Old speakers

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fingerlock
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Location: Chippenham, Wiltshire

Old speakers

Postby fingerlock » Tue May 05, 2009 7:24 pm

Hey guys, i have a puzzler that i am sure you technical guys may be able to help with.

I recently acquired an old set of Simms Watts speakers from a friend of mine at a ridiculously low price but i cant find out anything about them, anyone help?

They measure approximately 3 ft x 1.5 ft x 10 inches deep, inside each one is a pair of Celestion G12 M70 s and i assume a pair of tweeters. There is a serial no.20928 they have jack connections and there is a tag that says 16 ohm.

Somebody help me please?

Thanks in advance

Eddie

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Mike Stranks
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Postby Mike Stranks » Wed May 06, 2009 11:27 am

Hi Eddie

I don't know these particular speakers, but from your description they sound like a set of Marshalls I had some time ago. (Incidentally, I sold those for a LOT more than I paid for them; so I'd advise you to look after yours - they could be worth something!)

These speakers almost certainly derive from the late 60's or early 70's and were possibly sold originally with, or to pair with, a simple PA amplifier. The amp would probably have had an output of no more than 30 watts (puny by today's standards) and could well have been valve-driven.

You mentioned a tag saying "16 ohms". Is that on the speaker cabinet or is it on the actual drivers? Common practice in that era was to take two 8-ohm speakers and wire them in series - giving you the 16-ohms per side. (If there ARE tweeters in there, I'd be surprised - these cabs were intended for strictly vocals only and had a limited frequency response.)

Pairing these with a modern amp could have two issues:
* - You need to be careful you don't overdrive them and push the cones hard against their end-stops - permanent damage could result. Conect them to a modest PA amp and be careful about how much volume you feed them initially.
* - If they are rated at 16 ohms per side, then connecting them to a modern amp will make them quite inefficient. The output of modern amps is usually quoted into 4 ohms. You can either live with that and use a more powerful amp to compensate or rewire them (!!) to work in parallel. That would then rate them at 4-ohms per side. Of course, if you did that then you'd need to put them back as they were should you ever want to sell! (That's exactly what I did with my Marshalls!)

If it's unclear what is the impedance of each side and you have access to a multimeter then PM me and I'll explain how to measure this. Also if you could get a photo of the insides of these so that I can see how the two speakers are wired that would tell me if they are series or parallel.

Hope that's at least of some help. :D

Mike
The older I get, the better I used to be

fingerlock
Posts: 43
Joined: Sun Sep 30, 2007 9:56 pm
Location: Chippenham, Wiltshire

Postby fingerlock » Wed May 06, 2009 5:04 pm

Thanks Mike

The tag that says 16 ohms is screwed on the back of the speaker cabinet.
I did a little looking around last night and found a site selling the actual celestion speakers at around 150 each, it seems they are each rated at 70 watts.
I am just trying to fathom out what i need to run them or whether i should just sell them on.
I will take some pics later and pm you to find out where to send them
I knew you guys wouldnt let me down

Cheers Mike
Eddie

fingerlock
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Location: Chippenham, Wiltshire

Postby fingerlock » Wed May 06, 2009 5:28 pm

Oh and i forgot, the actual speakers inside have 16 ohms stamped on them

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Russ Gannicott
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Postby Russ Gannicott » Tue May 26, 2009 8:37 am

These sound interesting and from your description sound like they could be 'greenbacks' which in lower power ratings are very highly sought after. The higher power Marshals tend to be a little harsh for guitar use but would be great for a metal player loading up a 4x12 cabinet. 16ohms per speaker is fine for loading up a 4x12 or indeed a pair of 2x12's if they are wired in parallel to give 8ohms. Do you still have them? I'd be interesed in seeing a photo if you could post it please.
As an aside to Mike if he reads this - Mike, I think there must be a gap in my knowledge as I don't understand how impedence can be measured with a multimeter. If you could explain this to me I'd be delighted as I have a number of unknown speakers I'd love to know the impedence of!
All the best,
Russ

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Mike Stranks
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Postby Mike Stranks » Tue May 26, 2009 11:53 am

Hi Russ (and any other "electrics" anoraks!)

