Direct outs on an Altec 1567a

I would like to add direct outputs to my Altec mixer. I've been looking around all day trying to find an example of how to do this but im at a loss.  I'm thinking I would tie something on the output of p2 before r18 but what exactly that would be is what im interested in. Im sure someone is just gonna send a link to the perfect thing, but input on this output would appreciated.

you need a buffer amp stage, unless you are feeding a 250K ohm input impedance.  There is no perfect thing; it's more wishful thinking than practical reality.  You could do it SS most easily, but that's probably not the idea. 

A 6Sn7/12au7(6CG7) family cathode follower stage should get you to typical DAW inputs ok.  What you're interested in is a buffer stage like Doug mentioned to 1)provide enough current(power) to drive your desired input and 2) lower the output impedance

When you consider the amount of work and other requirements - extra heater power, physical space for each (4?) and possibly an output transformer  it would seem to equal out to just using the 4722s and building from scratch.

If there's something really unique to the stock sound that you like - that would include the tone control stage and output stage which will be gone with DOs taken after the first stage.

These things were kind of designed to be paired with Altec 1568/69 power amps which use a 200-250K pot to set the input impedance.  The inputs you're likely interested in driving are a lot lower than this.

I have two of these units (both with the octal based input and output TX's). I was considering gutting them and using tube sockets, PT, etc to make a couple four channel NYD1B's or something like that... Basically just gut them and do something cool with the parts.

After looking into the potential evil-bay value of the units (maybe $0.8k-$1.2k/ea), I am now considering selling these to fund my NYD1B's or whatever. I'm thinking that 1.5k-2k would yield better parts than gutting these units.

The coolest part is that I picked thes up about 9 years ago at a mere $200 for both!

My $0.02
-j

0dbfs said:

I have two of these units (both with the octal based input and output TX's). I was considering gutting them and using tube sockets, PT, etc to make a couple four channel NYD1B's or something like that... Basically just gut them and do something cool with the parts.

After looking into the potential evil-bay value of the units (maybe $0.8k-$1.2k/ea), I am now considering selling these to fund my NYD1B's or whatever. I'm thinking that 1.5k-2k would yield better parts than gutting these units.

The coolest part is that I picked thes up about 9 years ago at a mere $200 for both!

My $0.02
-j

Click to expand...

Your second suggestion makes mucho more sense . . er dollars for your budget that is.  Keep a pair of the inputs and you'll probably still get enough to make 4 channels.

800 to 1200 is really crazy money for these and a lot of it reflects greedy bandwagon hopping. I've seen a number of them sit when the bidding starts too high. 

Some of the blame is shared by the MC step up crowd chasing the fruit cans.  There was a guy on ebay several months back with a whole stash of super nice UTC or Gramer - can't remember which - dedicated MC iron - 100:100K.  Selling for ~$45.00 each.  Looked to be high quality large core cans. I almost bought one to try as a mic input.  They languished while people were paying silly money for the smaller Peerless, RCA, Ampex and Dukane units - and apparently they're getting hot on UTC A-10s now.

10-4 on that one!

Seems like I could make a "better" set of preamps for that scratch anyway. May go for putting together two 1RU dedicated 4-banger 312's since I already have a 3124 and really like it. Would be nice to have more channels of the same or similar.

In any case, I may need to clean up the 1567A's since they are not very "shiny" and I believe that there are some leaky filter caps. I did convert one to a five input line mixer. Used it a couple times and have not really looked back.

Best,
jonathan

Sell sell sell.  I have a pathological dislike of those things, for no reason other than the lemming factor of people liking them while being ignorant of all the other great stuff out there.  If that offends anyone, it's not my problem.   

I have a 1567.  I harvested the transformers and pitched it in the junk pile.  At one point, I bread-boarded part of the circuit.  Total waste of time.

Butterylicious said:

I have a 1567.  I harvested the transformers and pitched it in the junk pile.  At one point, I bread-boarded part of the circuit.  Total waste of time.

Click to expand...

I felt that way after breadboarding an MB-1 . . . and If I'd had the orig grid iron I would've used it elsewhere as well.

It has a sound I like which is hard to get any other way, unless someone has any suggestions??? I like the old school drum sound, calf skin heads, thin cymbals and lots of dark thump.
Ive ditched the idea of building direct outputs. I'm just going to put some pads a phase flip and phantom power into a box, and give myself some more options.

bluesbaz said:

It has a sound I like which is hard to get any other way, unless someone has any suggestions??? I like the old school drum sound, calf skin heads, thin cymbals and lots of dark thump.
Ive ditched the idea of building direct outputs. I'm just going to put some pads a phase flip and phantom power into a box, and give myself some more options.

Click to expand...

That sounds like a good plan.  Nice thing is you've got 3 spare input transformers to build whatever you want with or sale a pair for plenty of resource cash.  They're plug-ins so they're solderless and easily removed should they need to be reinstalled for resale. 

The sound you described - I kind of know what you're referring to and tend to think of it as predominantly to do with the drums and their set up first, and then mic (ribbons!) and amp choices to complement.  A Gates SA-39 comes to mind as a very well suited companion for that sound - dark with plenty of big thump.  And it doesn't necessarily require comp/limiting action to achieve that tonal flavor.

You may be able to equal or outdo what you like in the 1567 with a good 2 stage design.

Any particular two stage pres in mind?
-s

Any of NYDaves designs will be good solid circuits with a budget in mind - they'll work well with the Edcor outputs or transformerless outs.

Lots of the classic SE stuff - RCA BA2 or BA1,  Langevin 111/WE 120,  Collins 6Q - all very good sounding

One circuit of interest is :

http://www.audiosharing.com/archive/western/we_amp/pdf/No.141-A.pdf

I thought of this since it has a total gain figure a little closer to what the 1567 is in case that turns out to be the factor that's more important to the sound you're getting.  It also has a better output impedance for optimizing your recorder interfacing.  No output transformer needed.

emrr built one here:

http://www.groupdiy.com/index.php?topic=28447.0

I've been thinking of basing an 8 channel console on these.  Tiny panel - big amp.

I will be looking into a couple of those when I get back into town.
-s