Class 5 at bedroom volume secret

Marshall Class 5

Moderator: longfxukxnhair


DSL100 Dude
< 300 Posts
< 300 Posts
User avatar
Posts: 298
Joined: 16 Aug 2010, 20:59
Has Liked: 13 times
Been liked: 25 times
Contact:

Re: Class 5 at bedroom volume secret

Postby DSL100 Dude » 17 Jan 2011, 17:39

That is the best way to go for your needs I reckon.

But I am the wrong person to give advice here. I dime it everywhere.
1987x
DSL 100
Class 5
Class 5 Rojo
G30RCD
1960A

McQ7
<25
<25
Posts: 3
Joined: 17 Jan 2011, 13:39
Has Liked: 0
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby McQ7 » 17 Jan 2011, 19:19

Thanks--yeah, the mod seems like a piece of cake. I'm just worried that the Class 5 is going to be too quiet, really, after how quiet that Vox got at 1/4 watt.

DSL100 Dude
< 300 Posts
< 300 Posts
User avatar
Posts: 298
Joined: 16 Aug 2010, 20:59
Has Liked: 13 times
Been liked: 25 times
Contact:

Re: Class 5 at bedroom volume secret

Postby DSL100 Dude » 17 Jan 2011, 19:24

Well, you can get an attenuator. There is a little one that one of the other forum fellas has been swearing by. It is small as heck and rated perfect for the C5. I think he ended up mounting it in to the back of his amp. Decent price too if I remember right. Let me see if I can find it...

Here we go:
Image

I think the fella has an ebay store.
1987x
DSL 100
Class 5
Class 5 Rojo
G30RCD
1960A

McQ7
<25
<25
Posts: 3
Joined: 17 Jan 2011, 13:39
Has Liked: 0
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby McQ7 » 17 Jan 2011, 19:41

Ah, yes, I saw that on the mylespaul forum. Looks pretty perfect, and it might be in my future--saw it available on the bay for $75...still, it would be helpful to if anyone could say what is the equivalent volume knob setting at regular 5 watt mode and at 1/4 watt headphone bedroom mod. Is it like "volume at 7 on regular 5 watt mode equals volume at 10 on headphone 1/4 watt mode" or more like "volume at 3 on regular mode equals volume at 10 on headphone mode."

-- Mon Jan 17, 2011 11:02 pm --

P.S. Anyone try replacing the EL84 with an EL844 as a lower volume solution?

exotl
Bronze Member
Bronze Member
Posts: 328
Joined: 15 Nov 2009, 02:06
Location: Hamburg
Has Liked: 26 times
Been liked: 41 times
Contact:

Re: Class 5 at bedroom volume secret

Postby exotl » 18 Jan 2011, 03:21

McQ7 wrote:P.S. Anyone try replacing the EL84 with an EL844 as a lower volume solution?
I have one in mine and it works fine - it is still quite loud but the clean sound has become more thick & creamy and when you crank it the distortion is more "Marshall" than before, in fact it makes me wonder if the stock tube was worn already - yes, and the rattle is all gone!

KevinOConnor
<100 Posts
<100 Posts
Posts: 67
Joined: 04 Jan 2011, 21:56
Location: Canada
Has Liked: 0
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby KevinOConnor » 18 Jan 2011, 12:04

Hi Guys

There is a myth that operating a tube amp without a load will damage it - and this myth is incorrect. As we have detailed in our books, the only time an open load is an issue is when the load becomes open while the amp is driving it. This is called a "discontinuous load".

At the point of disconnection under drive conditions, the amplifier output can spike, just as the mains can spike when industries go off-line. The amp output - just like the power distributor's generator - has been delivering high current at a given voltage, trying to regulate the voltage output to a specific value. Disconnection of the load causes an irregularity in the regulation for a partial cycle or two, and the output voltage is suddenly unregulated.

If you disconnect the speaker and feed a signal into the amp, you can drive the amp to clipping, etc, to see how the amp behaves. This is a normal part of bench testing for new amp production and for repairs. You can run the amp like this forever without any issue. It gives a good indication that the amp is working properly, but the real test is to add a bench load and see how it behaves under load.

As was pointed out earlier in this thread, the headphone jack is fitted with a 100R resistor to protect the headphone. This is very common and is standard practice in hi-fi and MI and is perfectly safe to the amp. When you plug in the phones, the speaker is disconnected and the amp sees 100R plus the headphone resistance - which is insignificant compared to the 100R. The amp is now driving 100R instead of, say, 8R. Does the amp care? No.

Speaker impedances are "nominal". An 8R driver is only 8R over a portion of its frequency response. At resonance, driver resistance can soar to 80-100R. Impedance also rises in the treble range to many times the nominal value. This has been the case since dynamic drivers were first built prior to the age of electronics. Again, the amp is designed to deal with such loads because that is the nature of dynamic drivers.

Open loads are no problem to the amp. Varying impedances are no problem to the amp. The only things of issue are discontinuous loads as above, and shorted output. The latter will really cook an output stage.

The hard-wired connection of an amp to the speaker in a combo amp is a given. Fender dropped its speaker jacks back in the 1980s. It is s a simple matter to add such jacks, but they will void the amp's warranty. Having such jacks certainly makes experimenting with home-brew and store-bought attenuators easier.

In my experience, the Marshall OTs that failed did so because of bias failures in the output stage. These bias failures were most often caused by tube defects - poor quality EL-34s,and tubes that had been mishandled.

Have fun
Kevin O'Connor

Lowdown
<200 Posts
<200 Posts
User avatar
Posts: 137
Joined: 16 Dec 2009, 17:58
Location: http://www.reverbnation.com/shaunchristensen
Has Liked: 4 times
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby Lowdown » 19 Jan 2011, 01:38

:Thumbs Thanx for that and your other previous posts Kevin.
It's good to have another amp doctor around here. Your knowledge and insights are appreciated.

