dmp

Re: MixBuzz500 build/support tHread
« Reply #100 on: July 26, 2010, 01:47:22 PM »
About higher wattage resistors being small, I've noticed this also. My guess is that they are making resistors that have a higher rated max temperature.
From what I remember, higher wattage resistors used to be larger only to increase the surface area for heat transfer. The resistor's power dissipation is transferred to ambient as heat, where the larger the surface area the lower the required resistor temperature for a given power dissipation.


AudioGimmer

Re: MixBuzz500 build/support tHread
« Reply #101 on: July 27, 2010, 11:56:22 AM »
Well, coming along now.
Control boards all done, VCA boards done, just need to finish the Audio boards.
I had ordered all WIMA caps for the polys, and I could only get 100v rated ones, which it turns out are physically too big to fit in the sidechain filter part of the PCBs Doh!
If the suppliers are still out of stock, any other recommended brands/types to look out for?




AG

Igor

Re: MixBuzz500 build/support tHread
« Reply #102 on: July 27, 2010, 02:21:38 PM »
Photos: impressive! Looks very accurate.

Couple of questions

Quote
1. Power for the small board with time constants/ratio etc. Does this come from the 3 points at the top of either audio PCB just above the sym trim pot?

Yes, take the power for small PCB from one of audio boards. 3 wires can be soldered directly,
or with use of Phoenix 2.54mm pitch screw terminals, or with use of 3-pin 2.54mm pitch Molex connector.
Don't crimp, solder! :)
Quote
2. My relays have coil resistance of 360 ohm each. So the resistors R98 and R87 should be 60 Ohm right?
I couldn't get any .5watt 60R so I ordered some 60R4 0.6 watt. Now this is going to sound dumb, but they look physically small, like the rest of the 1/4 watt resistors. I guess as their resistance is low they aren't are physically big as say the .5watt 2K resistor in R89.
Does that sound reasonable or are these not right?

I used relays with approx. 1kOhm coil. Less power consumption, etc. 12V relays cost is almost same for
different coil resistance, BUT why spent additional milliamperes, especially in case of Lunchbox?
It comes up as 15-20 ma per slot difference. I'd like to spent them to OPA2604's
and quad (eight in case of 202X etc) VCA's.


However, 360 Ohm is OK, within the specs for power supply consumption.

Use regular, carbon, cheap, 1/2W, 10% 62, 68, or even 75 Ohm resistors, it is fine.
99% of relays have working range within 30% of specified coil voltage at least.

1/2W resistors will be about +30 deg C at home temp +25 C.
I think yours 60R4 will work fine as well.

Quote
BTW, thanks Igor, the PCBs are excellent to work with.
Thanx :) I love those little beasts too :)

Quote
I had ordered all WIMA caps for the polys, and I could only get 100v rated ones, which it turns out are physically too big to fit in the sidechain filter part of the PCBs Doh!

No need for cool audiofoolish capacitors in sidechain filters!
5mm pitch, 50-63V film capacitors.
Farnell have all values for up to $0.7/cap.
Mouser/Digikey should have the caps too.
Parametric search, pick nice looking ones in normal price range. Like:

http://il.farnell.com/jsp/search/browse.jsp?N=500004+1000229+5087885+5087887+5087944+5087945+565143+565129&Ntk=gensearch_001&Ntt=capacitor&Ntx=mode+matchallpartial&No=0&getResults=true&appliedparametrics=true&locale=en_IL&catalogId=&prevNValues=500004+1000229&filtersHidden=false&appliedHidden=false&originalQueryURL=%2Fjsp%2Fsearch%2Fbrowse.jsp%3FN%3D500004%2B1000229%26Ntk%3Dgensearch_001%26Ntt%3Dcapacitor%26Ntx%3Dmode%2Bmatchallpartial%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_IL%26catalogId%3D%26prevNValues%3D500004%2B1000229
« Last Edit: July 27, 2010, 02:27:52 PM by Igor »
http://www.ij-audio.com
(new site hopefully will be up in July)

AudioGimmer

Re: MixBuzz500 build/support tHread
« Reply #103 on: July 27, 2010, 02:33:24 PM »
Thanks igor.
Re. relays, I just picked those as they were on your BOM, I didn't consider the power consumption. Now you point that out it makes sense: However, don't think I'll desolder these just to swop over...

I'll order some more caps tomorrow....


... and I'll have some of the others leftover for your 500series 1176....!!

AG

Igor

Re: MixBuzz500 build/support tHread
« Reply #104 on: July 27, 2010, 02:56:56 PM »
:)
Cool. Regarding the power consumption, the unit will be within the specs with 360 Ohm relays.
With OPA2604, DBX202X, 360Ohm relays, we get about 65...80 ma per slot... fine.
http://www.ij-audio.com
(new site hopefully will be up in July)

zayance

Re: MixBuzz500 build/support tHread
« Reply #105 on: August 02, 2010, 01:43:44 PM »
Almost there, still need to check some things, but with all these beer talking in the Brewery, i need a break  ;) ;D


Igor

Re: MixBuzz500 build/support tHread
« Reply #106 on: August 02, 2010, 07:21:29 PM »
OOOOOO!!!!!!! Good job!

Really, guys. I am happy. This thing in right hands!!!!

