lonewolfsx
Well-Known Member
Hello everyone. You may remember I picked up a JCM900 SL-X 2100 head just a week or two ago... I'm on a spree now. Thanks to a GC mishap with some cancelled orders and my company giving me a few GC gift cards, turns out I have a few bucks laying around on my account. But to use those funds, you have to call to order - you can't just apply the funds in your account to an online order. I didn't know that, but it was a pleasant surprise.
I've been idly searching for a JCM800 to add to the collection but I still search the 900's and other models around the web and happened across another GC surprise - a JCM900 Mk III 1x12 combo listed for a mere 500 bucks. Seems like a great deal to me so I called in and snagged it. It just showed up on Wednesday so I've barely had the chance to play it, but I did do a little A/B ing with the SL-X.
Some quick info on this MK III - this is the 50w model. It has clipping diodes for the distortion circuit and I gather they are technically always on but really only doing anything when the "gain sensitivity" knob is turned up. Interestingly, if you turn the sensitivity knob completely off on this amp, you still get sound - on the SL-X, if I turn sensitivity to 0, the amp has no sound (I supposed because on that amp it controls the tube V2 so if that tube is off obviously the signal is cut). The cabinet it comes in is very small, in fact it's the smallest 1x12 I have, but it has really nice handles on the sides like a 4x12 which is great for carrying it any kind of distance without straining your back or shoulders. The speaker is the stock Celestion G12-H100, which I happened to have another of in my 4x12 and it's one of my all time favorite speakers - so that's very cool to me. This is a 1990 model (Y serial).
First thing right off the bat, playing it alone with nothing else to compare to and it's a blast - it has a bit of a fuzzier distortion characteristic than I'm used to with Marshalls, I suppose the attack is a little less immediate because it doesn't have the chunky brightness that hits you at the same time as your pick hits the strings. It's also intersting that the level of distortion feels about the same regardless of the preamp gain position if the sensitivity is maxed. I.e. if the preamp is at 5 but sensitivity is maxed, it still sounds about the same as with both of them maxed. So far I'm liking the preamp maxed then I fiddle with the sensitivity depending on the song I'm playing, anywhere from "off" to max - the whole range is perfectly usable.
The master volume is extremely good on this - I'm really surprised just how easy it is to keep the same tone even at lower volumes, most older amps like this I find the master is super sensitive, from whisper quiet and ham radio sounding at 1 and blowing the windows out at 2 - this amp on the other hand is great, I can get a good bedroom kind of volume in low power mode with vol on 2, up to my more normal playing volume with high power mode and the volume around 4, and I'm sure that would carry over to stage volumes (that I have no tested yet but I have no reason to believe it won't excel). I do think it sounds a bit better in high power (pentode) mode, so I'd only use low power if you needed true less-than-TV volumes for practicing.
Overall I think it makes for a really fantastic little combo that can be used for practice all the way up to small gigs or miced could do almost anything as long as you don't need two channels. I suppose the one way that you could REALLY improve this amp would be if you could switch the gain sensitivity on/off as well as the dual volumes. I think the preamp maxed / sensitivity off is killer for classic kind of sounds and can clean up with the volume on the guitar, but as soon as you bring in the sensitivity anywhere above ~3-4 (13-14 on the panel) it does kill some of the dynamics and you can't really get a clean tone anymore by manipulating the volume on your guitar. That diode fuzz is always there, so it doesn't really do the "dirty clean" thing either unless the sensitivity is completely off. I'm not ragging on the amp, but I can understand why this wouldn't be the amp for everyone based on that alone. If you could switch it in and out of the circuit with a footswitch, that would be awesome - kind of like having a built-in overdrive, with a great flat frequency curve, and uniquely situated in the middle of the circuit (as opposed to using an overdrive in front as a boost, which would sound different). You could effectively have a drive + smoother/fuzzier/moredrive sounds in the same amp, but with the same core tone.
