Hi mjraudio,
-Chris
Sorry you have to do it again. I have had one that I had to remove and clean the semi's individually. I would have replaced them if they were on hand. In transist, but I learned something.
-Chris
mjraudio said:
Sorry no italiano! 🙂 Well not much anyway.. Its from my favorite Rush song Red Barchetta..
Keep working you'll get it! I wish I had all the spare parts I need on the shelf though.. I have little patience to order parts and wait! I ended up scavenging one from a broken stereo (crappy one I might add)..
Can you post some pics of your filter caps you installed please?
Okay I will post them soon.
I have a system design question to ask you all.
The previous owner had input level controls installed on the back, basically variable resistors that decrease the input level of the rca inputs by twisting the knob.
I removed my preamp from the loop and now am runnning my CD player directly to my amplifiers, and massively cutting down the volume using the input level controls on the amplifier.
Is this a dangerous practice? if those input level controls failed, then the amplifier would jump from 2-5% output to 100% 300watt output and likely blow up my speakers!
It's amazing just how sensitive they are, moving them 1 millimeter increases the volume on an almost logarithmic scale! If I had the input level controls at zero (no decrease in input level), the amplifiers would be operating at 300watts!
Is this dangerous? Can those input level control variable resistors handle it?
I have a system design question to ask you all.
The previous owner had input level controls installed on the back, basically variable resistors that decrease the input level of the rca inputs by twisting the knob.
I removed my preamp from the loop and now am runnning my CD player directly to my amplifiers, and massively cutting down the volume using the input level controls on the amplifier.
Is this a dangerous practice? if those input level controls failed, then the amplifier would jump from 2-5% output to 100% 300watt output and likely blow up my speakers!
It's amazing just how sensitive they are, moving them 1 millimeter increases the volume on an almost logarithmic scale! If I had the input level controls at zero (no decrease in input level), the amplifiers would be operating at 300watts!
Is this dangerous? Can those input level control variable resistors handle it?
Hi mjraudio,
I do use tone controls from time to time, and I have more than one source.
-Chris
I wouldn't say dangerous as much as darned inconvenient. Find a preamp that you like.
I do use tone controls from time to time, and I have more than one source.
-Chris
Also depends on how they are wired... in one way, an open circuit will result in 0 watts, yet if installed another way, an open pot will feed 300 watts... so no good answer for you. There should always be a safety resistance incase a pot opens... again dunno how it was wired...
If the scale is logrithmic, then perhaps the value of the pot is too large...
If the scale is logrithmic, then perhaps the value of the pot is too large...
Mjraudio... sorry for offtopic but I have a question for anatech related to the 565.
Chris:
Do you reckon these brutes (565's) can be used to drive a 1 ohm band limited load?
I have four of these http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-854 that I may decide to wire in parallel.
The 565 will drive only the 60Hz to 800Hz range nothing else.
I have it currently wired for 4 ohm but can't find an amp that will feed 300w peaks to each driver... they are really power hungry. I currently have a Bridged Luxman M-117 driving the 4 ohm load... it clips too much for me to enjoy it... (not audible clip but the flippin' flickering LED's)... is too distracting.
A parallel connexion of 4 of them fed by a 565 will give them the juice they need. I am guessing the 565 can pump out 1200-1600 watts into 1 ohm.... and live?
20 OP devices.... should be able to do it... though Adcom never rated them into 1 ohm. I'd say about 80 watts per device max or 1 amp or less at full output rails at that power level should be around 70-72v so 1amp SOAR per device looks good.... not fully derated though..... possible?
I have many spare 424/554's I could stick in if the project blows up in my face... 😉
Chris:
Do you reckon these brutes (565's) can be used to drive a 1 ohm band limited load?
I have four of these http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-854 that I may decide to wire in parallel.
The 565 will drive only the 60Hz to 800Hz range nothing else.
I have it currently wired for 4 ohm but can't find an amp that will feed 300w peaks to each driver... they are really power hungry. I currently have a Bridged Luxman M-117 driving the 4 ohm load... it clips too much for me to enjoy it... (not audible clip but the flippin' flickering LED's)... is too distracting.
A parallel connexion of 4 of them fed by a 565 will give them the juice they need. I am guessing the 565 can pump out 1200-1600 watts into 1 ohm.... and live?
20 OP devices.... should be able to do it... though Adcom never rated them into 1 ohm. I'd say about 80 watts per device max or 1 amp or less at full output rails at that power level should be around 70-72v so 1amp SOAR per device looks good.... not fully derated though..... possible?
