Bare Knuckle Pickups Forum
Forum Ringside => Guitars, Amps and Effects => Topic started by: GuitarIv on October 15, 2013, 10:47:10 PM
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Cheers guys,
so, some of you may already have read about my decision to get a Jet City JCA50H, today it finally arrived and so I give you a New Amp Day thread! :D
I don't know where to start, I guess first of all I really have to give big props to Thomann for processing my request in such a fast manner, if my bank wasn't so lame and the money would have been transferred faster I'm sure I would have gotten the amp last week.
The packaging was solid and the head was secured inside in a way that only very rude behaviour could have damaged it, a Footswitch, a users manual and a Jet City sticker were included.
First impression of the head: solid and sturdy built, very tidy and nothing coming loose or indicating that it is "made in China".
So I plugged everything in, fired it up and started playing from Clean to Distorted, just kinda to go from good to better.
Cleans: Well, if you expect pristine Fender Cleans, this is the wrong amp for you. The sound isn't bad, it's a thousand times better than anything a 6505 head could ever give you, but it isn't exactly something you would be expecting from a Fender. Still way better than the cleans on the JVM 205 and somewhere near the EVH 5150. Very usable, throw in a Delay Pedal into the Effects Loop and there you are.
Crunch: Woah. I can't think of another word right now, the crispness this thing delivers is amazing, from Blues to Rock to all the AC/DC Hard Rock goodness this head slays. Very dynamic and responsive to pick attack and your playing, reacts great to the guitars volume and tone pot and note separation is superb.
Overdive: That's what I'm talking about. This thing spits mids, sounds warm and chunky, clear as a tear and sits somewhere in the old school JCM 800 Thrash Metal territory. A tubescreamer is a must as the Overdrive Channel isn't tight enough on its own, but as soon as you put the little green box in front everything works like a charm. If you're looking for a 6505 modern distortion tone then this won't suit you. I don't know how to explain it, the saturation the Jet City delivers is just something entirely different. As said it responds to your playing and thus it is unforgiving. I love it.
So to sum everything up: I can't believe I've gotten such an amazing amp for 300 quid. This is a bang for the buck and a huge improvement over my Peavey Valveking.
Cons: as with every piece of gear, there are some downsides:
This thing is bright. You want to keep the Presence and Treble Knobs on 5 or lower, otherwise it can get piercing. This is most likely the reason why a lot of people complain about the missing Depth Control Soldanos usually come with.
Fizziness: This is the reason I'm asking for some insight on changing tubes on the amp. I have read a lot of reviews about the JCA50H where people suggested to swap out the stock factory Chinese tubes for better ones. The fizz is not present in a way where dimming the highs would remove it, it's just constantly there. In the background. And it's a bit disturbing.
So my question would be: what kind of tubes should I get? Something that tames the brightness of the amp and is better quality than the stock Chinese tubes would be nice. The Amp has 5 12AX7s in the preamp section and two 6l6s in the power amp section. I read some threads about changing V1, V2 and V3 and how every of those positions affect your tone in a different way, I'm not an expert so some insight would be appreciated.
Cheers!
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Congrats on the NAD! Cool little insight on the first impressions, read it with great interest.
Concerning the tube swap I am not an expert either, though I have done a bit of swapping myself. What I can tell you is that the V1 will have the biggest effect on the tone. That is where the signal hits and everything after it uses what it produces. So if you happen to have a 12Ax7 laying round you might just wanne pop that in the V1 and see how much it changes. If that does not cure the issue go on the the other stages as well.
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v1 - tungsol RI
v2-4 JJ ecc83s
In the power amp id go JJ 6l6gc for a grindy thick tone tungsol for a brighter tone (not what you want right now but with different preamp valves it could work)
also for true cleans you need a small mod.
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Thanks guys!
As far as my understanding goes the preamp tubes have a bigger effect on the overall sound than the poweramp tubes?
I've read the users manual and it says I can safely swap tubes without having to adjust the bias as long as it's the same manufacturer and type of tubes. Does this mean as soon as I get JJs I will have to adjust the bias or is this obsolete?
Toe-Knee: thanks for your input, I always appreciate your thoughts very much. For the cleans I think they will do so far, I like a little bit of dirt on them. Anyway, are there any EU suppliers for tubes? Right now my only reference is Thomann and they have JJs, Mesa Boogies, Sovteks, TADs, AMTs, Groove Tubes and Engl Tubes for the 12AX7s, but no Tungsols...
