Slow Burn: Drip Fairchild 670 (V2) Build... as fast as I can afford it.

[thecr4ne]

I recently came up on a Drip Electronics 670 V2 pcb set. Despite this project being way out of my price range, I'm taking it on anyway. My plan is to buy parts as I can afford them, and find the best deals I can, since I'll have plenty of time while I'm waiting for my wallet to recover from each parts order. I consider myself a reasonably capable novice. I've modded a few mics and recapped/blackfaced my 1971 Bassman. The Drip documentation appears to be thorough enough that I can handle it.

I'm planning to use Hammond power transformers and Sowter audio transformers.
I'll probably make multiple parts orders, to spread out the cost.
Looking for a case or at least a faceplate.

What I have so far:
Drip V2 PBC set. (Main board, 2x Time Constant boards. Missing DC heater board and Auto AGC board. I've reached out to Drip)
4x New JJ 6386LGP
3x RCA 6973 (the search continues for the 4th)
1x Mullard EL-34
My choice of old 12ax7's
2x Female Neutrik XLR connectors
Some Bakelite knobs (mostly the wrong sizes, but all the right vintage vibe)

I welcome any advice, leftover parts, suggestions, and emotional support from the fine folks here on GroupDIY.  I promise lots of stupid questions like "what kind of wire did you use?"  and "what's a good substitution for discontinued component X?"
Here we go...

 

[thecr4ne]

No real progress made here, because $. I reached out to Drip, but they've been busy with new product releases and Greg's making a bunch of build videos. He said he'd look for a v2 MS Matrix (aka auto agc) board, but didn't actually say anything in his response about the DC heater board.

In a new video he posted for their Pultec v2 (https://vimeo.com/234069966) he mentions the DC heater being there to lower the noise floor and potentially prolong tube life, but that the design should allow for running it off AC instead. Can anyone speak to the concept behind this, and whether it applies to the 670 V2 as well? Pros/Cons?

 

[JCN1218]

Hi there, good luck to you on the build. Looking forward to following your progress. If you don't mind, I hope you could help me out with something.

I'd kind of like to get in the same boat as you, to get the boards and stuff them over time. I don't know if it's just me, but I can't figure out how to buy anything off of the drip website. I'd love to get my hands on the 670 boards, but I just don't know how to do it. Maybe they've just been out of stock. Any ideas?

 

[thecr4ne]

... I don't know if it's just me, but I can't figure out how to buy anything off of the drip website...

Email [email protected] if they've got it in stock, they will let you know the price and send you a Paypal invoice. I bought mine through another person who decided not to go through with the project, which is why I have v2 (and the above questions) instead of v3 (they told me the 670 v3 boards were $650 USD + shipping)

They are about to get in a shipment of their pcbs for the Pultec  eq in the next week or two, if you want to start with a simpler (and less expensive) build, you might be able to order one before they run out.

 

[JCN1218]

Thanks for the info! Those are some expensive boards, but they're still definitely on my wishlist, just in the future. Right now I'm just finishing up some EZ1290s and have boards for stereo 1176 and fripholm's TG1 coming in very soon. So I've got my hands full right now anyway, haha 

 

[shabtek]

If cost is no object: why not do it like the original?

 

[thecr4ne]

If cost is no object: why not do it like the original?

Because the 8x 6386 tubes will cost about $1000 for the set. When the fairchild 670  was designed, they were readily available and cheap. Today, old ones are nearly extinct and new ones are hard to find cheaper than $120 each. Greg explains in his recent videos for the V3 that the DC heater design is meant to regulate power to the tubes to  help minimize the potential for power issues to kill them.

 

[thecr4ne]

Minor update.
I've acquired all Hammond power transformers, 374BX (high voltage), 193J (high voltage choke), 167S6 (psu heater), 167L24 (bias supply), 167N10 (signal amp heater)  and 193H (bias supply choke[used the specs of the Sowter L302 to chose this one, thoughts?]) Total cost (including tax and shipping) $339.28

I ordered a Bud RM-14215 6U Case for $105. I can't justify the cost of a custom enclosure, and I've got access to a laser cutter I might use to etch the front panel.  I think I'll need to order a top and bottom separately, but I'll wait till I've assembled the back panel.

I won an ebay auction for 6x JJ 6386s for a total of $302.52. That puts me up to 10x JJ 6386's total at just over $50/each. Pretty stoked about this.

So far I'm about $1235 into this project total. Not bad. Hoping to keep the total under $5k. We'll see.

The next big step will likely be the Sowter order for the audio transformers. That's gonna be a big bite so I'll do my best to save and combine it with the Sowters for the 2x Drip EQ-1s I'll be building also...yeah, I know. (the boards arrived yesterday and they're beautiful)

I'm still lacking the DC Heater (aka Signal Amp Heater) board and the Auto AGC  (aka M/S) board from Drip, so I'm awaiting some sort of miracle from them (please let these be sitting in a drawer somewhere). Greg has said on the facebook page that he'll eventually re-release some stuff at some point as well.

I'll need to think about meters at some point and then I'll place the big Mouser order last for all the little bits.