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fletcher



Joined: 01/05/05
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Loc: london
speakers for a JC-120?
      #1026750 - 02/01/13 03:39 PM
Having to use my JC-120 again. I like the amp but never been "wowed" by it. Still I have had it for 24 years and it's always done the job where a clean sound is needed. I do prefer a tube amp, but mine needs a service (it still works but I get more worried every year I put off the service...) and until I get around to it the JC-120 will be used for the more important gigs.

Anyway as I have to use it, whilst puttin the christmas stuff back in the cupboard I saw my Marshall 2 x 12 1936 cab and wondered what the Jc-120 would sound like through it. Much improved was the answer. So now I'm thinking to change the speakers on the Jazz chorus. As I liked the celestion they would be an obviuos choice, but which one? My CPC catalogue has several. Should they 60w? Or maybe 75w I was thinking. 100w? Then they have Vintage and Blue models as well as Classic... and this is just Celestion! Thing is it's not like I can audition them, I have to buy blind. I might just pull off the back off the Marshall 1936 and see what type are fitted.

So if anyone has experience of fitting upgrade speakers to a JC-120 I would love a bit of advice. I seem to remember back in the 80's certain JC-120's had better speakers from the factory, not mine though I'm sure.

The only other thing on my mind is would I be dissapointed, I mean maybe the Marshall cab itself sounds better with it's closed back and thicker wood.


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shufflebeat



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Re: speakers for a JC-120? new [Re: fletcher]
      #1026774 - 02/01/13 09:09 PM
I let son #2 use my old JC when he needed some oomph. He put his Boss ME-25 into it and it really showed up the various modelling algs better than his little Marshall. A better 'blank canvas' I suppose.

It may be worth exploring this rather than a shot in the dark with speakers. Just a thought.

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fletcher



Joined: 01/05/05
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Re: speakers for a JC-120? new [Re: shufflebeat]
      #1026778 - 02/01/13 11:09 PM
Yes it is good for the amp modeling thingys, not for me though. I use them a lot when recording, like to stay away from them for live. It's not such a shot in the dark really, I have tried it with the celestion's and it sounds a LOT better. I A/B'd it sitting in front of the two cabs. It was what is missing from the sound for me. I just want to know what the ideal speakers for them would be. I would be quite happy with the same ones as the 1936 cab, but if there is someone who has a beeter suggestion or any tips on power rating etc. I would be grateful.

I clearly remember back in the 80's people would be fussy about which speakers you had in these things, I guess nobody remembers .

Or everyone here is a rocker and wouldn't go near a JC-120.

Hard times guys, can't afford a Twin at the moment. Actually I couldn't afford a JC-120 right now. Just under a £1000! Wow, why? I mean there's not much in them. A Twin is £1500. Shows what I know, I would have expected £600 for a JC-120.


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shufflebeat



Joined: 09/12/07
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Re: speakers for a JC-120? new [Re: fletcher]
      #1026790 - 03/01/13 01:04 AM
Quote fletcher:

Actually I couldn't afford a JC-120 right now. Just under a £1000! Wow, why? I mean there's not much in them.




That surprises me, I was disappointed to see a couple going unsold on eBay recently when I was considering a clearout. Sorry can't be more help but will be watching with interest.

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zenguitarModerator
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Re: speakers for a JC-120? new [Re: fletcher]
      #1026791 - 03/01/13 01:09 AM
In some ways a JC120 is a one trick pony, but it is a VERY good trick.

It might be worth contacting your local Roland dealer about the cost of genuine replacements. They would be a good starting point. And then you will have a ball park figure to compare alternatives.

Andy

--------------------
When the going gets weird, the Weird turn Pro.


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fletcher



Joined: 01/05/05
Posts: 1215
Loc: london
Re: speakers for a JC-120? new [Re: zenguitar]
      #1026793 - 03/01/13 01:44 AM
Good idea. Cheers.

I have tried some online research. Some people suggest 75-100w. Thing is I still have the "manual" - more of a pamphlet really. But it makes no mention of the speaker power rating or ohmage. Neither is there any info on the cones themselves. The ext. spk. connectors are for 8 ohm, but that is series connection with the built in ones. I might just get the old multi meter out, see whats in the Marshall and try to find out the ohmage of the Roland ones.

Still surprised nobody hear has any knowledge of this. I KNOW people would talk about which spks. were fitted back in the day, and I know I heard better sounding ones than my 1987 one. May have been the older ones came with different cones. Guess everyone here is too young to know.

I will be changing it soon though as I much prefered the tone. As nobody here seems to know I will let you know what I find. Has to be ready by late Jan.


