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Speakers for S5 K-16LS Kit

emretelci

Member
2015-10-23 12:17 pm
Hi there,

I am building an S5 K-16LS Kit which was originally 16 watts. I am modifying it with Edcor transformers and would like to ask how much watts will it be...

I am using two CXPP25-8-5Ks for output and one XPWR227 for power.

The reason I am asking is, I am also planning to build speakers too and I want to learn the new watts. Maybe in RMS too :) I will be glad if you show me a way to calculate...

Cheers..
 
Hi, emretelci.

No one has replied to you yet, so I'll give it a shot. Others will chime in if I am off base.

If the Edcor impedance is close to that of the original output transformers, the output power probably won't change much. The Edcor wattage rating (25 in your case) means the transformer can handle up to that power. You want to put less into those and keep some headroom available.

As you build your speakers, your primary concern would be to ask yourself at what levels you are planning to listen, and whether you need high SPL ratings for a speaker driver, or whether you can get by with a typical DIY speaker driver rated at, say 85-90 dB @ 1m. I use typical but very good drivers rated around 87 dB @ 1m, and I have plenty of volume in a 500 sq. ft. room using amps from 4 - 8 Watts output. But then I don't blast party music.

A line array with speaker in a series-parallel network can increase the final SPL if you need that extra volume, but you will need to know your final impedance to be sure it matches your 8 Ohm OPTs. Two 16 Ohm speakers in parallel, for example, will be 8 Ohms net, and can sound up to 3 dB louder than a single driver (I am generalizing, and 3 dB isn't all that much louder).

Just for kicks, do you have a signal generator and a good DMM that measures "true rms" AC? If so, you could run a 2V rms 1KHz sine wave into one input from the generator and connect the amp's output for that channel to an 8 Ohm "dead load," a high wattage 8 Ohm resistor (try for 30-50 Watts, and even that will get hot). Measure the AC voltage across the resistor with the DMM. Compute V^2/8 to get a rough idea of Watts output. As an example, if you measure 11 volts AC, you're outputting 15 Watts at 1KHz. Actual output across all frequencies, as in real music, will be less.
 
I couldn't find was the specification for the impedance of the original OPT. For example, was it 5K:4? How your Edcor OPTs differ from that and what the impedance curve looks like for the speakers you make will have some effect on damping factor, output power and distortion. Going from 4 to 8 ohms, your power output will be reduced.

All that said, the difference could be small in your actual listening experience. But by choosing the Edcor CXPP25-8-5Ks over those rather small original OPTs, you will have better sound, IMHO. You sure won't be hurting anything by trying this project. If you Google, you'll find that others have found them to be a good replacement.

Your power transformer choice may be 10 volts AC output more than the original. You'll just need to check your B+ to be sure you are operating the 6005s in a safe range.
 

emretelci

Member
2015-10-23 12:17 pm
I couldn't find was the specification for the impedance of the original OPT. For example, was it 5K:4? How your Edcor OPTs differ from that and what the impedance curve looks like for the speakers you make will have some effect on damping factor, output power and distortion. Going from 4 to 8 ohms, your power output will be reduced.

All that said, the difference could be small in your actual listening experience. But by choosing the Edcor CXPP25-8-5Ks over those rather small original OPTs, you will have better sound, IMHO. You sure won't be hurting anything by trying this project. If you Google, you'll find that others have found them to be a good replacement.

Your power transformer choice may be 10 volts AC output more than the original. You'll just need to check your B+ to be sure you are operating the 6005s in a safe range.

Thank you Jeff. I am learning electronics here and you people help a lot...

I am following a member (FishStix) and I have learned from him about the Edcors. He has used the same model Edcors so I am just copying him... :cool:

What I can tell you about the kit's original transformers are, they are very small :D

Adding a picture here, blue one is the Edcor (obviously) :roll eyes:

[IMGDEAD]http://www.emre.co.uk/wp-content/uploads/2016/04/IMG_1508.jpg[/IMGDEAD]
 

emretelci

Member
2015-10-23 12:17 pm
I have the 16ls with the same Edcor OPTs installed and I use a pair of Polk T15 bookshelf speakers with it. They sound fabulous with defined highs and good bass response. These speakers are only about $100 a pair and can get plenty loud with this amp if you ask them to.

Thank you Oldschool tube. I have a friend who has Polk T15, I have asked him to try them with my amplifier when I finish...

Now, I have a pair of JBL TLX 4, and planning to make Dayton Audio reference speakers. :rolleyes: