Tin Tuirtle Design

Cornwall bass motorboard

clock December 11, 2012 17:11 by author Bald Turtle

The bass section from the Klipsch Cornwall uses a modified motorboard design that moves the ports from the bottom to the side. This allows the 15" woofer to be mounted directly in the center of the motorboard. The assembly is a two piece design. If I build another pair I think I will change a couple of things. One, I will mill a rabbet for the outside diameter. The 3/4" drop is slightly too deep, and the 15.625 diameter is overly large. Other than that the assembly fit the speaker perfectly, and a test fitting to the cabinets was also perfect.

Here is the double sided tape method I use to cut the circles out of the MDF. This attaches the MDF to the backing/waste board so that when the circle is finally cut free it doesn't move around and cause a problem.

cutting a speaker hole

using a Jasper Circle Guide to cut a speaker hole

Klipsch Cornwall motorboard parts

Cornscala motorboard



Prepping for final finishing coat

clock December 8, 2012 19:01 by author Bald Turtle

The lower enclosures were dampened with carpet padding and automotive headliner fabric. Just some minor dampening to breakup any resonance that might happen, and help to clean up things for a little more clarity. A friend helped me with the final sanding prep using 400 grit. I learned a lot about final prep work, and these cabinets are really looking great. I did a quick stacking of the components to check proportions and get some idea as to what they will look like complete.

Cornscala dampening

Cornscala cabinet assembly

Goose Island Night Stalker



Upper cabinets are assembled

clock December 5, 2012 14:35 by author Bald Turtle

The Cornscala upper cabinets are assembled and now need to have the ports milled out in the bottom. I needed another small piece of walnut to finish these up so I picked up some over at Owl. This piece came from a large, commercial kiln that uses steam to blend their walnut. It gives it a more uniform look, but it also dulls it down. I really prefer the vertical strip that you see below that came from a local sawyer who uses a solar kiln.

Cornscala tweeter and squawker cabinet

steam kiln walnut versus solar kiln walnut



Settled on a finish

clock December 2, 2012 15:24 by author Bald Turtle

I went back to a finish that was similar to how I did the family room furniture. The base is a boiled linseed oil that is applied and sits for 24 hours. Then 3 coats of hand rubbed General Finish Arm-R-Seal in high gloss. Each coat is steel wooled and wiped, and after the third coat it is sanded using the Festool RO150 and 320 grit on vibe. That is followed by two coats of Arm-R-Seal in semi-gloss. The first pic shows the backs after the last coat has dried for about 4 hours. I should be able to start working on the bottom cabinets (finishing) tomorrow.

Cornscala back panel

The bottom cabinet shells have the ports routed into the upper chamber. There is a middle piece that has matching ports and serves to divide the upper and lower cabinets. The ports were routed with pattern bits and a template I made from scap MDF. Initial opening is cut with the jigsaw, and then the final cut is done with the pattern bit. Each mid piece is matched to a specific cabinet. It has been 9 years since I did a project with MDF and I would have no problem waiting for another 20 years before doing another one. It is the messiest, dirtiest material I have ever worked with. I had to wear a respirator while milling these parts.

Cornscala bottom cabinets



Bass Cabinet Shells are Ready

clock November 29, 2012 20:51 by author Bald Turtle

The shells are domino'd and ready for the ports to be cut. The backs are done and the access hole for the cross overs are done. They are downstairs and I am starting the finishing process on those.



Clamping panels for the Cornscala's

clock November 25, 2012 15:16 by author Bald Turtle

There were 3 boards of walnut left over from when we built the furniture for the family room. It is well aged (over 5 years) and it will help the speakers to match perfectly with the room. This was milled to the exact thickness of the A1 cherry MDF sheets. Then the components were milled with loose tenon mortises using the Festool Domino. It is an excellent joint, and far superior to the biscuit joiner. The tops and bottoms (8 each for 1 pair) were then clamped for 4 hours each under pressure to form flat panels.

Festool Domino

Cornscala cabinet build


Starting a pair of Cornscala speakers

clock November 24, 2012 06:51 by author Bald Turtle

The JBL's had another failure a few weeks ago and I decided it was time for them to retire after 25 years of service. I started looking at options, but I could not afford to buy a nice pair of new speakers. I looked at some used ones that were available within driving distance, but the more I looked the more I realized I could build something much nicer. I have never owned Klipsch or any other horn speaker, and I have always said it would be nice to try a high efficiency pair. While looking at used Klipsch speakers I found a guy named Bob Crites from Crites Speakers who supplies new crossovers and drivers to upgrade existing Klipsch. He also has a great design called a "Cornscala" that combines the best attributes of the Klipsch Cornwall and the Klipsch Lascala.

I started out only milling the motor board (baffle) and telling myself I would not really build a pair, I just wanted to see if I could mill the MDF pattern for the motor board. But that quickly spiraled into a full blown effort to modify Bob's original design to incorporate split cabinets and different grills. And that led me to really wanting a pair in China, so I thought I would build TWO pair.... I wanted to have the cabinets match the existing cherry furniture and in particular the coffee table. So I chose to use 3/4" MDF core cherry ply, A1 grade for the first pair. The layups were done in CutList Plus using a series of manual drawings I used to develop the design. The panels were VERY heavy, and I broke them up on the workbench prior to moving over to the table saw. I am starting the edge banding process today, and clamping the first of the tops and bottoms (total of 8 pieces per pair).

cutting cherry plywood

cherry speaker panels for cabinets



Lava Cable

clock April 4, 2012 13:57 by author Bald Turtle

Here is a new vid from Mark Stoddard over at Lava Cable. A long time ago I picked up my first cable from him and it was mostly to support the business than anything. It was pricey, and I wondered if it was really worth it but he seemed like a good guy, and the way I eat up cables if it lasted an extra year or two it would be worth it. What was really amazing was that I could actually hear the difference. I did not think it was possible for a cable to matter that much. They are great, and I brought a Retro Coil with me to China.



Getting back in the groove

clock January 5, 2012 13:54 by author Bald Turtle

It has been one week since I arrived back in Beijing. I got rid of my jet lag and put my kitchen back in order. The reverse osmosis unit has been a great addition to the apartment and really cut down on our expenses plus I have safe water. I really did not do much in the way of cooking over the holiday but starting Wednesday we began putting some things together. I will build up momentum over the coming weeks and we will host a few parties.

The sites need a serious revamp and some formatting work. The style sheets holding the Tin Turtle site together are some butchered copies I did from the original BlogEngine install and I need to build new ones from scratch. I didn't notice it as much here when I built the site last year, but when I got back to the U.S. and saw it on my 26" monitor it was painful. And I need to do browser checking, this site was developed in designed for I.E. with no regard for anything else, and with I.E. having less than 50% of the browser market that won't cut it. Mindspear has to be redone too, it hasn't been touched since 2002 and none of the cool projects I worked on in Chicago are even on the site.

The package I put together to practice guitar in China has worked out really, really well. I still have the laptop from 2009 which was a really good unit when new, and honestly still has pretty good performance. I had really thought out how to have a completely portable work station with enough ooomph to do full on development with VS and SQL Server. So when I added on Reason 6 with the Focusrite Saffire 6 pre it worked well. The tone in the Line 6 amp models built into Reason are very good - and I am a hard core tube guy. But they are more than adequate for what I am doing. And it all still fits in one backpack. There are some latency issues with the Focusrite and that seems to be in how the unit attaches to the internal USB hub. Once I have it ironed out I will post how I have this set up and what I am getting in terms of performance.



The Training

clock December 25, 2011 05:54 by author Bald Turtle

A well thought out training program is the key.....



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