In was told Stan played bass guitar through the Rotel RA820 amp until it sounded least troubled . He reasoned that bass guitar was an approximation to real needs . I wouldn't mind betting each amp has a perfect bandwidth . This will be made up of a dominant device ( VAS ) and many tiny adjustments ( e.g. input slew ) . This would seem to be " statements of the bleeding obvious " . I bet most amps are not optimum ? I suspect a tuned amp will also measure better ? I say tuned as many filtering ideas I try ruin an amp yet do not measure badly . My son has an RA840 . It has a multi transistor phono stage ( later NE5534 ) .
Sony , yes . Funny thing is Sanyo their industrial side is excellent .
The best cascode I found was in this amp . I have big doubts that the complex ones are as good as this ? The inclusion of a 33R resistor seems to do the stuff . Before anyone laugh's this was one of Ferranti's engineers and none comes higher in the world of transistors . I would place the bias a little higher .
A Paul Kemble web page - Practical Electronics Gemini amplifier.
According to my analog meter typical listening is done @ less than 10volts rms. with only the occasional peak exceeding , ok' speaker load is 1 ohm from 350hz-22k , so why all the heat and difficulty in playing this thing from most ...
Does this mean a 25volt amp @1 ohm will suffice ..? Or meter inacurracy ..?
Does this mean a 25volt amp @1 ohm will suffice ..? Or meter inacurracy ..?
I'm sure someone here would be able to now mathematically prove that anything below 300 wpc/8 Ohms simply cannot sound realistic.
My feeling is different. I feel that people buy say 200 WPC/8 Ohms not to have that many watts, but to have the much less watts they do need in as best a condition as they can. Manufacturers consistently underbuild lower power model power supplies, guiding you towards higher powered and more expensive models.
You can check this out yourself. Buy a cheap vintage amp and rebuild its power supply adding in capacity and quality, for example, replace the standard 15,000 uF with say 22,000 uF caps, raising the ante by 50% (make sure the rectifiers can handle this). You will INSTANTLY hear a difference for the better.
Before when you turned it up into some inefficient speakers, it would work, but its sound would soon change for the worse, and on occasion, even its lights might flicker. After the change, all this is either gone, or is moved much higher up the scale, and the flickering lights are a thing of yesterday.
Whenever you have a good base and generously invest in its power supplies, you could be left wondering who the hell needs anything more than 100 WPC/8 Ohms.
Some years ago, I refurbished an old Harman/Kardon 870 power amp that way. I swapped its 4x10,000 uF caps per channel with 4x15,000 uF, the rectifiers were already oversized and they could easily deal with this. Its already very good sound simply improved quite a bit and its impulse power into low impedance loads, excellent even in original form, now went through the roof, way above what it was ever likely to be required from it in real life (although the stupidity effect should never be underestimated). It was then essentially limited by its two pairs of NEC power transistors per channel, if I had been able to add a third pair, I guarantee its effective power would have increased even more.
THIS is how an objectively low power amp like the old Naim 30 WPC integrated amp from the early 80ies manaages to sound so big and often outshines both nominally and effectively much more powerful amps - the whole trick is in the fact that it has electronically regulated power supplies.
THIS is how tube amps, usually far lower powered than transistor amps, manage to sound so big - most of them have regulated power supplies. Sure, this costs money, but it also provides worthy results.
DVV, sometimes the numbers don't tell the tale, for eg. while we can calculate that 100 watts RMS should be sufficient for some reason putting a 1 KW amp sounds better , follow me now , not louder , better, more realistic in size , detail and dynamics..
In my eg , when using the Krell which is rated at 1600watts @ 1ohm , sounds the best on this speaker, I don't necessarily play it any louder than the other amplifiers, basically the same volume level ( less than 10volt rms) it sound very visceral, fast with a lot of attack and decay, the best for
tonal balance .
The A52 did sound good also, but it will shut down if you exceed the 10 volt rating , The S500's drives the load pretty well also , althought it is not rated for this operation, just not as well as the Krell and not as tonally correct. Funny on the Maggies with their 4 ohm nominal impedance it's the reverse with the the Krell not as favorable as the rest ...
Best to use amplifiers without current protection gimmickry ...
Hence the Krell,( KSA200) Threshold (S500) Adcom ( 565, 555) et al , will drive no problem ( fuse upgrade necessary) ..all have big supplies, non fully regulated,
In my eg , when using the Krell which is rated at 1600watts @ 1ohm , sounds the best on this speaker, I don't necessarily play it any louder than the other amplifiers, basically the same volume level ( less than 10volt rms) it sound very visceral, fast with a lot of attack and decay, the best for
tonal balance .
The A52 did sound good also, but it will shut down if you exceed the 10 volt rating , The S500's drives the load pretty well also , althought it is not rated for this operation, just not as well as the Krell and not as tonally correct. Funny on the Maggies with their 4 ohm nominal impedance it's the reverse with the the Krell not as favorable as the rest ...