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Billum



Joined: 02/05/08
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Re: speakers for a JC-120? new [Re: fletcher]
      #1026833 - 03/01/13 11:31 AM
Quote fletcher:

I might just get the old multi meter out, see whats in the Marshall and try to find out the ohmage of the Roland ones.




'Fraid that won't tell you anything - speaker impedance is only casually related to the wire resistance (which is all that a multi-meter will tell you, unfortunately).

As for power rating, I would certainly suggest greater than 60W apiece, as the JC amp, especially once it's distorting a bit, can generate peaks much higher than 120W, if you're inclined to give it some welly from time to time.

I think you may well have a point when you say that your Marshall cab sounds better, and it might just be the *cab itself* with its closed back that is making it sound good. So how about swapping the speakers between the two cabs and then see which you prefer??


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fletcher



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Re: speakers for a JC-120? new [Re: fletcher]
      #1026856 - 03/01/13 01:49 PM
Yes Billum, but you can get a ball park idea. After all in signal freq. terms audio isn't that far away from DC.

For what it's worth the Celestion's in the Marshall are G12T-75 16ohm (measure 12ohm on the meter). The Jazz Chorus stock measure 6ohm on the meter so I would expect they are 8 ohm. That is also the minimum stated on the JC's ext. spk output. Although as they are connected in series (I think - disconnecting the JC spks stops the ext. spks working as well) I would think this could be ignored. The fact that the extra impedance could have been making the difference can be discounted, I could still hear the JC sound unchanged. In case your wondering I had both sets of speakers on at the same time with the amps facing in different directions. I could move to be close in front of one cab or the other and so hear only the one sound.

So I will try the Celestion I guess, good news as they are the cheapest. £56 + vat each. I guess I could go for the 100w version but that would be £67 + vat. The 100w is only available as 8ohm.

Ohmage? Should I go for 16ohm or 8ohm. The stock as I have said are 8, but the Marshall cab has 16 ohm. I guess it doesn't matter much. I might get the 16ohm, then if it doesn't work out at least I have spares for the Marshall!!


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fletcher



Joined: 01/05/05
Posts: 1215
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Re: speakers for a JC-120? new [Re: fletcher]
      #1026858 - 03/01/13 01:58 PM
Update, I have found the ct. and yes the ext. spks are in series. The fitted spks are 8 ohm.

Beginning to think I should have started this thread in the DIY forum. Anyway in case it's of use to anyone else, here is the schematic.

http://www.freeinfosociety.com/electronics/schematics/audio/Roland-JC120-JC160.pdf

Edited by fletcher (03/01/13 02:01 PM)


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The Elf
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Re: speakers for a JC-120? new [Re: fletcher]
      #1026861 - 03/01/13 02:02 PM
Thanks for the schematic - useful indeed to keep my old JC-120 going!

I have to say I wince at the thought that someone would change the original speakers, but to each his own I suppose.

--------------------
An Eagle for an Emperor, A Kestrel for a Knave.


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Frisonic



Joined: 27/01/10
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Re: speakers for a JC-120? new [Re: zenguitar]
      #1026902 - 03/01/13 08:00 PM
Quote zenguitar:

In some ways a JC120 is a one trick pony, but it is a VERY good trick.




It certainly is!

--------------------
Strictly project and just for fun


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fletcher



Joined: 01/05/05
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Loc: london
Re: speakers for a JC-120? new [Re: fletcher]
      #1026907 - 03/01/13 08:27 PM
for the record I'm not trying to destroy my JC!

I do like it, just more inclined to use a valve amp these days. In the 80's, playing with synths and drum machines I found the clean sound worked best for getting the guitar sound to fit the band, rather than sound like some dated (this was the 80's remember) rock guitarist trying to stay with it. Of course fashions change and the warm sound came back and I went back to my valves with a smile. And yet....... the JC-120 does have something. So I kept it, and I live in London, space is in short supply! Not so easy to keep hold of all thig gear. So I must be a fan. even though I say I'm not

Also for the record, don't knock it till you try it, changing the speakers doesn't make it sound like it's not a JC. It just makes the tops sound a bit less brittle, dare I say it, a bit "warmer". My pony will still be able to do it's trick I promise.

As a side note, since I've been pulling this amp out at some shows, twice someone from the PA crew has said, "Oh, a Jazz Chorus, that's my favourite amp." Seems they are popular with the PA guys?


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zenguitarModerator
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Re: speakers for a JC-120? new [Re: fletcher]
      #1026928 - 04/01/13 12:54 AM
Quote fletcher:


As a side note, since I've been pulling this amp out at some shows, twice someone from the PA crew has said, "Oh, a Jazz Chorus, that's my favourite amp." Seems they are popular with the PA guys?