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Thanks guys!
As far as my understanding goes the preamp tubes have a bigger effect on the overall sound than the poweramp tubes?
I've read the users manual and it says I can safely swap tubes without having to adjust the bias as long as it's the same manufacturer and type of tubes. Does this mean as soon as I get JJs I will have to adjust the bias or is this obsolete?
Toe-Knee: thanks for your input, I always appreciate your thoughts very much. For the cleans I think they will do so far, I like a little bit of dirt on them. Anyway, are there any EU suppliers for tubes? Right now my only reference is Thomann and they have JJs, Mesa Boogies, Sovteks, TADs, AMTs, Groove Tubes and Engl Tubes for the 12AX7s, but no Tungsols...
I use hotrox. And i've found in most cases the power valves make a drastic difference. And yes you should rebias really.Its a JCA50h right? Most JCA's that i've come across come biased cold so you can probably get away with it but its not the best thing to do.
The bias could also be causing a good portion of the fizz.
Preamp valves you can swap without any adjustments
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Found the Hotrox site :)
Ok, so my next question would be: how does one exactly bias an amp? Any special tools I need for this or any chance I might get fried in the process? Only thing I remember is a cold biased amp will extend the valves life and a hot biased one will sound better but consume the tubes faster.
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So, I've done some research and from the information I gathered all Jet City Amps are fixed bias, so switching poweramp tubes will require an adjustment. They have "an internal variable resistor that allows for fine adjustment when desired". Is this the so called Bias Pot?
So basically I need the right tools to measure the bias value between pin 3 and pin 8 on the socket, calculate the right value and then trim it to the value of choice whereas 50% will be "cold" and 70% will be "hot". This can be done by turning the bias pot with a Screwdriver.
Anyone mind to confirm this?
I won't attempt to swap out the Power Tubes on my own right now, at least not before I haven't done more research on the subject. I'll try out different Preamp tubes though as those don't need an adjustment from what I gathered.
Help is appreciated as always, thanks! :)
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Yeah, you are going about it in the right way. Powertubes should only be done when researched properly.
With the preamps you can do them without issue. The way I would go about it is focus on the V1, cause that, as I said before, is the baseline, the center of the sound.
It is very important that you get this one right. The character of the distortion can change really dramaticly, especially how it reacts to being pushed by a boost or OD.
So there pick something that displays the general character you want. JJs for example I find to be nicely full, round and roary, kinda like the Crawler among tubes.
After you have the right base character use the following stages to shape it further. The V1 is the meal, the others are the spices.
I for example like a JJ in the V1 of my Orange TT, but I need to follow it with a Tung Sol or Tube Town, which are mich brighter. In V1 I find them to be too trebly and hard for my taste, especially with the way I boost, but in V2 they add in air, sparkle and depth to the JJ.
Make a educated plan, get tubes and then try around IŽd say. Try every tube you can get your hands on (even if it is just borrowing a tube a mate got lying around) and try them in V1 to get a sense of what they do. Once you got the right V1, build on it.
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Nice score :D
I haven't got round to swapping my tubes. I find using eminence v12 speakers tame a fair bit of the fizz etc., but most people seem to say that swapping tubes helps a lot, too, so it's probably worth considering. Toe-Knee will know way more than I do regarding swapping the tubes.
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@Kiichi: I will certainly get myself a bunch of preamp tubes and do some experimenting, after reading lots of great articles on the whole subject today this seems to be a safe and easy first hand solution. However first of all I'll get myself the 2*12 Palmer Cab loaded with Vintage 30s for the Jet City so I have a reference point as my Laney Cab loaded with Celestion 70 Eighties I'm using right now doesn't really do it for me, also I will have to open the cab up and recheck the wiring as there are some weird sounds coming out of it once in a while and being the third owner of the thing there might be some wear.
@Dave: Actually I'm still waiting for Toe-Knee to chime in as he knows his stuff :D
Anyway, I have a feeling this head will finally give me the opportunity to explore the world of amplifiers in depth, I found out how to swap Power Amp Tubes and bias an amp today and downloaded the JCA50H wiring schematic, lots of great articles and forums on the Internet and in the end the whole subject gets a lot less scary once you start to do your research and understand how those things work (and what you have to do in order to not get fried :lol: )
Cheers!
edit: I think I probably should ask someone to move this thread to the Tech section :P
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@Kiichi: I will certainly get myself a bunch of preamp tubes and do some experimenting, after reading lots of great articles on the whole subject today this seems to be a safe and easy first hand solution. However first of all I'll get myself the 2*12 Palmer Cab loaded with Vintage 30s for the Jet City so I have a reference point as my Laney Cab loaded with Celestion 70 Eighties I'm using right now doesn't really do it for me, also I will have to open the cab up and recheck the wiring as there are some weird sounds coming out of it once in a while and being the third owner of the thing there might be some wear.
@Dave: Actually I'm still waiting for Toe-Knee to chime in as he knows his stuff :D
Anyway, I have a feeling this head will finally give me the opportunity to explore the world of amplifiers in depth, I found out how to swap Power Amp Tubes and bias an amp today and downloaded the JCA50H wiring schematic, lots of great articles and forums on the Internet and in the end the whole subject gets a lot less scary once you start to do your research and understand how those things work (and what you have to do in order to not get fried :lol: )
Cheers!
edit: I think I probably should ask someone to move this thread to the Tech section :P
You have the general idea of biasing down.
However you measure the plate voltage at pin3 but you measure the actual bias voltage across a 1ohm resistor from pin 8 to ground. It isnt the most accurate method but it's the simplest.
again though this isn't something that should be done recklessly. Pin 3 will have around 480v on it which isn't something you want to mess with!
Eurotubes do a nice bias meter thats $99 i believe that measures both the plate & bias safely.
Once you have the plate voltage its time for some simple calculations but i'll go into that later :)
Focus on the preamp now.
V1 is your input & crunch channel gainstage & V2 is the lead channel (this is a semi educated guess)
Those two should be your initial focus.
The others whilst not as critical do still have some effect.
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Get the DVD Tube Guitar Amplifier Servicing and Overhaul - Gerald Weber.
If you can't bring yourself to pay whatever it costs you can find the torrent online somewhere.
It has a lot of stuff in there, including how to avoid being shocked!
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So, I've done some research and from the information I gathered all Jet City Amps are fixed bias, so switching poweramp tubes will require an adjustment. They have "an internal variable resistor that allows for fine adjustment when desired". Is this the so called Bias Pot?
So basically I need the right tools to measure the bias value between pin 3 and pin 8 on the socket, calculate the right value and then trim it to the value of choice whereas 50% will be "cold" and 70% will be "hot". This can be done by turning the bias pot with a Screwdriver.
Anyone mind to confirm this?
I won't attempt to swap out the Power Tubes on my own right now, at least not before I haven't done more research on the subject. I'll try out different Preamp tubes though as those don't need an adjustment from what I gathered.
Help is appreciated as always, thanks! :)
No, typically fixed bias implies that it cannot actually be adjusted. If it similar to what Peavey does, it is a quite "cold" bias that is safe for power amp tubes without biasing.
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So, I've done some research and from the information I gathered all Jet City Amps are fixed bias, so switching poweramp tubes will require an adjustment. They have "an internal variable resistor that allows for fine adjustment when desired". Is this the so called Bias Pot?
So basically I need the right tools to measure the bias value between pin 3 and pin 8 on the socket, calculate the right value and then trim it to the value of choice whereas 50% will be "cold" and 70% will be "hot". This can be done by turning the bias pot with a Screwdriver.
Anyone mind to confirm this?
I won't attempt to swap out the Power Tubes on my own right now, at least not before I haven't done more research on the subject. I'll try out different Preamp tubes though as those don't need an adjustment from what I gathered.
Help is appreciated as always, thanks! :)
No, typically fixed bias implies that it cannot actually be adjusted. If it similar to what Peavey does, it is a quite "cold" bias that is safe for power amp tubes without biasing.
Actually, fixed bias can be adjustable. The 'fixed' bit just refers a constant bias voltage being delivered to the grid of the output valve, which in a JCA50H, Soldano Hot Rod, Marshall JCM800 and a million other amps... it is. Those are 'Adjustable' fixed bias amps. The Peavey 5150 is fixed bias but not adjustable, the dual rec is like this too. Cathode Bias is the common alternative and is not set using the supply of a fixed/constant voltage to the output valve grids.
