Danelectro - BLT Slap Echo Variable Delay Mod

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Danelectro - BLT Slap Echo Variable Delay Mod

Postby soulsonic » 09 Feb 2009, 01:49

Hi everyone! I just modded my Dano BLT Slap Echo to have variable delay. It was super-easy and the results sound great!
Here's the step-by-step:
Needed parts:
- 50K linear taper potentiometer; smallest size you can find... ~9mm size works good.
- Resistor; 180 Ohm
- Wire; approximately 6 to 7cm of 22 gauge solid core.

Steps:
1 - Open it up and remove the boards.
2 - On the main board (the one with the controls on it), locate the PT2399S delay chip; it should be on the lower left-hand side if you have the control oriented along the top edge.
3 - Connected to Pin 6 of the PT2399S is a small chip resistor labeled "682". Remove this. Just heat up the solder joints and you should be able to push it off the board with the iron.
4 - Drill a couple small holes on the pads where the resistor used to be. I used a #71 size drillbit, but you can use whatever you usually use for drilling boards.
5 - Connect a 180ohm resistor to one pad (any value between 150 and 220 ohm should be fine), keep the legs long so it is able to reach up to the area where the controls are located. Put some insulation on the leads so it won't short against the LED legs.
6 - Connect a wire from the remaining pad and have it also be long enough to reach to the area where the controls are.
7 - Connect a 50K control to the wire and resistor. Connect the resistor to lug 3 and the wire to lug 1. Lugs 2&3 should be connected together. Locate the new control in the space between the two existing controls.
8 - Drill a hole in the box for the new control - there is a spot between the two controls that is already marked inside the box.
9 - Put it back together and you should be ready to go. The new control gives you variable delay time. The BLT is now a full-fledged delay/echo box instead of one-trick-pony it was before.

Enjoy!
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby sevinisthenumber » 12 Feb 2009, 20:46

Thanks!
"The man who says he knows everything will never know the truth"
C.S. Lewis
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby soulsonic » 13 Feb 2009, 09:54

You're welcome!
It was surprised at how good it sounds. Even at max delay time, the signal is still clean sounding. I worried that maybe the stock amount of filtering wouldn't be enough for the long delays, but it's fine as-is. It has what I would describe as a very neutral sound. It doesn't have a funky "warm" analog sound, but it doesn't have a chilly bad digital sound either. It's just neutral.
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby Ilikethewaythatburns » 04 Jun 2009, 10:14

I can't find the resistor labeled 682, is it connected to the 6th pin on the top or the underside of the chip?
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby Draal » 05 Aug 2009, 17:23

I'm a little late to the party but, this sounds like a cool mod to try! I have a BLT and find it does a pretty good slap back and surf, especially considering the price. But I agree that it's range is a bit limited. We'll change that soon enough!

Thanks for the post dude :D
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby IPickMyNoise » 13 Nov 2010, 18:22

Hi, I did this mod but without the small series resistor and I used 100K pot. I did this with the assumption that I might get a wider delay time range and higher possibility for chaotic effects. It sounds good and is super fun. But without having done the original mod I really can't compare.
Additionally, I was able to achieve greater than unity feedback when the repeat knob is dimed. I did this but following the center tap of the Repeat pot till I came to a resistor that was in series on this trace. I just jumped the resistor. Might have messed with the frequency response of the feedback gain as some frequencies seem to still decay while others grow, but I can get some nice swelling swatches of sound now.
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby ilcaccillo » 11 Sep 2016, 12:00

Nice Mods,
I would like to try these and also have some ideas I would like to implement.

Is there any chance anyone has a schematic for this pedal?

Thanks
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby Sir Fayzalot » 13 Sep 2016, 15:08

I have the Fab Echo, the delay length mod is the same: across 682 (in reality a 6.8K ohm resistor) on leg 6 of PT2399S.

Curious if the circuit is the same, the pots have the same controls.

Haven't modded mine yet, but I tried touching various resistors across that resistor. My favourite (out of the resistors I have) was a 10K, it gave a nice reverb like a reverb tank. It seems most people want to use this like a delay, I'm more interested in reverb and find the stock time too long.
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby ilcaccillo » 14 Sep 2016, 02:51

Sir Fayzalot wrote:I have the Fab Echo, the delay length mod is the same: across 682 (in reality a 6.8K ohm resistor) on leg 6 of PT2399S.

Curious if the circuit is the same, the pots have the same controls.


I'm also really curious to know if the circuit is the same between the BLT and the Fab Echo,
at least they use the same Chip so if not the same the circuits will be similar
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby Sir Fayzalot » 14 Sep 2016, 08:27

I tried to check out the demos of the BLT on Youtube, they're not that good to be able to tell if it sounds exactly the same.

Could just buy a BLT, but the only place that I've seen them for sale has them at 43 Euros, which is way too much. Maybe if I find a cheap used one.

There's also the Corned Beef, but the controls are not exactly the same. And even harder to find than the BLT.
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Re: Danelectro - BLT Slap Echo Variable Delay Mod

Postby ilcaccillo » 14 Sep 2016, 14:41

Yes they all use the PT2399 chip, although in the Corned Beef it's implemented to make a fake "kinda reverb" sound.
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