Finally got around to testing my speakers today. According to the mfg their efficiency is 93dB. Room size is 6x11 meters, but the speakers sit in the right half of that. The left side opens ( L shaped ) away from the speaker wall into another 4x8 room. Ceilings are all 2.66 meters. 2 volts was loud. 2.5 really loud. 3 volts would be drunken raucous party loud. I have no doubt they've been there before, and will be again.
All this is to decide which firstwatt amp to build first.....
All this is to decide which firstwatt amp to build first.....
I decided to build F4. All the voltage swing I need can be provided directly by the DAC. 😀
Pano, this is an excellent test.
But the volume control setting (and required power) depends on what music you play.
If you play something with clean but very high dynamic range like a very good small unaccompanied choir, your volume control will probably be set quite high as it would recorded at a low average level.
If you play, some modern compressed music (???), the volume probably has to be brought down as compressed stuff sounds terrible at too high an average level.
Why don't you say in the instructions that this test can be used to find out what voltage (and amp power) is required FOR YOU FOR EACH INDIVIDUAL PIECE OF MUSIC?
Of course there are people who NEVER move their volume control .. so they can ignore everything I say 😀
But the volume control setting (and required power) depends on what music you play.
If you play something with clean but very high dynamic range like a very good small unaccompanied choir, your volume control will probably be set quite high as it would recorded at a low average level.
If you play, some modern compressed music (???), the volume probably has to be brought down as compressed stuff sounds terrible at too high an average level.
Why don't you say in the instructions that this test can be used to find out what voltage (and amp power) is required FOR YOU FOR EACH INDIVIDUAL PIECE OF MUSIC?
Of course there are people who NEVER move their volume control .. so they can ignore everything I say 😀
Thanks! Hope it can be of some help to you.
Yes, very much so. This is important. (see below)
Please see post #2 of this thread. It is in the bulleted list. Play dynamic tracks.
Beyond that, I really can't help. You have to figure out for yourself what music you listen to that has a wide dynamic range. Most does not. Find a CD that is recorded at a generally low level, that should help. They tend to be the most dynamic.
Well I've been meaning to do this for a long time and nearly a year later I finally just brought in the O scope and measured the voltage directly. I have a 13 X 19 foot room with JBL 1400 Arrays with 89dB rated sensitivity and a pair of 2KW mono block amps.
I measured voltage while playing a bass guitar piece called Lords Tundra off the old Stereophile test CD #3. At 81 dBC level at my chair averaged over two minutes with peaks of 97dBC I have voltage swings of just over 20V peak to peak. Pushing it hard on the drum tracks I see well over 80V swings with the VU meters on the amps reading peaks of +2dB, they have 0.6 sec hold time. Seems about right as they will swing 68V constant.
No small amps for me! I was considering tube amps but they would have to be water cooled. Oh well.
Barry.
I measured voltage while playing a bass guitar piece called Lords Tundra off the old Stereophile test CD #3. At 81 dBC level at my chair averaged over two minutes with peaks of 97dBC I have voltage swings of just over 20V peak to peak. Pushing it hard on the drum tracks I see well over 80V swings with the VU meters on the amps reading peaks of +2dB, they have 0.6 sec hold time. Seems about right as they will swing 68V constant.
No small amps for me! I was considering tube amps but they would have to be water cooled. Oh well.
Barry.
Why didn't you just try Pano's test? For one thing it would be easier to compare with others' results.
Not sure how your monoblocks got their 2kW rating, based on the voltage swing. Will they drive down to 2ohm?
Recently I've been using my PA system as my home stereo.
At home, we're down in the milli-watt range (cabinets are all >96dB@1w). In PA mode, the clip lights on the sub amps can be made to light up (QSC USA 850, bridged), but it is very very loud at that: the sub is ~96db@1w, groundplane. I usually corner-load it which gives a few dB.
Call it 126dB peaks, and still sounding pretty clean. This is where true "dynamic range" lies.
Chris
This got me really curious so, I did the Pano 220Hz test. I used several songs for reference:
Cadillac Angels, Loves Heavy Chains, 2 min. avg. 96dBC, 99.9dBC peak, 220Hz 3.1V
Sara K, History Repeats Itself, 2 min. avg. 87.4dBC, 106.5dBC peak, 220Hz 12V, scope 42V
Jimmy Rogers, Blue Bird, 2 min. avg. 88.1 dBC, 102 dBC peak, 220Hz 5.7V, scope 40V
Dean Peer, Lords Tundra, 2 min. avg. 89.1 dBC, 104,6 dBC peak, 220Hz 9.75V, scope 80V
Dick Hyman, Topsy, 2 min. avg. 81.8 dBC, 95.7 dBC peak, 220Hz 5.1V
The first song is obviously compressed. On History and Blue the peaks are actually vocals. The scope voltage is the maximum visually observed voltage swing. The peak dBC is also visually observed. The 2 minute average dBC is done with a calibrated mic using TEF with the worlds worst RTA.
