The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products

    Great speakers for my new ST-120

    Share

    mantha3

    Posts: 286
    Join date: 2010-11-10

    Great speakers for my new ST-120

    Post by mantha3 on Mon Feb 14, 2011 1:53 pm

    I recently finished building a nice set of 3 way speakers and thought I’d share the detail. The speakers are designed by Troels Grevesen, they are 90dB and have valve friendly impedance.

    Troels home page - Speakers by Troels Gravesen

    The speaker project I built - 3 Way Classic


    I have been running my system (ST-120 amp) with some older 2 way Infinity book shelf speakers till I did this 3W speaker build. The sound was good till now… Now the sound is amazing. These speakers were made for this amp and the two pair up perfectly! I spent a lot of time pondering what speakers to build and I feel great about the choice I made. These speakers do it all and well. Any music I run (country, Hard Rock, Speed Metal, Jazz, Classic, Trance/Techo, Rap.. you name it) sounds better than ever.

    I was looking for a nice pair of full sounding speakers to pair up to my tube amp. Something that could reach low on bass… High in treble… with some some solid mid range… Speaking of the midrange, the MCA12RC in the sealed compartment is amazing. It is like a little stand alone full range driver parked between the low of the woffer and the high of the tweeter.

    I built using maple ply... Troels builds with hardwoods... Some debate on using hardwood VS MDF for speakers. These 8" woofers kick some bass!

    Anyway, these speakers really paired up well with the amp. This is a pretty good DIY project... But worth the work. These SEAS drivers from Norway are nice!

    Drivers - $400.00 (www.madisound.com)
    Crossovers (Jantzen) - $250.00 (www.partsexpress.com)
    wood $100.00 4' X 8' 3/4" high grade maple ply
    Misc $100.00







    mantha3

    Posts: 286
    Join date: 2010-11-10

    Re: Great speakers for my new ST-120

    Post by mantha3 on Mon Feb 14, 2011 2:00 pm

    PS - The speakers are designed by Troels Gravesen and not Troels Grevesen. Typo... Troels is a good help with questions and quickly responds to e-mails..

    Thought it should at least get his name correct!


    Bob Latino
    Admin

    Posts: 1957
    Join date: 2008-11-26
    Location: Massachusetts

    Re: Great speakers for my new ST-120

    Post by Bob Latino on Mon Feb 14, 2011 6:29 pm

    Andrew,

    Nice job on those speakers. Excellent workmanship. Kit speakers can be a real good value.

    Bob

    Tube Nube

    Posts: 328
    Join date: 2008-12-06
    Age: 51
    Location: Calgary, AB

    Re: Great speakers for my new ST-120

    Post by Tube Nube on Mon Feb 14, 2011 8:31 pm

    Nice Job! Those look great!

    There is great satisfaction in rolling your own speakers.

    And obviously, you've been "amp"- ly rewarded for your efforts.

    mathman
    Guest

    ported?

    Post by mathman on Mon Feb 14, 2011 10:09 pm

    Are these speakers ported? From the photo I couldn't see a whole in the cabinet. Thanks for any info.

    mantha3

    Posts: 286
    Join date: 2010-11-10

    Re: Great speakers for my new ST-120

    Post by mantha3 on Tue Feb 15, 2011 7:31 am

    Hi all,

    The speakers are ported with a 3" dia. port X 7" In long out the rear of the speaker.

    I sent a Thank you to Troels and provided some photos. Troels posted my speakers on his web site which is pretty cool. In this link to the site you can see the port out the back.

    http://www.troelsgravesen.dk/3WClassic-Andy.htm
    link to my speakers on Troels site

    It was not easy to decide on the speakers.. I was looking at some build projects and then looking at some Klipsch or Magnepan used. I also looked at Klipsch or Magnepan new but the price got up to closer to 2K or so. I think for the 900.00 or so these speakers I built are a great option for the tube amps talked about on this site. Some day down the road perhaps I drop some more serious $ into a nicer set. Buying used speakers seemed wrong to me for some reason.

    I appreciate the feedback all! I'm looking forward to the coming weekend to enjoy these!


    Tube Nube

    Posts: 328
    Join date: 2008-12-06
    Age: 51
    Location: Calgary, AB

    Re: Great speakers for my new ST-120

    Post by Tube Nube on Tue Feb 15, 2011 1:05 pm

    Is that 3/4 inch ply wood or 1"?

    mantha3

    Posts: 286
    Join date: 2010-11-10

    Re: Great speakers for my new ST-120

    Post by mantha3 on Tue Feb 15, 2011 3:10 pm

    That is 3/4" Ply

    You thinking of doing some building?

    mantha3

    Posts: 286
    Join date: 2010-11-10

    Re: Great speakers for my new ST-120

    Post by mantha3 on Tue Feb 15, 2011 3:12 pm

    PS - I have a lumber retailer that is great to work with... Buy a 4' X 8' sheet of premium maple ply for about 100 bucks... The pay about 14 bucks for all the cuts... Just do the full plan and outline the size of pieces. I've got the sizes and such if you want em.

    Tube Nube

    Posts: 328
    Join date: 2008-12-06
    Age: 51
    Location: Calgary, AB

    Re: Great speakers for my new ST-120

    Post by Tube Nube on Thu Feb 17, 2011 10:59 am

    That's a good value on the cost for cutting to your plan.

