Decoder needs 8 ohm speaker: use two 4 ohm speakers?

[philsandy]

I'm looking at buying a Zimo decoder (MX648 or 649) they must have an 8 ohm speaker. I have several ESU 4 ohm speakers.

Could I use 2 of these without any problems, ie. too low volume, and if so would they need to wired in series or parallel?

[Dagworth]

If you put a pair of 4 ohm speakers in series then it would give the 8 ohms impedance that the decoder is expecting. 
 

Andi

[Ray H]

I'm pretty sure that Zimo decoders will work with both 4Ω & 8Ω speakers.

[daltonparva]

3 minutes ago, Ray H said:

I'm pretty sure that Zimo decoders will work with both 4Ω & 8Ω speakers.

I think the big decoders do, but the small ones 8 ohms only (most sugarcubes are 8).

[Ray H]

We use the dual (parallel) sugarcube speakers in a lot of out O gauge stock but we also use single ones sometimes.

 

Aren't two 8Ω speakers in parallel the equivalent of 4Ω?

[pauliebanger]

Ray,

 

Yes, in parallel they are, and that's OK for the decoder types you are likely to be using.

 

But some ZIMO decoders have a recommended minimum impedance of 8 Ohms.

 

The miniature decoders, MX648, MX649, MX658N18, MX659N18 and other miniature types require 8 Ohms if you intend to use volume at the max.

 

ZIMO put that info with each decoder and in the manuals.

 

Most exclusively 0 gauge users will not encounter these types, as there is normally enough space to fit 'standard size' MX644, and MX645 types (as most usually used in 00) or the larger MX696 and MX699 types, all of which can use 4 or 8 ohms.

 

Best regards,

 

Paul

[Ray H]

With O gauge you can mount the speakers below the floor on some vehicles. I'm not sure I'd want to mount a decoder in the same place though.

[RAF96]

A pair of 4 ohm ESU speakers wired in series in a Class 31 with a TTS decoder.

 

[charliepetty]

If anyone wants any of those 4Ohms speakers I have a box of 50 for £35.00 inc post.

 

charlie@dckits.co.uk  

[RAF96]

They are a reasonable quality speaker with a sturdy decent fitting enclosure. Happy with mine, in fact I recently bought another 10, else I would have jumped at your offer Charlie.

[charliepetty]

5 hours ago, RAF96 said:

They are a reasonable quality speaker with a sturdy decent fitting enclosure. Happy with mine, in fact I recently bought another 10, else I would have jumped at your offer Charlie.

These are very old ESU speakers and as there are far better speakers on the market today I am clearing them out, we now use the superior 25x25x7mm Square Megabass Cube Speaker

[RAF96]

On 02/01/2021 at 22:22, charliepetty said:

These are very old ESU speakers and as there are far better speakers on the market today I am clearing them out, we now use the superior 25x25x7mm Square Megabass Cube Speaker

 

Agree the ESU items are the old tech cone diaphragm design whereas newer speakers are flatter, smaller and of relative hi-fidelity for their size.

 

 

[letterspider]

If you have two 4 Ohm speakers in series and the second fails with a short circuit, your sound chip will burn out.

Unlikely but is it worth the expense to save £4 on the appropriate speaker?

 

[Locoman58]

10 hours ago, letterspider said:

If you have two 4 Ohm speakers in series and the second fails with a short circuit, your sound chip will burn out.

Unlikely but is it worth the expense to save £4 on the appropriate speaker?

 

Which chip will do so?

What happens if a single speaker shorts?

[Mol_PMB]

I've been puzzling over this recently (I'm new to DCC sound).

I've got a fairly blank page with regards the decoder and speaker for my kitbashed O gauge industrial shunter.

The recommendations I've had from friends are for an ESU Loksound 5 with Legomanbiffo sounds and an adaptor board for extra functions, plus an Earthmover speaker.

That will fit and I hear good things about each of the components, but it's not clear to me whether the speaker is compatible with the decoder.

 

The decoder manual which I downloaded seems to recommend an 8 Ohm speaker and a power output between 1.5 W and 2 W. But the Earthmover is only 4 Ohm and 0.5 W.

Some people have said I need to add another speaker but I'm struggling to find space for a second one and there are risks highlighted in the thread above.

I wondered whether I could add a resistor in series but apparently that's a no-no.

I did try emailing one of the major suppliers of sound chips a couple of weeks ago, but have had no response.

 

I am finding the published data confusing and there seem to be lots of warnings about making expensive mistakes. I just want to make sure I buy and fit a compatible set of equipment.

After all, this is probably going to cost almost as much as the loco itself!

 

Is there a simple answer?

[Dungrange]

32 minutes ago, Mol_PMB said:

But the Earthmover is only 4 Ohm and 0.5 W.

