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What exactly is meant when people refer to high current amps - what's the need?

S

stuartkicks

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This may seem like an obvious one but I'd like to clarify if I can.

I'm been looking at a couple of sets of 3 ways speakers, I know one set has 3 pairs of binding posts so can be tri-amped. Now initially I was drawn to what I consider 'high-power- amps, anything +100w RMS I guess. But then I came across these little Class D amps at BK Electronics, @ £200 a piece in theory I could daisy chain 3 for each speaker and tri-amp.

There's 2 sets of speakers I particularly like the new MA Silver 10 and XTZ 99.36

http://www.monitoraudio.co.uk/products/silver/silver-10/

http://www.xtzsound.com/en/products/speakers/99-36-mkii-piano#

So driving these speakers would these little Class D amps be suitable or would they be out of their depth?

 

vacdac

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I have the XTZ 99.36mk.ii Piano finish version & Have previously owned MA RS8's & also run MA GR20's for around a month.

The M.A.'s are altogether easier to drive than the XTZ's. The XTZ's do require an amp with serious grunt as they present a 'True 4ohm load' & depending on how you have them configured* (* they are user configurable with a variety of different user set combinations possible) they range from pretty damn inefficient to fairly inefficient. Amps that are capable of good current delivery are best suited I've found. My XTZ AP 100 power amp can swing/sustain over 62amp of current. IIRC the Audiolab 8000x7 I've also used with them can swing around 30amps of current. The XTZ also gets closer than many amps to doubling W.P.C. output as impedence halves. It manages 186wpc into a 4ohm load.

If looking for suitable amps to drive the XTZ 99.36 you need to look at models that are stable into a 4ohm load & it is the 4ohm stated output that matters as this is the load the XTZ speakers 'Present' to the amp.

I don't bi-amp/tr-amp BTW......just a single sensibly specced amp that is fit for purpose in the first place. I use Van Damme Hi-Fi UPOFC 4mm cable which is prolly overkill but more than up ter the job. I've self built using Nakamichi BFA plugs & Sewell all copper spades for the single set of cables + 2 pairs of links for each speaker.

They're a great speaker & IMV better than M.A. GR20/RS8's by quite some margin. Personally I much prefer them to the current MA GX series floorstanders which I've heard a few times.

 

RobHolt

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Definitions will vary, but generally 'high current' would imply a near doubling of current as load impedance halves - at least from 8 to 4 Ohms and preferably on down to 2 Ohms.

Never quite doubles in practice due to various losses but these amplifiers sit in contrast those with a 4 ohm rating close to or lower than their 8 Ohm rating.

The need depends on the loudspeaker and it's impedance characteristic.

Clearly if impedance is low in areas of high power demand, some amplifiers will clip more easily while others will cope fine.

 

mr.me

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Talk to BK electronics and tell them what you want to do. I'm sure they will be helpful if they can

 
S

stuartkicks

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I have the XTZ 99.36mk.ii Piano finish version & Have previously owned MA RS8's & also run MA GR20's for around a month.The M.A.'s are altogether easier to drive than the XTZ's. The XTZ's do require an amp with seriouse grunt as they present a 'True 4ohm load' & depending on how you have them configured* (* they are user configurable with a variety of different user set combinations possible) they range from pretty damn inefficient to fairly inefficient. Amps that are capable of good current delivery are best suited I've found my XTZ AP 100 power amp can swing/sustain over 62amp of current & IIRC the Audiolab 8000x7 can swing around 30amps of current. The XTZ also gets closer than many amps to doubling W.P.C. output as impedence halves. It manages 186wpc into a 4ohm load.

If looking for suitable amps to drive the XTZ 99.36 you need to look at models that are stable into a 4ohm load & it is the 4ohm stated output that matters as this is the load the XTZ speakers 'Present' to the amp.

I don't bi-amp/tr-amp BTW......just a single sensibly specced amp that is fit for purpose in the first place. I use Van Damme Hi-Fi UPOFC 4mm cable which is proll overkill but more than up ter the job. I've self built using Nakamichi BFA plugs & Sewell all copper spades for the single set of cables + 2 pairs of links for each speaker.

They're a great speaker & IMV better than GR20/RS8 by quite some margin. Personally I miuch prefer them to th current MA GX series floorstander which I've heard a few times.
Hi vacdac thanks for taking the time to give such a detailed response it's much appreciated.

I'm glad to hear that you went for the AP100, it was easily one of the better well priced power amps that I have looked at, would you say that two of those beasts bridge would be overkill for the 99.36? What have you got in the way of a preamp, I'm quite keen on the idea of using something like the DacMagic Plus or M-Dac but I don't trust those digital volume controls, I have 3 young girls and I am worried they might somehow switch of the pre-amp mode and put the DACS into direct mode (probably causing death to the speakers, I think this might be irrational though).

