Build a Franklin Audio SS6 but far better sound quality

[xarolium]

Hi there,

As there is no forum about Direct Box i presume it is the most adapted forum to post it. (feel free to move the topic if i'm off)
As you probably see on the social media (too much besides) Franklin audio propose on his shop a stereo DI with 6 inputs and a rotary switch to select the desired input for 400USD or 340€.
I found it quite expensive but if they use high grade parts like audio transformer (Lundhal, Jensen, Carnhill, Haufe, Cinemag or Showter..) or rotary switch (Elma or grayhill...) it's ok but IT IS NOT THE CASE

The SS6 is equipped with Chinese transformer (Franklin Audio said custom made...) and alpha rotary switch like those one:

You can find those part on Aliexpress: the switch 5pcs for 3.71USD and the transformer for 7.56USD

The idea of a switched DI is very good but i think Franklin Audio can make it better or cheaper.

Let build my own using those part:
- Grayhill 71A36 rotary switch : 35.72€
- Lundhal LL1935 x2 : 82€/pcs
- Neutrik NRJ6HF jacks x12 : 0.9€/pcs
- Neutrik XLR NC3FB x2 : 3.7€/pcs
- A custom PCB (approximatly cost 10€)
- A Aluminium case 80x160x170mm 11.6€ (if more than 50 members are interested, i can make a silkscreened custom case with logos...)

And i'm done for less than 240€ i have a high end 6 input selected Direct Box.
Of course it can be customized with different transformer by adding different footprint on the PCB, add a input pad for each input.
It can be cheaper too if you need one, i can organize a bulk order for the parts. (50 parts minimum for the bulk order)
Anyone interested ?

 

[Jim50hertz]

Interested!

 

[ruffrecords]

Bear in mind that with a 10K:600 transformer this only works with regular line level signals such as you get from synths, pedals or drum machies. This will not work directly with guitars.

Edit: but with the Lundahl LL1935 wired 10:1 you should be fine.

Cheers

Ian

 

[ruffrecords]

I am not sure about the switch you have selected. For switching two balanced signals you need a four pole switch so you either need four decks or two decks with 2 poles per deck. If you use the 36 degree version of the Grayhill 71 series switch you will need four decks. If you use the 30 degree version you can get two poles by 6 ways per deck. You probably need something like the 71B30-02-2-06N

I chose the B version because it has a regular quarter inch shaft.

Cheers

Ian

 

[xarolium]

I am not sure about the switch you have selected. For switching two balanced signals you need a four pole switch so you either need four decks or two decks with 2 poles per deck. If you use the 36 degree version of the Grayhill 71 series switch you will need four decks. If you use the 30 degree version you can get two poles by 6 ways per deck. You probably need something like the 71B30-02-2-06N

I chose the B version because it has a regular quarter inch shaft.

Cheers

Ian

Hi Ian,

I don't need to switch balanced signal cause the switch choose input signal that are unbalanced so only two decks switch is enough to switch the stereo input signal

 

[Frankin Audio]

Hey guys!

Looks like a really fun DIY project!

I couldn't tell you if the transformer in the screenshot you posted comes from the same factory we use or not as that square shielding can is ubiquitous throughout China. You'll find a wide range of transformers inside that can. I've not seen our factory use the JQ marking before but who knows?

Evidently, I don't share the same feelings as the OP about Chinese made transformers, and I back our products and the transformers we use 100% - based on not only listening but more importantly Quant Asylum and AP testing. We shot heaps of transformers out against my large collection of new and vintage "household name" transformers and I have no reservations about our choice. There are a lot of brands you'll all know that are much bigger than us using the same factory.

If you can find our factory and you want to save a few bucks I'd highly recommend giving them a try - I think you'll be pleasantly surprised if you approach your testing with an open mind.

In any case I would second what Ian said, and suggest using a transformer with a much higher primary impedance than 10K if guitars might be connected. We used a 10K:600 transformer in the first SS-6's but our customers surprised us with how much it was being used for guitar so we swapped transformers more recently. 10K:600 is aslo only borderline enough attenuation to get down to mic level - 10:1 ratio works better. You won't find that in the square can so theres a hint for you supplier detectives

The link you've posted is not the rotary switch we use, looks like a copy. Again if anyone wants to save a few bucks and use the one we do its Alpha brand - similar to this. They feel great and work perfectly.

A couple of bits of advice for bulding a DIY SS-6:

1. If I were building a one-off or even a small run I would use stacking jacks like these instead of single mono jacks. That way you don't have to have two boards for the two rows of jacks and saves having to find a way to join the two boards. We only stopped doing that because mouser kept running out of the stacking jacks in the quantities we needed and the single jacks are available in much more steady supply.

2. If you use any kind of ribbon cable to join your boards to the rotary switch, or to another board just be sure to put a ground on every other wire otherwise you'll get crosstalk between inputs. Observe good layout practice when routing your grounds/returns and you can get the crosstalk to non-existant levels.

3. If you use switching jacks you can set up the switched tip on the right jack so it picks up the left input when nothing is connected. Multing the left input to both channels is great when you're flicking between stereo and mono synths!

4. They do end up with a lot of cables tugging on them. An alu enclosure is usually fine but we find the extra weight of a steel enclosure helps stabilise on the desk if the cables are trying to pull it off your table! Steel is a bit harder to drill DIY though!

I know a few places that offer short run, even one-off printing/milling etc if anyone wants the hookups just DM me and I'll point you in the right direction.

Happy building!

Nick