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Valve amps vs Solid State

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Because we are talking BASS here, there is a difference to the normal argument of solid state vs valve. In a domestic Hi-Fi situation, a well designed valve amp can be inderscernable from a well designed solid state amplifier. In that situation extremely low distortion figures along with a linear response over a wide frequency range combined with very low noise characteristics, are what matter. It's true however that most valve amps in a hi-fi situation introduce a warmth that is to be encouraged rather than designed out because it sounds so damned good. Output power in most domestic situations is relatively low and equipment remains static and not subjected to a rough ride in the back of a van every night!

OK let's move on to guitar amps. The electric guitar is predominently mid range and the demand that a player puts on his or her amplifier/speaker is usually out and out volume and as the volume increases so does the distortion. On a big HiWatt or Marshall, your ears can start bleeding before you start to hear any distortion (unless you overdrive the first stages and back off the master volume). With smaller amps, the audible distortion starts earlier and gets progressively 'dirtier' as you crank up the gain. Unless you're a C&W or jazz player most guitarists want distortion. They want volume and distortion and become deaf before they're 60. Pardon? So the argument for valve vs solid state is usually quite straightforward - valve amps sound great with guitars when they distort - even bad ones. Solid state amps sound crap when they distort. Guitarists wanting a clean sound only are probably better off with a solid state amp unless they're looking for a particular signature sound of something like a Fender Twin Reverb for instance.

So now it's the mighty bass, a punisher of all amps valve or solid state. Bassists seldom want distortion, we usually want 'punch' or 'tightness' or 'depth', maybe even something 'stomach moving' - it's a totally different vocabulary to guitarists and a totally different requirement for amplification. Unless you are prepared to spend a small fortune on a valve rig, there is generally more punch for pound in a solid state rig. It's easier to tightly couple an output stage to a speaker and achieve a high damping factor with a semiconductor amplifier than it is with a valve amp. The higher the damping factor (Zsource = Zload divided by DF), the greater control the amp has over the speaker movement and with bass this is really important. Valve amps usually have a much lower damping factor and lack the speaker control but nevertheless sound 'warmer'. There is much more need to audition bass amps and speakers than any other set-up because there are so many pros and cons in either camp. Personally, some of the best bass sounds I've heard have come from solid state rigs and that's coming from someone who's a huge valve fan! Also there's always a lot of focus on amps but choice of speaker is equally important with bass. The cone, and therefore coil excursion, is much greater at low frequencies and as the coil moves outward away from the gap the magnetic field is reduced. To some extent is self governing if the peaker can handle the power - however this results in a kind of compression which affects the punch. Using smaller drivers (that's why multiple 10" drivers are used a lot) rather than one massive speaker can minimise this, but you need more of them of course. Some drivers are designed for bass very much in mind whilst others are more generic, even though nowadays they're usually capable of handling the power. Beware the cheap bass cab!

Actually, I don't think that there is an argument for solid state vs valve; it's more 'horses for courses' and there's good and bad in both camps - I've started to use my ears more and be less biased towards the technology used to produce the sound. After all anything is better than what I started with - a Rosetti bass played through a rather inadequate hi-fi amp of the era into a couple of Wharefdale 8" speakers. I blew the speakers regularly and eventually used the bass guitar as a bow and arrow.

Steve

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[quote name='Zerofret' post='266650' date='Aug 20 2008, 09:53 PM']Because we are talking BASS here, there is a difference to the normal argument of solid state vs valve. In a domestic Hi-Fi situation, a well designed valve amp can be inderscernable from a well designed solid state amplifier. In that situation extremely low distortion figures along with a linear response over a wide frequency range combined with very low noise characteristics, are what matter. It's true however that most valve amps in a hi-fi situation introduce a warmth that is to be encouraged rather than designed out because it sounds so damned good. Output power in most domestic situations is relatively low and equipment remains static and not subjected to a rough ride in the back of a van every night!

