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WARNING: When using the DSL1HR head
for ‘silent’ practice or DI recording ALWAYS
disconnect the speaker cabinet from the
amplifier’s rear panel before switching on.
NEVER unplug the speaker cable from the
speaker cabinet while it is still connected
to the amplifier rear panel. This may stress
the amplifier’s power-stage and in extreme
cases may lead to valve and/or transformer
failure.

 

Can i use an emulated out with the cab speaker plugged in? 

asked 23 Feb 2021 at 09:59 AM

Wayne Howlett
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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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552

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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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Hello I'm considering to buy DSL1HR or CR for silent recording at home. But I would like to use fx loop SEND output to record raw valve soud to apply impulse response later.

 

Is it safe to unplug cabinet, and without connecting headphones use these amps in such manner? 

And if so, why? Usually valve amp needs speaker load

 

Thank you in advance for the answare!

Sergey

asked 04 Dec 2019 at 12:44 PM

Sergey Tereshkin
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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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1

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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)
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1

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4.6k

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Hallo,

I got a doubt on well interpretating the manual where it states:

WARNING: When using the DSL1HR head
for ‘silent’ practice or DI recording ALWAYS
disconnect the speaker cabinet from the
amplifier’s rear panel before switching on.
NEVER unplug the speaker cable from the
speaker cabinet while it is still connected
to the amplifier rear panel. This may stress
the amplifier’s power-stage and in extreme
cases may lead to valve and/or transformer
failure.

can someone confirm what I understand: if I want to play using an headphone for silent practice (connecting my headphone to emulated line Out), I shall prior disconnect the external speaker from the rear of the amplifier (shouted off), (and never from the rear of the speaker cabinet). So I can Play the amplifier using headphone without connection to the cabinet? is that correct? An this is applicable also if I connect the amplifier to a mixer (by using Line out). That is quite strange because all other amplifiers recommend to never disconnect the speakers, with or without an headphone or something helse. Please help! I don't want do damage my DSL1HR. Thanks. Cheers.

 

asked 06 Sep 2018 at 11:32 AM

Roberto ACErob71
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