Now I'm going to complain about something I just complimented it on - the tiny cabinet it comes in, even partially open backed like it is, really constricts what this thing is capable of. It's fine for practice but it sounds... "boxy" I think is the term... basically, as the volume comes up you definitely notice that the bass is not filling out like it should. For those not familiar with my setup, since I don't play out, I have a 4x12 cabinet that I have installed 4 different models of Celestion speakers, and each one has a separate jack, so I can jump between different speakers quickly but I keep the girth that a big closed back cabinet provides - essentially like having an extra oversized 1x12 cab. When playing this Mk III through its built in G12-H100, then switching to the G12H-100 that is in my 4x12, it's a massive difference. The bass fills out and the sound is suddenly way more balanced especially as the volume is increased. I think if the combo cab had been a little bit larger it would've sounded a lot better but as I said above I give it a lot of credit for its portability and you always have the option to use an external cab (and if you were going to use this to play out, I'd high recommend doing so). Juts something to keep in mind, obviously if I had the head it'd be going through the 4x12 all the time and I'd never would've noticed this. I'll take it as a bonus overall because if I'm going to a friend's place I can tell you what amp I'm taking now (and it's not a big head and cab, even though I have other 1x12 speaker cabs!).
Final words:
I think my '93 EL34 SL-X is better. Maybe controversial opinion I know, and I don't want to tear down anyone who likes the Mk III because it is also great. But so far, in an A/B comparison through the same speaker in the 4x12, I find the SL-X to be a lot better for what I want to do, which is set and forget and just use my volume knob for what I want. If the Mk III could footswitch the diodes in/out then I'd have a lot harder of a time deciding since they both have such unique tones (and really don't sound all that alike). I also think it'd benefit from a more bottom heavy speaker, not that the H100 doesn't have bottom but it also has a lot of brightness that contributes to the issues with the size of the combo cabinet. I will have to test it, but I have a G12-65 reissue that is very much tilted towards the bass end of the spectrum with reduced treble and I think that would be the perfect speaker to drop in here instead. Maybe I'll get around to that but the G12-65 is currently installed in my big cab and it's a pain to take it out.
Oh, and in classic Guitar Center fashion, they did screw something up, the knob for the presence control is missing. In the screenshot I took of it online it was there, but it was nowhere on the amp, in the amp, or in the packaging material - guess they just lost it and didn't care enough to replace it. Big surprise. Luckily a few replacement marshall knobs are easy to find.
Pics:
I'm also still working on a comparison video. I have so many marshall-like amps and speakers now it'd be a crime not to do some kind of decent play test. I'm a bit of a perfectionist though so it'll be a little longer. I have another amp on the way that should arrive today and if it sounds good I'll be adding that to the comparison as well.
Cheers!
I've been idly searching for a JCM800 to add to the collection but I still search the 900's and other models around the web and happened across another GC surprise - a JCM900 Mk III 1x12 combo listed for a mere 500 bucks. Seems like a great deal to me so I called in and snagged it. It just showed up on Wednesday so I've barely had the chance to play it, but I did do a little A/B ing with the SL-X.
Some quick info on this MK III - this is the 50w model. It has clipping diodes for the distortion circuit and I gather they are technically always on but really only doing anything when the "gain sensitivity" knob is turned up. Interestingly, if you turn the sensitivity knob completely off on this amp, you still get sound - on the SL-X, if I turn sensitivity to 0, the amp has no sound (I supposed because on that amp it controls the tube V2 so if that tube is off obviously the signal is cut). The cabinet it comes in is very small, in fact it's the smallest 1x12 I have, but it has really nice handles on the sides like a 4x12 which is great for carrying it any kind of distance without straining your back or shoulders. The speaker is the stock Celestion G12-H100, which I happened to have another of in my 4x12 and it's one of my all time favorite speakers - so that's very cool to me. This is a 1990 model (Y serial).
First thing right off the bat, playing it alone with nothing else to compare to and it's a blast - it has a bit of a fuzzier distortion characteristic than I'm used to with Marshalls, I suppose the attack is a little less immediate because it doesn't have the chunky brightness that hits you at the same time as your pick hits the strings. It's also intersting that the level of distortion feels about the same regardless of the preamp gain position if the sensitivity is maxed. I.e. if the preamp is at 5 but sensitivity is maxed, it still sounds about the same as with both of them maxed. So far I'm liking the preamp maxed then I fiddle with the sensitivity depending on the song I'm playing, anywhere from "off" to max - the whole range is perfectly usable.