OK let's move on to guitar amps. The electric guitar is predominently mid range and the demand that a player puts on his or her amplifier/speaker is usually out and out volume and as the volume increases so does the distortion. On a big HiWatt or Marshall, your ears can start bleeding before you start to hear any distortion (unless you overdrive the first stages and back off the master volume). With smaller amps, the audible distortion starts earlier and gets progressively 'dirtier' as you crank up the gain. Unless you're a C&W or jazz player most guitarists want distortion. They want volume and distortion and become deaf before they're 60. Pardon? So the argument for valve vs solid state is usually quite straightforward - valve amps sound great with guitars when they distort - even bad ones. Solid state amps sound crap when they distort. Guitarists wanting a clean sound only are probably better off with a solid state amp unless they're looking for a particular signature sound of something like a Fender Twin Reverb for instance.

So now it's the mighty bass, a punisher of all amps valve or solid state. Bassists seldom want distortion, we usually want 'punch' or 'tightness' or 'depth', maybe even something 'stomach moving' - it's a totally different vocabulary to guitarists and a totally different requirement for amplification. Unless you are prepared to spend a small fortune on a valve rig, there is generally more punch for pound in a solid state rig. It's easier to tightly couple an output stage to a speaker and achieve a high damping factor with a semiconductor amplifier than it is with a valve amp. The higher the damping factor (Zsource = Zload divided by DF), the greater control the amp has over the speaker movement and with bass this is really important. Valve amps usually have a much lower damping factor and lack the speaker control but nevertheless sound 'warmer'. There is much more need to audition bass amps and speakers than any other set-up because there are so many pros and cons in either camp. Personally, some of the best bass sounds I've heard have come from solid state rigs and that's coming from someone who's a huge valve fan! Also there's always a lot of focus on amps but choice of speaker is equally important with bass. The cone, and therefore coil excursion, is much greater at low frequencies and as the coil moves outward away from the gap the magnetic field is reduced. To some extent is self governing if the peaker can handle the power - however this results in a kind of compression which affects the punch. Using smaller drivers (that's why multiple 10" drivers are used a lot) rather than one massive speaker can minimise this, but you need more of them of course. Some drivers are designed for bass very much in mind whilst others are more generic, even though nowadays they're usually capable of handling the power. Beware the cheap bass cab!

Actually, I don't think that there is an argument for solid state vs valve; it's more 'horses for courses' and there's good and bad in both camps - I've started to use my ears more and be less biased towards the technology used to produce the sound. After all anything is better than what I started with - a Rosetti bass played through a rather inadequate hi-fi amp of the era into a couple of Wharefdale 8" speakers. I blew the speakers regularly and eventually used the bass guitar as a bow and arrow.

Steve[/quote]

Thanks for that Steve - really interesting and useful stuff! ^_^

Cheers Grahame

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this is such a long thread so please dont shout at me for not reading all of it but...

im thinking about getting a SWR 350x amp. it has a tube preamp. it says no where in the instructions about letting it warm up, so is this necessary? there is also no standby switch.

anyway i play a lot of RHCP covers, and play a lot of 'furious' slapping and tapping. i was just wondering if a tube preamp would sound alright? because i am worried it will just sound all overdriven with not much punch or growl.

any imput would be greatly appreciated

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[quote name='jjl5590' post='292923' date='Sep 26 2008, 05:42 PM']this is such a long thread so please dont shout at me for not reading all of it but...

im thinking about getting a SWR 350x amp. it has a tube preamp. it says no where in the instructions about letting it warm up, so is this necessary? there is also no standby switch.

anyway i play a lot of RHCP covers, and play a lot of 'furious' slapping and tapping. i was just wondering if a tube preamp would sound alright? because i am worried it will just sound all overdriven with not much punch or growl.

any imput would be greatly appreciated[/quote]
I tend to assoicate growl with mild overdrive, so saying you want one and not the other confuses me :)

No worries re. preamp valve, it shouldn't need time to warm up due tot eh way it is designed into that circuit.

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[quote name='Oxblood' post='2674' date='May 20 2007, 01:09 PM']+1 to BOD2's advice.