The amps will drive full power 20-20kHz into 2 ohm and nearly so to DC so they are indeed voltage limited into a 6 plus Ohm load. They are on a dedicated 240V 40 amp circuit so they are not supply limited.
I'm just kicking it listening at about 1.5V now. I don't think I'll be in for smaller amps.
Thanks for the fun Pano.
Barry.
Cadillac Angels, Loves Heavy Chains, 2 min. avg. 96dBC, 99.9dBC peak, 220Hz 3.1V
Sara K, History Repeats Itself, 2 min. avg. 87.4dBC, 106.5dBC peak, 220Hz 12V, scope 42V
Jimmy Rogers, Blue Bird, 2 min. avg. 88.1 dBC, 102 dBC peak, 220Hz 5.7V, scope 40V
Dean Peer, Lords Tundra, 2 min. avg. 89.1 dBC, 104,6 dBC peak, 220Hz 9.75V, scope 80V
Dick Hyman, Topsy, 2 min. avg. 81.8 dBC, 95.7 dBC peak, 220Hz 5.1V
The first song is obviously compressed. On History and Blue the peaks are actually vocals. The scope voltage is the maximum visually observed voltage swing. The peak dBC is also visually observed. The 2 minute average dBC is done with a calibrated mic using TEF with the worlds worst RTA.
The amps will drive full power 20-20kHz into 2 ohm and nearly so to DC so they are indeed voltage limited into a 6 plus Ohm load. They are on a dedicated 240V 40 amp circuit so they are not supply limited.
I'm just kicking it listening at about 1.5V now. I don't think I'll be in for smaller amps.
Thanks for the fun Pano.
Barry.
Sure thing! It will take me a bit to digest the numbers, but they look in the ballpark for your levels and speakers. Nice that you were able to take the 2 min SPL averages, too.
The Sara K track looks fairly dynamic, about 19dB average/peak. I thought I had the track to measure it, but can't find it.
The Sara K track looks fairly dynamic, about 19dB average/peak. I thought I had the track to measure it, but can't find it.
I've looked at you numbers again and can't make sense of them. For example:
2dB lower SPL needs over 5dB more voltage? Was the peak in a non-linear part of the speaker response?
Also, if you got 12V from the tone after the Sara K track, you should see 48V peak, right? But you report 42V. Close, but a little lower than I would have thought. Maybe the track doesn't hit 0dBFS?
Why would an SPL peak of 106.5dB show a 42V peak but a 104.6dB peak show 80V peak?
2dB lower SPL needs over 5dB more voltage? Was the peak in a non-linear part of the speaker response?
Also, if you got 12V from the tone after the Sara K track, you should see 48V peak, right? But you report 42V. Close, but a little lower than I would have thought. Maybe the track doesn't hit 0dBFS?
^ pano, wouldn't that non linearity infer that the drivers were maxed out, or hitting thermal compression region?
Neither the peak SPL nor voltage was data logged, only the two minute average SPL was. I know the numbers only roughly correlate. The active SPL numbers and traces on the scope are rapidly changing and I simply recorded what I saw with no attempt to fudge what I viewed.
I could set up and log all of it but this was just for fun and mild curiosity. I don't need to know if I need a 1000 watt amp or a 1200 watt amp. I do know I won't be happy with a 35 watt amp.
All the best,
Barry.
I could set up and log all of it but this was just for fun and mild curiosity. I don't need to know if I need a 1000 watt amp or a 1200 watt amp. I do know I won't be happy with a 35 watt amp.
All the best,
Barry.
Did you adjust the volume control to suit each different track?
I note that the first and last have the extreme in the range of average output (>14dB difference). That by my thinking would lead to a very different volume control setting for each to sound right.
Barry, thanks for the answer, I understand. From your measurements of the tones I'd say you need a minimum 150W amp. That's taken on the highest RMS voltage you got - 12V.
That seems reasonable given the efficiency of the speakers and the levels you want. You could probably get by with 50 watts RMS for most listening, but it would limit your headroom and party ability. 🙂
That seems reasonable given the efficiency of the speakers and the levels you want. You could probably get by with 50 watts RMS for most listening, but it would limit your headroom and party ability. 🙂
Hi a.wayne;
The amps are the AE Techron 7560/7570 series, "Gradient Drive Amplifier". The same chassis as the Crown M600 and Delta Omega.
Yes AndrewT, I did adjust the volume for each song. The compressed song Loves Heavy Chains had the volume knob at 12 O'clock, Lords Tundra was wide open. The gain stage in the amp yields near 0dB on the VU meter when the pre is wide open.
Barry.
The amps are the AE Techron 7560/7570 series, "Gradient Drive Amplifier". The same chassis as the Crown M600 and Delta Omega.
Yes AndrewT, I did adjust the volume for each song. The compressed song Loves Heavy Chains had the volume knob at 12 O'clock, Lords Tundra was wide open. The gain stage in the amp yields near 0dB on the VU meter when the pre is wide open.
Barry.
Measured today
Cool!
I performed the measurement today.