EDIT. Like Tony said though, Pin 3 has one of the highest voltages in the amp on it. I use Pin 3 to do bias but it means poking around at over 450volts and doing some light maths. I would get the bias tool for ease if you want to be as safe as possible.
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Wow, they really should rethink the term "fixed" then, it's kind of misleading for most people with a non-technical background.
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Wow, they really should rethink the term "fixed" then, it's kind of misleading for most people with a non-technical background.
Yeah. it is one of those things that is very very commonly mixed up. pretty easy to see why!
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Ok guys, I'm back with some results:
I played the amp some more today and really toyed around with it, coming to the conclusion that the fizz is killing me. I really love the midrange and cut this thing delivers, note separation and clarity are superb, however there's this constant fizziness going on that neither the presence nor the treble control can tame. It's just disturbing. I'm sure in a band context it'll be fine, cut through and you wouldn't even notice it at all, but playing in front of the amplifier is a complete different story.
Some other weird things I noticed: When I turn on the standby switch the sound fades away whilst playing like it's supposed to, but when I turn the amp off and keep on strumming there is silence followed by a slowly building up sound of my playing coming out of the speakers again before it fades (with the amp in standby).
I played my RG with an EMG 81/85 set tuned to Standard D through it and it seemed to remove some of the fizz (guitar before was my Jackson Dinky with a Painkiller/Coldsweat Set tuned to E-Standard and although I know the Painkiller can create some fizz and the tuning might contribute to this it's just overkill) but not all of it. So the EMGs sounded better but the amp still did it's fizzy thing.
The Footswitch seems to be either broken or have a faulty connection as it first made the amp silent, no sound emerged until I hit the switch on the damn thing, then it reversed the drive and clean channel. (Judging from the LED on it that is supposed to be on only when the OD channel is engaged).
Don't get me wrong, I'm really trying to like the amp, but there are some obvious issues I can't and won't ignore. I still have the 30 Day Thomann money back guarantee and will send it back if following things don't work out:
Changing the Speaker Cab. I had some issues with my Laney before so maybe it's the cab. I'll ask a friend of mine to borrow me his Vintage 30 Cab so I can do a comparison.
Switching Preamp Tubes. I guess I'll try out some JJs as those are said to sound warmer and darker. Don't know if this will make my guarantee invalid though.
Get a technician to switch out the Preamp and Power Tubes and set a warm Bias? I'm sure I could do it on my own but if a technician does it maybe my guarantee stays valid?
Now I'm really not sure what to do. If I just keep the amp and experiment with a warmer Bias and better tubes I'll lose 300 quid in the worst case. Like Toe-Knee pointed out the cheap china tubes and the factory cold bias could contribute a great deal to the fizz and there are still tons of mods that can be done to the amp to make it better, I even looked up Mercury Magnetics and O'Netics Output and Power Transformers that should get you close to the real thing but in the end you get what you pay for and the amp was cheap. Maybe I'm overreacting but I'm trying to find out whether it's worth it messing around with the head or I shall just get my money back :?
Thanks so far for all the input you have given me, especially Toe-Knee and Dmoney. More ideas what could be wrong are very appreciated. I might shoot you a p.m. anyway :)
Cheers!
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On the fizziness: keep in mind that the original SLO amps came with 5751 tubes in the preamp. The 5751 can be put in the amp without any changes but they have less gain (about 70 compared to 100 of a 12AX7). They also are warmer sounding. Try one in V1 and see if that's enough. If not, put one in V2, too.
Cheers Stephan
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I've never played one so can't comment on the fizz, but the circuit isn't a fizzy circuit. My JCA22H was fizzy. Now it just has JJ ECC83S' in and it's fine. It is bright compared to 100watt big bottle versions of the same thing though I reckon. I don't really use bright guitars or pickups. My Vigier is pretty balanced and both the Les Pauls I have a darker. Both LPs have Nailbombs in the bridge.
Try the extra cab. I have no idea what 70/80's sound like.
With the footswitch, the light should be on when OD is engaged. It's a VERY simple pedal. One switch, an LED and a resistor. open it up and see if something looks bust. I can send you photos of mine. I removed the fixed cable and installed a jack so I could use any length cable with it.