The thing I liked about the Silver 10 are those big twin bass drivers and the 3 way design, however when I get my sensible head on I start thinking about how much they're probably overpriced, for example you can get Dali Lektor 8's for under £1200, plus I bet you could get a good discount on them, I bet the MA's cost about the same to make. Whereas the 99.36 components cost more than the total package or so I am led to believe, so in reality the quality with these XTZ would appear to be on another level. Common sense is telling me to get the XTZ's and the 12yo inside me wants the MA...

- - - Updated - - -

Definitions will vary, but generally 'high current' would imply a near doubling of current as load impedance halves - at least from 8 to 4 Ohms and preferably on down to 2 Ohms.Never quite doubles in practice due to various losses but these amplifiers sit in contrast those with a 4 ohm rating close to or lower than their 8 Ohm rating.

The need depends on the loudspeaker and it's impedance characteristic.

Clearly if impedance is low in areas of high power demand, some amplifiers will clip more easily while others will cope fine.
Thanks.

Talk to BK electronics and tell them what you want to do. I'm sure they will be helpful if they can
I actually am, I'll fire off an email and post back here with the response, share the love and all that.

 

SergeAuckland

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Or instead of 3 amps for £600, buy one better amp for £600. :^
Although by having three amps, it makes it easier to go active. Passive tri-amping is a total waste of effort, but active tri-amping makes a great deal of sense.

I agree however, that without going active, either immediately as as a plan, one good amp is better than three poor amps.

S.

 

SergeAuckland

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Definitions will vary, but generally 'high current' would imply a near doubling of current as load impedance halves - at least from 8 to 4 Ohms and preferably on down to 2 Ohms.Never quite doubles in practice due to various losses but these amplifiers sit in contrast those with a 4 ohm rating close to or lower than their 8 Ohm rating.

The need depends on the loudspeaker and it's impedance characteristic.

Clearly if impedance is low in areas of high power demand, some amplifiers will clip more easily while others will cope fine.
One benefit of Class D amps is that they often have a switch-mode power supply that is regulated to maintain the DC voltage regardless of load within their capabilities. This means that many Class D amps do double their power going from 8 ohms to 4 ohms as the SMPS adjusts the supply volts to compensate.

Normal Class AB amps seldom actually double their continuous power as most have a conventional sagging supply.

S.

 
S

stuartkicks

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Although by having three amps, it makes it easier to go active. Passive tri-amping is a total waste of effort, but active tri-amping makes a great deal of sense.I agree however, that without going active, either immediately as as a plan, one good amp is better than three poor amps.

S.
I had been doing research on active crossovers, I think it's a bit beyond me but I imagined sticking the 3 amps in a box near the speaker and bypassing the speakers crossover, this was wild fanciful speculation though. The xover kits I found seemed to be reasonable priced, I didn't find any sites that sold finished products though.

 

HoopsOnToast

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Easiest and most compact soloution would be a MiniDSP module (although for 3-way you would need two) and a 6-channel amp like the Audiolab X7 in the classifieds :^

 

Tel

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Firstly it is absolutely pointless passively tri-amping MA (or any other speaker)

If you are going to actively tri-amp them them then there is a case but I hope you know what you are doing when you modify the cross overs.

Secondly don't bother with multiple cheap amps, buy one amp that will drive the speakers properly and of course save on all that wiring that you won't need.

 
S

stuartkicks

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Thanks for all the input peeps, I'm now steering away from the little Class D's.

 

SergeAuckland

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I had been doing research on active crossovers, I think it's a bit beyond me but I imagined sticking the 3 amps in a box near the speaker and bypassing the speakers crossover, this was wild fanciful speculation though. The xover kits I found seemed to be reasonable priced, I didn't find any sites that sold finished products though.
I don't know of any loudspeaker company that offers a ready-made conversion from passive to active, so if you're going to do that, as I did myself, then its a DIY affair. DSP-based crossovers like the Behringer DCX2496 are cheap enough and work really well, but do require a certain amount of knowledge and measuring kit or the willingness to fiddle-listen-fiddle some more until one achieves something acceptable.

As each loudspeaker design is different in terms of crossover frequencies, slopes and driver sensitivities, it wouldn't be possible for a manufacturer to offer conversion kits for more than perhaps one or two loudspeakers, much as Linn/Naim did for the Isobaric some years ago.

If you don't fancy the DIY route, then it would be sensible to give up on the idea of three amps and get one that drives the existing 'speakers as well as possible.

If you do fancy trying the DIY route, follow my signature below and see what I did with my 'speakers.

S.

 

vacdac

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Hi vacdac thanks for taking the time to give such a detailed response it's much appreciated.I'm glad to hear that you went for the AP100, it was easily one of the better well priced power amps that I have looked at, would you say that two of those beasts bridge would be overkill for the 99.36? What have you got in the way of a preamp, I'm quite keen on the idea of using something like the DacMagic Plus or M-Dac but I don't trust those digital volume controls, I have 3 young girls and I am worried they might somehow switch of the pre-amp mode and put the DACS into direct mode (probably causing death to the speakers, I think this might be irrational though).

