Anyone actually managed to try or buy one of the new marshall studio amps??

Nerine

The only thing Marshall should make now, is a JCM 800 2204x 50w 1x12 combo. With a Creamback, loop, etc. 
I'd buy one in a heartbeat. 

57Deluxe

ICBM said:

57Deluxe said:

more's the pity they don't.... 

They did!

...so confirmation that in the good old days you didn't need to offer large or XXL cos - there were no lard arses!!

ROOG

Eleven shillings for a T shirt and that included P&P. Bargain!

ICBM

A friend of mine just bought one - the SV20H 'Plexi' version. He's gone away for a few days and kindly left it with me to have a poke around.

Here are some pics - some explanations to follow...

Power supply/power amp


Preamp


Back


Resistors


Relays


Preamp valves


Back panel screw


First impressions are that it's well-made - a high quality double-sided PCB. Slightly disappointing that the chassis is not a fully closed box - it's open at the ends - but probably doesn't matter with the weight of the components here. The transformers look Chinese-made, to me - they're not marked, but the type of tape and varnish coating will be familiar to some of us.

The fairly large number of jumper connectors for such a simple amp, and the cheap plastic pots, are concerns, but it's nice to see all the larger resistors mounted well away from the board so heat damage in the event of a failure shouldn't be an issue. All the valve sockets are PCB-mounted, but the power valve ones are also bolted to the chassis which is fine.

Now some of the more technical stuff I know some of you will want to know... first, it's cathode biased as expected. The cathode resistor is the 150R one under the blue wire. The other 150R is the choke resistor - no actual choke - and the 1Ks are the screen resistors. Second, it's a common cathode resistor so the 1/4 power switch doesn't work by simply turning off one valve.

Further investigation reveals that it doesn't work by muting the signal input to one of them either - it appears to be a relay-operated... (Edit - I was wrong about this, it's actually a sort of power scaling - see later post!) The ICs are for the FX loop and what I assume to be a speaker-emulated DI output - I'm not going to lift the PCB since it's not my amp, so I haven't traced it out.

Very annoyingly, the HT fuse is internal and not in a back panel holder - this means that after a valve failure you're still likely to have to take the chassis out, which would otherwise be unnecessary with a cathode-biased amp. As supplied the power valves are JJ EL34s, and the preamps one JJ and two Shuguang ECC83s. I actually swapped the positions of the preamps - as supplied the JJ was in V1 and the second Shuguang in V3, I've reversed this in the pic. (Why later!)

Overall I'd give it 8/10 for build quality. Not impressed by the pots, and I'm not really a fan of jumper connectors, but everything else looks OK for a mass-produced amp. The only thing I think actually needs changing is the HT fuse location.

A final nice touch is that the back panel is not held on with woodscrews as Marshall have traditionally done - prone to stripping when they get taken in and out a lot - but machine screws into threaded metal inserts.

I'll update this with impressions of how it sounds when I've had more of a play around with it .

riffpowers

Excellent!! Thanks for that, I'll look forward to reading what you think of it!!

clarkefan

Nice one ICBM!  Would you prefer if it had a choke over the resistor?  Or no difference? 

Fenderish

What's this frickin' "Why Later" ? that's an unholy cliffhanger !!!  

ICBM

clarkefan said:

Nice one ICBM!  Would you prefer if it had a choke over the resistor?  Or no difference? 

I would normally have said I would prefer a choke, but in practice it may not matter. While I think there is a difference with some amps, it's not all - recently I A/B'd an old Traynor using a switch so I could flip back and forth on the fly while actually playing, and there was no detectable difference at all. Admittedly quite a different circuit from a Plexi Marshall though, it wasn't the Bassmaster.

Fenderish said:

What's this frickin' "Why Later" ? that's an unholy cliffhanger !!!  

I had some actual work to do .

Anyway, I've done some playing now!

ICBM

... and it sounds like a Marshall Plexi. (I knew that anyway, I'd briefly tested it before I took it apart.)

The test cab was my Marshall TSL122 combo sans amp section - containing a Marshall Vintage (V30) and a Marshall Heritage (G12M-70 I think) in series at 16 ohms. This is quite a nice cab, which I use for testing things in the workshop normally.