The power and standby switching is actually nicely done. They use DPDT switches to switch both the live and neutral wire going from your mains into the power transformer, where lots of amps normally just switch the live. They do the same thing with the high voltage secondary, switch both wires out of the power transformer into the rectifier. That leaves very little of the circuit at high potential (and still dangerous) when the amp is on. Normally a single pole switch is used after the first filter stage and in line with a fuse and the choke. That leaves the highest voltage node live when you switch the standby. It also means the switch is cutting DC voltage, which isn't always great. You can read about it all on the valvewizard site if you want. I wouldnt worry about it.
I think Jet City/Soldano stand by those transformers. O'netics and Merc's are probably worth twice the cost of the amp. I'm not sure if Merc Magnetics are worth the money either. As long as the OT isn't tiny then you should be getting a decent response from it and not loosing low end.
The bias recommendation I've seen for other soldano amps is 26mA idle current. Which is on the cool side, but I think it's chosen for a couple of reasons. It's not TOO cold by most peoples standards, It gives your power valves longer life and a more reliable set of conditions to work in. In comparison a 5150 i have in my flat is biased around 14mA per valve. 60% in that amp would be around 35mA each. If i got the scope on it I'd probably see a lot of crossover distortion in it. 70% is most peoples rule of thumb. A lot of people just bias using a scope and not looking at idle current. Some people do it totally by ear! I usually go lower than the 70% mark for my own amps. Also, in some amps when you add a bias test point from pins 1&8 you actually end up measure the plate and screen current draw summed together which means you usually end up biasing a few miliamps cooler than you think, unless you work out the screen current draw in advantage and take that away from what you read at the cathode.
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are you using 70/80s? It's ages since I've tried them, but I remember not being too fussed. They certainly don't have a great rep as far as celestions go. And certain speakers (looking at g12t75s here) can definitely add their own fizz that you can't dial out. maybe the 70/80s are similar. maybe not. I dunno :? :lol:
If your friend's v30s are broken-in, that should help.
i should probably add though that fizz doesn't really annoy me. I quite like a bit of fizz. :lol:
and yeah mine makes a noise when i switch off, even when i've switched to standby first. Dmoney will know more about the technicalities than I will, lol, so listen to him. I just assumed it was normal.
If you really aren't getting on with it, though, by all means send it back. it doesn't matter if I like it if you don't. :)
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Sure Thomann will give you the cash back after you've done all those changes to it? if there's such issues, just send it back right away and get something different. I had the same with the laney I had and I'm glad I sent it back and did not tinker with it for ages.
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Like Alex says too, if you don't think it's gonna work out, don't try anything too invasive and get it sent back. Best option if you've bought online.
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Ok, so I have an update: on Monday I'm borrowing my mates Engl 4*12 with broken in Vintage 30s. This should give me a definite answer if it's the cabs fault or not.
Stephan, Dmoney: Preamp tubes aren't expensive and if they really can cut out the fizz like you say I guess this would be the next step after messing around with the cab.
Thinking that I could still get my money back after fiddling around with the internals of the head was kinda stupid I admit, I just don't wanna take the easy way out and give up by sending a basically good amp back because it doesn't appeal to me stock. If a few euros for new tubes can remove the fizz (and that's the only thing that disturbs me) and changing my Painkiller for the Holydiver again can fatten the sound up, I see no reason why I shouldn't try it. I guess right now I need to decide wether to take the risk of loosing 300 quid or just let it be. I know myself well, so it's probably gonna be the former...
Regarding the footswitch I'll open it up and see if anything is loose.
I've just started my journey of delving into the world of amplifiers and how they work, so I will certainly consult the Valvewizard site, the more information I get, the better :D
The idea with the transformers was actually just... well an idea. Maybe I'll end up building my own SLO Clone one day anyway, that is if I gather the knowledge that's required.
The biasing will be the first big step I'll do after trying the cab and new preamp valves out. I'll certainly open up a thread/shoot some messages when the time is right.
Well, seems like I have already made a decision. I think I'll keep the amp. News on Monday :D
Cheers!
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Ok, so I have an update: on Monday I'm borrowing my mates Engl 4*12 with broken in Vintage 30s. This should give me a definite answer if it's the cabs fault or not.
