rowe cd100 external speaker need advice

[john8]

After the problems of an incorrectly wired speaker setup then a blown amplifier, the jukebox has been fixed and has been operating very well for quite some time.
The bass can be tight, punchy and loud but to me it doesn't sound deep enough.

I do have a large bass speaker with enclosure (4 ohm) that I would like to experiment with but reading the manual confuses me.
The manual is for a CD-100 Laserstar (1990)
Referring to table 2-5,

----- from the manual --------
phono power     phono speaker connections

113 watt           violet connects to Left E7, pink connects to Right E7

Do not move the black wire; it should stay on either the Left or Right E1 terminal.
With reference to phono power (113w); this value is the total for both channels. The power consumption for each channel is one-half of this value.
--------
BTW other 250w cd-100 manuals the info about the extension speaker operation read the same as above.

Does this mean, that the phono speakers use only 113w of the 250w available, the rest 137w is for external speakers if required?
If so, for me to add the bass speaker (general purpose), the phono speakers would remain on their present connections E1 to E7 left & right and the mono bass speaker (300w) would use tappings E5 to E5

The internal connections of the jukebox use light weight wire, what distance could I get away with using the same wire or do I just go to using a heavier duty wiring.

To my mind I like the sound of the jukebox to be centre stage, however in a Bar, Cafe or whatever, having additional external speakers using the available spare amp power so that the music is spread about is probably more acceptable, the manual allows for it with its worksheets.

Anyway all I want to do is add a 300w 4 ohm mono speaker to the jukebox please tell me if I'm doing or thinking anything wrong. How do I do it?

Thanks
John

[ami-man]

Hello John,

If I were using high power speakers, I would be temped to run these through slave amplifiers.
When we were in the operation of jukeboxes on site we used to run a jukebox on its maximum tappings in the case of the CD100 this would be on the E7 tappings on the output package.
We had one site with 3  x 250 watt stereo slave amps that the input was taken from the auxillary connections on the jukebox amplifier,  we then used a large number of Boss 301 speakers hung off of these slave amps.

You could use the E5 connections as you rightly say and into 4 ohms it would give you 113 watts.
Never connect speakers in a configruation of less than 4 ohms.

If using higher wattage speakers then  we always wired them in 2.5mm2 minimum cable to prevent loses on longer runs.

In installations such as toilet/stairwell speakers we always installed these on the 70 volt connections on the output package and used 70 volt line transformers on the speaker end, these we would wire in 1.5mm2 cable.

Regards
Alan

Alan Hood
ami-man
UK

[gtc]

----- from the manual --------
phono power     phono speaker connections

113 watt           violet connects to Left E7, pink connects to Right E7

Do not move the black wire; it should stay on either the Left or Right E1 terminal.
With reference to phono power (113w); this value is the total for both channels. The power consumption for each channel is one-half of this value.
--------
BTW other 250w cd-100 manuals the info about the extension speaker operation read the same as above.

Does this mean, that the phono speakers use only 113w of the 250w available, the rest 137w is for external speakers if required?

Regarding your questions as to power available ...

The amplifier is specified as being 250 watts, total, so a nominal 125 watts per channel (into 4 ohms).

The power output transformer voltage at terminal E7 is shown in Fig  5-9 of the service manual as 21.3 volts, so:

Power = (21.3 volts  x 21.3 volts) / 4 ohms = 113.4 watts, and I make that 113.4 watts per channel, not total as the manual says (highlighted in blue above).

[john8]

Alan thanks for the info, I decided to hook it up and give it a go and so far have been lucky with no problems
Initially I hooked  the internal and ext spkrs to lower output tappings just in case.
Now I have the internal spkrs on E1 to E7 and the ext on E4 TO E4.
That gave me about 10db extra at the bass end which now sounds good but undoubtably I'll fiddle some more so it just extends the lower end.
The spkr that I used was an old bose 302 tandem tuned unit. I have read reports that these should be used with a controller to get good results but so far so good.
I'll try and get one of those rowe accessory kits and try out an active sub that I have to see which sounds best.
GTC your right about the watts so maybe you can help me out.
my setup as above;
internal spkrs E1 to E7 113 each equals 226w
ext spkr mono 4 ohm E4 to E4 thats      64w
                                            a total of 290w - thats 50w in excess so I would have to reduce spkr tappings to give a total of 250w. Is that correct??
Thanks
John

[lilshawn]

the examples and calculations given in the manual are incorrect. This was in a time of misunderstanding of loudspeaker and amplifier operation..

