The main speaker on the Kenwood TS690-S is not a bad one. I’ve been using it now for around 5 months, and although no expert, it has been good in terms of being able to listen to what ever made it thru the antenna and to the audio stages of the transceiver.
However, with the addition of the Auto-tuner and DSP, there is quite a bit which ‘blocks’ the speaker. Whilst not muffled, its ironic that I have such a good DSP and not a good external speaker. I do have a very good mixing desk (Behringer X2222) which I use on ocassion to process and amplify the audio from the transceiver, but ordinarily I keep the radio audio seperate from the synths/drums/guitars. Another issue would be managing the sizeable ground loop between mixer and transceiver as the earth/bus bonding isnt the whole way around the ‘shack’ yet.
This lead me to search for a speaker for the TS-690s. Whilst not an ‘audiophile’ I do understand a little about speakers, housing and acoustics of them. I was very lucky to find a really great condition Kenwood SP-23 from ebay. The item itself is in incredbly good condition. I cant tell if its one month or 10 years old. It looks gorgeous. When findng the SP-23 I also searched for upgrades to it, this is without hearing it, but I’ve come to trust the reputable amateur sites on the internet, for example eHam reviews of the SP-23 talk about the quality *compared to other speakers* – I guess when you buy a speaker you want it to be the best buck for money. The most often given upgrade was to the GPH-K23X speaker and applying Phonema K23A PHITS acoustic coupling. I ordered both immediately and was amazed that these arrived from the USA in just a few days – amazing work from FedEx.
Having had the speaker for several days un-modded I was quite happy with the audio quailty. That said I still dont do enough telephony work to really say how good it was, and other than the internal speaker have no real reference on what ‘good’ is in terms of HF transceiver speakers.
As the kit arrived so quick, i jumped over a couple of other projects to immediatly upgrade the speaker and apply the acoustic foam.
Very well packaged a deent box for the foam 
The speaker box is very good dimensions 
A manual and parts for mounting the speaker, or not 
Briliant foam 
A good bag as well to keep it clean/dust free from factory 
further packing under the speaker 
parts packed nicely in a seperate bak 
the speaker looks very good quality 
the magnet and voice coil look substantial 
the foam is very dense 
very well packages 
even a spacer to keep it tidy – ensuring no bent edges 
a useful datasheet
I was really impressed with how well the speaker and foam had been packaged, its quality throughout and is a good sign that this is a quality purchase.
one last look at the unfettered SP-23 
a clever way to mount the speaker imho 
removed speaker 
woah its big 
side by side comparison 
so wheres it gonna sit ? 
how does that fix in there ?
I am always slightly relectant to make changes to orginal equipment, but when I do I make sure i can recover it back. In this case i carefully de-soldered the orginal speaker. I did have to cut a little of the positive wire as it has been wound so well, but it was a minor inconvieane.
I was then able to start trying to work out how to install the new GPH-K23. Reading the instructions it discusses a bracket and furthermore has pictures of ‘clamps’ which are not visible in either the kit or in the existing speaker. I was slightly confused how this could happen, give this speaker is designed for the SP23. In the website for the GPH-K23 is describes a ‘plastic’ front version of the SP23. Mine is very metallic. With that i was somewhat perplexed on how to mount the speaker, especially as I had now de-soldered the orginal speaker just moments ago.
how does that fix in there ? 
trying to use tweezers wont help 
this picture looks nothing like my speaker cabinet 
improvise.. 
adapt 
overcome 
succsses ? 
speaker cone very central positioned
I was undettered by the fact that the instructions and mounting didnt match. There must be a way to do this. I had kept the old parts safely, ready to be placed in the SP-23 box so that they are there for future records and changes if required. I examined the brackets which held in the orginal speaker. The backing card was too small (diameter of hole) and too thick (widness of backing card) to mount the new speaker on.
Looking at the parts I had and the design of the case, there was a possibility to use the ‘brass’ clamps from the speaker back to hold the new speaker in place. I tried out the existing screws to check a good fit, and sure enough i was able to use the brass/copper mounting plates to hold the speaker in place !
Looking from the front the speaker looks very centrally located.
Foam added 
and back in the stack!
The foam fitted really well in the speaker, i was very impressed with the cutting and density of the foam. Getting the case back on required some real effort to it fitted, but on it went and back in the stack it went !
Now, i think its very subjective on how good something sounds, so here it is in action.
I for one was very impressed and felt the additonal parts did bring something to the speakers audio clarity. I would recommend that anyone that does have the SP-23 to get the coner and baffilng. I had to choose between one or the other, start with the baffling !