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Hello y'all,

I've been having a problem with JVM 205Combo.
During corona-lockdown, when we were not allowed to rehearse with the band, I had took my amp home with me....
As I'm always curious to find other sounds, I started experimenting with connecting other speaker cabs to my JVM. But, as I later discovered, the cable I used was no good and I think I blew up the main amplifier. I looked for the fuse, for it seemed logical to me that the fuse was blown, but couldn't find it. I also have a JCM 800 2205 head, a JMP MK2 2204 head and I've been having a JCM900 4100 head in the past. Now, all these amps were fused, so if anything went wrong, it was just the fuse that was blown. In fact, I've experienced that!
But no fuse on the JVM....is that correct? Because if it is, my problem is bigger than I thought. In that case, what was blown instead? The output transformer? My tubes?

I hope somebody can help me out on this one. And I promise never to experiment with other speakers or whatsoever.

Thnx anyway!
Cheers!

 

asked 10 Sep 2021 at 08:23 PM

Arno Visser
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first time poster, long time tech. having experience with marshall amps I am familiar with issues stemming from problematic circuit boards (i.e.-DSL/TSL etc ) however my experience regarding this model is limited. can't say I have ever been a fan of DSP. for me ,as a player/tech DSP is a deal breaker. like the dreaded nintendo game format red circle of death, once the DSP bites it you're done.  I just seek a simple answer for my customer who bought one second hand,never re-tubed. amp lost power.sounds like a badly blown speaker (speakers test good). replaced output tubes and driver tube (original outputs tested badly). preamp tubes test good. supply voltages appear to be normal.overdrive channel LED switches from red to amber to slightly different amber but no green.  clean channel button switches normal. red-orange-green.master volume button doesn't come on.sometimes if you perform factory reset all buttons function but sound is still terrible. nice clean signal going thru to pin 7 of V7.  in between V7 and phase inverter something is haywire. my money is on the DSP board but not having a flow chart ??? tried to get a signal straight into the power amp but got nothing out. any input appreciated guys.  one thing more...i get the 2 separate heater voltages. V6 is 12vdc but the other for the remaining tubes originating at the tranny, is that standard 6.3 ? didn't see it on the schematic.

 

 

 

edited 29 Jun 2021 at 12:17 PM

gordon perry

asked 29 Jun 2021 at 12:16 PM

gordon perry
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Hello,

can I use my JTM60 speaker with a Marshall Origin 20H Head?

Also, my JTM60 has suffered some damage when my nephew tried to power on the amplifier, she cranked everything up but didn't succed, when I got home I didn't noticed it was all cranked up and powered it, it blew tubes and some more, I had it repaired but it didn't get back to the same sound as before... I'd like to have it checked by qualified personnel, can you indicate someone in Italy, please?

Thanks a lot,

Marco

asked 21 Dec 2020 at 02:25 PM

Marco Damian
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Hi,

 

Have a few questions about attenuator usage with SC20H amp.

 

1. Do I need two attenuators? My cabinet has two speakers (8 Ohm each), and SC20H has two separate outputs for each speaker, so does it mean I have to buy two attenuators, one for each speaker? I didn't manage to find SC20H schematics, so I'm not sure if those two amp outputs are connected in parallel internally, and I can just use one attenuator.

2. Do I need attenuator(s) at all? I want to run the amp with overdriven tubes, thus I have to set max level, right? Consultant at my local store told me it's enough to reduce "Master" volume, and EL34 will still be overdriven, if I set "Pre-amp" volume to max. But folks at Marshall forum say that it's still better to use attenuator, even in 5W mode. Again, I don't have SC20H schematic, so it's hard to tell who is right.

3. What if my cabinet only have one 4 Ohm input (2 x 8 Ohm speakers inside)? Is it enough to connect it to the amp with only one cable? Or I have to rework my cabinet to have two different inputs (separate input for each speaker)?

