Ok, here's the deal:
I would like to build a set of high sensitivity speakers that would be bi-amp'ed. So effectively each speaker will have it's own amp that will drive both driver units (2-way).
The amps are Meng X1 tube amps with a quoted max power of 24W per channel. With a pinch of chinese salt I'd stick to 20W per channel.
I was considering a 2-way speaker set because this makes it very simple to leave out the crossovers from the speakers and only use a crossover for low, and for mid/high.
The crossovers would be passive 1st order crossovers, and mounted between pre-amp and power amp (actually, the Meng X1 is an integrated amp, but the pre-amp is a Yaqin MS-12B, and it's output is at line level, so that should work fine).
The method I considered for calculating the passive crossover would be deducted from this simple calculator: Guitar Pedals: R-C Filter Calculator
I realise this may not be the best method, but its simple/easy/fast/cheap, and considering this will be the first time I bi-amp a setup, as well as build a speaker set, I prefer simple. Less can go wrong, and troubleshooting/improvements will be easier.
My question is: Can anyone advice me of a suitable design that's simple and cheap (budget is around 200-300GBP for the whole speaker set). Also, for a given design, could someone advice me of the recommended crossover frequency cutoff for low and for mid/high for the suggested speaker design?
Cheers,
K
I would like to build a set of high sensitivity speakers that would be bi-amp'ed. So effectively each speaker will have it's own amp that will drive both driver units (2-way).
The amps are Meng X1 tube amps with a quoted max power of 24W per channel. With a pinch of chinese salt I'd stick to 20W per channel.
I was considering a 2-way speaker set because this makes it very simple to leave out the crossovers from the speakers and only use a crossover for low, and for mid/high.
The crossovers would be passive 1st order crossovers, and mounted between pre-amp and power amp (actually, the Meng X1 is an integrated amp, but the pre-amp is a Yaqin MS-12B, and it's output is at line level, so that should work fine).
The method I considered for calculating the passive crossover would be deducted from this simple calculator: Guitar Pedals: R-C Filter Calculator
I realise this may not be the best method, but its simple/easy/fast/cheap, and considering this will be the first time I bi-amp a setup, as well as build a speaker set, I prefer simple. Less can go wrong, and troubleshooting/improvements will be easier.
My question is: Can anyone advice me of a suitable design that's simple and cheap (budget is around 200-300GBP for the whole speaker set). Also, for a given design, could someone advice me of the recommended crossover frequency cutoff for low and for mid/high for the suggested speaker design?
Cheers,
K
The calculator you linked to does not include the input impedance.
"This calculator assumes a low source impedance, which usually is small enough that it does not change the corner frequency. " This is not an assumption that I would want to make. Here's a formula that includes the input impedance. PLLXO
As far as a cheap effecient two way that could work with a 1st order crossover? That certainly narrows down the field. I would maybe consider a "fullrange" driver crossed over to a prosound 12"-15" somewhere in the 200-600Hz range depending on the size of the fullrange driver. Also considering if the prosound driver has any nasty breakups in the 1-2kHz region, which would certainly be a problem with a 6db/oct crossover.
Joe
"This calculator assumes a low source impedance, which usually is small enough that it does not change the corner frequency. " This is not an assumption that I would want to make. Here's a formula that includes the input impedance. PLLXO
As far as a cheap effecient two way that could work with a 1st order crossover? That certainly narrows down the field. I would maybe consider a "fullrange" driver crossed over to a prosound 12"-15" somewhere in the 200-600Hz range depending on the size of the fullrange driver. Also considering if the prosound driver has any nasty breakups in the 1-2kHz region, which would certainly be a problem with a 6db/oct crossover.
Joe
Hi K,
I'm not very much into active, others can help better, but you have to start in somewhere looking for your complete set, or for the drivers only, for a start. So, I would suggest a very sensitive and lovely 2-way that you can later in time upgrade with a sub-woofer for more punch (I just don´t know how the low impedance tweeter works with a tube amp).