Stephan, Dmoney: Preamp tubes aren't expensive and if they really can cut out the fizz like you say I guess this would be the next step after messing around with the cab.
Thinking that I could still get my money back after fiddling around with the internals of the head was kinda stupid I admit, I just don't wanna take the easy way out and give up by sending a basically good amp back because it doesn't appeal to me stock. If a few euros for new tubes can remove the fizz (and that's the only thing that disturbs me) and changing my Painkiller for the Holydiver again can fatten the sound up, I see no reason why I shouldn't try it. I guess right now I need to decide wether to take the risk of loosing 300 quid or just let it be. I know myself well, so it's probably gonna be the former...
Regarding the footswitch I'll open it up and see if anything is loose.
I've just started my journey of delving into the world of amplifiers and how they work, so I will certainly consult the Valvewizard site, the more information I get, the better :D
The idea with the transformers was actually just... well an idea. Maybe I'll end up building my own SLO Clone one day anyway, that is if I gather the knowledge that's required.
The biasing will be the first big step I'll do after trying the cab and new preamp valves out. I'll certainly open up a thread/shoot some messages when the time is right.
Well, seems like I have already made a decision. I think I'll keep the amp. News on Monday :D
Cheers!
Preamp valves can make or breakj an amp.
For me any chinese valve completely destroys the tone fizz, compression & really shrill high end.
In fact electro harmonix valves also do the same thing!
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I'm wondering what the 'fizz' is that you're hearing.
To me , this is a fizzy amp:
https://www.youtube.com/watch?feature=player_embedded&v=aAE3NMERwGw#t=263 (https://www.youtube.com/watch?feature=player_embedded&v=aAE3NMERwGw#t=263)
Is this anything like your Jet City ?
Personally, I don't like what I've heard of the Soldano high gain channel. I watched some clips of EC and Gary Moore in their Soldano days and hated the lead tones.
Like this, too MUCH fizz:
Eric Clapton and Mark Knopfler - Cocaine (https://www.youtube.com/watch?v=kInoeTycY60#)
I quite like a little fizz but there are limits. It could be the amp circuit. However, it's worth trying tube swaps and, as long as you put the originals back, there's no way of telling that you've done this so no worries about the warranty - as long as you've got time.
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Here's a bit of trivia, I have the details somewhere but... Clapton's SLO100s (or some of them at least, dunno how many he had but it was at least two) had an extra valve added to them to give them a different loop circuit. It was designed by Pete Cornish as a post master volume loop that worked at a level require for the huge Pete Cornish rack system clapton used, which also had all manner of gain controls for each effect in and out (I believe). I have a copy of the manual for it somewhere and a few more details. The circuit modification is not used by Soldano and the post master loop circuit they use is implemented differently without the addition of a valve, which reduces noise in comparison to the head in the EC rig.
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Like Alex says too, if you don't think it's gonna work out, don't try anything too invasive and get it sent back. Best option if you've bought online.
agreed.
might as well try the v30s and new preamp valves, though, i suppose.
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I find that my Peavey tends to be fizzy at 'house volumes', but when you get up to proper operating volume the fizz subsides substantially.
Or that could be an effect of the earplugs ...
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Richard: the fizz is in the background, "behind the sound" if that makes any sense.
Regarding the Preamp Tubes my local Music store has Sovteks, Tung-Sols, TADs, Mesa Boogies, Electro Harmonix and Groove Tubes in stock. I guess I'll get myself a Tung-Sol and a Sovtek to see how those sound. Would like to try JJs as well but those need to be ordered online.
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I understand completely what you are talking about. My previous amp ( jvm 205 ) has an awful, annoying fizz sound in the background...well, i changed all the tubes for TAD tubes and problem solved ! I sold the amp and the next two amps ( engl savage special edition and bogner uberschall clone ) has TAD tubes in all the positions and , dispite of using extreme high gain with ods, eq, sonic maximizer...they hasnt any kind of fizz sound. It doesnt matter the extreme amount of distorsion or if the guitar has extreme output pups ( like the ceramic warpig ) i think it worth the change ! the sound is more powerfull, thick, balance, organic and out of fizz !!
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some things to consider;.