I have many spare 424/554's I could stick in if the project blows up in my face... 😉
Hi Arif,
I also do not believe those woofers could actually dissipate the 150 W they say they can. Why not wire them into a 4 ohm composite and try them with the Adcom?
Now, if you were a truly sick individual (in the best possible way 😉 ), you could obtain a Carver Lightstar (600W X2 into 4R, 1200 into 2 R). When those meters peg it's time to buy more woofers.
Also a Carver PT2400. That one is silly (750W I think - in stereo). It also sounds good. Again, peak indications would mean more done voice coils. I'd like to be there for that. 😀 😎 At least send pictures, a video would be better,
Now, consider your power and cooling needs. Is everything securely fastened down?
-Chris
No, I really don't believe that's a good idea at all. Then there is the impedance dip to deal with on top of all that. I would expect the 565 to go into current limit protection - if you're lucky.
I also do not believe those woofers could actually dissipate the 150 W they say they can. Why not wire them into a 4 ohm composite and try them with the Adcom?
Now, if you were a truly sick individual (in the best possible way 😉 ), you could obtain a Carver Lightstar (600W X2 into 4R, 1200 into 2 R). When those meters peg it's time to buy more woofers.
Also a Carver PT2400. That one is silly (750W I think - in stereo). It also sounds good. Again, peak indications would mean more done voice coils. I'd like to be there for that. 😀 😎 At least send pictures, a video would be better,Now, consider your power and cooling needs. Is everything securely fastened down?
-Chris
Ok, lets send Safety Chris back home and talk to crazy Chris for a Sec... 😀
The 555 could supposedly handle 2 ohms on time limited basis... perhaps 3 ohms fulltime?.... yes / no? (Remember Tim the Toolman Chris...)
both amps have the same rails. If 8 devices can drive a 3 or 2 ohm load 20 devices should be able to double that quite easily...
So am I really off the mark??
Granted the 565 rails will hold better under load, still. We have a 250% safety margin over the 555.... I know the 2 ohm load was the cause of many coming to your shop for repairs but I know I have tested the 555 with 2 ohms and as long as I kept the amp cool enough.... I never fried it.
The 565 is a BEAST compared to the 555, it's more than 2x as robust... 20 vs. 8 OP devices.... surely, it borders... doable...
Once you factor in the Aircore I am using plus the cabling... I reckon the amp wont see anything below 1.25 ohms....
The 555 could supposedly handle 2 ohms on time limited basis... perhaps 3 ohms fulltime?.... yes / no? (Remember Tim the Toolman Chris...)
both amps have the same rails. If 8 devices can drive a 3 or 2 ohm load 20 devices should be able to double that quite easily...
So am I really off the mark??
Granted the 565 rails will hold better under load, still. We have a 250% safety margin over the 555.... I know the 2 ohm load was the cause of many coming to your shop for repairs but I know I have tested the 555 with 2 ohms and as long as I kept the amp cool enough.... I never fried it.
The 565 is a BEAST compared to the 555, it's more than 2x as robust... 20 vs. 8 OP devices.... surely, it borders... doable...
Once you factor in the Aircore I am using plus the cabling... I reckon the amp wont see anything below 1.25 ohms....
Hi Arif,
For you, go ahead and try it. I just can't give a blanket approval for everyone. I do know you're careful, plus one more thing. If you blow it up, you're the one that has to fix it!
Anyway, I know you don't want to rebuild these things, so you will be careful.
-Chris
For you, go ahead and try it. I just can't give a blanket approval for everyone. I do know you're careful, plus one more thing. If you blow it up, you're the one that has to fix it!
Yes, I agree. But you're forgetting the driver issues that can crop up. It's not the outputs that failed many times. The drivers would pack it in and take some outputs for a long walk down a short pier. I'd say you were lucky with the 555's as it's the peak currents that will take them out. Never mind 3 sec, measure this in msec before second breakdown claims more silicon.
Anyway, I know you don't want to rebuild these things, so you will be careful.
-Chris
I thought about the driver.... but it is pretty robust. A 130watt OP device... not a 1 watt 2sd649.😀 ... but I could replace it with a MJL4032a... or so...
I think I will be ok. 20amps sourced by the OP stage with a nominal gain of about 50 per device means 0.4 amps needed from the driver at about 70vdc.
