D-LA2A Support Thread

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[silent:arts]

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baadc0de said:
Also, she's in quite good company.. the rack itself is DIY ofcourse

now this is a nice collection of DIY gear 8)
BUT you will soon need to build another rack ;D

enjoy the family! ;D ;D ;D

DLA2A-baadc0de.gif
 

baadc0de

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Thanks for the banner, the PCBs and the advice, this dual la2a sounds awesome, really proud of it :)

Also, yeah, the second rack is already in the works.. since this one is getting filled up really soon
 

EHOFFA007

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I'm in a heated competition with myself to get my rack filled up by the end of the year!
I keep telling myself I need empty rack spaces in between each piece of gear for ventilation (Cheating):)
web.jpg

 

EHOFFA007

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I've gotten several cases from:
Www.diy-racked.com
Good service and prices, located in the EU so I've been getting my cases from dan at collective since he opened up.
 

desol

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Hey guys

Couple questions. I just got everything together today. I first powered it up without tubes/t4b. The left side neon didn't light but right did....then a little smoke from right side down by 3 watt resistor and HV capacitor. Quickly shut off. Noticed 7805  was dead(9v). Put a new one in...and removed yellow/green wire which i had with ground to iec. What is this wire..? I noticed some other builds with same transformer but not this wire. Nyway..fired back up also with new led's and now both neons and led's light ok(grounds hooked just not green/yellow wire from transformer)...and voltages look at about right level. So...added tubes...all good...but now there is a small buzzing, humming at power transformer...no short cause it didn't heat up...just a quiet buzzing...didn't think big deal...so, added t4. When on, same buzzing i think....but louder in speakers...relays are working (when switching relay...buzzing goes on and off with both channels.

Everything seems....ok...just don't know what to do about buzzing noise(no audio). Any ideas could help. thx. :)
 

briomusic

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hi desol, what is the model of power transformer you use?
on the transformer you will often find a description of each wire by colorcode, what does it say about the yellow/green?
(yellow/green is usually earth which should not be completely disconnected, but can be wired in different ways relating to hum issues)
is the buzz coming from the transformer or from the audio output (speakers)?
what is your grounding scheme, can you post this either as a diagram or hi-res picture of your build?
 

[silent:arts]

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if it is a Rondo-Mueller transformer yellow/green is screen.
there should be nothing wrong connecting it directly to the IEC ground.
(fact is I do this all the time)

buzzing: like Brio said, show us an inside photo. the wires going to the front are important.
use shielded cables for the pots. disconnect the limit/compress switch. buzz still there?
 

desol

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Hi Volker and Brio!

Ok. I uploaded some pictures and put a video on youtube. I figured best way is to hear it for real. So far, i know pots are reversed and shielding needs to be fixed on channel one pot. First channel meter seems functioning ok(needs new led)...but second channel meter has a problem. The buzzing/humming i haven't figured out yet...was golfing this weekend! :) I have new pots coming monday...the ones i have now have to small of bushing so they are just temporary. I tried moving some cables no real change in hum...i think maybe it's in power supply. Voltages at two 3watt resistors are at 220 and 320 volts roughly...same on both sides. I don't know if it's filter cap or not. Somehow output isn's working...so don't know if relays are switching properly...humphhh.

I built with love....but it has a bad temper now suddenly. I did have a little smoke near 3 watt resistor on left channel (which is why i asked about shield wire on power supply) but have it reconnect after blowing out with air...now no more smoke and neon is working ok. All tubes seem firing ok.... nyways, here are pics and video...





youtube
http://www.youtube.com/watch?v=Oa7JxDfQsKM
 

Audioman

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Hello All,
Finally i finish the two D-LA2A !!! (one is mine and the other i builded for my friend)
I have noticed two problems :

1- in my unit is some hum on the second channel when i switch on the channel (with the in/bypass switch)
2- the first channel of my unit works fine but if i bypass the channel in the audio a boom appears (maybe the switch is not good..)
3- in the second unit a strange distortion appears if i push the input and ouuput stage

Any help is appreciate !!
Thank you all
Fabio

i post some pictures
 

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creal

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Hi everybody,
Here is my new baby.
A new DLA2A is born and is sound very nice.
I love this comp.
I just buy some telefunken ECC83 on evil-bay to replace the electroHarmonics and Philipes tubes.
I also make a little pcb for the switches

Thanks Volker for make this dream a reality.
And thanks everybody for your advices and comments in this tread

Best
Cyril

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[silent:arts]

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desol: first remove the power switch from the middle of the case.
running 115V / 230V next to the potentiometer / switch wires is a very bad idea in this build.

Audioman, nice build with unique front panels :)
Audioman said:
1- in my unit is some hum on the second channel when i switch on the channel (with the in/bypass switch)
2- the first channel of my unit works fine but if i bypass the channel in the audio a boom appears (maybe the switch is not good..)
the switch only triggers the relay. any DC at the output?
Audioman said:
3- in the second unit a strange distortion appears if i push the input and ouuput stage
try swapping the tubes from unit 1 & 2. any changes?

Cyrill: congrats!
interesting 1178 front panel layout.
COOL  8) 8) 8)
 

creal

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[silent:arts] said:
Cyrill: congrats!
interesting 1178 front panel layout.
COOL  8) 8) 8)

Thx man, the DLA2A is in UREI familly and it looks nice in the rack with my LA4 and 1176s
;D ;D ;D ;D ;D
PS: the sound of this best kill me...
 

Audioman

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letterbeacon said:
Beautiful work!!

Thank you man !!! i'm glad you like it !!


[silent:arts] said:
desol: first remove the power switch from the middle of the case.
running 115V / 230V next to the potentiometer / switch wires is a very bad idea in this build.

Audioman, nice build with unique front panels :)
Audioman said:
1- in my unit is some hum on the second channel when i switch on the channel (with the in/bypass switch)
2- the first channel of my unit works fine but if i bypass the channel in the audio a boom appears (maybe the switch is not good..)
the switch only triggers the relay. any DC at the output?
Audioman said:
3- in the second unit a strange distortion appears if i push the input and ouuput stage
try swapping the tubes from unit 1 & 2. any changes?

Cyrill: congrats!
interesting 1178 front panel layout.
COOL  8) 8) 8)

Hi Wolker
now i try to switch the tubes between the two unit , after that i let you know if  anything change .
i search also for any dc at the output
can you tell the right procedure to calibrate the unit ??

i let you know the response of the test
Ciao
Fabio

P,S, i'm glad you like the front panel
 

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