i'm writing because i'm willing to do some modifications to my 1608 master channel: i'm going to remove the surround, center and LFE channels, to make room for vishay axial capacitors, and the bigger 2503 transformers in the booster circuits leaving only th left and right control room channels but need a suggestion here: i'm thinking about changing the control room left and right channels using That 1646 output instead of transformer output to have more space and maybe add the possibility to switch between two sets of output transformers in the boost section. what do you guys think? does that make sense or is useless?
insert quote here I’m curious, what transformers are in there now?
now there's the stock api's 2623 wired 1:2 on the ACA and another 2623 wired 1:1 on the booster.
insert quote here Why do you want to replace them?
i just want to try a 2503 on the booster as in the 70's api consoles
insert quote here And when you say using an IC balance in the CR out vs the boost are you talking about eliminating a transformer on an ACA?
I'm talking about replacing a transformer in the CR out ( again a 2623 wired 1:2) with That's 1646 or something more neutral as to listen to the sound of the summing without added color, i don't know if this makes sense.
Are you talking about the program aca and booster or the output transformer on the control room card?
On the API docs I've seen the 2503 and the 2623 have the same basic specs - 75 ohm primary impedance, 30-20kHz +/- 0.5 dB, +30 dBm maximum level. The only obvious difference is that the 2503 is 1:1,1,1 and the 2623 is 1:1,1. I would just get a 2503 and wire it in temporary-like before I started into major modifications to have it. I don't have good ears at all, so keep that in mind, but I would bet a lot of money that I could not tell the difference between a 2623 and a 2503 in a blind test.
On the CR out, I would guess that you should be able to to wire in a mult on the primary side (coming out of the 2520) to feed your "clean" circuit. Got a photo?
teak you dodgers, i'll look into it. maybe in the old days having the 2503 in the booster was useful for another output from the third secondary winding. in fact the legacy consoles, both old and new ones, have 2623 throughout the console. still i'm wondering why using a 2503 for example in the api 312 preamp? because i don't think it is wired 1:3 i either in the 312?
I’ve wondered that myself. The original 312 preamp out was a 2623. But I believe a balanced direct out would have been fed by a 325 with a 2503. The 312 is 1:2, I’m not sure what they do with the third winding.
I do know in the new 535 they have it selectable for 1:2 or 1:3.
I checked the 2488 console block diagram and seems like the 325 boosters are used for driving monitors in the studio and in the control room, but the diagram doesn't specify what was used in the ACA so maybe it was all 2623
A 325 used a 2503. The 2623 was, if I’m not mistaken, used for ACA and mic pres. Wiring a monitor path that doesn’t have an extra transformer vs what is being recorded seems like a reasonable idea. But, you could also just go unbalanced if it is a short run and if you don’t have a lot of noise.
I would test it with a breadboard before I started permanently modifying anything, but that’s just me.
yeah, but I was thinking about making a new board so I can remove the stock one and put my own in its place so I'm trying to figure what kind of changing are needed before committing to manufacturing the board. I don't mix 5.1 so I just need L&R channels. I don't want coloration in the monitoring so a trafoless out could be the solution. I'd also like the idea of trying different transformers and I was thinking how could I perform a switching between them without the need to remove the module. the main problem is the space in the module itself so i have to decide which priorities are the most important.
by the way, reading through some api312 document it's stated that the need for a three secondaries output transformer comes from the idea of using them to drive "microphone fader, a cue and/or echo bus" without causing "unwanted signal coupling in the DC commons, with may lead to oscillation or crosstalk".
Post by Cyrus Melchor on Sept 10, 2018 10:19:10 GMT -6
Here's an opinion- instead of the THAT output how about going passive and just upgrading the transformers to Jensen high nickel JT-11DM - or if you've got room, BM. You won't need to wire up any voltage or make pcb's and the Jensen's are pretty darn transparent. I put the BM in the main master out of my Yamaha PM-2000 and it really cleared things up nicely.
Give Jeff at CAPI a shout, he helped Noah and Roundbadge get more Classic tone out of their 1608’s.
thank you ericn, i've read the thread about the modifications the Jeff carried out to theirs 1608s, that is a part of the mods i'd do to the console, but for the time being i wish to work on the master module, then on the submasters and then create 8 new channels to go together with the existing ones in order to have 24 channels in the end
Cool! What all are the mods? Look like 1731s going in?
Yeah! 1731 were the ones i had at hand, but i will try stock api 2520 for comparison. so in the the end i decided for 2503 on the booster, 2623 on the aca, that 1646 on the control room output. i also ordered high nickel 2503 from Jeff to compare on the booster.
Hurray!!!! it's working! Finally i can monitor my master bus through that 1646 so i can hear better what is going on on my mixbus! I have used ne 5534 not make up gai amplifier through 1646 as output driver and the difference is definitely there! so happy!!!