Woofer, FANE SOVEREIGN 12-200, SPL=98, Fs=45Hz
Fane sovereign 15-400 12-300 10-275 15-250
Fane International, loudspeakers and high frequency drivers designed for the professional user
http://www.fane-international.com/downloads/Fane_Sovereign Series.pdf
Tweeter, Vifa DX25TG-09-04, SPL=96.5, Fs=680Hz
The SEAS tweeters are very lovely too, Seas T25C003, SPL=91, Fs=600Hz
SEAS PRESTIGE TWEETERS
SEAS EXCEL TWEETERS
I'm not very much into active, others can help better, but you have to start in somewhere looking for your complete set, or for the drivers only, for a start. So, I would suggest a very sensitive and lovely 2-way that you can later in time upgrade with a sub-woofer for more punch (I just don´t know how the low impedance tweeter works with a tube amp).
Woofer, FANE SOVEREIGN 12-200, SPL=98, Fs=45Hz
Fane sovereign 15-400 12-300 10-275 15-250
Fane International, loudspeakers and high frequency drivers designed for the professional user
http://www.fane-international.com/downloads/Fane_Sovereign Series.pdf
Tweeter, Vifa DX25TG-09-04, SPL=96.5, Fs=680Hz
The SEAS tweeters are very lovely too, Seas T25C003, SPL=91, Fs=600Hz
SEAS PRESTIGE TWEETERS
SEAS EXCEL TWEETERS
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Other tweeter candidates are,
Fostex FT48D Dome Tweeter
Sica Z009160 - LP 90.28/N92 TW 8 Ω 1.1"- 80W Dome Tweeter
Seas 29TFF/W 1" Dome Prestige Tweeter - H1318
GR-T6 Dome Tweeter (Not bad idea to have selected matched pairs)
The Seas T29CF001 - E0038 Dome Excel Tweeter Beast, SPL=93, Fs=550Hz. Cost no Object by Troels Gravesen.
Also the interesting SEAS Prestige 27TDFNC/GW (H1462)
Fostex FT48D Dome Tweeter
Sica Z009160 - LP 90.28/N92 TW 8 Ω 1.1"- 80W Dome Tweeter
Seas 29TFF/W 1" Dome Prestige Tweeter - H1318
GR-T6 Dome Tweeter (Not bad idea to have selected matched pairs)
The Seas T29CF001 - E0038 Dome Excel Tweeter Beast, SPL=93, Fs=550Hz. Cost no Object by Troels Gravesen.
Also the interesting SEAS Prestige 27TDFNC/GW (H1462)
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Sensitivity 2.83V/1m 96.53 dB
DC Resistance Re 2.75 ohm
So for 1W, you'll get a little under 92dB.
I can find drivers that have a high efficiency, but of course they need to go together with a cabinet that supports those drivers, and at the same time take into consideration that no crossover is fitted in the speaker.
Usually the behaviour of a speaker driver without a crossover is quite different from that of a speaker set that utilises a passive crossover.
As for input impedance of the amp, how do I determine that? Just put a multimeter on the input when it is on?
I also understand from Josephjcole's link that the low pass filter does not need to know the amp's impedance, only for the high pass?
Usually the behaviour of a speaker driver without a crossover is quite different from that of a speaker set that utilises a passive crossover.
As for input impedance of the amp, how do I determine that? Just put a multimeter on the input when it is on?
I also understand from Josephjcole's link that the low pass filter does not need to know the amp's impedance, only for the high pass?
Yes, yes, yes. Check the Audax TW025A28 Gold Dome Tweeter, measured at 0.5m (how much at 1m?)
http://www.madisound.com/catalog/PDF/TW025A28.pdf
and the hyper high sensitivity of the BEYMA T2030 - 95 dB, good option but for a 1.order I would chose less than 1KFs
K, you don't know yet if you can do it (unless you do it in active), as for BSC on the woofer you need some kind of passive components/inductor (no?) and for the tweeter you need a LF protection or cap. Also you are going to match both final sensitivities unless you do it with the amps/preamps.
All these drivers have very good behavior (if you pay attention).