And with the jazzers too.

The bottom line? Back in the 70's Roland got it right. All solid state, built in stereo mod/time fx, stereo power stage. Can't discontinue it, no matter how hard they try. Old examples are in demand and carry a decent premium on eBay. What's not to love? It does what it does regardless of fad or fashion, keeps on doing it, and they keep having to make new ones.

And I used to own a Roland Bolt 30. Always regretted selling it, would get a replacement if I had the cash, and my brother (who is a bass player who has played with countless fine guitarists with shedloads of gear) still rates it as one of the best live sounds he's heard from a guitarist.

Seriously, I would buy a clean Bolt 30, Bolt60, Bolt100, JC120, JC80, JC160, JC77, unseen any time if I had the cash. Real amps for real guitarists. The absolute best? No, but reliable and consistently delivering 95% of perfect day in day out, every time.

Tools is tools. Simples. Good tools is good tools. Equally Simples.

Andy

--------------------
When the going gets weird, the Weird turn Pro.


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Kwackman



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Re: speakers for a JC-120? new [Re: zenguitar]
      #1026948 - 04/01/13 11:04 AM
Quote zenguitar:




I used to own a Roland Bolt 30. Always regretted selling it,




Well, guess what I've owned since new.
Bought in 84, nearly only home use, and seldom turned on these days.
My Bolt 30 still has it's cover and manual.
Not for sale - although if in a few years it becomes desirable, it might be my pension fund!

Excuse the deviation from OPs original question- I couldn't ignore the Bolt 30 reference.

--------------------
Cubase, guitars.


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fletcher



Joined: 01/05/05
Posts: 1215
Loc: london
Re: speakers for a JC-120? new [Re: fletcher]
      #1026949 - 04/01/13 11:13 AM
Yes it is a good tool which has stood the test of time.

In that time however it has had several speaker changes. Like I said the 70's ones had the preferred cones - I seem to remember the label on the back of them may have been a different colour? Green I think, can anyone confirm? The later 80's ones had orange labels on the back of the cones. I think the early ones may have had JBL cones.

Interesting, it seems in the 90's they changed them again, and then later went back to the orange ones. However I suspect they just changed the badge back. People report that the newer ones aren't as heavy or loud as the older ones, which to me can only be the speakers being lighter.

So although the amp has been unchanged for a long time, the speakers have had quite a few switches.

I have just realised that I have tax to pay soon, plus my phone bill, gym membership..........might wait till March now


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4TrackMadman
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Re: speakers for a JC-120? new [Re: fletcher]
      #1027020 - 04/01/13 07:37 PM
I've had one available (JC120) for sale to me but can't say I liked it at all, it was awfully brittle and jangly, and not in a good way. It was ancient though, probably late 70s. I passed on in.

Looks like you got your issue sorted, so no use going over it again, but in my case I would've put in Eminence or Jensen speakers as they seem more full range and less mids heavy.

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www.descentintomadness.com


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fletcher



Joined: 01/05/05
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Re: speakers for a JC-120? new [Re: fletcher]
      #1028506 - 14/01/13 11:06 AM
Not sorted yet, out of stock till mid feb. Annoying as I wanted for gigs this month.

Will let you know how it sounds. If it all proves a mistake at least others can benefit from it. And I will have some speakers for sale on ebay!

Quite confident it will be all good. Promise to be honest on the results.


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Nico 3313



Joined: 12/07/06
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Re: speakers for a JC-120? new [Re: fletcher]
      #1029232 - 18/01/13 12:06 PM
Not only the speakers changed, there are I think at least three significant revisions of the circuits as well. Probably all various speakers used in them were made by Pioneer, at that time a major OEM speaker supplier to the (japanese) industry.

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fletcher



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Re: speakers for a JC-120? new [Re: fletcher]
      #1030051 - 23/01/13 11:03 PM
Good old CPC, arrived today, they had said mid feb.

As I said, I got the 100w 8ohm Celestions and have now fitted them. Not as easy as I'd hoped, had to knock out 8 bolts which weren't used on the Celestions. Slight damage to front mesh stuff. No big deal as mine was already tatty. Also I had expected to just drop the cones in, no such luck as the screw holes were ever so slightly out with the Roland ones. Getting all four in at once manipultaing a heavy but delicate cone was a bit of a struggle. One bloodied knuckle later....

