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No-one else gives a shit.
"SS power amp for clarity and no power amp compression to the sound." What power amp compression proff?
Yes, a cathode biased OP stage will self limit as you push it past "class A" but an AB stage won't. Then valve OP stages have a quality lacking AFAIK in all SS outputs. They beat, to some extent loudspeaker thermal compression.
This is the fact that as the voice coil heats up its resistance increases and so, for a given Vin, power will drop. SS amps are severely limited in the voltage they can deliver, 50W into 8R= 20volts (rms) and that's all she wrote for a SS amp*. A valve OP stage on the other hand CAN deliver more voltage into a higher net impedance so as VCR rises they can maintain much the same power. SS amps can't. TComp starts to bite at about 1/2 rated power and so having two (or more) speakers will deliver more final volume than one, but of course you might LIKE the TC of a strained speaker!
My earlier discourse mentioned an OP transformer? This gets over the speaker impedance issue where SS amps usually deliver max power into 4Ohms or so but would also make it possible to have a sophisticated "valve like" load characteristic but again, more development cost that is unlikely to ever be recouped!
*This ties in with power claims and the adpuf men. They are going to specify the best figure so, our 50watts/8R is probably totally genuine (but remember, MAINS voltage must always be taken into account. Is that 50W at 230V or 240?) but, if the amp is actually capable of say 70W/8R they will spec the higher figure.
But, power delivery is very hard to specify. Vout into X R at "visible clipping"? That is very imprecise and subjective. The only fair way is Vout (true rms) at XR at say 10% Total Harmonic Distortion (THD). And yes, many porkies have been told about SS power deliveries and mains consumption not tallying with claimed power out but then do we specify a 100W class AB valve amp's consumption at full, total clipping (nearer 200W) ? No, because the things are SO inefficient it would hardly matter!
Dave.
I believe ( rightly or wrong) that small valve power amps are more likely to impart more power amp distortion characteristics to the tone than a similar SS unit.
Take my case for example, I use a large amount of low end in my sound and detune too ( not massively drop C#) I have tried a great deal of smaller valve amps (bassbreakers, juniors,terrors,HT-20 etc) and universally found them far far to quiet, and when pushed decending into fartsville.
So I don't see how a 20w power amp seperate would be any different, the small valve combos and heads I've tried sounded great at low volumes but ran out of steam at anything over 5/6 on the volume, ergo the issue is not the preamp but the power amp.
My Velocity 120 produces 120w @ 8ohm and around 95w @ 16Ohms, overall not a huge amount louder than a 20w valve amp at full chat, but the tone difference is vast to my ears.
The new blues cube heads are £1299.. Jeezo thats ridiculous. they come with a 2 year guarantee which for that price I would expect at least 5 years. Plus the claims about reliability cant be proven yet. Just because something is solid state doesn't mean that it won't have issues.
The difference is that *if properly engineered and not just down to a price point* there is no reason for a solid-state amp to fail, whereas with a valve amp, no matter how well-engineered, valves can and will fail.
It's also true that with a properly designed valve amp, nothing other than valves and fuses should fail, so it's possible to get them going again quite easily, even at a gig - but a failed solid-state amp is almost always a bench job.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
With valve amps your using components that are made in much smaller quantities and parts that are much harder to fit into a modern automated production line ... you can put as much as you can on the PCB but with HT voltages that's generally not a good idea for long term reliability
So I do expect valve amps to cost more, luckily with modern PA's we no longer need big valve amps with their associated large HT and output transformers and large bottles ... these parts are the biggest cost. Well some of us don't ... playing though a large amp is a different feel to a small amp. Personally having done a few gigs recently with a Fender Twin I found it's huge headroom and complete lack of compression on the clean channel quite unforgiving to my dodgy inconsistent clean playing and I was wishing it was smaller
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Ah! We are talking about slightly different effects here. By "compression" I understood you to mean a gradual volume decrease (or slower increase IYKWIM!). Yes, a 20W valve GUITAR amp will power limit at LF because they all use pretty small OP transformers (Google the Quad ll and look at that traff and that is only a 12/15W amp!)