Although impedance is not the same as resistance, using a multimeter to test the resistance of a speaker is accurate enough to tell you whether it's rated at 3, 8, 16 ohms or whatever.

So (with apologies if I'm telling granny how to suck eggs!)... set the multimeter to read low resistances - on mine I think the bottom range is 0-20 ohms - and then simple connect the probes to one of each of the speaker terminals. It doesn't matter which way around you make the connection. You'll get a reading which gives a 'ball-park' impedance. [If you can't get-at the speaker terminals then you can put an open jack (speakon or whatever) into the cabinet connector and measure from the terminals of that. Of course, in that case you're measuring the resistance of the total cabinet configuration rather than an individual speaker.]

Incidentally, I wouldn't keep the connection for more than a few seconds as you're applying a DC voltage to the speaker cone. OK briefly, but not recommended for minutes at a time.

Anorak that I am, I'll keep going here! You can also use a similar technique to test speaker polarity/phase. Using a 1.5 or 9 volt battery, connect briefly to the speaker terminals. The cone will either move forwards or back. Thus, if you want to make sure that several speakers are in phase you simply ensure that you connect them in such a way that applying a voltage to the terminals will always result in the cone moving the same way in each. (If anyone wants to know more please PM me - I know that those who simply want to enjoy playing the guitar will be losing the will to live by now! :) )

Hope that helps.

Best. Mike
The older I get, the better I used to be

fingerlock
Posts: 43
Joined: Sun Sep 30, 2007 9:56 pm
Location: Chippenham, Wiltshire

Postby fingerlock » Mon Jun 08, 2009 10:29 pm

Getting a bit complicated for me now!!

Idid try them out as extra speakers on a Roland Cube 60 amp and they seemed to work perfectly well, although we had to try them one at a time.
I have now bought a 200 watt mixer/amp and they seem to work but with a lot of hissing?
On closer inspection i realised that i was using instrument cables(doh) :oops: Could this be the reason for the hissing?
I have heard the amp working perfectly with the owners own speakers.
Off out tomorrow to buy speaker cables

Thanks for your help guys
Eddie :)

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Russ Gannicott
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Postby Russ Gannicott » Mon Jun 08, 2009 11:43 pm

Sounds good Eddie. The hissing will either be down to the mixer amp or the cables, the speakers should only reproduce what's fed into them. Talking of cables, why not make your own? If you buy two core mains cable in a weird colour - blue, white or even orange, then you'll never get your leads mixed up and all you need to do it solder a couple of jack plugs on the ends.

Still like to see a photo of one of these speakers though!
All the best,
Russ

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Mike Stranks
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Location: Cirencester, UK

Postby Mike Stranks » Tue Jun 09, 2009 10:15 am

I agree 100% with Russ on speaker cables!

I always use orange two-core mains (minimum 6-amp - ideally 10-amp+ depending on the amp power) for the exact reasons Russ states. Whilst using instrument cables to connect speakers is OK (but not recommended) as long as the power output of the amp is modest, doing it the other way round can be disastrous - where did that hum come from?

If you're doubtful of your soldering skills - it's not difficult with practice - you can get made-up speaker cables from many sources which don't cost too much. I've just ordered some at a very reasonable price from Thomann in a fetching shade of grey as bright orange may be a bit too visually intrusive in this situation!
The older I get, the better I used to be

Trevor Raggatt
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Contact:

On the other hand...

Postby Trevor Raggatt » Tue Jun 09, 2009 3:47 pm

...and bearing in mind the little bit is Award Session geekieness going on elsewhere on the site you could order some bespoke made Cleartone cables from them.

I've pretty much gone over to them 100% - both instrument cables and speaker cables. Really good quality and very very reasonably priced. AND with some really nice little features... all made up bespoke. Also, if you've got some odd cable requirements like splitters, jack to XLR whatever they'll have them as one of their options.



http://www.award-session.com/cleartone_cables.html

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And a couple of reviews...

http://www.award-session.com/pdfs/silent2.pdf
http://www.award-session.com/_assets/pdf/Guitarist%20ClearTone%20Review%200902.pdf

Trevor


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