Best to use amplifiers without current protection gimmickry ...
Hence the Krell,( KSA200) Threshold (S500) Adcom ( 565, 555) et al , will drive no problem ( fuse upgrade necessary) ..all have big supplies, non fully regulated,
You're running 100W average level if your meter is accurate. That's a lot for a domestic setting. A 1 ohm load means a lot of current. It's no surprise you need an amp with a big power supply. And amp rated at 400W/4ohms might give you enough voltage, but only that big power supply will give you the heavy current your speakers need. You need an amp you can weld with.
Agree Sy of too few words, could you expound a bit more ...
See the Red Light District article on my website.
Could you hit me with a link? I need to get back to finish my RLD takeoff on a Meng. I want to contemplate it a lot more after the "schooling" I got in this forum on amps in general. I also have an old HK A300 that probably has much better transformers and may result in a decent amp.
Duck! Incoming!
The Red Light District: A 15W Push-Pull Amplifier
Since publishing this, I've made a few changes- higher plate voltage (410V), lower idle current (35mA), yielding over 22W per channel. the overload recovery is not compromised.
The Red Light District: A 15W Push-Pull Amplifier
Since publishing this, I've made a few changes- higher plate voltage (410V), lower idle current (35mA), yielding over 22W per channel. the overload recovery is not compromised.
You're running 100W average level if your meter is accurate. That's a lot for a domestic setting. A 1 ohm load means a lot of current. It's no surprise you need an amp with a big power supply. And amp rated at 400W/4ohms might give you enough voltage, but only that big power supply will give you the heavy current your speakers need. You need an amp you can weld with.
Big current not voltage , avg is closer to 6volt rms, peaks is what exceeds 10volt ...I maybe able to get away with 25volt
Ok, will have to modify my browser it blocks any article below 50 watts
Wow, I doubt my transformers can do 22. I get about 6 out of it right now with 6P1's. Thanks. Gives me some good reading. I have to remember where I left off as I have built about 4 amps in that chassis. Got to re-read Jones so I can get Self out of my head. But than again, that's not a bad idea anyway.
Recently Sony has been one of my un-favourite brands . I should have known better as Sony has often caused me troubles in the past .
Years ago I was forced to buy one of their big amps . It was a disaster . The rated power was considerably over 100 watts ( 175 ? ) . Hi Fi choice decided to do a new test of burst power into 1 ohms ( about 1983? ) . The NAD3020 managed to give 92 Watts , the Sony 2 Watts . That answered the doubts I had .
If completely penniless buy 2 x NAD 3020 and use one as a pre amp and the other as a power amp . Buy 3 and have monoblocs . Early ones are best .
Proton who made the 3020 also made their own version with posh transistors . It was not as good .
I often use a 3020 pre amp to do power amp tests . It has always surprised me and beat many expensive designs . I had an Audio Research once . Although better than a 3020 it wasn't as large a difference as I expected . Funny thing is a NAD was what I always said was just about OK to judge a front end with ( LP12 for example ) . I grew to like the 3020 more as time went on . I suspect speakers became more suited to NAD or it to them as time went on . EPOS ES14 a notable good combination . I have Nordost off cuts , I make them into NAD bridging conductors for friends ( Silver plated OFC for mains use ) .
Best ever surprise amp was to me Rational Audio a Check Republic design . I suspect it is these people below who made it ? It eat a Naim NAP 250 for breakfast into Linn Isobariks ( a noted difficult load ) . The amp in question was about 30 watts .
Krell with Isobariks was remarkably ( Jimmy Hugues with DNM pre amp when I visited one day ) . Surprisingly well suited and monster loud . Which for KEF units is unusual .
Feature Article
Years ago I was forced to buy one of their big amps . It was a disaster . The rated power was considerably over 100 watts ( 175 ? ) . Hi Fi choice decided to do a new test of burst power into 1 ohms ( about 1983? ) . The NAD3020 managed to give 92 Watts , the Sony 2 Watts . That answered the doubts I had .
If completely penniless buy 2 x NAD 3020 and use one as a pre amp and the other as a power amp . Buy 3 and have monoblocs . Early ones are best .
Proton who made the 3020 also made their own version with posh transistors . It was not as good .
I often use a 3020 pre amp to do power amp tests . It has always surprised me and beat many expensive designs . I had an Audio Research once . Although better than a 3020 it wasn't as large a difference as I expected . Funny thing is a NAD was what I always said was just about OK to judge a front end with ( LP12 for example ) . I grew to like the 3020 more as time went on . I suspect speakers became more suited to NAD or it to them as time went on . EPOS ES14 a notable good combination . I have Nordost off cuts , I make them into NAD bridging conductors for friends ( Silver plated OFC for mains use ) .
Best ever surprise amp was to me Rational Audio a Check Republic design . I suspect it is these people below who made it ? It eat a Naim NAP 250 for breakfast into Linn Isobariks ( a noted difficult load ) . The amp in question was about 30 watts .
Krell with Isobariks was remarkably ( Jimmy Hugues with DNM pre amp when I visited one day ) . Surprisingly well suited and monster loud . Which for KEF units is unusual .
Feature Article
Wayne, the short and curly of it is that when you have a decently done say 200 WPC amp, the ACTUAL say 50W it will be asked to deliver will very likely be more stable and less stressing for it than the same from a say 100 WPC amp.
Key word is "likely". It does not HAVE to be so, but in practice, due to mostly economic and marketing reasons, it very often is so. Should the manufacturer of a say 80 WPC amp decide to endow it with a full electronic regulation, then this will most probably NOT be so, and in fact, you might find that the lesser power amp plays better music.
Once upon a time, there was a small time operation called R.E. Designs, somewhere in the greater Boston area, run by a great guy and an excellent engineer called Dan Baquer. He made just one power amp, a nominally 80 WPC amp, which used two pairs of 250 W devices in its output (sic!) and had a fully regulated power supply. By listening to it, you would think the amp was more like 200 or 300 WPC - absolutely stable, rock steady imaging, and lots of it.
Unfortunately, Dan had a double family vrisis related to health and was forced to go out of business, but he did transfer all his copyrights to me, and I will produce both the original version and an enhanced version of it (DC coupled, servoed). But the first jury rigged version was way more than convincing, there's no doubt in my mind that he got it right and then some.
Because of the added complexity and parts, obviously that amp will need to cost more than its similar bretheren, but my feeling is that it will outplay them hands (er, transistors) down.
SY has a point. Solid state circuits in most audio gear that I have seen do not often consider the problem of overload recovery. And that is not something to be toyed with. But that's only one of several points one needs to consider.
This is one of the reasons why over the last 25 years, I have never made an amp which did not have separate power supply lines and which were not fully electronically regulated for the voltage gain amp and the predriver at least. Not that I made many of them, but I did follow this logic very consistently and will continue to do so.
And if your speakers do have an "impedance" of 1 Ohm, which is almost a short ciruit, then you do need an amp of heavy proportions capable of powering a welding iron.
As for protection circuits, I beg to differ. I have seen far too many amps which were wasted altogether, while their "protection" fuses remaind intact. But there's no doubt that one needs to be very careful with such ciruits, because they have a conflicting job to do, to protect the amp but to be non-intrusive right up to the very last stand position. That's why I make mine stay passive until the impedance drops to 1.8 Ohms, and even so to first stay passive for a short period in case that's only a transient.
Key word is "likely". It does not HAVE to be so, but in practice, due to mostly economic and marketing reasons, it very often is so. Should the manufacturer of a say 80 WPC amp decide to endow it with a full electronic regulation, then this will most probably NOT be so, and in fact, you might find that the lesser power amp plays better music.
Once upon a time, there was a small time operation called R.E. Designs, somewhere in the greater Boston area, run by a great guy and an excellent engineer called Dan Baquer. He made just one power amp, a nominally 80 WPC amp, which used two pairs of 250 W devices in its output (sic!) and had a fully regulated power supply. By listening to it, you would think the amp was more like 200 or 300 WPC - absolutely stable, rock steady imaging, and lots of it.
Unfortunately, Dan had a double family vrisis related to health and was forced to go out of business, but he did transfer all his copyrights to me, and I will produce both the original version and an enhanced version of it (DC coupled, servoed). But the first jury rigged version was way more than convincing, there's no doubt in my mind that he got it right and then some.
Because of the added complexity and parts, obviously that amp will need to cost more than its similar bretheren, but my feeling is that it will outplay them hands (er, transistors) down.
SY has a point. Solid state circuits in most audio gear that I have seen do not often consider the problem of overload recovery. And that is not something to be toyed with. But that's only one of several points one needs to consider.
This is one of the reasons why over the last 25 years, I have never made an amp which did not have separate power supply lines and which were not fully electronically regulated for the voltage gain amp and the predriver at least. Not that I made many of them, but I did follow this logic very consistently and will continue to do so.
And if your speakers do have an "impedance" of 1 Ohm, which is almost a short ciruit, then you do need an amp of heavy proportions capable of powering a welding iron.
As for protection circuits, I beg to differ. I have seen far too many amps which were wasted altogether, while their "protection" fuses remaind intact. But there's no doubt that one needs to be very careful with such ciruits, because they have a conflicting job to do, to protect the amp but to be non-intrusive right up to the very last stand position. That's why I make mine stay passive until the impedance drops to 1.8 Ohms, and even so to first stay passive for a short period in case that's only a transient.
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