Mix Out Noisy/Distorted

Discuss Nava construction and related issues

Re: Mix Out Noisy/Distorted

Postby AonFluX » Sep 28th, '16, 06:34

KlangGenerator wrote:Ok, I've just added the 10uf caps. I am very happy with the result. The noise floor is way better now. Still not as perfect as on the individual outs, but for me it is absolutely tolerable like this.

Also as a nice side effect the overall output level of the instruments, especially of the BD, is a bit higher now on the mix out compared to the separate ones. Sounds really nice! :mrgreen:


Which part-nr are you talking about? Where did you add the 10u?
AonFluX
 
Posts: 68
Joined: Apr 27th, '16, 07:26

Re: Mix Out Noisy/Distorted

Postby KlangGenerator » Sep 28th, '16, 07:10

KlangGenerator wrote:Also very interesting:

https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/584333-tr909-owners-stereo-out-less-bass-than-individual.html

I will try replacing the caps with 10uf ones as I don't want to lose all that bottom end on the main outs.


C153/ C154
User avatar
KlangGenerator
 
Posts: 305
Joined: Aug 8th, '16, 16:36

Re: Mix Out Noisy/Distorted

Postby redstorm » Nov 26th, '16, 08:26

Don't want to make another thread, so bumpin' this.
I'm building the remaining seq&mixer part currently and if i understand correctly, i can omit safely all the parts that is belong to the muting circuit [ To name the parts exactly - C142, C143, D193, D194, D195, R468, R469, R470, R471, R472, Q82, Q83 ], if i don't need that muting circuit, that is used only once on power on. One thing i only think about, is to put some high resistance (100k-1M) between Q82, Q83 collector and emitter to have some ground current path for opamp.
redstorm
 
Posts: 25
Joined: May 18th, '16, 13:09

Re: Mix Out Noisy/Distorted

Postby e-licktronic » Nov 27th, '16, 03:26

redstorm wrote:Don't want to make another thread, so bumpin' this.
I'm building the remaining seq&mixer part currently and if i understand correctly, i can omit safely all the parts that is belong to the muting circuit [ To name the parts exactly - C142, C143, D193, D194, D195, R468, R469, R470, R471, R472, Q82, Q83 ], if i don't need that muting circuit, that is used only once on power on. One thing i only think about, is to put some high resistance (100k-1M) between Q82, Q83 collector and emitter to have some ground current path for opamp.


Dear Redstrom,

To bypass the muting circuit simply omit both transistors Q82 and Q83 and you don't need all part from the muting circuit (C142, C143, D193, D194, D195, R468, R469, R470, R471, R472)

Best regards,
e-licktronic
Best regards,
e-licktronic
User avatar
e-licktronic
Site Admin
 
Posts: 548
Joined: Feb 16th, '11, 13:36

Re: Mix Out Noisy/Distorted

Postby Mochi_Stryper » Jun 12th, '17, 04:42

I also battled with an overwhelming noise floor on my master output. No amount of shielding or ferrite beads or good vibes managed to remedy the noise. Frustratingly, I found no issues with my board either. Fed up with the noise I verified that the muting circuit was the culprit and populated Q82 and Q83 with sockets so that I may test a new pair of 2SC2878. The next pair worked like a charm. I recommend that anybody populating a Nava PCB socket these transistors as it seems that many of them are leaky and ironically the source of much noise and bad juju.
Mochi_Stryper
 
Posts: 2
Joined: Dec 24th, '16, 06:58

Re: Mix Out Noisy/Distorted

Postby lukep_gdansk » Jul 12th, '17, 17:32

After the last build of Nava I also had have terrible noise, but it its gone after complete cleaning the board. I found a little piece of wire shorted one of the transistor. After that master is absolute clean and free of distortions. My suggestion is check build for shorts and bad components (I repaired one Nava with noised master. One of the 69 ic was bad) first!
lukep_gdansk
 
Posts: 98
Joined: Dec 22nd, '16, 17:04

Re: Mix Out Noisy/Distorted

Postby gihaume » Mar 12th, '19, 09:00

I had the same issue as the OP and found this is very likely because of a too weak external voltage transformer. E-licktronic tells us to get a 15VAC 1000mA, just as the Yocto, but I found that the Nava will eat two times more current (just measured). So if like me you used a same transformer, it may explain the issue... Additionally I was measuring the output of various transformers I had and found that the 12V ones were just giving 15V, so thought they were not accorded to their specs and lucky me it would then be just like a 15V one... but in fact they're totally right and it's planned that when loaded their voltage will drop and be as specs.

What I think happens in this case is that the regulators will still want to reach their high spec'd voltage but the transformer can't give enough and the voltage constantly drop of a few mV, producing a more or less nice bassy saw wave which can be heard a bit in the background noise and in my case very noticeably in the Extra9 HH Steiner Parker filter.

About the Master Out being (the only one) distorded, I think the issue is because its level is pretty high, so its amp would like to use the whole +-15V of power and when going high on the same frequencies that the saw/drops from the power rail(s), there will be some distortion.

15VAC 1000mA transformers are not that common... this is just a bit higher than what can be found easily. I'm planning to order the Mascot 8710 (1000mA) or 8810 (1300mA) which should be fine.
gihaume
 
Posts: 225
Joined: May 12th, '14, 14:48

Previous

Return to Nava Hardware

Who is online

Users browsing this forum: No registered users and 1 guest