We now know that it doesn't matter how many watts of speakers you hook up to the amplifier.... you must have a proper speaker load. THIS is why amps blow out...it's because the speakers are basically presented as a dead short across the output.

you need to keep your speaker load between 4 and 8 ohms regardless of how many speakers you have.

for instance, if you have two 6 ohm speakers (commonly referred to as "4/8 ohm compatible" speakers) and you wire them in parallel, you end up with about 3 ohms presented to the amp output. if you run them in series, the speaker load presented to the amp output is 12 ohms.

3 ohms is too low of an output and while it may work, at high volumes and hard driving, the amp will eventually blow.

12 ohms is a little on the high side. running speakers this way won't result in damage, but you'll have to crank the volume to get any output from the speakers since the load is so high.

ideally in the 6 ohm speaker case, you want 4 speakers with 2 sets of 2 wired in parallel and the 2 wired sets wired in series. that way when you combine the two 3 ohm loads in series you end up with a 6 ohm load. perfectly in between the 4 to 8 ohm load range.

you can have 100 speakers hooked up, you just need to properly wire them in series/parallel to present a proper load.

for reference:

when you series the connections you ADD the values together 8 ohms + 8 ohms = 16 ohms ( or alternatively with 3 speakers 8+8+8 ohms = 24 ohms)

when you parallel the connections you DIVIDE the value by the # of speakers 8 ohms / 2 speakers = 4 ohms (alternately - 8 ohms / 3 speakers = 2.66 ohms)

you must also realize, the speaker taps are a PARALLEL connection to the AMP so if you have two 6 ohms speakers, one on E7 and another on E6 this is a 3 ohm load, too low.

I looked up the Bose 302 speakers but bose has a terible habit of reusing product ID's so the "302" comes up as 3 or 4 different speakers. but most of the home bose speakers are 6 ohms.

[gtc]

GTC your right about the watts so maybe you can help me out.
my setup as above;
internal spkrs E1 to E7 113 each equals 226w
ext spkr mono 4 ohm E4 to E4 thats      64w
                                            a total of 290w - thats 50w in excess so I would have to reduce spkr tappings to give a total of 250w. Is that correct??
Thanks
John

I went back and looked more closely at what the service manual says and it seems I am wrong. The specifications specifically state under the Transformer Package section:

Power levels for phonograph speakers .... 1, 4, 16, 64 watts
(Provides 70-volt line for extension speakers)

and for Power Amplifier it states:

250 Watt Stereo
4 ohm loads @ 1%THD  ... 250 watts RMS
70 v lines @ 1% THD   ...   126 watts RMS

My take from this is that Rowe is saying that the output transformer is capable of delivering a total of 113 watts for the internal speakers plus 126 watts for extension speakers wired to the 70 volt taps, for a grand total of 239 watts. (I guess the 11 watt difference is accounted for by losses in the output transformer.)

In any case, Rowe's two cardinal rules for speaker connections are (1) do not exceed a total power demand of 250 watts, and (2) do not let the combined speaker impedance fall below 4 ohms. Breaking either of these rules will cause amplifier overload.

So, going to your example, I now make it:

internal spkrs E1 to E7 = total 113 watts
ext spkr mono 4 ohm E4 to E4 = 64 watts

Total = 177 watts

[lilshawn]

no, see that's the thing... The manual is incorrect. I can not stress that enough. it was written in a time where they thought too many watts of speaker load was bad for an amplifier. This is absolutely not the case. At all. Ever. I have no idea who thought this was the case but it's 100% wrong.

