Hi guys, I've serviced/upgraded quite a few of these amps now and one of the best things I find to change are the 4.7uF & 10uF elco's on the preamp. I use some small 4.7uF film caps and for the 10uF, either the smallest decent film cap I can find or a Nichicon Muse bypassed with a 10nF MKP1837. They're in the signal path so definitely worth changing.
Cheers, Lee.
Cheers, Lee.
well its more of the ultimate quality rather than power. I do like it to be able to handle a decent volume, well only when the neighbours are out, now thats not saying its going to be heavy rock, far from it, more than likely it will be Norah Jones or similar. I just love the fact that its so much more involving when there are a few watts hitting my ears.
Maybe to get the sort of quality that I am after, I need to ultimately invest in a different amp (somewhere down the line). As said I loved the characteristics of the meridian 557 and the quad 405, but that might have had nothing to do with the wattage available.
I just dont want to upgrade the amp (audiolab) and be dissapointed, as you said Mooly, its unlikely to change the characteristic of the sound, is upgrading the caps really going to tighten and lose that harshness when I turn the volume up, or is it a waste of money.
I was very impressed by upgrading the caps in my cd player, but respect your opinions if anyone thinks that its not really worth it, and will only make slight improvments. After all the power caps are rather large and will be costly to upgrade.
They all seem to be Elnas at the moment, which surely are not that bad a cap. I would probably replace them with silmic 2's after the sucess on the cd player.
Maybe to get the sort of quality that I am after, I need to ultimately invest in a different amp (somewhere down the line). As said I loved the characteristics of the meridian 557 and the quad 405, but that might have had nothing to do with the wattage available.
I just dont want to upgrade the amp (audiolab) and be dissapointed, as you said Mooly, its unlikely to change the characteristic of the sound, is upgrading the caps really going to tighten and lose that harshness when I turn the volume up, or is it a waste of money.
I was very impressed by upgrading the caps in my cd player, but respect your opinions if anyone thinks that its not really worth it, and will only make slight improvments. After all the power caps are rather large and will be costly to upgrade.
They all seem to be Elnas at the moment, which surely are not that bad a cap. I would probably replace them with silmic 2's after the sucess on the cd player.
Thats all right
How much power do you really need though... I have a little test you can do if your interested... all you need is a CD with test tones recorded at max level of 0db at around 100hz and a meter that reads AC volts.
Always interested me.... so what does that involve then. You do realise that as I have and am having great sucess in upgrading my CD player (thanks to you) that I will probably never be 100% satisfied, but then that is what the hobby is all about I suppose. Get ready to see my threads all over this site.........sorry in advance
Enjoying myself too much....
with all these potential mods and tweaks.
One thing at once methinks
Excellent strategy.
If you change sometyhing and it doesnt work you can always take a step back.
My personal strategy is if it works leave well alone coz you will break it !
OK... and it's just my personal opinion... is that you won't really change the basic sound of the amp.
As to power, obviously a 'scope is the quick accurate way of seeing just what voltage is being put across the speakers under music conditions.
Anyway this is how the test goes. A disc recorded at 0db (max level) corresponds to the absolute maximum level a CD player can put out. It's an absolute being digital, no transients or peaks can go over that level. When a music disc is recorded the level is set so that transients are as near to this point as possible so giving maximum headroom and dynamic range.
So what you do is play a music disc... try and select one that is recorded at a "loud" level, and play it back at as loud a volume as you would ever use.
Now disconnect the speakers from the amp and play the test tone CD.
Measure the AC voltage across the speaker terminals of the amp, which gives an RMS voltage reading.
From that calculate power. So if you measured 16 volts, the power is (V*V/R) which is 32 watts RMS assuming an 8 ohm speaker load.
That power reading corresponds to the power needed to maintain not the average music level but the absolute maximum level encountered. The average power would be much lower, perhaps only 3 or 4 watts.
So that max power value tells us an amp of 32 watts rms would be needed for that level of sound. If we rearrange the formula we get back to voltage = square root of (W*R) which brings us back to 16 volts RMS.
Now 16 volts RMS is 22.6 volts peak (vpk = vrms*root2, which is 16*1.414). The peak to peak value is 45.2 volts (vpk times 2).
So we need an amp that runs off at least a -/+22.6 volt rail to achieve that... in practice it's more because of losses in the output stage. You would be looking at nearer -/+27 volts in practice.
If you repaet that test at different levels you will see how little power is needed for normal listening, probably under 1 watt, but that as you turn things up the power jumps dramatically.
As to power, obviously a 'scope is the quick accurate way of seeing just what voltage is being put across the speakers under music conditions.
Anyway this is how the test goes. A disc recorded at 0db (max level) corresponds to the absolute maximum level a CD player can put out. It's an absolute being digital, no transients or peaks can go over that level. When a music disc is recorded the level is set so that transients are as near to this point as possible so giving maximum headroom and dynamic range.
So what you do is play a music disc... try and select one that is recorded at a "loud" level, and play it back at as loud a volume as you would ever use.
Now disconnect the speakers from the amp and play the test tone CD.
Measure the AC voltage across the speaker terminals of the amp, which gives an RMS voltage reading.
From that calculate power. So if you measured 16 volts, the power is (V*V/R) which is 32 watts RMS assuming an 8 ohm speaker load.
That power reading corresponds to the power needed to maintain not the average music level but the absolute maximum level encountered. The average power would be much lower, perhaps only 3 or 4 watts.
So that max power value tells us an amp of 32 watts rms would be needed for that level of sound. If we rearrange the formula we get back to voltage = square root of (W*R) which brings us back to 16 volts RMS.
