Trio (Kenwood) KR-3600 Revamp and Veneer

amplifiers, receivers and loudspeakers
GreenNeedle
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Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 27 Oct 2019 10:18

Just to pre-empt the question. No these aren't expensive units. I just like things to look nice so why not make them look so. I can't afford expensive things but I can make them look (nearly) as nice within my budget and the turntable sounds great, the KR-3600 22wpc also sounds superb. The radio is fantastic with a tuning knob that you can roll your hand over the top and it keeps spinning for a second or 2. Connected to my old unused analog roof top ariel socket you can get the FM radio stations tuned in with zero interference. On with the project to make this cheaply available undesirable stereo receiver look like the ones that go for silly money.

I had been using a Rotel RX-150A Stereo receiver with my Trio KD-1033 turntable but I wanted something a little more powerful and smooth and I thought it might be a good idea to match it with the turntable so I bought a KR-3600 off ebay for £50.

I have already done this project once but the veneer I used doesn't match the veneer I used on the turntable...........so I decided that I will re-veneer them both in the same veneer from the same batch.

This time I will be using Santos Rosewood, a little redder, a little lighter in colour. Should look quite nice.

So I'll start from the original revamp that I did.

The KR-3600 has wooden sides, with a black metal top plate and silver front. I like the look of the Marantz boxes so I decided to make the sides part of the box with MDF top and bottom completing the enclosure.
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Kenwood KR-3600
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Kenwood KR-3600
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Last edited by GreenNeedle on 27 Oct 2019 10:47, edited 1 time in total.

GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 27 Oct 2019 10:33

First things first. Opened her up and she was quite dusty. Hoovered that out. (yes I know but I was careful and with a very fine (2cm diameter) brush head tube:
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K£-3600 Dusty
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KR-3600 Cleaned
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Next there were some bulbs that need replacing on the front. There are 5 bike light size bulbs in the main strip and a smaller rice type bulb behind the fine adjustment tuning square (excuse me for not knowing the actual terms for these 2.) I can't remember the exact wattage/voltage/ampage these were but I researched and got exactly the same.

These go into rubber grommets which have 2 lips to fit either side of the holes they are to go in. I didn't just replace the ones that were out. I replaced them all and then removed a couple that weren't matching until they all looked the same. I also had to file some of the metal enclosure of the bulbs to fit them in the grommets:
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KR-3600 Before light replacement
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KR-3600 Rice bulb
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I didn't go mad on the tidyness here. I just snipped the old bulbs out, slipped some heatshrink over each wire, soldered the old wire to the new bulb wires and then slid the heatshrink over the solder and shrunk it. The heatshrink is green in these pictures:
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KR-3600 heatshrink bulb cables
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GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 27 Oct 2019 10:42

Finally I fired her up and voila. Working like new:
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KR-3600 new bulbs working
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KR-3600 new bulbs working
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Next step was the usual de-oxit tretament. sliders and dials and pots were given a blast. turned/slid back and forth and back and forth. Left to drain / dry. Given a repeat treatment and then the next day faderlube on the sliders. Result? No more scratchy noises when using the controls. We have a winner.

Onto the box. You will have to ignore the ebony veneer that is in these posts. That is how the unit looks at the moment but will change again.

Copying the style of Marantz boxes I wanted a big central grill on the top of the unit. The Kenwood has it's grill on the left of the top plate so the visible hole of the box will be centred but the left side will also be hollowed out so that the MDF is not actually blocking half of the whole. Then I want to put a silvered "holey" grill in the visible slot.

Most of the Marant boxes have a protruding chamfered edge from the front plate of the actual receiver, however I like things to be flush with the front plate so that will be the only change I make to what is normally seen. Prior to this I have shaved the black plastic trim from the sides of the metal front plate. I want metal only inside the wood border.

The actual unit will retain it's bottom and top plate and just slide into the box which has had cutouts top and bottom to give the same vent paths as the original plates. Internally there are routed grooves to facilitate screws that the original unit used.

It is secured within the box solely by recessed washer and screws where the feet were on the original. The side mountings are unneeded (and unwanted from an aesthetic point of view) as the sides are now part of the box.