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a better method of doing PLLXO:
Passive Line-Level Crossover
(edit: I see JJcole beat me to it)
for what you're proposing, I'd suggest using a full range driver such as the Fostex FF85K, crossed over at ~ 200Hz (or baffle step freq) to woofers of your choice will give max benefit of biamping
Passive Line-Level Crossover
(edit: I see JJcole beat me to it)
for what you're proposing, I'd suggest using a full range driver such as the Fostex FF85K, crossed over at ~ 200Hz (or baffle step freq) to woofers of your choice will give max benefit of biamping
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Thanks Pete, I will consider that. Out of curiosity, to what extend does it matter what shape and size cabinet I use for the foster and low end driver? I would imagine I have to match the recommended volume of the manufacturer of the driver?
Usually (looking at Troels Gravensen's website) when making hi-end speakers, the drivers, cabinet and crossovers work together, so I'd imagine for optimisation the story becomes more complex. I guess I could start off with a basic shape that contains the recommended volume for the relevant driver, and chuck in a crossover between pre and power for teh 200Hz (if I go for the fostex).
Question:
1) How do I determine the input impedance of my amp?
2) How do I determine which frequency to use for the crossover? (Pete's sugegstion gives me a start, but if I were to use different drivers, the crossover frequency can change too...). Is there a rule of thumb for this?
Usually (looking at Troels Gravensen's website) when making hi-end speakers, the drivers, cabinet and crossovers work together, so I'd imagine for optimisation the story becomes more complex. I guess I could start off with a basic shape that contains the recommended volume for the relevant driver, and chuck in a crossover between pre and power for teh 200Hz (if I go for the fostex).
Question:
1) How do I determine the input impedance of my amp?
2) How do I determine which frequency to use for the crossover? (Pete's sugegstion gives me a start, but if I were to use different drivers, the crossover frequency can change too...). Is there a rule of thumb for this?
No (easy) rule.
The main point here is that you know very well the drivers (Fs comes to mind, response in freq.) and you decide they are good for the commitment and then about two options arise or you cross them low or high. Like in a 4-Way/PA system there are drivers crossing at 800Hz. You don't want that, because is where the human voice/perception is more predominant and where you will find the flaws in phase matching between the drivers, pinpointing/balance, etc. So you cross low, as Pete said (he is mentioning BSC) 100-400, or you go high in the 1k6-3k band depending on the drivers you choosing and app.
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re:impedance
Impedance - What and Why?
Do you have the schematic of your amp? if so, it's easy to work out from the resistor on the input grid/ volume control - probably ~500K?
Re cabinet size - depends on the parameters of the drivers, best way to get a handle on this is to download Winisd or Unibox (both free) and learn to use them - not very hard.
re shape - with clever dsign, almost anything goes, (but width of cabinet affects baffle step)
choosing xover point:
http://www.speakerbuilder.net/web_files/Articles/xover article/xpointmain.htm
Impedance - What and Why?
Do you have the schematic of your amp? if so, it's easy to work out from the resistor on the input grid/ volume control - probably ~500K?
Re cabinet size - depends on the parameters of the drivers, best way to get a handle on this is to download Winisd or Unibox (both free) and learn to use them - not very hard.
re shape - with clever dsign, almost anything goes, (but width of cabinet affects baffle step)
choosing xover point:
http://www.speakerbuilder.net/web_files/Articles/xover article/xpointmain.htm
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Hey Pete, I think K means about his "cabinet size" for a mid, that in this case doesn't need to be the same than one for a woofer. A driver may need a certain volume (WinISD) box as a woofer but then, the same driver, if it's used as a mid, most of the times can just have a small closed box behind (I´m not including OB for that matter
). "Recommended volume of the manufacturer of the driver" should be only used in the case as a woofer... not if you use your "woofer" as a mid, where there's (almost) no movement of the cone.
). "Recommended volume of the manufacturer of the driver" should be only used in the case as a woofer... not if you use your "woofer" as a mid, where there's (almost) no movement of the cone.
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actually I was considering in the ways of Pete's suggested setup, full range plus 10 or 12" for lows. I don't really want to go towards the term "woofer" as it sounds too much like "sub-woofer" which is a completely different ball game.