The master volume is extremely good on this - I'm really surprised just how easy it is to keep the same tone even at lower volumes, most older amps like this I find the master is super sensitive, from whisper quiet and ham radio sounding at 1 and blowing the windows out at 2 - this amp on the other hand is great, I can get a good bedroom kind of volume in low power mode with vol on 2, up to my more normal playing volume with high power mode and the volume around 4, and I'm sure that would carry over to stage volumes (that I have no tested yet but I have no reason to believe it won't excel). I do think it sounds a bit better in high power (pentode) mode, so I'd only use low power if you needed true less-than-TV volumes for practicing.
Overall I think it makes for a really fantastic little combo that can be used for practice all the way up to small gigs or miced could do almost anything as long as you don't need two channels. I suppose the one way that you could REALLY improve this amp would be if you could switch the gain sensitivity on/off as well as the dual volumes. I think the preamp maxed / sensitivity off is killer for classic kind of sounds and can clean up with the volume on the guitar, but as soon as you bring in the sensitivity anywhere above ~3-4 (13-14 on the panel) it does kill some of the dynamics and you can't really get a clean tone anymore by manipulating the volume on your guitar. That diode fuzz is always there, so it doesn't really do the "dirty clean" thing either unless the sensitivity is completely off. I'm not ragging on the amp, but I can understand why this wouldn't be the amp for everyone based on that alone. If you could switch it in and out of the circuit with a footswitch, that would be awesome - kind of like having a built-in overdrive, with a great flat frequency curve, and uniquely situated in the middle of the circuit (as opposed to using an overdrive in front as a boost, which would sound different). You could effectively have a drive + smoother/fuzzier/moredrive sounds in the same amp, but with the same core tone.
Now I'm going to complain about something I just complimented it on - the tiny cabinet it comes in, even partially open backed like it is, really constricts what this thing is capable of. It's fine for practice but it sounds... "boxy" I think is the term... basically, as the volume comes up you definitely notice that the bass is not filling out like it should. For those not familiar with my setup, since I don't play out, I have a 4x12 cabinet that I have installed 4 different models of Celestion speakers, and each one has a separate jack, so I can jump between different speakers quickly but I keep the girth that a big closed back cabinet provides - essentially like having an extra oversized 1x12 cab. When playing this Mk III through its built in G12-H100, then switching to the G12H-100 that is in my 4x12, it's a massive difference. The bass fills out and the sound is suddenly way more balanced especially as the volume is increased. I think if the combo cab had been a little bit larger it would've sounded a lot better but as I said above I give it a lot of credit for its portability and you always have the option to use an external cab (and if you were going to use this to play out, I'd high recommend doing so). Juts something to keep in mind, obviously if I had the head it'd be going through the 4x12 all the time and I'd never would've noticed this. I'll take it as a bonus overall because if I'm going to a friend's place I can tell you what amp I'm taking now (and it's not a big head and cab, even though I have other 1x12 speaker cabs!).
Final words:
I think my '93 EL34 SL-X is better. Maybe controversial opinion I know, and I don't want to tear down anyone who likes the Mk III because it is also great. But so far, in an A/B comparison through the same speaker in the 4x12, I find the SL-X to be a lot better for what I want to do, which is set and forget and just use my volume knob for what I want. If the Mk III could footswitch the diodes in/out then I'd have a lot harder of a time deciding since they both have such unique tones (and really don't sound all that alike). I also think it'd benefit from a more bottom heavy speaker, not that the H100 doesn't have bottom but it also has a lot of brightness that contributes to the issues with the size of the combo cabinet. I will have to test it, but I have a G12-65 reissue that is very much tilted towards the bass end of the spectrum with reduced treble and I think that would be the perfect speaker to drop in here instead. Maybe I'll get around to that but the G12-65 is currently installed in my big cab and it's a pain to take it out.
Oh, and in classic Guitar Center fashion, they did screw something up, the knob for the presence control is missing. In the screenshot I took of it online it was there, but it was nowhere on the amp, in the amp, or in the packaging material - guess they just lost it and didn't care enough to replace it. Big surprise. Luckily a few replacement marshall knobs are easy to find.
Pics:
I'm also still working on a comparison video. I have so many marshall-like amps and speakers now it'd be a crime not to do some kind of decent play test. I'm a bit of a perfectionist though so it'll be a little longer. I have another amp on the way that should arrive today and if it sounds good I'll be adding that to the comparison as well.
Cheers!
] I've walked away from a Marshall...
