TBDD-500, TBDD-Rack, TB550A, TB2S

[nielsk]

Payment sent for 2 kits!

 

[horvitz]

Thank you!!

 

[earl]

Got the kit.  Excellent.  Very well done sir.  Will definately be ordering another.  Thank you.

 

[rickc]

are the build docs onlline somewhere?
have you gotten pics online yet?

thanks,
--rick

 

[horvitz]

Earl, glad you like it!  Have fun with the build.

Rick, the build manual is sent along at ship time.  It is 51 pages long, so it would be pretty cumbersome to put online.

I do still need to take some inside pics of the final unit.
There are some good prototype shots on page 3 of my original thread:
http://www.groupdiy.com/index.php?topic=45190.49

Pretty much, the only difference between that and the production unit are the knobs and L-bracket.

 

[horvitz]

Just a quick note that EA2503s are back in stock at ClassicAPI.  If you have been waiting for them, don't delay!  They'll sell out quickly.  Link is in the first post.

  Brian

 

[Songguy]

Horvits!
This is an awesome kit! And definately one of the better build manuels I have seen..great detail and pics.
Not quite sure why some complain about the kit price..it's well worth the money. This build has some serious guts in it. Definately get what u pay for and them some.

Great job ;D

 

[rickc]

I first saw the 550A schematic in 1974. I've had the hots for them ever since. The switching scheme in the rotary switches in the original design makes cloning it yourself quite difficult.  I have been tempted to have a run of switches made (which is what would be required), but minimums and just the hassle of describing the switching logic made it difficult to impossible. Separating the freq and boost/cut switches was the master step in making this doable instead of a random dream.

Horvitz has figured it out, no small feat, and done the homework to get us a board, the hard to get parts (switches), and the metalwork. No small feat. Laying out circuit boards is anything but trivial, much easier now with CAD software, but still, not something any monkey can do. Likewise the metalwork, and then getting all of the different holes in the different pieces to line up.

Let those who think his price is too high try to do it themselves. It's a task that would make many people go postal.

 

[horvitz]

Hey, thanks guys.  Really after all the blood and sweat I put into this thing it means a lot to me that you all are enjoying the kit.  Makes all the effort 100% worthwhile.  So, I do very much appreciate the positive feedback that I've been getting.  And yes, there were definitely times that I was damn near postal (I do love that expression) working through this thing but I couldn't give up the quest.

Point of interest, Rick.  Early on in the project I performed some very nasty surgery on some Grayhill 71s and actually figured out how to modify them to function like the custom switches that API uses.  It's actually not TOO difficult to do but unfortunately the little spring contacts inside get a bit unreliable after the modification so I scrapped the idea.  Doing it the way I have it adds about $15 in extra capacitors and a bunch more assembly work but I feel that the added reliability is certainly worth it.

  Brian

 

[rickc]

I think I figured out how to do the boost/cut part with ordinary switches, but I was obsessed with getting concentric switches...

Yeah, their cut rotors did save on capacitors, but your solution is just fine.
The original was a point-to-point nightmare. this is so much cleaner!

 

[Songguy]

Brian what a great kit! i cant believe that you included every single piece in the kit to make a 550a eq. it sounds awesome, especially on drums and electric gtrs haven't tried it on other sources yet but im really looking forward that.
thanks for your awesome customer service and at the same time, teaching me about how the gain and frequency circuits work.

i have wanted this eq for my lunchbox for the past few years. thanks so much. looking forward to building the other one.
here's a pic of my newest addition.
best,
chris

 

[horvitz]

Awesome!  I'm glad we got it all worked out.  Really nice work.

 

[Biasrocks]

Payment sent for 2 kits.

Regards,
Mark

 

[horvitz]

Thank you for your order!  Will ship today.

  Brian

 

[Songguy]

Hi Brian,
It's time for kit #2!
Thanks,
Chris

 

[luis]

Payment sent for 2 kits.

Regards,
Mark

Hey, since you never sent me the 2 api 2520 that I bought from you a year ago, and you did not replied to the last pm that i sent (also some time ago) remembering you, I accept one of these that you bought, for free.
Let me know when should I espect them to arrive!

(to the op- Sorry for hijacking this thread)

 

[Biasrocks]

Hey, since you never sent me the 2 api 2520 that I bought from you a year ago, and you did not replied to the last pm that i sent (also some time ago) remembering you, I accept one of these that you bought, for free.
Let me know when should I espect them to arrive!

Ah, okay.

Your opamps went out long ago.

Perhaps another PM might be in order friend.

Regards,
Mark

 

[rhythminmind]

Looks really great, I have a pair of Hardy 990's looking for a home. Would these cause any problems if used to replace the 2520's?

 

[horvitz]

Looks really great, I have a pair of Hardy 990's looking for a home. Would these cause any problems if used to replace the 2520's?

Will it work?  Should do.. although I haven't tested it myself.  But of course there's always a "but".  A little quick looking shows me a few comments from John Hardy on exactly this topic:

http://www.audiobanter.com/archive/index.php/t-10845.html
http://www.gearslutz.com/board/1028565-post6.html

If you do it, definitely let us know how you make out!

  Brian

-- Edit: Spammy link removed and replaced with correct link.

 

[rhythminmind]

Well I'll give it a shot, seems like it's really only a bias issue. I'll see if it's worth a resister mod or not. Order on the way!