Tube Swap - how would you do it?
- Thread starter Mr Grumpy
- Start date
R. um you going to drink it all ??
Hold my beer I will be right there..generally yes-- however I will share
OP
Mr Grumpy
Ambassador of Comings and Goings
This arrived... Kinda forces me to open up the amp again and have a go at that soldering. I'm not that keen, as I only have a very basic gas soldering iron and a few tools. Nonetheless, that should be fine to sort out pin 7, and to make pin 4/5 safer.
OP
Mr Grumpy
Ambassador of Comings and Goings
Ok, this isn't pretty, buckle in... 
I do not have the tools, I only have a crap gas soldering iron, some
e solder, some huge pliers and some Arduino bits and pieces to do breadboard play-abouts...
Started off in the drainage business (left the amp for 10 minutes):
It's really tight and ugly down there, no space to do anything - that's my excuse... My soldering iron was too big, I was worrying about doing some damage, so I just barely did some work on the 7 pin; I know it's not good, sorry, but it has a firm connection now - not pretty, but now fully connected (before it was hanging loose and touching rather than soldered in. You'll notice that my connection, my solder, has no connection at all with the mountains of solder down at the bottom of the pin which isn't actually doing anything - just as Sysco pointed out)...
Here's a shot of the EL84, and I noticed two things:
1) the base is a different colour (that may be normal or one of them may have been changed later - I don't know.
2) the green wires (two of them) are around the attachment nut, not inside it.
So, I placed the 12ax7 problem wire (green one from pins 4/5) in that better position around the bolt. This is how it looks:
I do not have the tools, I only have a crap gas soldering iron, some
e solder, some huge pliers and some Arduino bits and pieces to do breadboard play-abouts...Started off in the drainage business (left the amp for 10 minutes):
It's really tight and ugly down there, no space to do anything - that's my excuse... My soldering iron was too big, I was worrying about doing some damage, so I just barely did some work on the 7 pin; I know it's not good, sorry, but it has a firm connection now - not pretty, but now fully connected (before it was hanging loose and touching rather than soldered in. You'll notice that my connection, my solder, has no connection at all with the mountains of solder down at the bottom of the pin which isn't actually doing anything - just as Sysco pointed out)...
Here's a shot of the EL84, and I noticed two things:
1) the base is a different colour (that may be normal or one of them may have been changed later - I don't know.
2) the green wires (two of them) are around the attachment nut, not inside it.
So, I placed the 12ax7 problem wire (green one from pins 4/5) in that better position around the bolt. This is how it looks:
Last edited:
OP
Mr Grumpy
Ambassador of Comings and Goings
I thought about it, and the entire area needs taking apart, dealing with properly and putting back together. I can't do that with the tools I have. I don't trust any Korean guitar shop I know to do the work.
Thus, I thought about and consider a great British option: bodgit, butcher it, find a two bob solution and get the hell out of dodge. This type of Bodgit&Scarper approach is when you're doing other folks' work and getting out of town fast, but as it's my apartment that's gonna burn down, I wanted at least a semi-ok solution. Sadly, I couldn't find one, so I came up with this solution:
1) I cut a crocodile clip up and stole some of the insulation wire then cut it to fit the 12ax7 base screw. I checked the size on the EL84 because there was more room to work.
2) After much trial and error, I found a way to get it onto the screw in the tiny 12ax7 space... Imagine the self taping screw is the 12ax7 base screw, well, I delivered the insulation wire to the base screw then moved it into place with the pliers which were about 3 orders of magnitude too big for the job:
3) We're on, but not as smug as I'd like and the green wire has bare areas near other solder which I'm not happy about - no better than before really (maybe a tad better).
So, I manipulated it around the baseplate screw with a tension which was firm. The wire is bare as a baby's bottom...
Safer than before? Certainly a temporary fix. I don't like that bare wire, but there's nothing around for it to touch...
What I will do is have another go, but this time cut from the remainder of the crocodile clip so that I get a shape that fits the entire nut and bolt... That'll keep the wire safe from below, and there's nothing above for it to touch.
Turned the amp on, it didn't explode, and for the last hour has sounded pretty good - really really like a bell chiming AC10; nice.
Do I get a TTR award for the worst amp 'repair' ever?
I feel quite ashamed of it, but without getting a set of tools and rewiring the 4/5 pin, I can't see what else to do?
Thus, I thought about and consider a great British option: bodgit, butcher it, find a two bob solution and get the hell out of dodge. This type of Bodgit&Scarper approach is when you're doing other folks' work and getting out of town fast, but as it's my apartment that's gonna burn down, I wanted at least a semi-ok solution. Sadly, I couldn't find one, so I came up with this solution:
1) I cut a crocodile clip up and stole some of the insulation wire then cut it to fit the 12ax7 base screw. I checked the size on the EL84 because there was more room to work.
