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FLEXIMIX for preamp

PostPosted: Mon Jan 21, 2013 5:01 am
by Victoria
Hello !

I'm French, so my english isn't very good .

I'm looking for a trident console, to have 12 trident preamps on my studio.
(not to mix with)
Some technician told me about a TRIMIX 16 he sells .

What do you think about preamps ?
I know 80 series or - less - triden S20 preamp, I love trident sound, but what about TRIMIX ?

I have to tell you that the console is in a really good condition, with 48 V on all tracks, penny & gilles faders, etc ....

Thanks for your answer

Re: FLEXIMIX for preamp

PostPosted: Tue Jan 22, 2013 11:58 am
by Jim Williams
The series 70, or "Tri-to-mix" has a pretty messed up mic pre design. Unlike the series 80 and Flexmix that both used the same card, this one is a 5534 opamp design with an attenuator in front of that opamp. That will degrade the s/n ratios at lower gains and also loads down the transformer secondary at lower gains. Like the 80 designs, you get either peaking or damping dependent on the gain settings.

I would rewire it so that attenuator gain pot is wired into the first opamp stage feedback loop, then s/n ratios are maintained. Then you can short out that input blocking cap. Drop in a National LME49710NA opamp and enjoy.

Re: FLEXIMIX for preamp

PostPosted: Wed Jan 23, 2013 2:40 am
by Victoria
Thank you for your answer !

I don't know if I have all well understood,
but, to you, the big diference is about the S/N ratio.
And do you think preamp have good sound for studio recording ?

But what I don't understand is about the attenuator.
Do you mean each opamp 5534 on the fleximix has one ?
(I don't see any PAD button so I think it's what you mean).
Or only on line input ?

So if I understand, to have a good S/N ratio, I have 2 option :
- wire the attenuator on the first opamp
- put a National LME49710NA opamp

is it ?

I have to say that the fleximix I saw is 48 V , all "recapped" (condenser, P&G fader) and separated Alim.
Maybe can I ask the technician to make one more modification on opamp ...

thank you !!

Re: FLEXIMIX for preamp

PostPosted: Wed Jan 23, 2013 11:29 am
by Jim Williams
Some like those Trident preamps, I'm one that prefers clearer sounding gear. Flexmix and 80 preamps can be fixed up but that requires cutting traces on the cards and rewiring it non-inverting. I've done some with Jensen JT-13KC input transformers and those sound excellent.

It will be work, but I like the results far better than the stock designs and transformers.

Re: FLEXIMIX for preamp

PostPosted: Tue Feb 12, 2013 9:16 am
by zilla
Mr Jim Williams,

I read so much useful stuff from you all over the place online regarding these type of things, i know little of what ti all means but just wanted to send respect to you for always taking the time to answer the questions that float around....

Secondly, I have a Trimix and really like it although i actually don't use the pre's as i'm mainly summing from my DAW and using a the Trimix EQ's here and there...

My question is whether i'd see some vast improvement by getting a new PSU built? My desk is only 16:8:2 so i've read that the original Trident PSU that came with it would happily power the channels because it was designed for two times as many channels potentially...

But if i wanted to do any IC upgrades or whatever would i then need a new PSU? Would a new PSU generally help performance? I get the odd crackle here and there which seems to be on the master LR? but this stops happening when i've been powered up for a bit and the desk is "warmed up"?

Maybe i need to recapp the PSU? The whole desk was recapped recently while i've owned it...

Any thoughts or explanation as to why a new PSU would improve the quality of the audio or signal to noise ratio would be greatly appreciated.... I find it a bit confusing tbh...

But i do like the console, the EQ is nice to my ears although i'd like to lower the bottom band from 100 to 60 on a couple of channels at least...change caps? I read that somewhere...

If you had time, could be bothered to chime in should you see this... then thank you..


Re: FLEXIMIX for preamp

PostPosted: Tue Feb 12, 2013 11:15 am
by Jim Williams
Trident power supplies are weak like many Brit console supplies. Best to replace it. A pair of Power One 9 amp 15 volters would do it. Add a 1/2 amp 48 volt for phantom. The results are less noise, greater low end depth and energy, a clearer top end with better transients. Reliability goes way up.

Re: FLEXIMIX for preamp

PostPosted: Tue Feb 12, 2013 7:10 pm
by zilla
Thanks Jim, I will pass this info on to Tim @ StudioSystems who was saying he could build me a new PSU for my Trimix...

When I get it done and experience the results I will post further gratitude along with my findings here to help others...

Can you offer insight on whether changing the values of these two caps on the EQ can change the LF pot from 100 down to 60 as I have been told elsewhere?

Okay, sorry for endless questions I'm sure you're busy... I sure wish you where local to me in the UK!

Thanx again.