Despite popular myth, valve amps are not inherently less reliable than solid state gear. In fact, it can be argued that the opposite is the truer case. A well-designed/built valve amp that is new, or an older one that has been properly maintained, will give years of loyal, worry-free service. While of course you should treat them with care, mechanically valves are pretty rugged (hell, they got us through WWII !), and electrically they'll withstand an astonishing amount of abuse, whereas solid state devices have a lovely habit of falling over STONE DEAD in the blink of an eye as soon as they get a bit too much voltage on the power rails or receive a static shock. :)

Also, by and large, valve amp circuits tend to be a lot simpler than their SS equivalents, and are usually made up of tried-and-trusted architecture with which any good valve technician will be familiar, even if he/she hasn't got access to a circuit diagram. Consequently, should your valve amp develop the odd fault that needs professional attention, it'll be a whole lot easier to diagnose and fix than a box stuffed with a thousand tiny, fragile devices, some of which may be:
1. difficult or impossible to identify without reference to the manufacturer's data
2. one-off chips only available through the manufacturer at a premium price
...or in the case of vintage SS gear,
3. obsolete types for which there is no drop-in modern equivalent!

By now, I hope you're beginning to feel that owning a valve amp is a pretty attractive proposition. However, your biggest challenge lies in trying to obtain something worth having, given your limited budget. Sadly, these days, even half-knackered tatty old valve gear in need of a total overhaul will sell for silly prices because it's supposedly "vintage" or "rare". The days of stumbling across a lovely old Vox/Marshall/Sound City head in your local junk shop are long gone!

One classic British brand with plenty of character that still occasionally goes for reasonable money is Selmer. Tone? Think Ronnie Lane/Small Faces. Nice! There's usually at least one Selmer amp on eBay at any given time. For instance:

[url="http://cgi.ebay.co.uk/Selmer-Super-Zodiac-100-Valve-Head-Circa-1969_W0QQitemZ260119349277QQihZ016QQcategoryZ10171QQssPageNameZWDVWQQrdZ1QQcmdZViewItem"]Selmer Super Zodiac Twin 100[/url]
2 channels, 100 Watts, pre-set tone selector ...AND tremelo![/quote] i am making 1 a 10.5 do you think i should crpet it

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I know absolutely f*** all about the technical argument at play here (although I find it fascinating) But one piece of information I picked up about valve sound in general seems to ring true. I'll give it to you, you make of it what you will.

Valves in their operation set up imperfections in the reproduction/powering/creating of sound (not sure how or why) and it is these imperfections that appeal to us as Earth beings as it represents natural based as opposed to synthetic or manufactured product.

As I said this is a piece of information that I am simply regurgitating, so I would be interested to hear some informed opinion on it.

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just dont get a new ampeg classic! the new ones are mass produced rubbish, the build quality is crap. they still sound amazing but if you're going for valves get something hand wired. a properly built hand wired valve amp (no circuit board rubbish!) is rugged, reliable and beautiful. apparently oasis blew up 16 brand new svt classics on their last tour!

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I've been using my 'new' vintage valve head for last few practices, I've noticed even after warming up for the time it takes to set up the drum kit, it takes playing for about 20 minutes for the sound to stabilise from sounding dreadful to sounding great. Kinda concerned. My solid state head started meh and stayed meh throughout.

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[quote name='drthirkenstein' post='323163' date='Nov 6 2008, 03:16 AM']just dont get a new ampeg classic! the new ones are mass produced rubbish, the build quality is crap. they still sound amazing but if you're going for valves get something hand wired. a properly built hand wired valve amp (no circuit board rubbish!) is rugged, reliable and beautiful. apparently oasis blew up 16 brand new svt classics on their last tour![/quote]
+1 on pcbs melting and being unreliable

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i used solid state amps for about the first year of playing when i got a bit cash i decided to go buy a new amp. i tried a ampeg b2re and hated it took it back to the shop after 2 days. moved onto a ashdown abm and again hated it. so i ended out splashing out on a marshall vba 400 with 4x12 cab and have never looked back. sound is absoloutly amazing imo valves rock

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[quote name='lee_remedy' post='387465' date='Jan 21 2009, 01:21 PM']i used solid state amps for about the first year of playing when i got a bit cash i decided to go buy a new amp. i tried a ampeg b2re and hated it took it back to the shop after 2 days. moved onto a ashdown abm and again hated it. so i ended out splashing out on a marshall vba 400 with 4x12 cab and have never looked back. sound is absoloutly amazing imo valves rock[/quote]
my fifty pence worth..

ive had an all valve ampeg svt classic for nine years now, and have learnt a couple of lessons i will gladly pass on based on my own experience.