I cannot find the datasheets for the 2sa1516 but I am pretty sure it can source 0.4amps at 70vdc rails...
The only variable left unaccounted for is the temp deration... as the temps rise, the devices will probably be half as robust... thats why I can understand your not wanting to give this a blanket approval.
Well we will find out !!!
My back-up plan is to rebuild the OP stage with 21195/96 and the driver with MJL4302's... then I am sure they will live...... as for my enthusiasm to rebuild 40 TO-3's goes... thats not so rosy.
I think I will be ok. 20amps sourced by the OP stage with a nominal gain of about 50 per device means 0.4 amps needed from the driver at about 70vdc.
I cannot find the datasheets for the 2sa1516 but I am pretty sure it can source 0.4amps at 70vdc rails...
The only variable left unaccounted for is the temp deration... as the temps rise, the devices will probably be half as robust... thats why I can understand your not wanting to give this a blanket approval.
Well we will find out !!!
My back-up plan is to rebuild the OP stage with 21195/96 and the driver with MJL4302's... then I am sure they will live...... as for my enthusiasm to rebuild 40 TO-3's goes... thats not so rosy.
Hi Arif,
2SA1516 : 180V 12A 130W hFE 55~180 From the '99 transistor manual.
I really only worry about the peak current conditions. I think it will survive, but nobody I know and trust to tell the truth has actually done this.
May the <electromotive> force be with you! 🙄
-Chris 😉
2SA1516 : 180V 12A 130W hFE 55~180 From the '99 transistor manual.
I really only worry about the peak current conditions. I think it will survive, but nobody I know and trust to tell the truth has actually done this.
May the <electromotive> force be with you! 🙄
-Chris 😉
anatech said:
... I guess I will begin by replacing the 10A rails fuses with 15A fast acting types.....rest when I get home on Friday...
NOOOOOOO!!!!!!!!
Both my amplifiers are picking up radio stations!
I can hear them every so softly coming through my speakers when at high amplification levels!
I currently have both turned on and plugged into my dvd player (no tuner).
Whether the dvd player is turned on or off makes no difference as I can still hear the radio station through both amps!
This is so so bad, what is causing this??
Both my amplifiers are picking up radio stations!
I can hear them every so softly coming through my speakers when at high amplification levels!
I currently have both turned on and plugged into my dvd player (no tuner).
Whether the dvd player is turned on or off makes no difference as I can still hear the radio station through both amps!
This is so so bad, what is causing this??
Why complaining... it's a free add-on... now if you could find a way to tune to station you like....😀
Does it happen with the RCA's disconnected?
What about the Amp's input RCA shorted out?
Does it happen with the RCA's disconnected?
What about the Amp's input RCA shorted out?
Re: NOOOOOOO!!!!!!!!
RF entering your input section. Notice any large cranes in your area putting up towers? Also, you might want to get out your aluminum foil and make yourself a nice RF brain hat.
In all seriousness.. ferrite bead on the power cords? I know it works in the computer world...
🙂
RF entering your input section. Notice any large cranes in your area putting up towers? Also, you might want to get out your aluminum foil and make yourself a nice RF brain hat.
In all seriousness.. ferrite bead on the power cords? I know it works in the computer world...
🙂
Hi mjraudio,
Your speaker leads are picking RF and it's being demodulated by the input stage. The feedback network is your second input to an amplifier (most of them anyway).
-Chris
Ferrite beads on your speaker wires with a 100 pF cap across on the speaker side to make an RF filter.
Your speaker leads are picking RF and it's being demodulated by the input stage. The feedback network is your second input to an amplifier (most of them anyway).
-Chris
It's the source!
Thanks for your responses gentlemen.
I have discovered the problem, it is the Pioneer ELITE DV-50A DVD/SACD player source.
When the RCA interconnects are connected to the amps from the source (on or off), the radio station is transmitted through IC cables to the amps and audible. When ICs are still connected to the amps but disconnected from the source, it is silent! I left the amps on like this for about 5 minutes and still they were silent, then next minute I connected the cables to the source, switched the amps only on and the station was audible. Thanks to K-amps for the troubleshooting tip!
I am going to build a custom RFI/EMI shielded power cord for the source which uses multiple conductors in a braided design toachieve CMNR in addition to having a copper foil shielding around the conductors, then I'm going to get a big ferrite core and attach it to the cable. Then I'm going to design a small power strip and use AC bypass capacitors to help filter some of the noise from the AC line. Thanks barchetta for the idea of the use of ferrites.