Having adjusted the volume control so as to achieve a 'realistic' (as in: like in a Jazz club) level with some fairly dynamic jazz recording ('Art Pepper meets the rhythm section'), the -12dB, 120Hz sine wave test tone gave a reading of 6V. At the same volume setting, '0dB' peak levels will therefore require 4x such voltage, i.e. 24V.
My speakers are ~93dB/W(m), and my listening position is ~3m away from the speakers. So according to my back-of-the-envelope calculations, this corresponds to instantaneous peak (0dB) levels of ~105dB at the listening position, which sounds about right for a subjectively 'realistic' level with that kind of music.
Incidentally, it also means that a ~70Wpc/8Ohm amplifier is required to provide such undistorted and unclipped peaks - despite what is often claimed by those who say that with fairly efficient speakers such as mine a 10W minimalistic amp is all that's needed... (and if the speakers had been some of the common 'audiophile' 87dB/W(m) ones, then a ~280W amp would have been called for!)
Thanks Pano for suggesting this test!
Marco
Cool!
I performed the measurement today.
Having adjusted the volume control so as to achieve a 'realistic' (as in: like in a Jazz club) level with some fairly dynamic jazz recording ('Art Pepper meets the rhythm section'), the -12dB, 120Hz sine wave test tone gave a reading of 6V. At the same volume setting, '0dB' peak levels will therefore require 4x such voltage, i.e. 24V.
My speakers are ~93dB/W(m), and my listening position is ~3m away from the speakers. So according to my back-of-the-envelope calculations, this corresponds to instantaneous peak (0dB) levels of ~105dB at the listening position, which sounds about right for a subjectively 'realistic' level with that kind of music.
Incidentally, it also means that a ~70Wpc/8Ohm amplifier is required to provide such undistorted and unclipped peaks - despite what is often claimed by those who say that with fairly efficient speakers such as mine a 10W minimalistic amp is all that's needed... (and if the speakers had been some of the common 'audiophile' 87dB/W(m) ones, then a ~280W amp would have been called for!)
Thanks Pano for suggesting this test!
Marco
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Marco - you are welcome! Yes that sounds about right, 105dB peaks is plenty loud for most material. But I see you as needing a 40W RMS amp, not 70W. Not that a 70W amp would be bad, it would have all the headroom you ever need.
I figure it this way: If you need to hit 24V peak, then you need 17V RMS. That means a power amp rated clean @ 36W-8 ohms RMS. Call it 40W and be happy. 🙂 And you are correct, a 10W RMS amp would not work for you at those levels. You'd be under your peak voltage be at least 6dB.
I figure it this way: If you need to hit 24V peak, then you need 17V RMS. That means a power amp rated clean @ 36W-8 ohms RMS. Call it 40W and be happy. 🙂 And you are correct, a 10W RMS amp would not work for you at those levels. You'd be under your peak voltage be at least 6dB.
To Pano, Hi, I'm new in diyAudio forum. I wanted to know about my custom sound system which is built with STK4231v. Honestly I haven't any idea about rms, watt, ohms and db but I have much interest about sound sys. Thats why I want to know am I using the right speaker with right amp or not?
Please see below my custom amplifier and speaker system.
My Amplifier:
IC: STK4231v (100w + 100w MIN.)
Transformer: AC 35v and DC+/-48v
Ampere: 8
Capacitor in the split power supply: 6800mfd, 63volt
Tone circuit: BASS and TREBLE with C828 transistor driven preamp with master volume and setup before AMP circuit. (CD/DVD directly input to the tone circuit then power amp.)
My Speaker system:
3 way custom speaker system
One horn with 80wrms, 6ohms
One 5" midrange with 35wrms, 8ohms
One 15" speaker with 300wrms, 8ohms
All are connected parallels with 15" speaker.
With the Horn, 2.2mfd with 50v bi-poler cap. (parallel con. with 15", 8ohms speaker)
With the Midrange, 10mfd with 50v bi-poler cap. and 10ohms 20watt register, both are serially connected (parallel con. with 15", 8ohms speaker)
Now kindly tell me the condition of the above.
Thanks.
Please see below my custom amplifier and speaker system.
My Amplifier:
IC: STK4231v (100w + 100w MIN.)
Transformer: AC 35v and DC+/-48v
Ampere: 8
Capacitor in the split power supply: 6800mfd, 63volt
Tone circuit: BASS and TREBLE with C828 transistor driven preamp with master volume and setup before AMP circuit. (CD/DVD directly input to the tone circuit then power amp.)
My Speaker system:
3 way custom speaker system
One horn with 80wrms, 6ohms
One 5" midrange with 35wrms, 8ohms
One 15" speaker with 300wrms, 8ohms
All are connected parallels with 15" speaker.
With the Horn, 2.2mfd with 50v bi-poler cap. (parallel con. with 15", 8ohms speaker)
With the Midrange, 10mfd with 50v bi-poler cap. and 10ohms 20watt register, both are serially connected (parallel con. with 15", 8ohms speaker)
Now kindly tell me the condition of the above.
Thanks.