The test guitar was an Epiphone SG400 - actually a good-sounding guitar with decent pickups, so don't laugh .

So - yes, it sounds very like a smaller Super Lead. It doesn't quite have the sheer dynamics and intimidating attack of course, but that's a good thing as well as bad. It *is* loud - I would say loud enough to gig with quite comfortably in the 20W mode. Channel 1 is, as usual, almost unusably harsh and edgy at low volume due to the oversized bright cap, and Channel 2 sounds like a bass amp being played underwater... but jumper the channels, turn it up a bit and it's perfect - set the underlying volume with Channel 2 and add as much Channel 1 as you need to make it come alive. It's more compressed than I expected when it's flat out, but I think that will be the cathode bias, and possibly the lack of a choke. As usual the tone controls aren't the most effective on an amp - the balance between the two channels is at least as useful - but it's hard to make it sound bad.

The 5W mode isn't quite as good. I tested it both normally and with my Powerbrake so I could equalise the volume and see what was happening - two clicks is 6dB, or the same as the change in power of the amp, so I could get the same final volume. But it just doesn't sound quite as full and natural at 5W. (Edit - I was wrong about how this works, although in hindsight for the right reason! See later post.) It just sounds slightly 'strangled' at the 5W setting, and I think it would have been better - as well as simpler from a circuit point of view - to do it by turning one valve off and using it single-ended. As it is, it sounds better running at 20W with the attenuator two clicks lower, than it does at 5W with the attenuator two clicks higher. Which isn't to say it sounds bad at 5W, just not as good as it does at 20.

Why the preamp valve swap? Because I hate JJ preamp valves! At least in 'gain' positions... they sound muddy, dark and oddly slightly harsh at the same time, to me. But I like Shuguangs, so seeing what was in the amp I swapped V1 and V3, making the JJ the phase inverter where it does the least harm. (V2 has to stay as a Shuguang since these are the best modern valves in cathode-followers.) And immediately, the amp sounded noticeably better - brighter, with a bit more gain and grit, and that classic Marshall 'ring' which is more like a clean-ish sound with 'teeth' than a thick overdrive. Given that there are two different valve types in it Marshall must have chosen them deliberately, but it *really* is much better this way round...

20W mode - 9/10. 5W mode - 7/10.

I haven't yet tested the FX loop or the DI output, but at some point in the next few days I will.

fastonebaz

Excellent and interesting reading.  Thanks for posting. 

Modellista

Superb info, @ICBM  . Not sure this is an amp I’m interested in, but if it were, this would be really useful.  Enjoyed reading it anyway!

pintspiller

Good to see Marshall appearing to get a thumbs up for a change.

ICBM

pintspiller said:

Good to see Marshall appearing to get a thumbs up for a change.

Praise be given where it's due...

Now they've finally made a modern amp that looks like a classic Marshall, sounds like a classic Marshall, appears to be built well enough, and has some useful modern features as well. (FX loop, DI out, low-power mode.)

The worst niggle is that HT fuse - that really makes it far less user-friendly than it could be, especially at a gig if a valve goes down. With a holder on the back panel you could change the power valves and the fuse and get going again in minutes, completely safely since no high-voltage parts need to be exposed. As it is it's only another four screws to get the chassis out, but you'll have to make sure the amp is fully disconnected, tip the amp onto its front to get at them, lift the chassis out, poke around on the PCB to get the fuse out of the clips - and there's more than one fuse there, so you'd need to know which - and then put it all back together... far more of a job, and probably enough to put most people off trying it under pressure. Both Orange with the Rocker 30 and Laney with the LA30BL put the HT fuse on the back panel.

If I owned one of these and was gigging with it I would seriously consider drilling a hole in the back and fitting a panel holder - obviously that would invalidate the warranty though.

Ddigger

Quality post, exactly why I come here.  Thanks for posting.

CarpeDiem

Thanks @icbm for your insight, which is really helpful and informative.