 

The EM1 is only 0.5W - https://www.dckits-devideos.co.uk/index.php?route=product/product&path=223_239&product_id=431

 

The EM2 is 1W - https://www.dckits-devideos.co.uk/index.php?route=product/product&path=223_239&product_id=433

 

I'm not sure about the EM3, which I think is for 0 Gauge, but doesn't seem to be on the DC Kits website.

[Dagworth]

On 05/01/2021 at 09:32, letterspider said:

If you have two 4 Ohm speakers in series and the second fails with a short circuit, your sound chip will burn out.

Unlikely but is it worth the expense to save £4 on the appropriate speaker?

 

If you have an 8 ohm speaker that fails with a short....  

 

very unlikely for drivers to fail short circuit if kept within ratings. I’d be stunned if a small sound decoder had enough oomph to burn out a speaker. 
 

Andi

Edited January 25, 2021 by Dagworth

[Mol_PMB]

Ok, many thanks, that’s good to know that the V5 is OK driving a single 4 Ohm speaker. 

I certainly have space for an EM1 but I’m less sure about an EM2 - I’ll have to check once I have built the chassis. 

I think the speaker itself would fit in the bonnet but not leave room for the decoder. But the decoder might fit in the chassis somewhere. I’m sure I can work something out. 

[charliepetty]

1 hour ago, Dungrange said:

 

The EM1 is only 0.5W - https://www.dckits-devideos.co.uk/index.php?route=product/product&path=223_239&product_id=431

 

The EM2 is 1W - https://www.dckits-devideos.co.uk/index.php?route=product/product&path=223_239&product_id=433

 

I'm not sure about the EM3, which I think is for 0 Gauge, but doesn't seem to be on the DC Kits website.

The EM2 will be fine with a V5 Normal 8Pin or 21Pin, L Decoder OR XL Decoder.

 

If you are using a 8Pin decoder and thinking of chopping off the plug, ('Don't) Always use the 8Pin Harness to keep the decoder warranty.  See Link:

https://www.dckits-devideos.co.uk/index.php?route=product/product&path=223_75&product_id=424

 

If the EM2 fits it will sound impressive, the Class 05 sound with Mechanical Gearbox is a classic industrial loco sound.     

 

Charlie-Legomanbiffo Sounds

[charliepetty]

Just found one off our earlier movie clips including our 05 & 03 Drewery Shunter.  Enjoy.

 

 

 

[Mol_PMB]

5 hours ago, charliepetty said:

The EM2 will be fine with a V5 Normal 8Pin or 21Pin, L Decoder OR XL Decoder.

 

If you are using a 8Pin decoder and thinking of chopping off the plug, ('Don't) Always use the 8Pin Harness to keep the decoder warranty.  See Link:

https://www.dckits-devideos.co.uk/index.php?route=product/product&path=223_75&product_id=424

 

If the EM2 fits it will sound impressive, the Class 05 sound with Mechanical Gearbox is a classic industrial loco sound.     

 

Charlie-Legomanbiffo Sounds

Many thanks, that’s good to hear. 

My prototype is a 1960 Hudswell Clarke 0-6-0 diesel mechanical with jackshaft drive, so it has a lot in common with the 05 and 03 including the Gardner 204hp engine. I was trying to choose between the two so your recommendation and video is excellent!

 

I think the basic V5 decoder has plenty of amps for the motor. I want to include several lighting functions (5 or 6) and a friend advised the normal V5 21-pin decoder with adaptor board to help achieve that.

i will have another measure up, as it sounds like the EM2 will be a worthwhile improvement over the EM1. 

I am planning to bolt it to the inside of the bonnet top. I’ve been advised to mount it with some form of flexible mount with rubber grommets or similar - is that right?

 

Thanks again

Mol

[charliepetty]

On 26/01/2021 at 06:06, Mol_PMB said:

Many thanks, that’s good to hear. 

My prototype is a 1960 Hudswell Clarke 0-6-0 diesel mechanical with jackshaft drive, so it has a lot in common with the 05 and 03 including the Gardner 204hp engine. I was trying to choose between the two so your recommendation and video is excellent!

 

I think the basic V5 decoder has plenty of amps for the motor. I want to include several lighting functions (5 or 6) and a friend advised the normal V5 21-pin decoder with adaptor board to help achieve that.

i will have another measure up, as it sounds like the EM2 will be a worthwhile improvement over the EM1. 

I am planning to bolt it to the inside of the bonnet top. I’ve been advised to mount it with some form of flexible mount with rubber grommets or similar - is that right?

 

Thanks again

Mol

The New V5 without the board will do 4 X Aux Outputs.     Charlie

 

PPs I like the 05 better than the 03, more clunking and clanking.    Charlie

[Mol_PMB]

11 hours ago, charliepetty said:

The New V5 without the board will do 4 X Aux Outputs.     Charlie

 

PPs I like the 05 better than the 03, more clunking and clanking.    Charlie

Many thanks! I have now placed an order. I can fit the decoder and adaptor board between the frames which means that an EM2 speaker will go in the bonnet above the motor.

Cheers,

Mol