OT
O.K. I know I'm breaking my own rule here, but I couldn't resist.
Last night I stumbled across a a great track for my test group. It has the following outstanding features - IMO:
1. The general balance and blend is exceptional.
2. Piano is one of the hardest to record. Note the pads falling at the intro and the final run.
3. The guitar shines through where it should on both comping and arpeggios
4. May have to listen a few times, but the individual horns in the sax section are easy to distinguish - specially the bari.
5. When the bass is prominent along with the brushes it's clear the full spectrum is being presented. There is a crystal clear soft cymbal crown hit if you can find it.
6. The brass is smooth, warm and still resonant.
7. Most important !! - on my system the entire room is filled with with ambiance and presence - almost holographic. That's what made me get out of my chair and investigate.
Bonus - Listen for the air leaking into the sax mouthpieces at the beginning of the last chord....
It's a keeper for sure. It can be played online but I hope some other FE builders will download it to play on their systems.
Please don't post/respond here on the thread, but I'd appreciate comments via PM and/or email.
Test Track CB
P.S. Just finished setting up the BLAT (beta builds) with standard air cooling. Now turning back to FE RC hum.
O.K. I know I'm breaking my own rule here, but I couldn't resist.
Last night I stumbled across a a great track for my test group. It has the following outstanding features - IMO:
1. The general balance and blend is exceptional.
2. Piano is one of the hardest to record. Note the pads falling at the intro and the final run.
3. The guitar shines through where it should on both comping and arpeggios
4. May have to listen a few times, but the individual horns in the sax section are easy to distinguish - specially the bari.
5. When the bass is prominent along with the brushes it's clear the full spectrum is being presented. There is a crystal clear soft cymbal crown hit if you can find it.
6. The brass is smooth, warm and still resonant.
7. Most important !! - on my system the entire room is filled with with ambiance and presence - almost holographic. That's what made me get out of my chair and investigate.
Bonus - Listen for the air leaking into the sax mouthpieces at the beginning of the last chord....
It's a keeper for sure. It can be played online but I hope some other FE builders will download it to play on their systems.
Please don't post/respond here on the thread, but I'd appreciate comments via PM and/or email.
Test Track CB
P.S. Just finished setting up the BLAT (beta builds) with standard air cooling. Now turning back to FE RC hum.
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Hi Bob,
I was about taking the measurements i promised, than actually realised that didn't get where to connect the probes 😀 were u talking about AC voltage from trafo on the boards input?
I was about taking the measurements i promised, than actually realised that didn't get where to connect the probes 😀 were u talking about AC voltage from trafo on the boards input?
Got it, thanks! Well in that case i get 0 AC as my SE is not connected to the chassis yet and virtually is floating in the air. Once i finish with copper screens and front panel i'd connect SE to the case as it should be by all rules 🙂
Due to Dario's help and kindness I will have a working and cased amplifier by some time this evening.Tomorrow I have nothing much planned so am looking forward to an extended listening session. 😀
That's good to hear. Please let us know your impressions of the sound produced.
If you would, can you report what was causing the problem? I might be helpful to other builders.😉
If you would, can you report what was causing the problem? I might be helpful to other builders.😉
Thanks
First of all Thanks to Dario, Bob and everyone. As mentioned I changed transistor, zener and regulator. Now I have a completely working amplifier. Bass is good from the beginning. I expect more change after a long run. During connecting everything I by mistake shorted the faulty board's speaker terminal at that time smoke came from regulator, but i think its not from regulator. Did I again damaged the board? Even the sound is coming and did the measurement in Power supply section. Reading is as mentioned by Dario in Transistor, Zener and the cap section. After a half an hour run I heard a hum noise from right speaker. So I take the PGND and hum gone. I didnt ground the input properly. Could it cause hum noise? No noise, very dark and running good so far. The DC Offset is
Right = 5mV
Left = .6mV
Once again thanks all.
