Just a quick update - I gave myself a nasty scare - I kept getting "F70 PWM Switch off amplifier" message about 5 seconds after I turned it on - I thought, that's it already blew a pair of lovely speakers and now an amp - looked it up in the service manual "communication error between
sub-microprocessor & its LSI" - oh bugger!!!!!!!!!. I checked lots os connectors but everything looked OK - still every power-up gave this error
I was attempting to put in a clock, so I undid everything I had done, including reconnecting the onboard clock. I also checked the daughter board style connection on the DSP board which connects to the main board as I felt with all the taking off of the DSP board it could have loosened up it's connections.
When I powered on again everything was fine , phew! I suspect it may have been the connector but I'm worried about the clock now and reluctant to try connecting again!
Has anybody else encountered this problem?
sub-microprocessor & its LSI" - oh bugger!!!!!!!!!. I checked lots os connectors but everything looked OK - still every power-up gave this error
I was attempting to put in a clock, so I undid everything I had done, including reconnecting the onboard clock. I also checked the daughter board style connection on the DSP board which connects to the main board as I felt with all the taking off of the DSP board it could have loosened up it's connections.
When I powered on again everything was fine , phew! I suspect it may have been the connector but I'm worried about the clock now and reluctant to try connecting again!
Has anybody else encountered this problem?
Mike,
I did check all the cables & found one that wasn't quiet seated well - one of those Aha moments but quickly dashed when I turned on again & got the error back.
I think it must be the daughter board connection on the bottom of the DSP board that plugs into the main board - it's 26 pins slotted connector and works along the lines of those telephone connections that you push a wire down into a slot and it cuts through the insulation to make the connection - so this requires two elements either side of the wire squeezing with sufficient force to penetrate the insulation.
So if you take on & off this sufficient times the connection weakens - I think this is what happened - I was removing this DSP board every time I took out the main board - I'll leave it in place in future.
But this happened when I was testing a clock connection to the DSP board which is a finnicky job & I'm not particularly happy with the connection to the resistor pad - it's tiny & right beside a smd cap - wish there was a better place to connect
Anyway, to get everything working again, I bridged accross where the resistor once was & checked all my connectors going over the slotted one with a pin teasing out the microscopic contact wires in each slot - turned it back on & it worked, phew!
I did check all the cables & found one that wasn't quiet seated well - one of those Aha moments but quickly dashed when I turned on again & got the error back.
I think it must be the daughter board connection on the bottom of the DSP board that plugs into the main board - it's 26 pins slotted connector and works along the lines of those telephone connections that you push a wire down into a slot and it cuts through the insulation to make the connection - so this requires two elements either side of the wire squeezing with sufficient force to penetrate the insulation.
So if you take on & off this sufficient times the connection weakens - I think this is what happened - I was removing this DSP board every time I took out the main board - I'll leave it in place in future.
But this happened when I was testing a clock connection to the DSP board which is a finnicky job & I'm not particularly happy with the connection to the resistor pad - it's tiny & right beside a smd cap - wish there was a better place to connect
Anyway, to get everything working again, I bridged accross where the resistor once was & checked all my connectors going over the slotted one with a pin teasing out the microscopic contact wires in each slot - turned it back on & it worked, phew!
Ok, Here's what I found so far
Let me explain my test setup first because it's relevant to the results:
I wanted to test lots of caps in the the place of the 1,000uf XE Panasonic caps in the output so I decided to remove that cap and replace it with a socket to enable caps to be plugged in & removed easily.
I did this on the center channel first as it was the last one on the pcb board & easiest to get at. When testing caps on this channel I noticed a large difference between them but mainly in terms of the uF value used, with larger values sounding louder! This worried me along with the fact that I could only listen to this centre channel when I switched to multichannel with all the processing that intails.
So I decided to remove the cap from one of the front channels & put in a socket there also. That way I can listen to one channel modded & one channel stock in non-processed mode. The caps all sound similar in this position, including the Blackgates.