Garrincha
<25
<25
Posts: 14
Joined: 16 Jan 2011, 07:09
Has Liked: 0
Been liked: 1 time
Contact:

Re: Class 5 at bedroom volume secret

Postby Garrincha » 19 Jan 2011, 02:00

Kevin, do you have a lizensed builder in Germany or somebody selling and installing kits? I'd like to put London Power Scaling in my Class 5 but I haven't found a german source on your website.

KevinOConnor
<100 Posts
<100 Posts
Posts: 67
Joined: 04 Jan 2011, 21:56
Location: Canada
Has Liked: 0
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby KevinOConnor » 27 Jan 2011, 09:52

Hi Guys

There was a guy who was interested but I never heard back from him. The closest is in The Netherlands, called Ed's Custom Shop run by Ed Thoen, or the guys in Sweden and UK.

There is a list on our site.

Have fun
Kevin O'Connor

Beck-Ola
Platinum Member
Platinum Member
User avatar
Posts: 788
Joined: 19 Jun 2010, 12:11
Location: S. Calif
Has Liked: 24 times
Been liked: 13 times
Contact:

Re: Class 5 at bedroom volume secret

Postby Beck-Ola » 27 Jan 2011, 15:57

@Kevin:

That's some very interesting information regarding no loads, discontinuous loads, shorted loads, etc. A lot of cherished myths being driven to ground.

What's your take on the possibility of harm caused by an impedance mismatch of the output and speaker? Based on what you said earlier in this thread it seems it would not be harmful in any case to mismatch so long as it's not discontinuous or a shorted load.

I've often heard that a 2:1 mismatch is acceptable either direction but that power output or frequency response may not be optimal. For example, going from an 8 ohm output into a 4 ohm speaker load, can we be confident nothing would be harmed?

Thank you very much. :yea
Against stupidity the very gods themselves contend in vain. ~ Friedrich von Schiller

Kind of know how he feels.

Sandra
<25
<25
Posts: 1
Joined: 27 May 2011, 21:44
Has Liked: 0
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby Sandra » 27 May 2011, 21:49

SteveD wrote:It seems that some people are concerned about the volume of the Class 5 for home use. Well, if you have a spare cab, any cab, you can plug it into the headphone out socket which is derived straight from the main speaker out (not just from the preamp) so the preamp and poweramp and output transformer will be giving you that tone at bedroom volume - Viola!! Works great.
:rocker

NOTE! The only thing you have to ensure is that the speaker lead is only plugged HALFWAY into the headphone socket because it is a stereo headphone socket remember and you'll earth the signal out if you have a mono jack plug (which you probably will). But don't worry no damage can be done.

Feel free to pass this info on to any forum where the bedroom volume issue arises.
I will pass this.
Bed Perth love this stuff

SteveD
Knighted
Knighted
User avatar
Posts: 3830
Joined: 23 Jun 2007, 09:44
Location: South Shields, England
Has Liked: 936 times
Been liked: 930 times
Contact:

Re: Class 5 at bedroom volume secret

Postby SteveD » 28 May 2011, 04:37

Welcome to the forum Sandra. :Thumbs
Still my guitar gently weeps

bender
<25
<25
Posts: 11
Joined: 11 Jan 2012, 12:30
Has Liked: 1 time
Been liked: 0
Contact:

Re: Class 5 at bedroom volume secret

Postby bender » 11 Jan 2012, 12:39

Hi, I was lamenting the lack of the power attenuation switch on the head, seeing as it's on the new combo - then I saw this thread. Would I be right in thinking that the new power attenuation switch on the combo is in fact exactly the setup discussed here - i.e. it uses the headphones output for the internal speaker?

eastwood6
<100 Posts
<100 Posts
User avatar
Posts: 28
Joined: 30 Nov 2010, 09:47
Has Liked: 0
Been liked: 3 times
Contact:

Re: Class 5 at bedroom volume secret

Postby eastwood6 » 13 Jan 2012, 18:02

On the Class 5 head, to use the low power output option you connect the speaker cable to the headphone jack 3/4 of the way in, and then connect the speaker cable to whatever extension speaker cabinet you want to use. Make sure the output switch on the head is set to headphones.

On the new C5 combos, you would set the switch to headphone but not connect anything to the headphone jack. The internal wiring will automatically send the output to the internal speaker.
Marshall 3203 Artist 30 head
Marshall 1965 A & B 4 x 10" cabs
Marshall C5H Class5 head

FullMetalHippie
<200 Posts
<200 Posts
User avatar
Posts: 117
Joined: 19 Jan 2013, 16:29
Has Liked: 26 times
Been liked: 8 times
Contact:

Re: Class 5 at bedroom volume secret

Postby FullMetalHippie » 03 Mar 2013, 19:51

Necro alert! :wtf

This is still key for us C5 head owners :yea So if I don't need a load, could I then also run from the Headphone out plugged in 3/4 and dimed, to a Direct In like the Behringer Ultra-G GI100 DI and then to a Focusrite interface? In that scenario would the DI even be required? I was thinking it would bring the dimed (low power) signal down to where the interface could handle it. :dunno

*For the dimed signal strength aspect, I'm running the EL844 so its lowered there a bit too.
Marshall Class 5 Head
ESP LTD EC-1000T/CTM Traditional Custom (the Cherry Sunburst w/Duncan Alnico's)
Fender Jazz Bass (MIM)

Return to “Marshall Class 5”

Who is online

Users browsing this forum: No registered users and 5 guests

cron