1) buy something with a good established rep, do whatever you have to do to find the money..(i had to sell a bleeding motorbike!! for a bloody bass amp!!)

2) find a really, really good valve tech who will do your servicing and repairs, someone who genuinly knows what they are doing, and only ever let him touch it, and whatever he suggests let him do.

3) buy a good quality well padded flight case, made slightly higher internally so you keep a spare amp base shaped square of foam on top of it inside the cab, and take that out and put it on your cab before sitting the amp down onnit at gigs, to stop the cab vibes transmuting to your valves(dunno if thats a word or not but i like it ;) )

err, thats about it i think. my amp is trouble free, gets as hot as hell at some of the venues we play and gets used every weekend, hard. it always provokes comment on how good it sounds, though the ev loaded 4x10 mesa cab is a big part of that too. i'd like to think it will be the only amp i ever play for the rest of my life, though the weight, especially flight cased, is immense. and the last time i saw colin hodgkinson, even he had given in and was using a markbass...

one last thing, ive only had to have a total revalve twice now, but both times using decent matched valves it required a second mortgage.. :P

enjoy..

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[quote name='ogri' post='398278' date='Feb 2 2009, 08:15 PM']my fifty pence worth..

ive had an all valve ampeg svt classic for nine years now, and have learnt a couple of lessons i will gladly pass on based on my own experience.

1) buy something with a good established rep, do whatever you have to do to find the money..(i had to sell a bleeding motorbike!! for a bloody bass amp!!)

2) find a really, really good valve tech who will do your servicing and repairs, someone who genuinly knows what they are doing, and only ever let him touch it, and whatever he suggests let him do.

3) buy a good quality well padded flight case, made slightly higher internally so you keep a spare amp base shaped square of foam on top of it inside the cab, and take that out and put it on your cab before sitting the amp down onnit at gigs, to stop the cab vibes transmuting to your valves(dunno if thats a word or not but i like it ;) )

err, thats about it i think. my amp is trouble free, gets as hot as hell at some of the venues we play and gets used every weekend, hard. it always provokes comment on how good it sounds, though the ev loaded 4x10 mesa cab is a big part of that too. i'd like to think it will be the only amp i ever play for the rest of my life, though the weight, especially flight cased, is immense. and the last time i saw colin hodgkinson, even he had given in and was using a markbass...

one last thing, ive only had to have a total revalve twice now, but both times using decent matched valves it required a second mortgage.. :P

enjoy..[/quote]

IMO absolutely spot on!

Nothing like the common sense approach!

Well done that man!

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New here but thought you might like to hear the storyu of my valve amps. 1977-2009.

Hiwatt 100 w bought in BRum in the year of punk (see photo); never had a valve change never had electrolytic converters changed (whatever they are). Loud beyond its station, this amp has never had a problem with me. It's only had a flight case since 2002, and has lived in at least ten homes before I 'settled down'. It has been knocked against walls, used as a weights exercise, and gigged with at least 300 times (more prob); used to play through it every day in the 80s. Initially with an Electrovox speaker it now goes through a 500w Ampeg speaker. I've used guitar leads, made up leads, crap leads to connect it to speakers. It's a 1973 model according to serial number/website info. #5310 DR103

Hiwatt Number 2; bought in PEterborough 1979 ex-owner was a member of 801 (Roxy Music offshoot). Exactly as above except maybe 200 gigs and it's a 1974 model. Had all the valves changed and new elec-converters last year. Don't know why - just thought I should, but I kept the old valves of course. EL34s.

All I did with these two amps was to treat them with a respectful indifference - they are amps, they will work they will weight a ton, they do the job. I have played thru some truly awful rigs; often Trace Elliot nonsense - why do bass players think 'wooden thunmk' is a sound; do they mistake it for 'warmth'. Ashton is another one.

I think I was very very lucky to have bought very sensibly as a teenager. Friend should not be 'electric' but I look after these beauties now.
So, I guess I'm on the fence when it comes to valve amps: )

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Hi

heres my 10 pence worth,
was feeling a bit flushed a while ago, and the wad was burning hole in my pocket, so went and bought a ENGL Powerball E645 valve amp,
man this thing is brute force, compared to the ampeg svt i had, it blows it away, but only problem, it massive overkill for my home,lol,
so on the valve vs solid state i rate valves, but thats IMHO, as i dont know squat about amp techie stuff , all i know is that this thing is a beast and i never letting it go.

steve

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Just to weigh in with my views, biasing an amp is NOT something that only a tech can do, and NOT soemthign you should always factor into being a running cost of a valve amp.