TTBZ

I spent a bit of time with the Studio Classic over the weekend. It's a great amp but I ended up preferring my Jubilee still. Just more versatile - doesn't have quite the same picking response and is more compressed but I guess I prefer that. Or I'm just more used to it. It can sound very similar just with more gain and options on the jubilee. I do love the Studio Vintage (plexi) though

Twinfan

ICBM said:

Why the preamp valve swap? Because I hate JJ preamp valves! At least in 'gain' positions... they sound muddy, dark and oddly slightly harsh at the same time, to me. But I like Shuguangs, so seeing what was in the amp I swapped V1 and V3, making the JJ the phase inverter where it does the least harm. (V2 has to stay as a Shuguang since these are the best modern valves in cathode-followers.) And immediately, the amp sounded noticeably better - brighter, with a bit more gain and grit, and that classic Marshall 'ring' which is more like a clean-ish sound with 'teeth' than a thick overdrive. Given that there are two different valve types in it Marshall must have chosen them deliberately, but it *really* is much better this way round...

I believe Marshall, and other amps manufacturers, tend to use JJs in V1 as they're a bit more robust and less prone to microphonics.

Fenderish

Strange I see that often (brands putting a JJ in V1 and chinese one in V2/V3...). Wonder why, as I have the same opinion about those JJs at V1 (except on clean amps where they do their joob good enough)

edit : the answer to my question was posted between my reading and my posting

ICBM

Twinfan said:

I believe Marshall, and other amps manufacturers, tend to use JJs in V1 as they're a bit more robust and less prone to microphonics.

Possibly true, but they just don't sound great. (In my opinion.) Shuguangs aren't usually very microphonic either - it would have made more sense and been simpler just to fit three of them. Or are we back to people actually wanting a muddy tone?


Part 3: outboard stuff.

The FX loop is bypassed with one of the relays, not with the actual switch on the back panel being in the audio path - so the bypass signal stays on the main PCB - but that said, with just a single patch cable in the loop it's as close to perfectly transparent as I can tell anyway... I can't hear any real change in either tone or level at any volume setting, even when toggling back and forward with chords ringing. All loops should be like this.

The loop operates at a slightly higher level than a guitar signal, but not as high as line level - with a quite level-sensitive pedal (Boss PH-1R) in the loop, it's possible to make the pedal distort a bit, but not too badly and without a noticeable level drop. The loop is also far enough on in the circuit that with a volume control in the loop and turned down low you can get a bit of preamp distortion from the amp too, but it's clearly not as much as the full-tilt sound.

I'm still not completely convinced a loop is needed at all on non-MV amp, but it is at least about as perfectly implemented as possible - and if you want, you can also use it as a power amp input if you're using a multi-FX and the into-the-front sound is too dirty... it really is quite difficult to get a truly clean sound like that! I didn't try this but you could also use it to link two (or more) amps together from one preamp. So much better to have it than not.

Of course, it goes without saying that it takes drive pedals in front brilliantly, although at higher volume settings it does seem to mush out a lot more than a full-size Super Lead. But at least by the same token it has less of a tendency to blow your head clean off if you accidentally set the pedal too high and then turn it on .

Lastly, the DI output which as expected is speaker-emulated. Hmmm... well, it sounds better than un-emulated! I tested it into a basic PA amp and cab since I don't have a recording set-up in my workshop, and for that purpose it's OK - it still needs a bit of careful EQ'ing on the PA to sound close to what's coming from the guitar cab, and it's at least fairly plug-and-play compared to using a separate box - but it is rather flat, buzzy and artificial-sounding. Interestingly it sounds closer to the 5W setting than the 20W, so if you need to use it for going into the PA at a gig where they won't allow you to use the full power, it's possibly a more useful option. But for recording I think you'll still want to mic the cab, or if that isn't possible then use a proper load box and off-board emulation.

Like to a much lesser extent the FX loop, I wonder if it was really necessary or if the cost would have been better put into upgrading something else. It's a difficult balancing act - if you make it too basic it gets criticised for not having those sorts of features as well... but I think overall I would have preferred to see a slightly more basic amp with a less complex means of power reduction if it was necessary at all, a few component upgrades and not bother with the DI out, but you can't please everyone!

Twinfan

ICBM said:

Twinfan said:

I believe Marshall, and other amps manufacturers, tend to use JJs in V1 as they're a bit more robust and less prone to microphonics.

Possibly true, but they just don't sound great. (In my opinion.) Shuguangs aren't usually very microphonic either - it would have made more sense and been simpler just to fit three of them.

Just passing on what I've read