 

Thanks!

asked 25 Oct 2020 at 02:18 PM

Sam Protsenko
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1

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543

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Hello,

I am a recent ower of a Marshall Origin 20, which I got in July. I've really enjoyed the amp until I plugged in last night and got out absolutely no sound out of it. I couldn't figure out why, as nothing as happened to it and it worked fine two days ago. I took it apart to do some trouble shooting and found that when I have all the knobs max'd and output on 20 watts, I can hear a whisper of my guitar signal (nicely saturated, presumably by the preamp tubes) through the speaker. This sound is affected by all of the knobs. However, if I plug my guitar directly into the return of the effects loop, and activate the effects loop I get no sound whatsoever; no guitar, no hum, nothing. Because of this, I'm sure my speaker is not the problem. These things led me to think it was a power amp section issue, so I went down and purchased a new set of matched EL34's, threw them in there, and nothing changed. I'd really like to know if there's anything I can do to fix this, because this amp is not even a year old and I should not be having these kinds of problems with completely normal bedroom use.

 

Thanks,

Alex

asked 12 Sep 2020 at 06:27 PM

Alex Peters (1)
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Hello everyone,,

I own both a Stanmore and a Woburn (recently), and I have never had a single issue with either. I've used the Stanmore literally daily for a few years as my main living room speaker for both streaming and AV-vinyl, and the sound and punch are both absolutely incredible. The price you've quoted sounds like a steal, and if it is in good shape I would internet cafe sweepstakes providers snatch that up. You might get the odd pop when it's turned up which can be startling when it happens, but small price to pay for tubes and quality.

I stream mainly from my laptop, and the only thing you may find is that for some reason mobile streaming from Spotify tends to be underpowered for some reason, although I had a similar issue streaming Spotify from my phone to a proper event hall AV system via aux cord so I wouldn't really fault the Stanmore for that.

Ultimately it is incredible sound and to be honest even my Sonos Play:1s have a hard time competing with a single Stanmore. The Sonos provide slightly crisper sound and the stereo is a clear advantage if that's important to you, but the Marshall sound is warm with deep powerful bass that easily makes up for some of the clarity loss (and I really can't stress enough that unless you're an audiophile and actually sit and compare them in an intense back and forth, you would have a hard time deciding which is better - I actually prefer the Stanmore for certain types of music).

I hope that helps and let me know if you have any questions!

 

edited 19 Aug 2019 at 09:45 PM

Berlin Khan

asked 18 Aug 2019 at 06:38 PM

Berlin Khan
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1

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622

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I know that turning a "TUBE" amp on without a speaker load on the output will damage the amp.

(the no-load condition will cause the output voltage to increase until the output tubes burn out, which can then lead to other component  damage)

 

Is this also true for a CODE 100 amp?  Is there a risk of damage to the output section, with turning the unit on without a speaker cab load connected?

Would it be safe to operate the amp with just headphones connected instead of a speaker cab?

Would it be safe to operate the amp without either a speaker cab or headphones connected?

I ask because my computer (which is a desktop) is in a different location in my house than my amp.

Doing firmware updates or testing out patches requires either moving my computer or my amp, both of which are very inconvenient.

It would be much easier if all I had to move was the head.

 

asked 09 Jul 2019 at 01:42 PM

A. Todd Henker
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1

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811

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Hey Mates,

 

Having issues with a clients amp, seems that after a retube that i did, he was playing and after about 30 min, it gradually started losing sound and then cut sound completely.  I did the re-tube myself, and biased it properly and i was able to play it for about 40 min with absolutely no issues.  List of troubleshooting steps i have done:

tried a different speaker cable

tried a different guitar cabinet

tried a different guitar and guitar cable

tried the old tubes, additionally bought a 12ax7 and tested each pre-amp tube

tried a different power source

Have tried different power tubes

have checked and replaced the fuses

 

Now this is what i am THINKING is the problem, I think it might be something with either the heater curcuit fuse, or i think it's called a BRT1 Rectifier?  I did alot of research and it seems that the people having MY issue, explain the same symptoms of what i am having.

 

Now i have to make this clear, I AM NOT A PROFESSIONAL TECH, just a guy helping bands out with tech stuff that they don't know how to do.  So any help is appreciated.

 

Thanks!

asked 27 Jun 2019 at 08:01 PM

Austin Hetrick
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So I've been thinking about buying a Celestion F12-X200 speaker for my code 50 and was wondering it this would work. The reason I need to know this is because even though I know you can use an 8ohm speaker on a 4ohm tube amp, I'm not sure about a digital amp. Could anyone tell me if this is possible.

asked 01 Jun 2019 at 05:01 PM

Keenan Borgerson (2)
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3

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856

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High, first off, I am new to the modeling world, my main rig is peavey and Line6 DT25 tube rigs.

I bought a Code 50 as a quick and reliable solid state backup/practice amp to gig with if needed.

