form of issue that might be held with the stock tubes.

Now I would like to know how many of each tube i'd need in each section.

What do you recommend:

V1:

V2:

V3:

V4:

V5 (Phase

As I've explained I know next to nothing about this stuff, like location of each section and how many tubes are in V1 as opposed to V2? My figure is 2 each, is that right?

I would get some chinese preamp tubes, I also like a couple EH preamp tubes mixed in there...Experiment and see what sounds best to you.... Ruby EL34 are the most recommended for Cobras.... Bias around 33 MA as mentioned.... I agree with a lot of what the guy said in the post above this one

 

[Oriphen]

Thanks everyone.

Really helpful stuff.

I got my attenuator so I'll be testing at a reasonable low volume, high-gain signal today.

some common question keeps being overlooked though.

I know what tubes I want to get kind of, but I don't know what goes where.
I've never taken apart my Cobra to any degree. Or any amp for that matter.
Is everything labeled in there? Nothing has been recommended for my phase inverter?
Is my VI Preamp? and V2 Power amp? Are there 2 tubes per section or what?

I don't want to beg for the answers; I just want to learn, and make sure before I go doing something that can damage my amplifier.