Badri
First of all Thanks to Dario, Bob and everyone. As mentioned I changed transistor, zener and regulator. Now I have a completely working amplifier. Bass is good from the beginning. I expect more change after a long run. During connecting everything I by mistake shorted the faulty board's speaker terminal at that time smoke came from regulator, but i think its not from regulator. Did I again damaged the board? Even the sound is coming and did the measurement in Power supply section. Reading is as mentioned by Dario in Transistor, Zener and the cap section. After a half an hour run I heard a hum noise from right speaker. So I take the PGND and hum gone. I didnt ground the input properly. Could it cause hum noise? No noise, very dark and running good so far. The DC Offset is
Right = 5mV
Left = .6mV
Once again thanks all.
Badri
You're welcome Badri 🙂
I can't understand... your're talking about the past or the present?
Sure, a bad input ground connection can cause hum.
Very good values.
Present. Now When I am connecting the speaker I left the faulty board speaker output floating. Smoke came from regulator side. But I dont know where exactly it is from. May be LM318 [My guess]. I didnt want to remove everything and I left it like that and measured the values. It is expected values. Any suggestion.
Thanks
Badri
Sorry badrisuper but I'm still not clear. Is your question about possible damage as indicated by some smoke, but both amps are now working - or are you saying one of them needs to be repaired again?
Sorry for not making it clear. My question is for the possible damage as indicated by some smoke even though both the amps are working.
That's the happy answer🙂 The only thing I would suggest is playing a mono track through each amp, one at a time and determine if you can hear a difference. I might even keep the bulb tester connected for a few days just to be safe.Congrats on you perseverance and let know how you like the sound.
Edit: Usually when something smokes there is a blemish or some residue left on or near that component. When you get the time, use a good magnifying glass and try to find it.
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keeping the bulb tester in circuit achieves very little.
The energy stored in the capacitors is likely enough to damage any semiconductor if there is a mishap. The bulb will light AFTER the mishap. Too late to do any good.
The bulb tester is great for first powering up after a modification. There it prevents the capacitors and circuits charging up if there is already an excessive current draw. That is also why I start with a very low wattage bulb and work upwards after I know there are no gross wiring errors.
The energy stored in the capacitors is likely enough to damage any semiconductor if there is a mishap. The bulb will light AFTER the mishap. Too late to do any good.
The bulb tester is great for first powering up after a modification. There it prevents the capacitors and circuits charging up if there is already an excessive current draw. That is also why I start with a very low wattage bulb and work upwards after I know there are no gross wiring errors.
Thanks for the clarification Andrew. I was thinking it would act something like a fuse. Would smaller value fuses give him some protection during the burn-in?
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Not really.
DC triggered relay to protect the speaker.
Semiconductors fuse too quickly to allow physical protection.
Electronic protection/limiting can work quickly enough for some abuse, but probably not all abuse we throw at circuits.
the "burn-in" should be on the bench ! and if necessary with a dummy load applied and if necessary a signal passing if some heatsinks need testing.
Not while speakers are attached and listening to music.
DC triggered relay to protect the speaker.
Semiconductors fuse too quickly to allow physical protection.
Electronic protection/limiting can work quickly enough for some abuse, but probably not all abuse we throw at circuits.
the "burn-in" should be on the bench ! and if necessary with a dummy load applied and if necessary a signal passing if some heatsinks need testing.
Not while speakers are attached and listening to music.
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Since I have your ear - Your PM box is full and won't accept messages till you clear some space. That is if you want to open up that channel. 😉
Too many beginners are asking for private help from me. I can cope with one or two a month, but when it's every other day !
I am tired directing them to the Forum to ask all the experts, that are there, to read and answer their questions, better than I can.
The beginners have not yet discovered the Email system !
I am tired directing them to the Forum to ask all the experts, that are there, to read and answer their questions, better than I can.
The beginners have not yet discovered the Email system !
I understand and thought that might be the situation. Will use the boards and email in the future. Thanks
OK... maybe the smoke come from one of the current setting resistors (Caddock MP915) or from R3.(Caddock MP930)..
Visual inspect them.
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