You might be able to tell here that the MDF width is 18mm but the rim where the grill will go has been routed internally leaving 5mm of MDF. Internally that 5mm depth carries over to the left side under the MDF where the original vent hols are.
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KR-3600 box with ebony veneer
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GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 27 Oct 2019 11:17

This was the original veneering process which shows what I did but this veneer will be replaced:

First I joined the ebony up to make pieces to fit each surface. Below is one piece to fit the top:
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Ebony veneer joined
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This was then glued on and weighted on top. Each side left overnight to dry, trimmed and then the next side glued and left overnight etc. Thus the 4 main surfaces takes 4 days. Then the front strips done in the same way but I did all 4 in the same day and then left them overnight. Then the little 5mm lip where the vent will go. I ironed this one because I couldn't clamp it. Simply wood glue on both surfaces, leave to cure for 15-20 minutes and then iron it on to re-activate the glue. Must do this in the first half hour or so because if the glue cures fully it won't work as well. I usually use Titebond Original but I didn't have any left and didn't want to but anymore of it so I used some standard off the shelf wood glue from the hardware store:

Here you can see the thin veneer in place in the grill recess ready to be trimmed. You can also see some of the internal routing grooves to allow the unit to slide in with it's protruding screws in place:
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grille recess veneer before trimming
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The grille is held in very simply by scrap pieces of MDF away from the viewable section of the recess. I cut it 20mm wider than the recess hole and tried to make sure with my cut that it would be uniform all around. I didn't want the left side to have holes to the edge and a gap on the right. I want the holes to be equally spaced all around the edge of the recess. I'm a bit obsessive about that kind of symmetry.

Here it is with grille in place and danish oiled, buffed and ready:
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KR-3600 complete
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KR-3600 complete
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Last edited by GreenNeedle on 27 Oct 2019 11:28, edited 1 time in total.

Tinkaroo
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by Tinkaroo » 27 Oct 2019 11:18

Great job, both beautiful and unique! 8)

I've got a Kenwood KR-5600 from the same series which also has the side wooden panels. To their credit they did use real veneer on those pieces. They were a nice looking series and the dial pointer looks beautiful lit up.

GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 27 Oct 2019 11:21

And just for fun here is a family of refinished receivers. From the left:
The Original Rotel RX-150A I was using. Veneered in the same ebony as the turntable
The Trio KR-3600 I am now using.
An Alpha (by highgate) I bought for a fiver (£5) on a whim. Veneered in some "scrap" flame/tiger maple I had already. This little unit is the oldest but sounds suprisingly good with 50s/60s music, Jazz etc. I gave this to my Dad who listens to it virtually all day long :)
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Left to right - Rotel, Trio, Alpha
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Left to right - Rotel, Trio, Alpha
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Left to right - Rotel, Trio, Alpha
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Top to bottom - Rotel, Alpha, Trio
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I will try to take better pictures during the revamp process. The camera I had at this time was not so great.
Last edited by GreenNeedle on 27 Oct 2019 11:57, edited 1 time in total.

GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 27 Oct 2019 11:24

Tinkaroo wrote:
27 Oct 2019 11:18
Great job, both beautiful and unique! 8)

I've got a Kenwood KR-5600 from the same series which also has the side wooden panels. To their credit they did use real veneer on those pieces. They were a nice looking series and the dial pointer looks beautiful lit up.
I've just noticed in the picture lit up above your post that the FM Stereo light looks red.........reason being I tried a little piece of transparent red film placed behind the dial "glass." I didn't like it so removed it and it is back to the "warm white" glow.

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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by john_will » 28 Oct 2019 10:37

Nice to see someone else liking a KR3600. I bought mine new in the late 1970's and have used it almost every day since.
Apart from an annual dust removal it has had no work done.

GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 28 Oct 2019 18:25

john_will wrote:
28 Oct 2019 10:37
Nice to see someone else liking a KR3600. I bought mine new in the late 1970's and have used it almost every day since.
Apart from an annual dust removal it has had no work done.
I think it sounds sensational. It's great that only the later "super-power" receivers are in demand :)

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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by lenjack » 28 Oct 2019 20:09

Amazing how much dust these things catch. We should open these things up every few years for a cleanup. Even if you can't see it, a dust coating can cause substantial heat buildup, and possibly circuit board shorts.

GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 13 Nov 2019 16:58

OK a little reminder of how this unit looks before it is stripped and re-done. This is the 2-tone affair which was Maccassar ebony and these pictures show the grooves within the unit much better to allow for the screw heads on the units actual top within.
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GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 13 Nov 2019 17:25

I had become a little bored with the ebony of the unit and also wanted the unit to match the Trio turntable so I am re-veneering both. I also had moved into a train of thought that if I am going to have a 70s receiver and a 70s turntable then it would be quite cool for the veneer to be more typical of the 70s (which the macassar ebony wasn't.)

So I settled on this "Santos Rosewood" veneer which came paperbacked and in a 34cm x 2.5m roll. I think it looks quite similar to the faux wood vinyl the was so prevalent on 70s stereo equipment. The difference here off course is this is real wood veneer and not vinyl, so it will be much more 3D and light will make the grain pop.

So on with the process. The old veneer was removed with a heatgun to melt the old glue and a scraper. Took some getting off in places. Then I filled in all the dents and scrapes.
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stripped and filled.
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veneer close up.
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I then sanded the whole thing (filler and wood) and used a tack cloth to pick up any dust left on it.

At this stage I cut the veneer. Top piece, bottom piece, 2 sides. then 4 strips for the front and 4 strips for inside the front. Pieces for the grille section will be cut ad-hoc to fit afterwards. I may go back and do the back and the bottom cutout later but these are not visible parts when in situ:
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veneer pieces cut to fit.
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The process I am using this time is a basic iron on method. I use a mini foam paint roller to spread wood glue on both the surface of the unit and the rear of the veneer and let it dry. Once dry I position the veneer on the unit, cover with an old t-shirt and then iron it on, which melts the glue from each piece together. I then push over with a flat wooden block to make sure it is hard and flat. It is allowed to cool for half an hour and I test it around the edges to see if there are any parts not stuck, then tap the rest to see if any is not stuck. If I find anything then I iron them again and run over with the wood again. Once happy I trim the edges flush with a fresh Stanley blade then sand with some P400. Then I can move onto the next piece.

The order I do them is the bottom, then the sides, then the top. Then the inside pieces, then the front pieces. Lastly I do the inside of the grille. It is just the order I usually do things so that the very thin visible edge of the veneer is on the least noticeable areas of the unit.
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First piece (bottom) fitted ready to trim.
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First piece (bottom) fitted ready to trim.
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Next it will be trimmed and then I'll do the sides using the same process.

GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 13 Nov 2019 17:33

Her we have move on to fitting the grille "lip". I try as best as possible to match the grain patterns so it looks like it is one piece of wood. I do the flat sides and attempt to bend them around the corners. Sometimes works sometimes doesn't because the veneer is quite weak along its grains and thus likes to snap around the bends, especially for such thin strips as this.

When this happens I just cut more pieces to fill the gaps in. The rest of the unit in this picture is complete, veneer glued on and trimmed.
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Adding thin strips of veneer to the grille lip.
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GreenNeedle
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by GreenNeedle » 13 Nov 2019 17:45

The whole unit's veneering process complete now. This picture shows the unit after the first application of Danish Oil, which was applied using P400 wet and dry. The first coat or 2 soaks into the veneer so you don't get that "sheen" straight away. Through the coats it will darken as well as glow more as the oil works its magic popping the colours within the wood. Will look very different to this picture (might not show in photos) when complete. This unit at the moment looks like the vinyl veneer versions with a matt finish.


Applying the first couple of coats with wet and dry helps to get a glossier finish at the end because as you "sand" with the oil it creates a mush of oil and tiny sawdust. this fills into the grain to get a smoother surface. Also when you first wet wood the grain raises and if you use a cloth straight away it will catch on the raised grain. The result of that at best is fluff caught in the grain, very likely though is pulling splinters out of the veneer. After 2 coats applied with the wet and dry you can decide at that point whether you want to go all the way to smooth or are happy to have a sheen with grain still showing.

My plan is 2 coats applied with wet and dry, then 3 coats applied with pieces of an old t-shirt, then I'll look at the finish and proceed with more wet and dry moving down the P numbers to try and get it to shiny shiny.

If you want to keep some of the grain then 2 coats with P400. A day to cure in between. then 2 coats with a lint free cloth. So 4 days there, then leave for at least a week (2-4 is better) before buffing it to a sheen.
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After first coat of Danish Oil
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Tinkaroo
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Re: Trio (Kenwood) KR-3600 Revamp and Veneer

Post by Tinkaroo » 13 Nov 2019 21:52

Looking great so far! =D>

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