Members elsupermanny14 Posted April 9, 2008 Members Share Posted April 9, 2008 Just curious. As I was reading through the user reviews in the review section of Harmony Central I kept reading how people mention that the JCM900 isn't entirely a tube amp. What does it mean that it isn't entirely a tube amp? I thought the amp has tubes in it? It doesn't appear to be any less of a tube amp than other Marshall amps. Well anyways I'd really appreciate it if you guys can help me out with my question. Link to comment Share on other sites More sharing options...
Members trill Posted April 9, 2008 Members Share Posted April 9, 2008 Solid state rectifier? Link to comment Share on other sites More sharing options...
Members riffy Posted April 9, 2008 Members Share Posted April 9, 2008 It has a silicon diode in the input stage to aid in preamp tube clipping... Much like a Jubliee did. Link to comment Share on other sites More sharing options...
Members V-Type Posted April 9, 2008 Members Share Posted April 9, 2008 It is all tube. It has clipping diodes in the gain circuit though. No big deal IMO and the 900's are Very good amps in the right hands. Link to comment Share on other sites More sharing options...
Members fuzztone Posted April 9, 2008 Members Share Posted April 9, 2008 Solid state rectifier? That is interesting.How many modern "tube amps" have SS rectifiers? Link to comment Share on other sites More sharing options...
Members Prages Posted April 9, 2008 Members Share Posted April 9, 2008 It has a silicon diode in the input stage to aid in preamp tube clipping... Much like a Jubliee did. That's what I thought too. I have a buddy that's got a 50 watt dual reverb. I never really cared for the sound of it until we flipped it to 25 watts and ran it cranked into my isolation cabinet. That really brought out the creamy rich goodness I always thought it lacked. Unfortunately, running it through his 1960 cabs with the master volume pretty low didn't even come close to reproducing that tone. Link to comment Share on other sites More sharing options...
Members Mr Songwriter Posted April 9, 2008 Members Share Posted April 9, 2008 The DSL's have diodes in their input cicuitry too, don't they? Link to comment Share on other sites More sharing options...
Members jrkirkish Posted April 9, 2008 Members Share Posted April 9, 2008 the 900 is as much a tube amp as my twin reverb. no-one's saying that isn't an all-tube amp. Link to comment Share on other sites More sharing options...
Members Help!I'maRock! Posted April 9, 2008 Members Share Posted April 9, 2008 its definitely a tube amp. but i like Bruce Bennett's description that "its got more chips than a bag of Doritos." Link to comment Share on other sites More sharing options...
Members relictele Posted April 9, 2008 Members Share Posted April 9, 2008 That is interesting.How many modern "tube amps" have SS rectifiers? Lots I think. My Trem-O-Verb has both (switchable between SS and tube). So there! Link to comment Share on other sites More sharing options...
Members bigfatmonkeyboy Posted April 9, 2008 Members Share Posted April 9, 2008 if it sounds good, does it matter? Link to comment Share on other sites More sharing options...
Members elsupermanny14 Posted April 9, 2008 Author Members Share Posted April 9, 2008 That is interesting.How many modern "tube amps" have SS rectifiers? A lot! I'd say the majority of the tube amps out on the market right now. Link to comment Share on other sites More sharing options...
Members elsupermanny14 Posted April 9, 2008 Author Members Share Posted April 9, 2008 It has a silicon diode in the input stage to aid in preamp tube clipping... Much like a Jubliee did. And what are silicon diodes? lol sorry I don't know anything about internals when it comes to amps and guitars for that matter. So yeah what are they what do they do? And what is different about amps that don't have these? Link to comment Share on other sites More sharing options...
Members Fatcat Posted April 9, 2008 Members Share Posted April 9, 2008 I'll throw in my take. My main gigging amp is a 4100 100W DR. Most venues I play dont allow me to get my master volume past 9 o'clock(yes even at half power mode). To have the saturation i like, I have to run the gain at about 3 o'clock. With those settings, it really sounds like a tube amp with a pedal outfront. If I roll the gain back to about 1 o'clock and the MV at noon, it definitly sounds more tubelike, but way too loud. I recently purchased a Weber Mass 150 that I am experimenting with. As a side note, there is a 4500 50W in my rehearsal room that sounds amazing with the 1 o'clock gain and Noon MV settings. Moral? F opinions, plug in and fiddle till you find a good tone. If not, move on. Link to comment Share on other sites More sharing options...
Members csm Posted April 9, 2008 Members Share Posted April 9, 2008 All I know is that the 900 was when Marshall jumped the shark ... before their triumphant revival with the Vintage Modern series. I know a few Marshall players who wouldn't touch anything made between the JCM800 and the VM. Link to comment Share on other sites More sharing options...
Members elsupermanny14 Posted April 9, 2008 Author Members Share Posted April 9, 2008 I want to get a JCM900 (50watt version) cuz they're dirt cheap! I've seen them go for as low as $450 and $650 with a 4x12 cabinet before. The guy from Thursday plays one as does Dave Navarrow and those guys have awesome sound! Link to comment Share on other sites More sharing options...
Members GilmourD Posted April 9, 2008 Members Share Posted April 9, 2008 That is interesting.How many modern "tube amps" have SS rectifiers? Almost all non-tweed Fender amps have a solid state recto. Just about every Marshall has a solid state recto except the original JTM45. As far as the JCM900s... Anybody who mentioned diodes in the signal path for clipping hit the nail on the head. It's like having a built-in distortion pedal instead of relying on the tubes for distortion. The reason that is a big deal is because classic amps, even those that could be considered high gain like some JCM800s with a master volume, don't have anything in the signal path but tubes, resistors and capacitors. Link to comment Share on other sites More sharing options...