As for schematics, I don't have any. I have been looking around but haven't been able to find one. My pre-amp is a Yaqin MS-12B, and my main/power amp is a Meng X1. The Meng I suspect to be very similar to the Meng Yue Mini. The X1 has a higher power output, using 4 6P1's per channel rather than 2 per channel. I suspect the driver stage to be the same.
A colleague of mine told me today that it's a bad idea to use a passive crossover between pre and power, because the crossover would be optimised for one frequency signal only. He said that probably the input has a cap before the resistor to ground, meaning you cannot take that resistor as input impedance. He says that in theory it is correct, but considering that the signal will contain a wide range of frequencies, the crossover should be powered, i.e. active, which results in the input impedance not being relevant.
This of course drives the price up again. If that results in a new, higher budget, I could also opt for building some proper high efficiency speakers (95dB or up) with build in passive crossovers. This would become a completely different threat though...
As for schematics, I don't have any. I have been looking around but haven't been able to find one. My pre-amp is a Yaqin MS-12B, and my main/power amp is a Meng X1. The Meng I suspect to be very similar to the Meng Yue Mini. The X1 has a higher power output, using 4 6P1's per channel rather than 2 per channel. I suspect the driver stage to be the same.
A colleague of mine told me today that it's a bad idea to use a passive crossover between pre and power, because the crossover would be optimised for one frequency signal only. He said that probably the input has a cap before the resistor to ground, meaning you cannot take that resistor as input impedance. He says that in theory it is correct, but considering that the signal will contain a wide range of frequencies, the crossover should be powered, i.e. active, which results in the input impedance not being relevant.
This of course drives the price up again. If that results in a new, higher budget, I could also opt for building some proper high efficiency speakers (95dB or up) with build in passive crossovers. This would become a completely different threat though...
re: 'it's a bad idea to use a passive crossover between pre and power' - I have to disagree strongly with this, it works very well for me. However, it's very cheap to try - 8 components for 2 channels - give it a go & see if you like it.
preamp schematic here:http://yaqin.slickpepper.org.uk/wp-content/uploads/2009/01/ms-12b_schematic.jpg
Looking at the only Meng X1 schematic I could find, I'd use input impedance value of 50K ohms
(if you make the HP resistor ~ 4.7K, the input impedance of the amp won't have much effect on the outcome)
preamp schematic here:http://yaqin.slickpepper.org.uk/wp-content/uploads/2009/01/ms-12b_schematic.jpg
Looking at the only Meng X1 schematic I could find, I'd use input impedance value of 50K ohms
(if you make the HP resistor ~ 4.7K, the input impedance of the amp won't have much effect on the outcome)
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Thx Pete, for the advice and the schematic!
I think my colleague just expressed his opinion. I told him your thoughts and he seemed pleasantly surprised you stuck to your advice.
It's also good to know your technique is tried and tested succesfully. Gives me some extra confidence.
Could you by any chance point me to that schematic of the meng x1 please. I've not managed t find it.
As for the speakers themselves, is there a recommended shape, eg wide baffle thin body, or thin baffle narrow deep body? (assuming a full range driver and a woofer).
Has anyone happen to have wad the latest klang & ton (german sit speaker magazin I picked up on the airport. Dont really understand the text, my German isn't good enough.). Anyway it contains a cheap design using a tweeter and a woofer, with the whole speaker beinf 95 dB sensitive. at 200e per speaker.
I think my colleague just expressed his opinion. I told him your thoughts and he seemed pleasantly surprised you stuck to your advice.
It's also good to know your technique is tried and tested succesfully. Gives me some extra confidence.
Could you by any chance point me to that schematic of the meng x1 please. I've not managed t find it.
As for the speakers themselves, is there a recommended shape, eg wide baffle thin body, or thin baffle narrow deep body? (assuming a full range driver and a woofer).
Has anyone happen to have wad the latest klang & ton (german sit speaker magazin I picked up on the airport. Dont really understand the text, my German isn't good enough.). Anyway it contains a cheap design using a tweeter and a woofer, with the whole speaker beinf 95 dB sensitive. at 200e per speaker.
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