New 1 Watt Amp Day

[royslead]

Well, based on info here and vids I saw, I did it. Got myself a JVM1-H. Nearly brand new condition, box, manual, coa, foot switch. Played it most of tonight and...it's good. I don't know for sure if I will keep it or not. I guess it just depends on how soon the honeymoon phase ends. So far, I am pleased, but I do have other amps that will achieve the same or similar tone.

 

[Dogs of Doom]

I think that the thing that makes it really invaluable, is that you can use it as a pre-amp, or a direct box & get that tone. It makes for a great practice amp, but it is loud for being 1 watt!

It's more economical to use for just about everything. There are just times, where grabbing a 100 watter & a 4x12 just aren't as easy to grab & go, or just grab real quick & plug in.

That said, having the JMD1, I can also use it as a direct box, use it at low volumes, etc., but, the JVM is still easier. I also have a JMP-1 rack pre-amp, & still choose the JVM1.

YMMV...

 

[Solid State]

They really are collector's items I'm noticing. They have far better sound than other low wattage solutions. The only exception I've seen so far is that the Laney has a 15 watt head that can exactly mimic the JCM1. Overall, I'd love to get my hands on one of these one watt heads - any of them really.

 

[royslead]

I like it for a lot of different reasons. A "grab and go" rig is not necessarily one of the reasons I bought it, I have a Vox VT50 that handles that chore really well; but on the other hand, this could do that. It really is surprising how loud that 1 Watt is, heck even the .1 Watt setting, when turned up, is borderline too loud for when everyone is sleeping. I have not yet tried using it as a preamp, that will have to wait until the weekend, I think. Currently, I am only running it through an over-sized 1x12. That is all I have here at the house (well, a pair of them, actually). The speaker is an Eminence Man O War, which is similar to a G12-T75, I'm told. I have a Vintage 30, and a Seventy/80 laying around, and may seek another cab to test those, but I would like to try a Creamback or similar as well.

 

[royslead]

One thing I have found peculiar, the foot switch LED glows red, when on the clean channel, and is not lit when on the OD channel. Whereas, the amp LED is green on the clean channel and red on the OD channel. Dogs - does yours do that, too?

 

[Gianni]

Well, based on info here and vids I saw, I did it. Got myself a JVM1-H. Nearly brand new condition, box, manual, coa, foot switch. Played it most of tonight and...it's good. I don't know for sure if I will keep it or not. I guess it just depends on how soon the honeymoon phase ends. So far, I am pleased, but I do have other amps that will achieve the same or similar tone.

How many of your other amps can you actually crank up at home, so as to get some sweet power-tube distortion at less than ear-bleeding volumes?

Congrats , and here’s a little pressie:

(1231 JVM-1 Combo and 1094 Head units were produced in 2012)

 

[royslead]

Thanks for the valve location call out, Gianni. I also wondered about production numbers. You're right, I cannot really crank up my other amps for power tube saturation, but I can get similar tone from them at lower volumes, so I don't NEED to crank them up. The more I play with this amp, the more I am liking it, though.

 

[slide222]

loverly amps and they do hold their value, plus , I have the first 3 all set up with 2x12 's and they sound huge , going tru 4x12 must be amazing and massive

 

[royslead]

Well, I have had a bit of a like/dislike relationship with the amp, only because I can get similar tones from other equipment I already have. So, sometimes it is hard to justify keeping anything that sounds "redundant" in tone. However, after spending more time with it, I am finding you guys were right, it truly is a great sounding amp.

I have edited this post to now reflect the actual feelings I have regarding the amp.

 

[Gianni]

Well, the honeymoon is over. You guys were all right, it is a great amp, just not for me. I just listed her for sale in the classifieds. Oh well...

Some more info about the JVM-1, originally meant to help you bond with it, should now hopefully help you sell it.

JVM-1 Owner’s Manual:
https://cdn.marshallamps.com/wp-content/uploads/2013/08/JVM-1-hbk1.pdf

Marshall 1-Watt Series Webpage:
https://marshallamps.com/products/amplifiers/one-watt-series

Marshall 50th Anniversary Catalogue (2012):
www.jedistar.com/pdf/marshall/marshall_catalog_2012.pdf

Marshall 2014 Catalogue (Pages 12-13, 50-53):
www.marshallamps.com/wp-content/themes/marshallamps/pdfs/Marshall%202014%20Product%20Catalogue_web.pdf?dafdde


* Santiall (Santiago) is the designer of the DSL and JVM 1-Watt amps.

fixed bias can be adjustable or not, the JVM1 and DSL1 have non adjustable fixed bias as there is no need for it in such a small power amplifier. One can change the output tube without having to rebias anything.

On the other hand 100W marshall amps have adjustable fixed bias.