I will ultimately shield my braided 0.5M CAT6 DIY speaker cables with copper EMI/RFI shielding, then create little 4" RF Filter 'pigtails' (with 100pf axial film capacitors) which can bridge the speaker cable and the speaker binding post as Chris suggested, thanks.
I will also design custom cables for each amp with ferrites on both.
If the source still leaks RF through the interconnects I will be convinced to the poor build quality of this Pioneer Elite component.
Man do I need a new digital source! Mass-produced 'consumer' gear like this DVD player has really gotten on my nerves today.
BTW: What are your guys' thoughts on using an EMI and/or RFI filter at the AC input of high-current power amplifiers or digital sources? I'm referring to those little $8 IEC inlets with EMI filters built-in.
Thanks for your responses gentlemen.
I have discovered the problem, it is the Pioneer ELITE DV-50A DVD/SACD player source.
When the RCA interconnects are connected to the amps from the source (on or off), the radio station is transmitted through IC cables to the amps and audible. When ICs are still connected to the amps but disconnected from the source, it is silent! I left the amps on like this for about 5 minutes and still they were silent, then next minute I connected the cables to the source, switched the amps only on and the station was audible. Thanks to K-amps for the troubleshooting tip!
I am going to build a custom RFI/EMI shielded power cord for the source which uses multiple conductors in a braided design toachieve CMNR in addition to having a copper foil shielding around the conductors, then I'm going to get a big ferrite core and attach it to the cable. Then I'm going to design a small power strip and use AC bypass capacitors to help filter some of the noise from the AC line. Thanks barchetta for the idea of the use of ferrites.
I will ultimately shield my braided 0.5M CAT6 DIY speaker cables with copper EMI/RFI shielding, then create little 4" RF Filter 'pigtails' (with 100pf axial film capacitors) which can bridge the speaker cable and the speaker binding post as Chris suggested, thanks.
I will also design custom cables for each amp with ferrites on both.
If the source still leaks RF through the interconnects I will be convinced to the poor build quality of this Pioneer Elite component.
Man do I need a new digital source! Mass-produced 'consumer' gear like this DVD player has really gotten on my nerves today.
BTW: What are your guys' thoughts on using an EMI and/or RFI filter at the AC input of high-current power amplifiers or digital sources? I'm referring to those little $8 IEC inlets with EMI filters built-in.
I only wish my ferrite bead idea would solve my blackberry invading my deskphone.. digital cell phone are so invasive these days.
BTW- if you make friends with your local computer recycle place you can get zillions of these things.
BTW- if you make friends with your local computer recycle place you can get zillions of these things.
New findings, definitive!
NOTE: I believe that my findings in the previous post are incorrect, regarding the source being the root cause of the RFI problem! I now believe that the problem is caused by running both amplifiers simultaneously powered on while connected to the source (which can be either on or off and plugged in or not).
Also, the table below is complicated and I have double-checked each instance to make sure it accurately reflects the situation-at-hand. Thanks in advance to all of you gents!
I have made yet another discovery. This is complicated so I will present my findings in a quasi-table (since HTML is not allowed), please bear with me.
The following are situations which describe two GFA-565 amplifiers and one dvd source.
Power Environment:
Amp 1 is connected to Circuit 1.
Amp 2 is connected to Circuit 2.
Source was connected to Circuit 2
Source was connected to Circuit 3*
*When source was connected to its own dedicated circuit versus sharing Circuit 2 with Amp 2, there were no audible reductions or changes regarding this RFI issue.
In all instances, power cables to both amps are always connected to the receptacles.
Instance 1: The following conditions result in AUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC connected to source, powered ON
Source - Plugged in, powered OFF
Instance 2: The following conditions result in AUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC connected to source, powered ON
Source - Plugged in, powered ON
Instance 3: The following conditions result in AUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC connected to source, powered ON
Source - NOT Plugged in, powered OFF
Instance 4: The following conditions result in INAUDIBLE RFI
Amp 1 - RCA IC disconnected from source at source end (still connected to amp), powered ON
Amp 2 - RCA IC disconnected from source at source end (still connected to amp), powered ON
Instance 5: The following conditions result in INAUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC disconnected from source, powered OFF
Source - Plugged or NOT plugged, ON or OFF = same result
Instance 6: The following conditions result in INAUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC disconnected from source, powered ON
Source - Plugged or NOT plugged, ON or OFF = same result
*Instance 5 & 6 may explain the most, when EITHER amp is disconnected from the source (but still powered), the RFI becomes inaudible, as soon as I connect the other amp to the source, RFI becomes audible on both amps. Whether the source is on or off, plugged in or not makes no difference.