The thing I liked about the Silver 10 are those big twin bass drivers and the 3 way design, however when I get my sensible head on I start thinking about how much they're probably overpriced, for example you can get Dali Lektor 8's for under £1200, plus I bet you could get a good discount on them, I bet the MA's cost about the same to make. Whereas the 99.36 components cost more than the total package or so I am led to believe, so in reality the quality with these XTZ would appear to be on another level. Common sense is telling me to get the XTZ's and the 12yo inside me wants the MA...

- - - Updated - - -
Hi Stuart,

If you have a v large room there may be some mileage in 2 X AP100's run as mono's. But given the silly levels my single unit manages completely unruffled I doubt you'd have serious need for more grunt. Best to buy one first & run it a while to see if any doubts set in. :^

Summat also to consider here is that if bridging an amp......Yes the output power will be significantly raised. However the load that a bridged amp actually sees will be a further halving of load. So in the case of the XTZ 99.36's it would actually be 'seeing' a 2ohm load. this means you will be giving the amp a tougher time than with 8ohm or 6ohm speakers.

I had been doing research on active crossovers, I think it's a bit beyond me but I imagined sticking the 3 amps in a box near the speaker and bypassing the speakers crossover, this was wild fanciful speculation though. The xover kits I found seemed to be reasonable priced, I didn't find any sites that sold finished products though.
I haven't got round to trying my Topping TP60 with my 99.36's as yet* (I use this for driving my MA RSFX rears). I'll prolly try it out for fun at some stage.

However to drive them well I'd prolly look at the Ghent Audio B&O Icepower based amps, as these produce decent power into a 4ohm load in the stereo chassis version & IIRC these can be bridged to provide more power too. You'd have to check & see if they are stable into loads of 2ohm or less when doing this....If not I'd rule out bridged use but I seem to recall them outputting 190wpc into a 4ohm load w both channels driven.

I've liked the look of the Rotel Class D stuff too. But haven't heard any as yet. :?

EDIT/UPDATE

I currently run a Musical Fidelity A1fbp as my main 2ch pre-amp. This offers all I could want in a pre-amp w excellent SQ. As a bonus it allows seamless integration of my Audiolab 8000AV processor for surround duties. I can also use this as a 2ch Pre-amp/DAC too.....Or a brand nooo joy has been true single speaker mono using the Audiolab to drive my Adam F7 Active Monitor that I use as my centre speaker. I have a number of mono ceeedeees ripped for streaming + also some mono L.P.'s recorded from vinyl using the mono setting on my Icon phono stage. All recorded in Dual mono @ 24bit/48khz & nicely edited/manually declicked & tagged properly w album artwork etc. :geek: :geek:...Sounds triff thru a single quality monitor in a nice central room location. :cool:

 

Tenson

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You may not need anything more than one of those Pear-Drop amps on each speaker. With the MA for example it has 90dB sensitivity so the clean 75watts each little amp delivers into 4 ohms will be plenty. Don't waste your money and be happy that good amps are highly affordable.

 

vacdac

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You may not need anything more than one of those Pear-Drop amps on each speaker. With the MA for example it has 90dB sensitivity so the clean 75watts each little amp delivers into 4 ohms will be plenty. Don't waste your money and be happy that good amps are highly affordable.
Yeah they would indeed be adequate with prolly the worst speaker option being considered here. :cool:

I bet the MA's cost about the same to make. Whereas the 99.36 components cost more than the total package or so I am led to believe, so in reality the quality with these XTZ would appear to be on another level. Common sense is telling me to get the XTZ's and the 12yo inside me wants the MA...
Yup the Driver Lineup used on the XTZ's is v tasty:love:. You don't typically see the same driver ranges used for much below £2K normally. The same Fountek ribbons are prolly best known for M.A. using them in the Platinum/GX range & I think Marten have also used them. They're pretty well liked by serious multi way active speaker DIY'ers too. The same SEAS Excel magnesium coned bass/mid driver is also highly respected & variants have appeared in Jamos well liked Concert series + their R series open baffles:love: :22: . I think Audiosmile also use a smaller variant in their scrummy Kensai mini monitor. The SEAS Prestige treated paper bass drivers are also v good & hardly bargain bucket.

Prices vary when sourcing the drivers used by XTZ. When I've looked the Fountek ribbon tweeters are generally around £170/£180 a pair, the 180mm basket SEAS Excel driver I've seen for as much as £175ea & as low as £140'ish at different times from the same supplier. I think the Prestige series bass driver is around £70/£80.

The cabinetry of the piano finish variant stands up well to scrutiny & is both heavy & well put together. I've done some surgery on them when I had to remove the drivers & install the Mk.2 crossover boards myself last year to bring em up to current spec. :geek: I think the replacement crossover boards retail @ around £200 & given the size of the inductors & general component quality that seems a v fair price to me. Managing all this in a single package for under £1100 seems pretty impressive to me.....The quality of drivers used in M.A.'s RX series must be nowhere near this level TBH.....but hey they're Shiny Shiny. :cool: ................ :nup:

 

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