(www.marshallforum.com/threads/1-watt-bias-question.45789/#post-682626)
(www.thetubestore.com/Bias-Types)

let's start with the 1W amps. The first three, JTM1 / JPM1 / JCM1, have an internal load and a series resistor with the speaker to attenuate the power. That means that when you plug them into a line input you will see a rather high voltage as the external load impedance it is quite high. Theoretically you will put approx 6V peak into whatever you connect them if you use the 16ohm output, approx 4Vpeak if you use the 8ohm output. That's more than enough to overdrive 9V powered stompboxes and some FX return in amplifiers even in the +4dB setting.

The DSL1 and JVM1 use an L-attenuator that serves both as load and output voltage attenuator so those will deliver an output voltage that is much more independent of the input impedance of whatever you connect them to, being the voltage more or less constant an approx 1.8V peak. This is the reason why the DSL1 and JVM1 use a combined single output speaker and don't need to be switched into 0.1W to operate safely without load.

(www.marshallforum.com/threads/question-for-santiago-yjm100.44889/page-2#post-768009)


* James Marchant – Designer of the JTM and JCM 1-Watt amps.
(www.ax84.com/bbs/dm.php?thread=460389)

“Here's the skinny on the 1 watts.

The 5 models were designed by three engineers here. I did the 60s and the 80s, the 70s was by another engineer, Steve and the 90s and 00s were by Santiago.

All the amps are push pull ECC82/12AU7 except the 70s which is single ended ECC81/12AT7.

The 60s and 80s are both 3 gain stages with cathodyne PI as has been correctly suspected. The 90s and 00s use a long tail pair.

The 60s has an input stage that has a cathode r/rc network designed to imitate the frequency response of a jumpered input with a little more bright than normal volume level, then gain then anode follower then the tone stack from a JTM45 - 56k slope and 220p treble. Only the treble control is fitted as a tone control. Then there is another anode follower to the PI. There is about 6dB of NFB into the grid of the PI.

The 80s has the expected 2k7 680n cathode arrangement followed by the preamp volume then a clipper stage (works like a 10k but has a bit more gain) then the expected 820R biased stage and a LND150 follower. I experimented with omitting the MOSFET, but it was my opinion that the improvement in tone and feel was worth it. Then there is a cathodyne and the output. The NFB is similar to the 60s. The boost button changes the clipper stage to be effectively a mid biased stage and brings in the bridge and led clipper used in the Jubilee amps.

The 70s is a bit of a strange beast. The circuit has changed a couple of times and I have not kept up to date with it.

The 90s and the 00s are essentially the preamps from the amps of the period (DSL and JVM) with the ltp push pull power amps. Interestingly, Santiago and I did not agree on the OT impedance and they are quite different with mine quite a bit lower.

The low power mode was set in my house. While the family were in another room watching the TV, I turned up the power until I got a complaint and set it a little lower. In this mode, the OT is fully loaded and I have used 1 watt amps driving the effects loop of a bigger amp. This is particularly effective when there is an event where there are several bands and the backline is supplied. I could get my tone with the minimum of fuss.

I hope this answers a few questions.”

 

[royslead]

Some very good information you have shared with me, Gianni. Thank you. It will come in handy either way. I'm still going to play with the amp, if it sells, it sells.

 

[JAC]

Love my JTM1H. Someday if it is suppose to happen I will get a JMP1H.

 

['2204']

Love my JTM1H. Someday if it is suppose to happen I will get a JMP1H.

Hi--I have a mint JMP1-H available if you or anyone else is interested--great amps! Please PM me if interested!

 

[KelvinS1965]

I've only tried the JMP1-H (in my avatar) but I love it. I find it really works well with my EP boost on the front end of it to push it a little more. I find that 1 watt mode is still pretty loud for home use (with a 98dB/1 watt Celestion speaker), so I tend to end up using 0.1 watt mode quite a bit. I've tried it through a 4x12 at the rehearsal studio we use and it really comes alive, so I'm squeezing a 2x12 (twin Greenbacks) into my room as I haven't room for a 4x12.

 

[Jakeboy]

My avatar is my JMP1h atop a cab with 2 10" GBs.
It is the perfect home and recording setup for the 70s tones that I grew up on and love. Plus mic'd or better, run through my Badcat Unleash 100 watt reamp, it is giggable. Since I am in full recording mode now, this amp is perfect. I will never let it go. Never.

 

[slide222]

I have my jtm1H tru a 2x12 eminence 50watt cannabis rex speakers and it works well and is loud -soft cleans that breakup nicely when pushed

 

[wakjob]

I see a JTM1-h in the GC used online store...
$999.00 ---- yikes!

It's the only 1 watt Marshall that interests me.

I have a Randall RD1-h that kicks all kinds of a$$ for high gain type stuff.

 

[JAC]

I see a JTM1-h in the GC used online store...
$999.00 ---- yikes!

It's the only 1 watt Marshall that interests me.

I have a Randall RD1-h that kicks all kinds of a$$ for high gain type stuff.

I have one. It is a great amp. I got mine new with $100 off from SA for my JTM1H and it was still $649.99. Those Randall RD1-H is an awesome single watt metal amp.

 

[hector gomez]

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[hector gomez]

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