Members V-Type Posted April 9, 2008 Members Share Posted April 9, 2008 Ive owned 6 Marshalls so far. 2 were early 70's Plexi's 2 Jcm800's,1 TSL and 1 50/100 Silver Jubilee.Guess which one Kicked the most ass and consistantly.The Silver Jubilee and it has clipping diodes much like the 900.I played an 900 on a few ocassions and it had a nice clean as well as Mucho useable Gain.Again VG amps and a steal for under $600. Link to comment Share on other sites More sharing options...
Members Wyatt Posted April 9, 2008 Members Share Posted April 9, 2008 It has nothing to do with the SS rectifier, Fender has been using SS rectifiers on their amp heads since they were introduced in '60 or so, and the Twin Reverb, Marshall Plexi and dozens of other famous amps are all SS rectified as well. Rectifiers convert AC to DC, and while they do have an affect on the tone and performance of an amp, they are in the power supply and not the signal path. Several people here got it, it is the clipping diodes in the 900 mean that the preamp distortion isn't all tube. Clipping diodes are an old-school solid-state fuzz design. It was Marshall's cheap way of getting more distortion without having to use dedicated tube gain stages like Mesa, Soldano and the other high-gain big boys use. People feel it makes the 900's overdrive too artificial and "buzzy." And some of the other drive stages...like the effects loop...are op-amp driven, but I don't think anyone cares about that. EDIT: GilmourD beat me to my post. Link to comment Share on other sites More sharing options...
Members vanderwaal Posted April 9, 2008 Members Share Posted April 9, 2008 it is, most assuredly, a tube amp. my carvin bel air has diodes in the preamp stage too but it is, again, a tube amp. in fact there is a procedure for the bel air that you can do to bypass the diodes but honestly, i like the way it sounds so i'm not doing it. besides, about 75% of the time i run the clean channel with a dirt box out front which is great gives me, in effect 3 channels. clean, clean+od pedal and then there is the gain channel (carvin calls it "soak" whatever that means). however, the "soak" channel with a lot of gain dialed in with an od on top doesn't sound very good. the "soak" channel by itself though is very, very good. long story short (too late) the 900 is a tube amp. Link to comment Share on other sites More sharing options...
Members Lucio Posted April 9, 2008 Members Share Posted April 9, 2008 As usual a lot of people just repeat what they've heard without using their ears. I hear the JCM900s get knocked all the time because they used diode clipping, but everyone sings the praises of the Jubilee series which did too. Marshall probably added this in for a good reason: people wanted more gain from the amp, and adding valves just becomes impractical. I have one of the later jcm800s and it has 5 preamp valves (one more than the TSLs I believe), and I'm paying for it now they have to be replaced... Link to comment Share on other sites More sharing options...
Members _pete_ Posted April 9, 2008 Members Share Posted April 9, 2008 It has nothing to do with the SS rectifier, Fender has been using SS rectifiers on their amp heads since they were introduced in '60 or so, and the Twin Reverb, Marshall Plexi and dozens of other famous amps are all SS rectified as well. Rectifiers convert AC to DC, and while they do have an affect on the tone and performance of an amp, they are in the power supply and not the signal path. Several people here got it, it is the clipping diodes in the 900 mean that the preamp distortion isn't all tube. Clipping diodes are an old-school solid-state fuzz design. It was Marshall's cheap way of getting more distortion without having to use dedicated tube gain stages like Mesa, Soldano and the other high-gain big boys use. People feel it makes the 900's overdrive too artificial and "buzzy." And some of the other drive stages...like the effects loop...are op-amp driven, but I don't think anyone cares about that.EDIT: GilmourD beat me to my post. What's the difference between that and running a distortion pedal in front of an "all tube amp"? Link to comment Share on other sites More sharing options...
Members Wyatt Posted April 9, 2008 Members Share Posted April 9, 2008 What's the difference between that and running a distortion pedal in front of an "all tube amp"? The clipping diodes come after the preamp tube gain stages. You don't get to pick the pedal. And you can't turn it off. Link to comment Share on other sites More sharing options...
Members Phishmonkey Posted April 9, 2008 Members Share Posted April 9, 2008 Damnit there are way to many threads about this. In truth the 900 only has like a 1/2 tube gain stage. The preamp is mostly SS. As proclaimed by the lord Pames Jeters Here's some readinghttp://acapella.harmony-central.com/archive/index.php/t-1219091.html This doesn't apply to all 900s, the SLX and Mk III are all tube. And I'm not saying they're bad amps, but they are definitely not all tube. SS preamp into tube power section Link to comment Share on other sites More sharing options...
Members GilmourD Posted April 9, 2008 Members Share Posted April 9, 2008 Damnit there are way to many threads about this. In truth the 900 only has like a 1/2 tube gain stage. The preamp is mostly SS. As proclaimed by the lord Pames JetersHere's some readinghttp://acapella.harmony-central.com/archive/index.php/t-1219091.htmlThis doesn't apply to all 900s, the SLX and Mk III are all tube. And I'm not saying they're bad amps, but they are definitely not all tube. SS preamp into tube power section Actually, from the schematic, it appears there are 3 tube gain stages that I can absolutely see (given the crappy quality of the schematic). I'll link to it here because it's too big to embed in the post. I'll check my schematics at home, too, because I'm sure the Aspen Pittman books have better copies of them. http://www.drtube.com/schematics/marshall/jmp52-02.gif Link to comment Share on other sites More sharing options...
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