I love the sounds of it but at times the BASS just takes over even when Bass knob is rolled to

zero. no matter what settings i use the Bass is booming. I am thinking of a speaker upgrade

possibly but is there any advice on settings that may help me pull the mid range out more. I 

use Super Cleans and Gritty Gains. Hard Rock/Metal sounds

 

Wes

asked 13 Mar 2019 at 04:12 PM

Wes Eubanks
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1

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812

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I'm using a Origin 50 combo. I find when I crank the master volume and play at higher volumes, I get what sounds like glassy tube rattle. There is also just generally more noise than I would expect. I tried it with a different cabinet. It seems to be worst when using the internal speaker or when the amp is sitting on top of the external cabinet... my assumption is that the physical vibrations due to high volume are causing the tubes to rattle. The rattling is getting passed through the speaker, meaning that it is not just simply a physical rattle, but it is a transferred into the signal.

It sounds similar to some of the problems on the internet with the Class 5 that had rattling. Someone suggested that tube rings would fix it. Any suggestions?

asked 27 Dec 2018 at 08:29 PM

Chris Holtmeier
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1

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2.2k

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Hello,

I've noticed that there is rattling/jangling coming from the amp (not the speaker) when playing notes between low  A and C and their respective octaves above. It sounds like it is coming from the EL34 valves - is this due to the way that they are mounted without spring dampers? They have not gone microphonic as far as I can tell, and are otherwise performing as expected, so I feel this is more a mechanical issue with the chassis/mounting, or it's just an undesirable characteristic of the valves themselves. What I'd ideally like to know is, do all Origin 20Cs do this or is this the first anyone has heard about this?

I've removed every external variable there could be, moving the amp to another location and isolating it from floor vibrations in the studio. I've taken the 'amp' out of the cabinet so that I could lightly tap the valves, and check the screws around the supports are not loose. You can generate the rattle (or very similar) just by tapping lightly with the handle of a screwdriver, on both valves. This is what I was expecting if it was just physical vibrations from the speaker causing them to rattle in sypmathy. The rattling sound does not get amplified, so it's not in the audio path.

It's enough to be offputting when tracking/practicing in the studio unless pushing out really high volume so that you can only hear the guitar. I play fairly clean a lot of the time so it is more obvious under those conditions.

Would really appreciate some advice. If the answer is, "It's the same for all and there's not much that can be done..." then ok, I just need to know. That said, I spotted there was some sort of similar issue perhaps on Class 5 amps that a kit was developed for to resolve? I may have misunderstood though.

If there is any further mechanical troubleshooting to be done then please let me know. I wouldn't want to void the warranty status if possible. For what it's worth, I'm a systems and support engineer for a large format mixing console company, so I'm competent enough to poke around as required... just figured someone may have alreday solved this one before I carry on!

Kind regards,

Ed

 

edited 09 Sep 2018 at 11:28 AM

Edward Arnold (1)

asked 09 Sep 2018 at 11:27 AM

Edward Arnold (1)
0

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1

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486

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I have had this amp for a few months and still can't seem to dial in a good sound. It is my first Marshall and first tube amp. I have looked on-line for settings to no avail. This also has the upgraded Creamback speaker from Sweetwater.

I use this mostly at home and am looking for a good clean tone and a good distorted tone.  Any help would be greatly appreciated. I use the 20 watt setting.

 

Thanks

asked 28 Aug 2018 at 07:21 PM

Peter Schwotzer
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0

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535

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Hi, i have just aquired a haze 15 head in great nick.

please anybody could you advise on what marshal power tubes are used as in maker ?

Also they use three ecc83 the first being a different code ( this is the one with the aluminium cover) is this the higher gain one? if so could i swap for a lower gain with no problems.

Also has anyone upgraded the speaker that is fitted ( marque) ? if so to what just interested

Thanks John

asked 07 Jul 2018 at 12:29 PM

John Smith
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2

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908

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Hey, 

So this is my first personal all valve amp. Ive had a few around but never one of my own, i know how to use them and what not to do, but ive never owned/played one long enough day to day to realise if the tubes are not properly working. 

The other day, i turned on my amp (It's a 110 volt made for USA mini jubilee head that i run through a transformer at 230 volts mains) as usual, and after i let it be on standby for about 10 minutes, when i turned it on, there was no sound. I proceeded to turn it back on standby and check all my cables in my signal chain on my board, and turned it on again (this happened a few times, maybe 4 or 5) and still no sound. 