Valves do not "wear out" at all. Their electrical needs change slightly over time and several manufacturers, most prominently Mesa Boogie, have used this to sell more of their valves, by fixing the bias in their amplifiers so that when the tubes age the amp doesn't sound as good. The customer goes and buys new tubes.

Basically, biasing is all about giving the valve enough juice while it is "idling" i.e. not doing anything. This is a DC voltage measurement. Here are some vieos on setting bias and a little more info, the Eurotubes ones are especially no-bullshit:

[url="http://www.eurotubes.com/euro-video.htm"]http://www.eurotubes.com/euro-video.htm[/url] - click links

[url="http://www.expertvillage.com/video/68249_tube-amplifiers-biasing.htm"]http://www.expertvillage.com/video/68249_t...ers-biasing.htm[/url]

Not all amps have an adjustable bias, Mesa don't, and Peavey 5150 amps don't for example. These can be converted for what should be a small fee by any decent tech, from which point on you can bias your own tubes. The job basically involves replacing a fixed resistor with a variable resistor.

The upside to this is firstly one of cost - when your tubes age, you can re-bias them and save yourself a ton of money on power tubes. On my Mesa 400+, 12 matched 6L6GC's will be about £100-£120, if they're JJ's. Mesa's are more expensive as they have some white paint sprayed on them in the shape of a Mesa logo. This stunning piece of graphic design adds about 20% to the cost. A driving factor in these costs is that the tubes have to be tested by the vendor and matched to the particular fixed bias that comes in the particular amp, people like Lord Valve, Bob @ Eurotubes and Watford valves do this for you, why? Because not all tubes come out of a factory with the same tolerances. Hence, having adjustable bias means you can get any tube and make your amp work with those tubes within it's acceptable limits.

Many lazy players might see this as a lot of hassle, but then again I'm guessing most decent bass amps come with adjustable bias from the factory. So to save yourself hundreds in tube costs, al you need to invest in is at worst a multimeter from Maplins, some bias probes from Eurotubes or similar, and a small screwdriver to turn the bias knobs.

Now I'm not saying a valve will last forever - it is an electrical component and will suffer wear, but then again so will anything. Even if you only change tubes half as much, you're saving twice as much money. Another advantage is that you can tweak your amp's tone through the bias setting, hotter for more breakup and so on.

/rant

Valve amps are a little more work, they're a little more fragile and they don't like being turned on without a speaker plugged in, but if they work for you then these are small prices to pay. Weight wise, my Bass 400+ in rack weighs the same as my old SVP-Pro + QSC setup. An SVT2 is worryingly heavy though!

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[quote name='Dan_Nailed' post='446545' date='Mar 26 2009, 09:51 PM']Not all amps have an adjustable bias, Mesa don't, and Peavey 5150 amps don't for example.[/quote]

That isn't true, the original 5150 didn't, but the Mark II, which is the one to have, due to seperate eqs on channels, has bias sockets on the back.

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Good rant and in line with most of what I've picked up about valve amps. If kept correctly biased power tubes should outlast the electrolytic caps!

To head off on a tangent, would I be correct in presuming that Class A valve amps don't have adjustable bias because the valves always have full current running through them? And Class B (as used in radio transmitters) have no idle current at all?

Alex

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[quote name='Dan_Nailed' post='446545' date='Mar 26 2009, 09:51 PM']Not all amps have an adjustable bias, Mesa don't, and Peavey 5150 amps don't for example. These can be converted for what should be a small fee by any decent tech, from which point on you can bias your own tubes. The job basically involves replacing a fixed resistor with a variable resistor.[/quote]

I think you might be talking about just the Peaveys here, because I've had a long & hard look at my Mesa's schematics and as far as I can figure out the only way to convert Mesa's to adjustable bias is by a substantive board re-design, not a resistor swap-out.

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[quote name='Hamster' post='446722' date='Mar 26 2009, 11:28 PM']I think you might be talking about just the Peaveys here, because I've had a long & hard look at my Mesa's schematics and as far as I can figure out the only way to convert Mesa's to adjustable bias is by a substantive board re-design, not a resistor swap-out.[/quote]

Agree.