Now 16 volts RMS is 22.6 volts peak (vpk = vrms*root2, which is 16*1.414). The peak to peak value is 45.2 volts (vpk times 2).
So we need an amp that runs off at least a -/+22.6 volt rail to achieve that... in practice it's more because of losses in the output stage. You would be looking at nearer -/+27 volts in practice.
If you repaet that test at different levels you will see how little power is needed for normal listening, probably under 1 watt, but that as you turn things up the power jumps dramatically.
I'd forgotten about this,
http://www.diyaudio.com/forums/soli...er-do-you-really-need-domestic-listening.html
And from another thread of mine illustrating how important speaker sensitivity is in all this. This compares two speakers, one of 92db/watt and one of 82db and the amplifiers needed for the same output.
92 db/watt speaker.........and........an 82 db/watt speaker
92db for 1 watt rms..............82db for 1 watt rms
95db for 2 watt rms..............85db for 2 watt rms
98db for 4 watt rms..............88db for 4 watt rms
101db for 8 watt rms..............91db for 8 watt rms
104db for 16 watt rms..............94db for 16 watt rms
107db for 32 watt rms..............97db for 32 watt rms
110db for 64 watt rms..............100db for 64 watt rms
113db for 128 watt rms..............103db for 128 watt rms
The 82 db speaker is a real example -- Celestion SL6 -- used to use these a few years ago.
Speaker sensitivity is far more important than power. The first example is "louder" on 4 watts than the other is on 32 watts.
Even then it's not that straightfoward as a 3 db increase in level is barely perceptible to many. To get that extra 3 db which may not even be noticable adds hugely to the cost /size of everything.
If you do try a test tone I mentioned using around 100hz... that's to be sure the meter reads it accurately. Most are OK at much higher frequencies but check.
Also low frequency is kinder to the amp... anything over 10khz and the output zobel network in the amp might overheat... no such issues at lower frequencies.
http://www.diyaudio.com/forums/soli...er-do-you-really-need-domestic-listening.html
And from another thread of mine illustrating how important speaker sensitivity is in all this. This compares two speakers, one of 92db/watt and one of 82db and the amplifiers needed for the same output.
92 db/watt speaker.........and........an 82 db/watt speaker
92db for 1 watt rms..............82db for 1 watt rms
95db for 2 watt rms..............85db for 2 watt rms
98db for 4 watt rms..............88db for 4 watt rms
101db for 8 watt rms..............91db for 8 watt rms
104db for 16 watt rms..............94db for 16 watt rms
107db for 32 watt rms..............97db for 32 watt rms
110db for 64 watt rms..............100db for 64 watt rms
113db for 128 watt rms..............103db for 128 watt rms
The 82 db speaker is a real example -- Celestion SL6 -- used to use these a few years ago.
Speaker sensitivity is far more important than power. The first example is "louder" on 4 watts than the other is on 32 watts.
Even then it's not that straightfoward as a 3 db increase in level is barely perceptible to many. To get that extra 3 db which may not even be noticable adds hugely to the cost /size of everything.
If you do try a test tone I mentioned using around 100hz... that's to be sure the meter reads it accurately. Most are OK at much higher frequencies but check.
Also low frequency is kinder to the amp... anything over 10khz and the output zobel network in the amp might overheat... no such issues at lower frequencies.
Large speakers tend to be efficient, the 82db Celestion is an extreme example of an inefficient one, and yes you were aware of that in use in that the volume had to be turned higher for the same level.
Typical values more probably in the 88 to 93 db range I guess.
It's also easy to measure speaker impedance with a accurate DVM (accurate over 20 to 20khz) and a variable frequency test sweep. My B&W 703's are classed as 8 ohm by the manufacturer yet they freely mention in the specs that the minimum is 3 ohms... although that is only at a specific frequency.
Typical values more probably in the 88 to 93 db range I guess.
It's also easy to measure speaker impedance with a accurate DVM (accurate over 20 to 20khz) and a variable frequency test sweep. My B&W 703's are classed as 8 ohm by the manufacturer yet they freely mention in the specs that the minimum is 3 ohms... although that is only at a specific frequency.
Well I finally finished adding news Electro caps (Elna Silmic IIs) to the amp and changing to decent silva micas. Changed all the phono sockets (well the ones I need) and the speaker connections.
One word wow!, I really never expected that much difference.
Its done several things
1. Tightened up the bass less flabby
2. Smoothed the harsh top end
3. Added a cleaner detail (probably due the harshness reduction)
I had the amp turned up to volumes I have never had it to before, the kind of level where you only realise how loud it is when you try to talk to someone.
I just wanted to keep turning it up and up.
All for the price of £60 in total, bargain.
Clean crisp and tight sound, the amp has had almost a top flight service.
Now to complete my HiFi rack, which is almost there and will post pictures where complete.
One word wow!, I really never expected that much difference.
Its done several things
1. Tightened up the bass less flabby
2. Smoothed the harsh top end
3. Added a cleaner detail (probably due the harshness reduction)
I had the amp turned up to volumes I have never had it to before, the kind of level where you only realise how loud it is when you try to talk to someone.
I just wanted to keep turning it up and up.
All for the price of £60 in total, bargain.
Clean crisp and tight sound, the amp has had almost a top flight service.
Now to complete my HiFi rack, which is almost there and will post pictures where complete.
didnt replace these, do you think that would help, up for any slight improvments?
well without your help, I wouldn't be having so much fun, and made my hifi sound like a million dollars for a very very small outlay.
Thanks so so so much for your help and support, I will continue the DIY route from now on, its so much fun and so rewarding
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