"Some other weird things I noticed: When I turn on the standby switch the sound fades away whilst playing like it's supposed to, but when I turn the amp off and keep on strumming there is silence followed by a slowly building up sound of my playing coming out of the speakers again before it fades (with the amp in standby"
This is normal, my marshall does the same thing, it's your capacitors discharging the remaining current.
About fizz: It can be several things (and many times combined).
1) V30's are a bit harsh in the high end but it usually disapears in band situation. Have you tried it with a full band?
2) Is your cabinet standing in front of a clean wall, with a distance smaller than 2m?
3) preamp tubes: go NOS. If you want to get rid of fizz, maybe some old green label siemens would be a nice shot. Stay away from blue label GEs (but they work NICE as phase inverters - v5). Also look and OLD tung sol, RSD...
4) power tubes: GO NOS!! I use RFT EL34s and comparing to my old JJs, they KILL... more punch and less harsh high end, and my amp distorts the power section a lot. Also consider KT66s, 6550s or 5881s (as they can fit 6L6s with bias adjustment) other than 6L6. I'd go with 5881s for warm mids or KT66/6550's for more punch/clarity. RFT, Siemens, Sylvania, RSD, GE, Raytheon, RCA, Tung Sol, Phillips... A lot of good brands to look at...
5) Where is your master volume at? Many amps cut the fizz when you make the power tubes work, maybe that's your case... try to make it louder (like 5 or 6) and see wha happends...
I have never seen the JCA 50H schem, but from what you say, it has a lot more to do with the JCM800 than it's tone :lol:.. JCM's can be harsh and fizzy at times, but usually you can fix this without modding your amp.
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Well, after a long and busy week I'm finally back with results. Borrowed my mates Engl cab with em V30s in it and surprise: it made everything better. The fizz of the JCA50 is still there, but not to the huge extent it was before and pairing the cab with my Valveking it even resolved the excessive highs I had after the tube change. (The Power Tubes in the VK where changed to Tube Town 6L6GCs, took a look inside).
It seems that the major factor contributing to the ugly sound I have is the Laney Cab, or rather the Seventy 80's in it. Now I'm going to keep the Jet City (although I still was quite unsure about it until recently) and swap out the preamp tubes (same with my Valveking) and the power amp tubes either on my own or get em swapped. I'm too much of a DIY and modding freak to give up any piece of equipment.
Next thing I'm going to get is the Palmer 212 with V30s for home use and then when I have the cash order some new speakers, I really wanna try out the G12T75 and V30 X-Pattern combination in the Laney Cab. :D
fhn:
1.) Didn't try it in a full band context yet but playing it side by side with my bass player the fizz wasn't hearable anymore. I'm sure it will work splendid in a full mix. I'm sure as well it has something to do with the volume too, the more I dial the Master back to bedroom levels, the more noticeable the fizz gets.
2.) Nope. Our rehearsal room is small but I have it placed in the corner facing towards the other corner of the room (with my bass players rig and himself standing there 90% of the time)
3.) and 4.) yeah that's the next thing to do. Experiment with different tubes. :D
5.) As said higher volume levels work. Unfortunately my bassist is a sissy and always tells me to turn the volume down (don't worry about my ears I always wear earplugs when going to 11) :lol:
I'll keep coming back with results as time passes. Thanks guys, you all have been very helpful. :)
p.s.: I attached the JCA50 schematic
Cheers!
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Don't get the palmer cabinet, it's not plywood. The harley benton g212vintage is plywood and good on the cheap if you want v30s.
glad to hear the speakers helped, though. :)
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I just looked up the Palmer Cab, it says it's made out of MDF. Then I looked up MDF versus Plywood... well I guess I could still get the Jet City 24S 2*12 (even cheaper than the Harley Benton and made out of Plywood as well, it seems like prices on the whole Jet City range are being dropped like crazy) and that would leave me with their Eminence Speakers. I could always experiment with that and order Vintage 30's if I decide the stock speakers don't suit me. :lol:
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I dare say those Eminence speakers will be a big step up from Seventy 80s
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I'm sure they will be. They are said to be based on the Legend Series, either the V128 or the M12 (don't remember exactly which one right now). In the worst case I can still open it up and swap em out + the cab has the option of choosing between open and closed back.