Transistorized amps have no such LF limitations. Even the older models with a big OP coupling capacitor could deliver near full power at 40Hz (with a good whiff of 2nd Harmonic!) your Velly 120 is almost certainly a DC coupled OP stage and thus could put ~100W out down to 5Hz!
Dave.
And how did it work out? Quite a few have been buying them for the very same reason!
"Just because it's never been done before, is the very reason to make it happen" - Me!
"Just because it's never been done before, is the very reason to make it happen" - Me!
I've been recommended small valve amps in shops and at normal home volumes they just don't sound as good as a decent SS/digital amp like the Boss Katana or many others.
Now if you play big gigs where it gets hot and you can drive the heck out of them.. well good on you, or if you live in the middle of nowhere and have a garage or basement, but those of us in semi-detatched houses with non-guitar playing neighbours arent going to get anything out of valve amps, even little 1 watters.
Boss Katana all the way
Here is some a good assessment of organic non-sterile SS tones from it...
It sounds just fine thanks.
Bit pickier on what I put through it, the sparkly tanglewood in my Avatar for example sounds weak and nasty, whereas it's inherent weak and nastiness is what makes it sound mighty through a cranked WEM dominator.
Stick anything with P90s into the cube though, and it sounds every bit as huge as you could want. Ironically, it likes a tubescreamer in front of it rather than the built in overdrive. And a RAT, but everything sounds better with a RAT.
I'm still a bit squicky about taking the final step and using a solid state power amp. I really, really want to...but I can't bring myself to dump the cash on such things as an experiment. Particularly since a solid state power section which can replicate that wondrous "boom" I get from my current rig will likely cost significantly more than another 20W Jet City amp.
The Rockette:30 is in no way up to the standards we achieve today... although, the technology used is identical! Work that out if you can. That demo does show signs of sounding a little 'flat and a tad lifeless'... she simply had something very important missing fro the power amp! Plug that preamp into the BluesBaby and your jaw would drop!
It's down to the design and the fact that our modern amps employ 'current drive' in the power amp. The lack of current drive is the very reason the older SS amps sound sterile. This is why 'hybrid' amps, tranny front ends and valve power amps, came on the scene. They knew that SS power amp were not right, but not how to cure it! Valve amps create current drive naturally and that's due to the output transformer... NOTHING to do with the valves at all.
If you put an output transformer on to a transistor output stage, it will achieve the same result. In fact, the very early transistor amps that did have output transformers sounded great... they were just not right for guitar use yet in other ways, or reliable.
We use an extra feedback path in addition to the normal negative feedback - yes, transistor amps have negative feedback too, or they simply would not work! This makes them tonally respond just like a valve amp.
SESSION was the first company to have the audacity to create a solid state version of a well known big selling valve combo... the BJr and we called it BluesBaby. The Guitar & Bass review of last year cemented it as, well, extremely good and doing everything you'd expect a valve amp to do. We now even do a 45 Watt version. http://www.guitar-bass.net/gear/award-session-bluesbaby-22-review/
A lot of people think we pay the magazine to publish reviews, when in fact we don't and never know what they are going to say until it's actually published... the same time as you guys get to see it. This is the same for all instrument manufacturers.
"Just because it's never been done before, is the very reason to make it happen" - Me!
Read my last reply above... now you can understand your own nervous behaviour! You won't find a suitable power amp with current drive is my prediction. Plug you rig into a BluesBaby 'AUX IN' and those worries will completely disappear! Promise! It really is the missing link!
The bottom end will be more 'boomy' just as you'd like; and the treble nice a sparkly/chimey. Plug in a Tele set to the middle PU selection and you're in rhythm heaven. Just like that guitar on the Direct Line advert (I love that tone.)
Where do you live... maybe I should pop along with one for a blast using your rig to drive it?????
"Just because it's never been done before, is the very reason to make it happen" - Me!