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Guitar pre Rocktron Pro G.A.P. 2 ,noisy..related to display
Hi to all the people here
I bought the old preamplifier,i remember it as pretty silent,and the "apparent" S/N ratio is further increased by the proprietary noise gate called "H.U.S.H." This is a good pic of the board ,found on a website https://images.reverb.com/image/uplo...aqvapl3ygx.jpg I'm finding it a bit too noisy,and this noise sounds as "digital noise",more than white noise..it sounds like the frequencies composing the noise are related to the activity of the segments digits of the display.Adding a piece of wire as antenna to the resistors between IC driver and display increases some particular frequency to the heared noise,confirming my impression . I tried shorting ground points with good cables,it does not change anything. I tried adding some metallic shield with minimal or null impact. I ask your opinion about the decoupling capacitors,they are 1uF ceramic capacitors,with relatively long leads.Do yout think that it is worth replacing them?Maybe with SMD capacitor directly to IC VDD and GND? Another idea is to replace the displays with new ones more efficient,needing much less current,and then ,to increase the resistor values,less current=less noise,but i still dont know if such display exists. I would like to know your opinion. Thanks for your time Diego --- Questa email è stata esaminata alla ricerca di virus da AVG. http://www.avg.com |
Guitar pre Rocktron Pro G.A.P. 2 ,noisy..related to display
Another idea is to replace the displays with new ones more efficient,needing much less current,and then ,to increase the resistor values,less current=less noise,but i still dont know if such display exists. I would like to know your opinion. Thanks for your time Diego --- Questa email è stata esaminata alla ricerca di virus da AVG. http://www.avg.com what type of display LED? can you use standard signal tracing to determine which audio stage is picking up the noise, does the volume control effect it, tone controls etc. ? m |
Guitar pre Rocktron Pro G.A.P. 2 ,noisy..related to display
On Monday, 1 July 2019 16:36:27 UTC+1, blisca wrote:
Hi to all the people here I bought the old preamplifier,i remember it as pretty silent,and the "apparent" S/N ratio is further increased by the proprietary noise gate called "H.U.S.H." This is a good pic of the board ,found on a website https://images.reverb.com/image/uplo...aqvapl3ygx.jpg I'm finding it a bit too noisy,and this noise sounds as "digital noise",more than white noise..it sounds like the frequencies composing the noise are related to the activity of the segments digits of the display.Adding a piece of wire as antenna to the resistors between IC driver and display increases some particular frequency to the heared noise,confirming my impression . I tried shorting ground points with good cables,it does not change anything. I tried adding some metallic shield with minimal or null impact. I ask your opinion about the decoupling capacitors,they are 1uF ceramic capacitors,with relatively long leads.Do yout think that it is worth replacing them?Maybe with SMD capacitor directly to IC VDD and GND? Another idea is to replace the displays with new ones more efficient,needing much less current,and then ,to increase the resistor values,less current=less noise,but i still dont know if such display exists. I would like to know your opinion. Thanks for your time Diego The simple way to find out if replacing a cap will help is to bridge it with another cap. If the original is ok, it makes no difference. If the original is bad, it solves the problem. Sometimes you can just hold the 2nd cap & touch it onto other caps one after another to dx a fault. NT |
Guitar pre Rocktron Pro G.A.P. 2 ,noisy..related to display
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Guitar pre Rocktron Pro G.A.P. 2 ,noisy..related to display
On Wednesday, 10 July 2019 15:40:24 UTC+1, Phil Hobbs wrote:
On 7/10/19 9:18 AM, tabbypurr wrote: On Monday, 1 July 2019 16:36:27 UTC+1, blisca wrote: Hi to all the people here I bought the old preamplifier,i remember it as pretty silent,and the "apparent" S/N ratio is further increased by the proprietary noise gate called "H.U.S.H." This is a good pic of the board ,found on a website https://images.reverb.com/image/uplo...aqvapl3ygx.jpg I'm finding it a bit too noisy,and this noise sounds as "digital noise",more than white noise..it sounds like the frequencies composing the noise are related to the activity of the segments digits of the display.Adding a piece of wire as antenna to the resistors between IC driver and display increases some particular frequency to the heared noise,confirming my impression . I tried shorting ground points with good cables,it does not change anything. I tried adding some metallic shield with minimal or null impact. I ask your opinion about the decoupling capacitors,they are 1uF ceramic capacitors,with relatively long leads.Do yout think that it is worth replacing them?Maybe with SMD capacitor directly to IC VDD and GND? Another idea is to replace the displays with new ones more efficient,needing much less current,and then ,to increase the resistor values,less current=less noise,but i still dont know if such display exists. I would like to know your opinion. Thanks for your time Diego The simple way to find out if replacing a cap will help is to bridge it with another cap. If the original is ok, it makes no difference. If the original is bad, it solves the problem. Sometimes you can just hold the 2nd cap & touch it onto other caps one after another to dx a fault. That's a great way to blow stuff up, too. Cheers Phil Hobbs how? I never have that way. Obviously some clue is required, not applying a 400v charged cap to a base somewhere. NT |
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