2) After much trial and error, I found a way to get it onto the screw in the tiny 12ax7 space... Imagine the self taping screw is the 12ax7 base screw, well, I delivered the insulation wire to the base screw then moved it into place with the pliers which were about 3 orders of magnitude too big for the job:
3) We're on, but not as smug as I'd like and the green wire has bare areas near other solder which I'm not happy about - no better than before really (maybe a tad better).
So, I manipulated it around the baseplate screw with a tension which was firm. The wire is bare as a baby's bottom...
Safer than before? Certainly a temporary fix. I don't like that bare wire, but there's nothing around for it to touch...
What I will do is have another go, but this time cut from the remainder of the crocodile clip so that I get a shape that fits the entire nut and bolt... That'll keep the wire safe from below, and there's nothing above for it to touch.
Turned the amp on, it didn't explode, and for the last hour has sounded pretty good - really really like a bell chiming AC10; nice.
Do I get a TTR award for the worst amp 'repair' ever?
I feel quite ashamed of it, but without getting a set of tools and rewiring the 4/5 pin, I can't see what else to do?
Last edited:
OP
Mr Grumpy
Ambassador of Comings and Goings
I went back in... My fix is holding - I checked it from all angles, and it's firm, no bare wires have a chance to touch anything else; it does look bad, I know, but it's working (and I reckon it's safe too - I checked from all angles, close up, and the only area of bare wife is facing nothing - ideally, I'd like to cover it with insulation tape or change the wire, but it's just too small and cramped to get in there with the tools I have).
EL84s
The JJ sounds nice, but not that balanced, the high strings come out more.
The Philips Mullard is better balanced, still a tad more in the highs (might be the amp) and more musical, fuller notes, etc.
The Brimar is the best balanced on this amp to my ears, very nice and full low strings which the other two don't have; there's a bit more tightness while still being musical. Also, the Brimar holds the distorted tones together better without me having to take so much off the tone knob when adding gain. Thus, Brimar is in for now.
How is the amp - great. I'd say it's AC10ish, but at AC4 or lower volumes. At 5w, playing hard, you get the AC10/AC30 sound. Did I mention before I got this amp that it was Plexi style? It's not at all, it's a take on the VOX sound. I like it.
With the new speaker cable, I plugged into the 1x12 - don't like it; too airy, no wallop, I prefer the 8" speaker that comes in it, go figure...
Is it worth putting a greenback in to see if the 1x12 sounds better (they're quite cheap)? The amp sounds good, doesn't need a speaker swap.
EL84s
The JJ sounds nice, but not that balanced, the high strings come out more.
The Philips Mullard is better balanced, still a tad more in the highs (might be the amp) and more musical, fuller notes, etc.
The Brimar is the best balanced on this amp to my ears, very nice and full low strings which the other two don't have; there's a bit more tightness while still being musical. Also, the Brimar holds the distorted tones together better without me having to take so much off the tone knob when adding gain. Thus, Brimar is in for now.
How is the amp - great. I'd say it's AC10ish, but at AC4 or lower volumes. At 5w, playing hard, you get the AC10/AC30 sound. Did I mention before I got this amp that it was Plexi style? It's not at all, it's a take on the VOX sound. I like it.
With the new speaker cable, I plugged into the 1x12 - don't like it; too airy, no wallop, I prefer the 8" speaker that comes in it, go figure...
Is it worth putting a greenback in to see if the 1x12 sounds better (they're quite cheap)? The amp sounds good, doesn't need a speaker swap.
Last edited:
syscokid
Ambassador of War & Peace
Considering your situation in not having more appropriate tools, you did a great job in keeping you and your amp safe. Hopefully you can now enjoy your amp and focus on all the glorious sounds you can get out of it... 
I must say, that I really don't care for all that heat shrink tubing at the lugs of the tube sockets. What a PITA when the amp needs to be serviced.
I must say, that I really don't care for all that heat shrink tubing at the lugs of the tube sockets. What a PITA when the amp needs to be serviced.
I’m happy to see that you’ve made a go at making your amp safer. Considering the available equipment, it looks better. I hope that you are able to make a more permanent repair eventually.
I’m saddened to read that you are unhappy with your 1X12. I’m happy to read that you are happy with the onboard speaker.