Aren't Mesas usually fixed biased? A marketing ploy for you to buy their colour coded tubes perhaps...? They give very little information away about the rating of their tubes... so you either get the amp rebiased manually (and get the tech to fit the variable pot ideally), try your luck with any set of tubes (not the best...) or you buy a replacement colour coded set of Mesa tubes...

Edited by EBS_freak

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[quote name='josh3184' post='446759' date='Mar 26 2009, 11:52 PM']whats the idea behind biasing? I.e. why? Just curious[/quote]

[url="http://en.wikipedia.org/wiki/Bias_(electrical_engineering)"]http://en.wikipedia.org/wiki/Bias_(electrical_engineering)[/url]

Alex

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[quote name='josh3184' post='446759' date='Mar 26 2009, 11:52 PM']whats the idea behind biasing? I.e. why? Just curious[/quote]

In a valve, you have an anode (positive) and a cathode (earth). Electricty wants to flow between the two of them. It would do so uncontrollably unless there was something in between them - that's called the grid.

The grid needs to have some negative voltage on it to limit the current flowing through the valve. That's why valves are called valves - it's like a water pipe with a tap on it - the grid is the tap and it limits the flow going from one end of the pipe to the other.

The grid can only limit the current flow if there is negative voltage on it. The more negative volts, the more the current is limited. More negative volts on the grid is like turning the tap down.

This negative voltage is the 'bias' voltage. It sets a standard current flow. Without this bias voltage the current would flow too much, overheating the plates and destroying the valve.

The more bias voltage you apply, the less current flows through the valve. If you let too much current it destroys the valve as it can't dissipate the heat. Too little and it doesn't start cooking.

More current gives you more volume and clarity but shorter tube life. Less current gives you less volume but more distortion and longer tube life.

Pick your bias to achieve what you want.

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[quote name='Mr. Foxen' post='446655' date='Mar 26 2009, 10:47 PM']That isn't true, the original 5150 didn't, but the Mark II, which is the one to have, due to seperate eqs on channels, has bias sockets on the back.[/quote]

No it isn't, the mark one is far better! No terrible solid state clean channel.

Unless you mean the 6505 series, which are a different beast.

[quote name='Hamster']I think you might be talking about just the Peaveys here, because I've had a long & hard look at my Mesa's schematics and as far as I can figure out the only way to convert Mesa's to adjustable bias is by a substantive board re-design, not a resistor swap-out.[/quote]

This is a variable bias mod on a 400+, doesn't look like a board redesign to me...


As for the colour coding Mesa thing, it just means that they've tested and graded the tubes with their own arbitrary system. Most decent valve sellers (Bob at Eurotubes definitely) can supply you with some drop-in tubes that will work with any fixed bias amp, as they've had these amps on a bench usually and have measured what their native bias is. They then rigorously test their stock of tubes and catalogue where their natural bias point is currently sitting, and mark them as suitable for certain fixed bias amps.

Edited by Dan_Nailed

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[quote name='alexclaber' post='446672' date='Mar 26 2009, 10:56 PM']Good rant and in line with most of what I've picked up about valve amps. If kept correctly biased power tubes should outlast the electrolytic caps!

To head off on a tangent, would I be correct in presuming that Class A valve amps don't have adjustable bias because the valves always have full current running through them? And Class B (as used in radio transmitters) have no idle current at all?

Alex[/quote]

I haven't read up on this for a while, but it would make sense for Class A as premaps are always singled-ended Class A circuits and don't require any Bias. I always thought Class C was for radio transmitters...Class B does have bias, but the bias is set such that when idling, the tube actually turns off and lets nothing through. Basically:

A - Never turns off
B - When idling, lets nothing through

A good, but dense, read on this is available [url="http://www.mesaboogie.com/US/Smith/ClassA-WebVersion.htm"]here.[/url]

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[quote name='Dan_Nailed' post='446798' date='Mar 27 2009, 12:45 AM']This is a variable bias mod on a 400+, doesn't look like a board redesign to me...[/quote]

You've got me interested now! - have you got a schematic for the mod you've done - or can you direct me to who did it for you?

Cheers

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