First impression on comparing the old drivers is the Roland ones are a lot lighter and "cheaper" looking. As to the sound, well the new ones were a LOT louder, which I didn't expect. The sound is better, more tone in the mid range where the Roland seemed off. Less brittle at the top. Also much better in the bass end. I esp notice this with the octave pedal, I am prone to doubling the bass line from time to time. Didn't sound very good with the Roland spks, but now I can resume having fun with the bass player. Better with the distortion pedal too, never enjoyed soloing with the JC before, maybe that will change now. The strangest thing for me is the built-in Distortion sounds good now. I ALWAYS hated it before. So I'm happy and glad I did it.

Of course I realise this is hard to prove (no way are you going to switch spks back just to see) so before changing spks I set up a mic about 1.5 meters away from the amp and played several things. I recorded it and left mic and settings untouched. I also marked the amp position so it could be put back exactly as it was. Once the new spks were fitted I returned the amp to it's original position and played and recorded the same things I had played before.

The recordings were proof I wasn't fooling myself. Every impression I had whilst playing is apparent in the recording. Quite a few dbs louder and the sound was more "middy". The original spks also sounded good on the recording though. I feel they sounded a bit like when mixing you add some tops to a guitar part, perhaps more than you would like whilst playing. So both speakers sounded good recorded to be fair, but different. The new spks had the richer tone, but I can see why sometimes the thinner sound of the Roland spks works. I just prefer a warmer, less brittle sound whilst playing.

So I'm glad I did it, the sound is more "me" now. Its first gig will be next weds in Birmingham - we'll see.

My only concerns, it's noticibly heavier. Also it's louder, I hope not too loud. Big venues though so it should be ok.

Now I have two original 1980's Roland JC-120 spks. maybe eBay can get me some money back - I have the perfect packing thanks to Celestion.


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fletcher



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Re: speakers for a JC-120? new [Re: fletcher]
      #1030053 - 23/01/13 11:16 PM
4 got to say, only thing is I can't see two silver cones through the front mesh anymore. Whether that's a good or bad thing I don't know. Let's see how many PA guys say something when they go to mic it up


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ef37a



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Re: speakers for a JC-120? new [Re: fletcher]
      #1031482 - 31/01/13 10:52 PM
Hi Fletch,
Did you go for the Hot 100 or the GK12-100? If the latter yes, you picked a really heavy mother! But as you say, very sensitive.

They will (both) last for ever, Celestion power ratings have always been very conservative (not so many others!). In any case, if the voltages on that circuit are correct the amps can only put out about a 50W sine. Driven into hard distortion maybe 80W but I doubt you would do that because it would not sound good.

If you do ever get the amp serviced and you have no need of the speaker extension jack, get the tech' to short it out. Can be a source of unreliability as the contact tarnishes with the years in smoke filled bars.

I would have suggested a pair of Century Neos but they are quite expensive. Easier on the old back tho! For a solid state 50watter their 60W rating would be fine, bit marginal for a valve 50 but as I say, Celestions are the good guys and I doubt you would ever blow one.

A note on speaker resistances re impedance. Pretty near a perfect relationship for "hi fi" drivers in that practically all 8R units, regardless of size, power or brand read ~5.6Ohms. Guitar speakers tend to be closer to the nominal Z, 16s being 13-14 Ohms as a rule.

Dave.


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fletcher



Joined: 01/05/05
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Loc: london
Re: speakers for a JC-120? new [Re: ef37a]
      #1031496 - 01/02/13 12:42 AM
Dave it was the GK12-100. And you are bloody spot on. It has gotten to be a heavy m.f.!! Luckily the driver carried it in and out for me on it's debut gig last night in B'ham.

I found the amp to have a much improved repsonse and got some compliments from the M.D. for my tone. I'm happy with it. For me it was worth it, not being a huge fan of the original spks. They seem more sensitive as well as being louder (which I guess stands to reason) and I found that I could more easily control the dynamics.

I will keep that tip in mind about the spk ext connectors, thanks for the tip. I used this amp a lot in the 80's, went back to the valve amp in the mid 90's. For this group the JC-120 seems the more practical and suitable amp so it's having a re-birth.

Happy with the new cones, glad you think they will last. I was only picking from the CPC catalogue range as I have an account with them. I thought the 75w would do, but erred on the side of caution and went for the 100w. Also they (the 100w) were reported to have a good bass response and as I like to step on the octave pedal I went for it.



cheers Dave


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fletcher



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Re: speakers for a JC-120? new [Re: fletcher]
      #1079220 - 13/12/13 11:04 AM
Sorry to drag an old topic back to life. Just wanted to say now I've lived with the amp for 10 months I can confirm it really was worth doing. A much improved tone, a better amp now by far.


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