If you look at the pcb the PS comes in where the front channels are and the center channel is furthest away from this feed
My conclusion is to bring power to each channel directly by wiring power directly to the 1,000uF cap of each channel!
What do you guys think?
Let me explain my test setup first because it's relevant to the results:
I wanted to test lots of caps in the the place of the 1,000uf XE Panasonic caps in the output so I decided to remove that cap and replace it with a socket to enable caps to be plugged in & removed easily.
I did this on the center channel first as it was the last one on the pcb board & easiest to get at. When testing caps on this channel I noticed a large difference between them but mainly in terms of the uF value used, with larger values sounding louder! This worried me along with the fact that I could only listen to this centre channel when I switched to multichannel with all the processing that intails.
So I decided to remove the cap from one of the front channels & put in a socket there also. That way I can listen to one channel modded & one channel stock in non-processed mode. The caps all sound similar in this position, including the Blackgates.
If you look at the pcb the PS comes in where the front channels are and the center channel is furthest away from this feed
My conclusion is to bring power to each channel directly by wiring power directly to the 1,000uF cap of each channel!
What do you guys think?
I replaced the XE cap on the left channel of the Front speakers with a socket & left the cap in place on the right channel so i could do a comparison by changing balance left to right! I left all the other XE caps in place on all other channels (except centre channel, which was the first one I modded)
I suppose my point is that the PS is affected as it moves from where it enters the board (at Front Speakers) to channel furthest away prom this entry point (center channel)
I suppose my point is that the PS is affected as it moves from where it enters the board (at Front Speakers) to channel furthest away prom this entry point (center channel)
I don't know what you mean - here's a pic of the set-up - what you see is a Black Gate 1000uF STD cap in the Left(?) channel of the front speakers -and at the other end a blank socket where I took the XE cap out of the centre channel and put in a socket.
I know the socket will add some extra impedance but?
I also socketed the inductors for the front speaker left channel but the standard inductors are in place at the moment!(using Micrometals T106-2 recommended inductors again made no difference to the sound)
What I'm saying is that this 1000uF BG cap made a huge,noticeable difference in sound in the center channel but none in the front channel so I surmise that the PS supply is degraded as it feeds later channels (impedance?)!
What you see with the red+black wires going under the board is the power connection directly to the cap & the speaker output wires!
I know the socket will add some extra impedance but?
I also socketed the inductors for the front speaker left channel but the standard inductors are in place at the moment!(using Micrometals T106-2 recommended inductors again made no difference to the sound)
What I'm saying is that this 1000uF BG cap made a huge,noticeable difference in sound in the center channel but none in the front channel so I surmise that the PS supply is degraded as it feeds later channels (impedance?)!
What you see with the red+black wires going under the board is the power connection directly to the cap & the speaker output wires!
Attachments
I'm trying to use an oscilloscope on the PS before I do any more tests - here's my first bumbling efforts http://www.diyaudio.com/forums/showthread.php?s=&threadid=120687
I had a hunch that the batterry I had was not good so low output current gave a dissapointing sound.
Got a good battery & wow, sound is stunningly realistic! This is more like the reports I have read about using batteries with this amp. Defintely the reference against which all mains powered (SMPS or linear) supplies will be measured or maybe I'll just stick with batteries.
I think would need 2 batteries in series for 24V to get to really loud levels - with one battery sound level rises up to -44dB on the XR57 vol dial and is flat up to -32db? - the area where vol is is normally controlled by PS voltage adjustment - (I didn't try the higher end of the vol control where the vol is controlled digitally again).
Anyway, this sounds great even though there still appears to be a amount of PS modulation with the music as seen on the scope! I'm wondering how this might beeliminated & how much better the sound might get? (yes I do have a 10,000uF cap in parallel with battery) - maybe paralleling some batteries would give even more current & avoid this modulation?