    I'm curious to ask about finishing work you did on the cabinets? As I say, they look great, and should encourage other members to take the opportunity to build their own speakers, as they did their amps.

    mantha3

    Posts: 286
    Join date: 2010-11-10

    Re: Great speakers for my new ST-120

    Post by mantha3 on Thu Feb 17, 2011 2:07 pm

    I probably should have included some mention of tools you'd need. The big one is a plunging router. You can use a non plunging router but it is a little more tricky.

    you really need the router and then some form of circle cutting jig. I have this one:
    Circle Jig at Parts Express

    You need a bit to cut the holes... You run a 1/4" bit in this jig... Cut a hole and then re-set the jig a little smaller.. Run a hold again..

    You can do it nice and do a larger recess hole for the speaker edges to sit in and then a smaller hole thru the wood. The speaker sitting in the recessed hole looks nice. With the router and the circle jig it is easy and fun. Just keep zipping circles.

    I also used a rounder on the face and back

    Wood clamps are realy handy when building the boxes.

    The rest is a drill... Bits... Sandpaper. I think most people have this.. Then a solder iron and solder. I think most people on this forum have this.

    If you think you may build some speakers like this then I'd get the router and circle jig.. play with some cheap wood to get a hang of it. The rounder is a piece of cake... it has a ball bearing on the bottom to guide it

    Tube Nube

    Posts: 328
    Join date: 2008-12-06
    Age: 51
    Location: Calgary, AB

    Re: Great speakers for my new ST-120

    Post by Tube Nube on Thu Feb 17, 2011 3:17 pm

    What is it that the guys who do a lot of routing always say? Oh yeah, "hey buddy, can you spare a finger?"

    Maybe it's table routers that are dangerous, but those things scare me.

    I used a hand held belt sander to round the outside edges of my Saburos. For the driver hole, used a drill attachment to make a 4" hole, I think it was, and then a sander attachment for the same drill to get the bevel. Not a exactly pretty, but reasonably symmetrical. Router would have been best I think.


    Luddite

    Posts: 235
    Join date: 2009-02-04
    Age: 64
    Location: Texas

    Re: Great speakers for my new ST-120

    Post by Luddite on Thu Feb 17, 2011 3:47 pm

    I agree with everything mantha3 wrote! Here's an additional suggestion: If you don't have access to a good quality table saw, I would highly recommend finding a wood supplier that does have one and will pre-cut all of your cabinet pieces. The cutting charge is usually minimal compared to the cost of the wood. Yes, you can buy pre-cut wood at the mega home centers No , but they typically do their cutting with imprecise panel cutters, not table saws. You will find that having all your pieces consistently and accurately cut will make the assembly much, much, quicker and easier!

    Best Regards, Charlie

    P.S. Tube Nube...I have been using routers for years and still have all nine (uh, I mean ten Wink) of my fingers. Seriously, all power tools (actually all tools!) can be hazardous if used carelessly. But then, we builders of thermionic electronics routinely work with potentially lethal voltages which, if caution were not employed, might produce far worse results than just a missing finger.

    mantha3

    Posts: 286
    Join date: 2010-11-10

    Re: Great speakers for my new ST-120

    Post by mantha3 on Fri Feb 18, 2011 7:53 am

    Yup, find a good smaller family owned lumber supplier who sells higher quality maple, oak or even better Baltic birch (Troels Gravesen and others in Norway like this). Anyway, find a lumber supplier who has a saw. The place I went to had a giant one and could cut to size. The blade was not the best... One side of the cut board may be rough... Just have that on the inside of the speaker. Go to the lumber yard with a clear layout of the cuts like this:



    Then put a plan together for the build... This is from Troels on his side for these speakers.. he does mm... So I started to convert to inch.



    PS - I don't think a router is that dangerous... Not much more then a drill. table routers I can see being more of an issue.

    Building the crossovers is supuer easy for someone who built or re-built these amps... Go to www.partsexpress and they have some "how-to" on building crossovers and speakers.. Just busy work that is rewarding. Troels also is great with e-mail response. Like the Bob Latino of speaker building. Check the other speakers Troels has designed.. He has 2 or 3 tube amps and has many other speaker designs better then the pair I built.. But more $$ for the parts.

    Luddite

    Posts: 235
    Join date: 2009-02-04
    Age: 64
    Location: Texas

    Re: Great speakers for my new ST-120

    Post by Luddite on Fri Feb 18, 2011 11:37 am

    mantha3 wrote: The place I went to had a giant one and could cut to size. The blade was not the best... One side of the cut board may be rough... Just have that on the inside of the speaker.

    It may not have been the blade after all. The veneer layer on plywood is typically about 3/64" thick and is prone to tear-out on the bottom side of the piece being cut, even with a sharp blade. This can be minimized by using a solid insert in the saw table and then running the blade up through the insert for close tolerance, however this procedure is not practical at a commercial lumber supplier. Of course, as long as all cutting is done with the good side up, then the "rough" edges will (as you noted) be hidden inside.

    Best Regards, Charlie

    P.S. If you really want "razor" accurate edges, then cut the pieces a few thirty-seconds oversize and plane them down to exact size on a wood jointer. Years ago, I built a couple of folded horn enclosures using that procedure, however that was mainly due to the odd angles required on many of the edges. Finally, if you're really particular and willing to pay the bucks (ouch!!!) find a cabinet shop that can cut everything, including the driver and port openings, on a CNC wood cutting machine...now that's nearing perfection. Very Happy

      Current date/time is Fri Oct 24, 2014 11:47 am