I then checked the back because i do connect some pedals in the effects loop, and to my shock the speaker cable wasnt connected! (someone must have moved it around while cleaning and i never noticed as its on the back flush to a wall) 

I immediately turned the amp off. and then connected the speaker cable of my cab to the right speaker out, and after a few minutes, started up the amp, after giving it a good 10 minutes on standby. It worked! and the EQ was reacting normally, everything seemed fine. I had friends over so didnt really sit down and check in depth or notice anything off tone wise. Plus it was running on fairly low volume since it was late. 

It's been about 3 days, and i played yesterday, didnt notice anything odd. But today, i feel the overall volume the amp is giving out is really low compared to before. and i know this amps clean isnt really super clean with humbuckers but im feeling like its breaking up way too much and quickly as you turn up.  Could it be that i busted a power tube or pre amp tube? The amp is a year old and played fairly reglarly and gigged only 10 or so times. 

Any help, advice on the matter will be appreciated! Thank you in advance! 

 

asked 28 May 2018 at 06:31 PM

Shashvat Pandit
0

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1

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3.1k

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Hello!  I have a Marshall DSL40c, which I absolutely love.  I swapped the speaker out for a Celestion Vintage 30 (16 ohm) a little over a year ago, and it sounds great.  However, I recently got a lower wattage tube amp (Vox AC4TV) and have been running it through the DSL40c (basically using the DSL as a speaker cab, with the power chord disconnected). 

So here's the problem:  After 2 days of using this configuration, the DSL has started making a sound when I play the vox through its speaker.  The best way I can describe the sound is that it is like a tabmourine, like those little metal disks jingling together.  It does this on certain notes, like the open low E string, or a C chord, but not on other notes like a B chord (i.e. 1 fret away).

When I run the the Vox alone through its internal speaker - no issues at all.  When I run the DSL amp section alone through it's vintage 30, no tambourine sounds, although it seems that the green clean channel is lower volume than it used to be (the other 3 channels seem to me the same volume as normal).  There is also some instability in the volume (goes in and out, but in a sublte way).  There is some clicking and popping when I first fire it up, but this stops after it has been on for a while so not sure if this is normal or not.

I have been looking up reasons why amps may rattle, but everything I am finding describes issues with the tubes that are being played through - my issue seems to be a bit different, since the rattling (tambourine jingle) sound I am hearing seems to be coming from the Marshall when I am not using its tubes (playing through the Vox as a head).

Is it possible that a tube has gone bad in the Marshall, and when I play the Vox through the Marshall's speaker, the vibration is rattling the broken tube and making this tambourine sound?  Would a reduction in the volume of the green clean channel imply it is a preamp tube vs power amp tube (since the other channels are unaffected?)

Thanks for any help you can offer.  I don't mind taking it in to a tech, but I have read a lot of posts of people who took their amps to techs and had tubes changed, etc. and the problem persisted.  I want to have a pretty good idea of the problem before I start investing in having it fixed.

Thanks!

asked 15 Mar 2018 at 03:12 PM

David Halaney
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1

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999

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Purchased used amp, jcm 2000 tsl 100 2003 with 2003 1960a slant cab. Bought footswitch, being shipped. my questions are 1) will dsl 100 cover fit my tsl 100   2) where can i get replacement tubes 3) Can i get paper manuals for amp and cab    4) is there a rt angle speaker cord available

asked 11 Oct 2017 at 12:58 AM

martin peters
0

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2

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2.6k

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I have looked for a definite answer to this and have not found one. I played my amp the other night with no problems, but last night as I turned on the amp it just died on me as soon as I turned the standby off. There was no noise, pops, crackles, fizzes. It just turned off. I checked the main fuse and it was blown. I have not had any issues with tubes and they have not shown any signs of wearing out. I made sure my amp was connected to the cab correctly (remember i have had this rig for 8 years) and that I had a speaker cable rather than a guitar cable.  I found online there could be issues with impedence and what not. I took the back off of my cab and noticed that a positive lead on one of my v30's became disconnected.  I thought, 'Could it be?" So I reconnected it and replaced the fuse and the amp worked as advertised. I played for an hour or so and no problems yet. Could it be that the discoonnected positive lead on one speaker caused it to blow a main fuse?

asked 11 Apr 2017 at 03:11 PM

David Bradley
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