I need some beers too, but later :)

To all guys, in case of whatever:
Don't forget to put stoppers on switches at right positions :)
(just had a mail about this)

I am bit busy till Aug 7th, but in case of whatever feel free to mail.
http://www.ij-audio.com
(new site hopefully will be up in July)

Brizco

Re: MixBuzz500 build/support tHread
« Reply #107 on: August 06, 2010, 12:12:14 PM »
Finished!
after i used the ina137 everything just worked, calibration was easy. the whole kit is just awesome, everything fits like it should!

thank you igor!




...69eq arrived this week, but still missing the pcb's, i emailed you :)

AudioGimmer

Re: MixBuzz500 build/support tHread
« Reply #108 on: August 06, 2010, 12:40:34 PM »
Nice work Brizco. Genuine DBX VCAs?

I'm all done apart from calibration and final assembly. No time at the minute  :(

How did you calibrate yours? inside a rack or externally with long power/audio leads


AG

Brizco

Re: MixBuzz500 build/support tHread
« Reply #109 on: August 06, 2010, 01:25:33 PM »
i have an a-design 500hr with opened top for testing and calibrating my 500projects. for the mixbuzz i used longer ribbon-cables, about 30cm.

yes, original dbx 202's.


ultra-alex

Re: MixBuzz500 build/support tHread
« Reply #110 on: August 06, 2010, 03:06:35 PM »
nice build, briz...
where did you get those dbx202?
cheers, alex

Brizco

Re: MixBuzz500 build/support tHread
« Reply #111 on: August 07, 2010, 05:26:43 AM »
nice build, briz...
where did you get those dbx202?
cheers, alex

got them from the black-market.. but dont know anymore from which member.

AudioGimmer

Re: MixBuzz500 build/support tHread
« Reply #112 on: August 07, 2010, 12:50:33 PM »
Well, finally finished up the Mixbuzz.
Adjusted for zero DC on IC 11a&b for audio and sidechain outside of lunchbox, and then stuck the audio cards in to take a listen.




On program material it sounds great, very pleased. I do have 2 issues though.
1. The ratio switch seems reversed: for a given threshold for onset of compression 2:1 gives more GR than 4:1 which gives more than 10:1 .....Hmmmm

2. I need to adjust where threshold for zero is [i.e. for onset of compression feeding 0VU into the unit]. Having never built a GSSL design before, I don't know the procedure. Can anyone run me through it. I did install trimmers at RV1 on audio boards, and I preset them to 5k1 before soldering 'em in.

Great project Igor, thankyou.

AG

pacemaker

Re: MixBuzz500 build/support tHread
« Reply #113 on: August 07, 2010, 05:52:59 PM »
Hi Guys,
i am now finishing my mixbuzz too,
will post some pics later,
i am using THAT 2181LB VCAs,
so i guess some resistances values need to be adjusted
Sorry for being such a noob,
i've tried to fi nd the solution by myself,
but couldn't suceed,
Any help would be really appreciated,
and Igor , amazing job !!!

stereokillah

Re: MixBuzz500 build/support tHread
« Reply #114 on: August 07, 2010, 07:27:46 PM »
AudioGimmer,

for your ratio check your resistor on the controle board

R65,72,73,77,78,79,80,82,85,86,90,91,92,93 if you've got the good value

on my pictures you could see one line with 620k  diode 68k 270k and 510k and the second 620k diod 68k 510k and 270k

perhaps you did a error here.


pacemaker

how many VCa on your DBX202X REPLACEMENT BOARD ?
« Last Edit: August 07, 2010, 07:33:10 PM by stereokillah »
if your neighbour is hunger .. don't give him fish, teach him how fishing ...

AudioGimmer

Re: MixBuzz500 build/support tHread
« Reply #115 on: August 08, 2010, 03:47:08 AM »
Hey, Stereokillah. You're up early!

I'll get a chance to check tomorrow. Thanks.

AG

pacemaker

Re: MixBuzz500 build/support tHread
« Reply #116 on: August 08, 2010, 04:48:02 AM »
Hi Stereokillah,
only one VCA per boards,
thanks for your help mate!
francois
« Last Edit: August 08, 2010, 05:47:15 AM by pacemaker »

pacemaker

Re: MixBuzz500 build/support tHread
« Reply #117 on: August 08, 2010, 07:00:14 AM »
And my mistake,
i'm using 2180LB , not 2181LB
thanks for your help,
Francois

stereokillah

Re: MixBuzz500 build/support tHread
« Reply #118 on: August 08, 2010, 07:01:02 AM »
Quote
For "more sound" use only one THAT2181C, bit misadjusted for more harmonics.
In this case, install only one VCA and according resistors on input board,
no change in control port circuit (NE5534, 100R, 732R).
In this case, R3=20k, R6=0R (jumper), R100=909R.
It is possible to lower C1 down to 22pF.

it's same for THAT2181LB, i think the only difference is the  harmonics

Quote
Trimpot adjustment.
Adjust for minimum distortion with analyzer (audio) and 0mV dc offset (sidechain).
Don't have analyzer?
Sidechain: adjust for 0.0 mV DC at IC11a, NE5532, pin1
Audio: adjust for 0.0 mV DC at IC11b, NE5532, pin7
if your neighbour is hunger .. don't give him fish, teach him how fishing ...

stereokillah

Re: MixBuzz500 build/support tHread
« Reply #119 on: August 08, 2010, 07:05:22 AM »
ok if it's 2180lb
Quote
Sidechain VCA's.
Simplest and cheaper solution is THAT2180C, don't install SC_SYM trimpot and R33.
There's no need for A version VCA in sidechain.
if your neighbour is hunger .. don't give him fish, teach him how fishing ...


 

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