The problem seems to be caused only when both amplifiers are running at the same time AND connected to the same source via RCA ICs (again, the source can even be off and disconnected from the power)... Remember though that both amps can be running at the same time with no connection to the source and the RFI is INAUDIBLE. So the RFI is caused by a combination of running them both at the same time IN ADDITION TO having them connected to the source.
When both amps are connected to source, because of the fact that it makes no difference whether the source is plugged into the wall outlet or not and that the RFI is still audible, leads me to believe that the source is not introducing the RFI into the system, but somehow the combination of both amplifiers when connected to the source results in the amplification of the RF signals.
This is very strange, any thoughts on what could be causing this? Some weird ground loop RFI-amplification problem?
It is 6AM and the RFI radio channel that I'm hearing seems to be even louder. This is so incredibly annoying I want to pull my hair out.
NOTE: I believe that my findings in the previous post are incorrect, regarding the source being the root cause of the RFI problem! I now believe that the problem is caused by running both amplifiers simultaneously powered on while connected to the source (which can be either on or off and plugged in or not).
Also, the table below is complicated and I have double-checked each instance to make sure it accurately reflects the situation-at-hand. Thanks in advance to all of you gents!
I have made yet another discovery. This is complicated so I will present my findings in a quasi-table (since HTML is not allowed), please bear with me.
The following are situations which describe two GFA-565 amplifiers and one dvd source.
Power Environment:
Amp 1 is connected to Circuit 1.
Amp 2 is connected to Circuit 2.
Source was connected to Circuit 2
Source was connected to Circuit 3*
*When source was connected to its own dedicated circuit versus sharing Circuit 2 with Amp 2, there were no audible reductions or changes regarding this RFI issue.
In all instances, power cables to both amps are always connected to the receptacles.
Instance 1: The following conditions result in AUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC connected to source, powered ON
Source - Plugged in, powered OFF
Instance 2: The following conditions result in AUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC connected to source, powered ON
Source - Plugged in, powered ON
Instance 3: The following conditions result in AUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC connected to source, powered ON
Source - NOT Plugged in, powered OFF
Instance 4: The following conditions result in INAUDIBLE RFI
Amp 1 - RCA IC disconnected from source at source end (still connected to amp), powered ON
Amp 2 - RCA IC disconnected from source at source end (still connected to amp), powered ON
Instance 5: The following conditions result in INAUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC disconnected from source, powered OFF
Source - Plugged or NOT plugged, ON or OFF = same result
Instance 6: The following conditions result in INAUDIBLE RFI
Amp 1 - RCA IC connected to source, powered ON
Amp 2 - RCA IC disconnected from source, powered ON
Source - Plugged or NOT plugged, ON or OFF = same result
*Instance 5 & 6 may explain the most, when EITHER amp is disconnected from the source (but still powered), the RFI becomes inaudible, as soon as I connect the other amp to the source, RFI becomes audible on both amps. Whether the source is on or off, plugged in or not makes no difference.
The problem seems to be caused only when both amplifiers are running at the same time AND connected to the same source via RCA ICs (again, the source can even be off and disconnected from the power)... Remember though that both amps can be running at the same time with no connection to the source and the RFI is INAUDIBLE. So the RFI is caused by a combination of running them both at the same time IN ADDITION TO having them connected to the source.
When both amps are connected to source, because of the fact that it makes no difference whether the source is plugged into the wall outlet or not and that the RFI is still audible, leads me to believe that the source is not introducing the RFI into the system, but somehow the combination of both amplifiers when connected to the source results in the amplification of the RF signals.
This is very strange, any thoughts on what could be causing this? Some weird ground loop RFI-amplification problem?
It is 6AM and the RFI radio channel that I'm hearing seems to be even louder. This is so incredibly annoying I want to pull my hair out.
Amplifiers like to draw current in big spikes, so try not to install anything that is resistive in the AC power circuit.
With this much RF floating around, filter the speaker cables first and see if that reduces the problems a little. At that point some other treatments will be more effective.
-Chris
With this much RF floating around, filter the speaker cables first and see if that reduces the problems a little. At that point some other treatments will be more effective.
-Chris
- Status
- Not open for further replies.