Got a good battery & wow, sound is stunningly realistic! This is more like the reports I have read about using batteries with this amp. Defintely the reference against which all mains powered (SMPS or linear) supplies will be measured or maybe I'll just stick with batteries.
I think would need 2 batteries in series for 24V to get to really loud levels - with one battery sound level rises up to -44dB on the XR57 vol dial and is flat up to -32db? - the area where vol is is normally controlled by PS voltage adjustment - (I didn't try the higher end of the vol control where the vol is controlled digitally again).
Anyway, this sounds great even though there still appears to be a amount of PS modulation with the music as seen on the scope! I'm wondering how this might beeliminated & how much better the sound might get? (yes I do have a 10,000uF cap in parallel with battery) - maybe paralleling some batteries would give even more current & avoid this modulation?
i'm writing an experimental paper on amplifier output impedance, so i'm investigating power supply impedance as part of the amplifier impedance. power supply impedance is a limiting factor on how low amplifier impedance can go. power supply impedance is (for some this is going to be a stretch) in series with output impedance in an amplifier, so it must be made as low as possible to begin with.
I wanted to give one sonic effect I noticed with this amp after mods:
The image just snaps into place & is presented with an even handedness to all frequencies. This is due to the dig amp as I noticed it also with test speakers - nothing gets over-emphasised, just presented as is.
My memory of some music (like Steely Dan, for instance) is that when there is a guitar solo, the soloist gets emphasised in the mix as if he's stepping out from the band (not a bad effect) but I notice the solo now being performed more in unison with the rest of the music.
Has anyone experienced this?
The image just snaps into place & is presented with an even handedness to all frequencies. This is due to the dig amp as I noticed it also with test speakers - nothing gets over-emphasised, just presented as is.
My memory of some music (like Steely Dan, for instance) is that when there is a guitar solo, the soloist gets emphasised in the mix as if he's stepping out from the band (not a bad effect) but I notice the solo now being performed more in unison with the rest of the music.
Has anyone experienced this?
Hi Jkeny.
Regarding your battery-story:
I am running my Amps and DAC with 100Ah Northstar batteries. They come with 2mR Ri. None of the big caps will have a lower ESR than these kind of batteries. It makes a big difference if you run a 25mR or a 2mR battery.
Keep also in mind that Ri increases over time! Never use old
car batteries.
I don't like the big caps for buffering. Most of the good battery PS I've seen buffer in the range of 8*470uf low ESR type and putting a sniffer in parallel.
Cheers
Regarding your battery-story:
I am running my Amps and DAC with 100Ah Northstar batteries. They come with 2mR Ri. None of the big caps will have a lower ESR than these kind of batteries. It makes a big difference if you run a 25mR or a 2mR battery.
Keep also in mind that Ri increases over time! Never use old
car batteries.
I don't like the big caps for buffering. Most of the good battery PS I've seen buffer in the range of 8*470uf low ESR type and putting a sniffer in parallel.
Cheers
Thanks Soundcheck,
I will investigate the ESR of my batteries - they are 7aH and are old so as you say maybe esr is not as low as it could be! I'll also try a parallel bank of low esr caps for buffering!
Does desulfonating the battery bring it's ESR back to nearly-new levels?
As-is the sound is very good/stunning/incredible. Even my wife thinks so & that is high praise indeed - with my previous amps she wondered what the difference was to what came before - now she agrees. BTW, her hearing goes up to near 20KHz so any shrillness is more noticeable than by my mere mortal 15KHz ears
I will investigate the ESR of my batteries - they are 7aH and are old so as you say maybe esr is not as low as it could be! I'll also try a parallel bank of low esr caps for buffering!
Does desulfonating the battery bring it's ESR back to nearly-new levels?
As-is the sound is very good/stunning/incredible. Even my wife thinks so & that is high praise indeed - with my previous amps she wondered what the difference was to what came before - now she agrees. BTW, her hearing goes up to near 20KHz so any shrillness is more noticeable than by my mere mortal 15KHz ears
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