Also found those two comparison vids:
http://www.youtube.com/watch?v=W0PVnHz77cw (http://www.youtube.com/watch?v=W0PVnHz77cw)
http://www.youtube.com/watch?v=fB7Y48QYLL0 (http://www.youtube.com/watch?v=fB7Y48QYLL0)
The stock speakers sound inferior in both samples to my ears but not bad.
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I don't know as if I'd say that they are inferior to either. To me they sounded pretty good in that cab, nice and clear. The V12 Legends sounded a little muffled to me under gain and the V30s have their characteristic rasp. The stock speakers sound like they might have a broader tonal palette than either loaded in that cab.
Put them in a heavy 412 closed back cab and it might be a different story, but I say go for it, they will be much better than the Seventy 80s. I've never heard a Seventy 80 cab that impressed me.
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Will do. The cab sells for 150 bucks at Thomann right now. That is a steal :D
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I just looked up the Palmer Cab, it says it's made out of MDF. Then I looked up MDF versus Plywood... well I guess I could still get the Jet City 24S 2*12 (even cheaper than the Harley Benton and made out of Plywood as well, it seems like prices on the whole Jet City range are being dropped like crazy) and that would leave me with their Eminence Speakers. I could always experiment with that and order Vintage 30's if I decide the stock speakers don't suit me. :lol:
it's far cheaper to just get the harley benton cab with the v30s. the jet city speakers are not bad for oem-type speakers, but i didn't think they were anywhere near as good as name-brand speakers, either.
alternatively you can get the HB cab with HB speakers (cr@p) for less than the jet city cab. And as I said below, it may be my imagination but I wouldn't be surprised if the HB actually is the better-sounding cab. and then you can pop v12s into it.
I don't know as if I'd say that they are inferior to either.
They are. If you ask me. They're a bit harsh and tinny- better than most OEMs I've tried, but not great either.
Now... I didn't give them the best try. I didn't break them in or anything, since I already had v12s sitting waiting and was kinda chomping at the bit to get the jet city speakers out and the v12s in. :lol: But even out of the box, I thought the v12s were better.
I also fancy the HB cab might sound better than the jet city, but that might just be in my head (that was my feeling, I didn't get to do a head-to-head). The HB is slightly bigger and I fancy sounds slightly bigger. Granted the jet city has the option of open-backed or closed-backed operation, which I guess is handy, but the way the back's been designed, you have to take the whole back off to remove the little removable panel. Which is daft, it makes it "set and forget". I have other cabs where all I have to do is remove 4 screws.
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Dave, I see what you're saying but I still think I'll go for the Jet City Cab. I like matching stuff and having that rather vintage looking combination on stage whilst playing face ripping metal with it has it's own charm hahaha :lol:
Regarding the speakers I'm sure the HB Cab does it's job well, read quite a few reviews and heard some samples where the only downside to it was being branded as "Harley Benton". I'm not a brand whore so no issue for me. (And you can always remove the logo). Anyway I'm still not sure if I will really go for Vintage 30's so having the JC 24s with the stock speakers will give me a good idea in what direction to go. Apart from the Jet City and my Valveking sounding bright my guitars aren't really dark either so it may very well be that I will go for something a bit darker speakerwise. If the JC speakers sound anything like the Eminence Legends that should give me an idea how Eminence speakers sound in general as I've been only using Celestions so far.
I guess G12T75s aren't a solution due to the fizziness, Vintage 30's are good so far but still a bit raspy. I might just go your route and follow Toe-Knees recommendation, buy a set of V12s and pop em in. Will see :D
Cheers!
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Yeah I went for the jet city cab because it matched, too. :lol: No worries there. :D
when they're broken-in, v30s sounded pretty good with the jet city, I thought. But I still preferred v12s. So yeah if you get the jet city cab with the intention of eventually swapping them with v12s, that would be fine (of course if you like the stock speakers, that's even better- mine weren't broken-in but i thought they sounded closer to v30s than to v12s... not that there's a *massive* difference between either, but the v12s were a fair bit darker/smoother, I thought).
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Yeah as said I'll just go with the stock speakers and see how I like em. Will of course report back with results as soon as the cab arrives. I'm kinda anxious right now as I'm approaching the point where I'm finally "done" with my rig. After the Cab all that's left to get are a few pedals as addition to my board together with the Carl Martin Octaswitch and the Fuel Tank Chameleon, then I'm through with my list. Stoked! :D
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nice :D good luck :)