I can wire up four 5 watt speakers that would blow up the amp the second you power it up. 20 watts  is well under the 200 watt "recommendation". I can also easily wire up 2500 watts of speakers with no problem (I've done it in a very large bar) which is many times over the recommend "load".

the only thing that really matters is the resistive load of the speakers attached to the amp. it must be kept between 4 and 8 ohms. you can attach as few or as many speakers as you like, but you MUST keep the resistive load of the speakers between 4 and 8 ohms.

the only time watts matter is if you are hooking up one or two speakers up to an amp and you plan on pegging the volume straight up. then your speaker must be rated for the watt output of the amp or better or you risk blowing your speaker.

ignore the manual.
ignore the calculation sheet.
ignore the watts.

how many speakers do you have inside....how many do you have outside....how do you need to control the volume on them? are you planning on using the juke speakers as well?

[john8]

It seems to me that when they mention watts they are talking about the power handling capabilities of the speaker not the amplifier.

I'm not a techie but here goes! The output of the amplifier will depend on the resistive load of the speaker i.e. in this case 4 ohms or 8 ohms (the 4 ohm will be louder). So I can have an amplifier designed to output 100w, into a load of 4 ohms at full volume, feeding a speaker of 4 ohms rated at 20w, the speaker will probably blow whereas, if it was feeding into a speaker of 4 ohm 200w it would play all day.

I'm not sure about how the output package works, in some other AMI jukebox amps the circuit is something similar, the E1, E7 taps are from the amp whilst the other tappings came from the transformer.

Some jukeboxes owners will use the internal speakers only or external speakers only or a combination of both.

For a 250w CD100 I don't think 125w per channel is available to just the internal speakers only, I think you can get 125w channel but it will involve using the extension speakers as well.
For the internal speakers on E1 to E7 you get 113w total so only 56.5w channel and 68w (125-56.5) sitting idle, reserved for ext speakers??.

I got this info below from the net, it is not a rowe cd100 but a "AMI nitehawk internet jukebox 1000w" 500 channel. I assume thats 1000w total into 4 ohms (resistive load).

Quote:
1. The Grand Total is the amount of power that the jukebox will need to supply to the extension speakers. If the Channel 1 Total or the Channel 2 Total is more than 438 watts, you must reduce the power used by that channel’s extension speakers, and then recalculate that channel’s power consumed. The jukebox internal speakers consume 62 watts per channel (factory wiring). This leaves (500-62.5) 437.5 watts per channel for extension speakers.
End quote.

I've ordered an accessory kit and will most likely add a powered sub to avoid any errors in interpreting the manual but if the spare power is available I would like to use it, if required.

Comments

John

[lilshawn]

the manual has a stupid calculation sheet and you have to write down all the speaker wattage values on the watt taps you need and add them up and they have to be under a certain wattage for that amp. This is so wrong it's not even funny. Wrong, incorrecto, faux, falsch, geuleusdoen.

it is the assumption the speakers "consume" the power of the amp, which is absolutely not the case.

someone should have gotten fired over it...but I wonder how many amp rebuild kits they sold as a result of this false information.

the only reason I think this poppycock has remained in the manual is because they just copy/paste the info and don't even bother looking at it.

[FosterVS]

Alan thanks for the info, I decided to hook it up and give it a go and so far have been lucky with no problems
Initially I hooked  the internal and ext spkrs to lower output tappings just in case.
Now I have the internal spkrs on E1 to E7 and the ext on E4 TO E4.
That gave me about 10db extra at the bass end which now sounds good but undoubtably I'll fiddle some more so it just extends the lower end.
The spkr that I used was an old bose 302 tandem tuned unit. I have read reports that these should be used with a controller to get good results but so far so good.
I'll try and get one of those rowe accessory kits and try out an active sub that I have to see which sounds best.
GTC your right about the watts so maybe you can help me out.
my setup as above;
internal spkrs E1 to E7 113 each equals 226w
ext spkr mono 4 ohm E4 to E4 thats      64w
                                            a total of 290w - thats 50w in excess so I would have to reduce spkr tappings to give a total of 250w. Is that correct??
Thanks
John

After years of running 100+ Rowe CD100 jukeboxes, I learned NOT to add speakers to the E7 tap. Seemed to always blow the outputs. We never tapped higher than E6.