I’m saddened to read that you are unhappy with your 1X12. I’m happy to read that you are happy with the onboard speaker.
ivan H
Ambassador of Tubes & Grooves
I've got to agree with Sysco & Don. Considering the tools you had at hand, you've done well in making the amp safer & able to be played reliably. Ingenious fix to the heater wiring problem. I'm hoping you can effect more permanent repairs in the future (electric iron, good quality solder & more suitably sized tools). I should have mentioned this before (apologies), but remove the tube from the socket while repairing the pin wiring. It will act as a heatsink & draw heat away from the pins as you attempt to solder or de-solder.
Unusual that it has a two completely different socket types. Both types are available with or without the shields.
Glad you are liking the NOS EL84's. Brimar are great tubes, rivaling the quality of any of the great British made tubes. Enjoy that Voxy goodness. Cheers
Unusual that it has a two completely different socket types. Both types are available with or without the shields.
Glad you are liking the NOS EL84's. Brimar are great tubes, rivaling the quality of any of the great British made tubes. Enjoy that Voxy goodness. Cheers
OP
Mr Grumpy
Ambassador of Comings and Goings
I hope that's gonna be true - it's safer. I'm not happy with the state of affairs, but it's messy down there.. TBH, I'd think twice about buying another amp from this manufacturer - the design isn't great at all, poor accessibility, the 12ax7 doesn't fit into the metal frame well, so when you take a tube in/out you're affecting the wiring too much - putting pressures and stresses on. It's a compact amp, but there's still enough space to have designed a better layout with better choices (and far better soldering around the tube sockets).
Yeah, the amp does sound very good - I'd say somewhat better than an AC4 (although I've only played them in the shop not at home), and better sounding than other amps I've owned (Bugera T4, Marshall DSL5/Origin 20) excluding the Randall RD which really holds its own against anything out there - surprised more folks don't have them; cheap and amazing sounding.
Thanks, it's a bodge, but functional. A permanent repair would involve the 7 and 4/5 pins being desoldered, new wires on the 4/5 pins then resoldered properly - I can't see that happening anytime soon.
I suspect the 1x12 would sound good in a big space from a distance at higher volumes.
All three of you have been very helpful - it now sounds great, the power level is consistent (must've been that 7 pin?) and it's safe. I should've cut the crocodile clip differently to cover the entire screw/bolt, but the wire is very tight, so I wanted to just ease it into place without pulling the wire and damaging it. Now it's done, I can see a better solution... I suppose, not knowing the amp (or any) it's step by step learning...
Good to know, thanks.
Yes, I probably understated the Philips a bit - they are equally nice, the Mullard is a bit more musical and has a bit more bite/growl, but with the amps characteristics and the way I like to play, the Brimar just suits better for now.
Going back to the original theme of the thread - yes, all tube changes make a significant difference to the sound, and all in different sound sculpting ways.
Because I never got charged import tax on this amp, it has worked out pretty reasonably priced (saved me 30% off retail), but I could certainly see another route as being an 10" speaker AC4 (a version with volume and gain) then a full tube and speaker (greenback) replacement would have you in a nice musical spot for about $400 or so. An AC10 with the same changes and an attenuator would also do the job for about $600.
The amp does sound really good, and the tubes help add to the tone.
I'm still slightly confused by the amount of gain available - I don't think it comes from the pre-amp swap alone; something changed along the way; whether it was hampered and too clean before or something affected a resistor/capacitor and the amp now gives out more gain than it's designed to do (this is my guess). Not sure, but something...
ivan H
Ambassador of Tubes & Grooves
I'm thinking the amp is now performing as it always "should" have regarding the amount of gain produced, whereas previously the poor connection at pin 7 resulted in reduced performance. Cheers
syscokid
Ambassador of War & Peace
Sure makes me wonder about all the other soldered connections on Grumpy's amp...
. I'm obsessed in finding out if this is par-for-the course for Cornell products.I just like it when you talk like that...
Last edited:
OP
Mr Grumpy
Ambassador of Comings and Goings
I sent a very polite email, with picture, mentioning that I'm not after anything, I'll get it fixed locally, but they might be interested for QC reasons. No answer... perhaps that says something in itself.
You know, when I had the two Marshall amps, I think both were Vietnam made (?), I was always impressed by the quality of fit and finish, layout, the space for easily getting inside and getting at everything from the speaker to the tubes to the circuitry. It's only when you see something lesser you appreciate the design approach of the former.
Maybe this is a new amp space for the brand, a lower price point, a smaller size, and they just compromised in a few areas? I'd imagine their bigger Fender and Marshall style amps are better although I won't personally be finding out... If this amp had've been perfect, maybe I would have gone after the 6V6/6LS sound in their Romany amp...
I don't wanna talk bad about a small builder, but I can only speak from experience.
Last edited: