ATI (Amplifier Technologies) Owners Thread

[Sly]

He might also be a little more prone to "bias of all sorts" than others.

Yeah his reaction wasn't very conclusive.
Though ati suggest 7 days of playing music to break it in lol. Never noticed speaker break in let alone amps.
Yep refrence 1, wasn't to sure of the power needed hence me asking, they look difficult but sure those amps would have decent current, don't perticually want to go overboard as they end up expensive n really heavy.
My fault for settling on a/b me thinks lol.

 

[PENG]

Though ati suggest 7 days of playing music to break it in lol. Never noticed speaker break in let alone amps.

Dr. Floyd Toole put it well in saying something like "It's the ears that got broken in", not the speakers, or electronic gear I guess..

Yep refrence 1, wasn't to sure of the power needed hence me asking, they look difficult but sure those amps would have decent current, don't perticually want to go overboard as they end up expensive n really heavy.
My fault for settling on a/b me thinks lol.

In my opinion, your choice of going with amps rated 200 W 8 ohms, 300 W 4 ohms is about right for the Reference 1. When manufacturers say 50-200 W, you know it is better to go with 200 W, so peak would be 400 W, and that should get you the best out of those speakers, in terms of satisfying their voltage/current need, more may be better, say up to 400 W 4 ohms capable amps. There are good information in the linked review, but that's for the Reference 1 Meta, the non Meta version will be different but I am sure they would be similar enough in terms of current requirements.

Kef Reference 1 Meta Bookshelf Speaker Review

From the measurements, you can see that the Ref.1's loves currents, and it has rather low EPDR (a misleading spec, that says more about heat dissipation, than currents). That, from my understanding, you may be better off using class D amps such as the popular Hypex or Purifi modules based power amps. Class D amps seem less prone to low EPDR than class AB amps that would have to dissipate lots of heat in the output devices, but obviously the ATI signatures should be good with that too.

 

[Sly]

Dr. Floyd Toole put it well in saying something like "It's the ears that got broken in", not the speakers, or electronic gear I guess..




In my opinion, your choice of going with amps rated 200 W 8 ohms, 300 W 4 ohms is about right for the Reference 1. When manufacturers say 50-200 W, you know it is better to go with 200 W, so peak would be 400 W, and that should get you the best out of those speakers, in terms of satisfying their voltage/current need, more may be better, say up to 400 W 4 ohms capable amps. There are good information in the linked review, but that's for the Reference 1 Meta, the non Meta version will be different but I am sure they would be similar enough in terms of current requirements.

Kef Reference 1 Meta Bookshelf Speaker Review

From the measurements, you can see that the Ref.1's loves currents, and it has rather low EPDR (a misleading spec, that says more about heat dissipation, than currents). That, from my understanding, you may be better off using class D amps such as the popular Hypex or Purifi modules based power amps. Class D amps seem less prone to low EPDR than class AB amps that would have to dissipate lots of heat in the output devices, but obviously the ATI signatures should be good with that too.

View attachment 74317

Was definitely my brain getting used to the arendals, took about a week, but i could tell how used i'd got to my q accoustics which had an extended treble so you could hear "detail", once i figured it was boosted i was determined to give more time n patience to my next speakers. I'd tried out at least 12 other speakers.
Its funny you mentioning that class d might be better, reading through Rich.b's thoughts and the thread about the ati class d, and having second thoughts about it.
Have been under the impression though that the added simbilance might not to my taste, leaness (which could be eq'ed out - so should'nt be concern) maybe worrying about it to much but don't want to make an exspensive mistake.
Thought 400w@4ohm would be best though, you confirmed my lingering concerns.

 

[PENG]

Was definitely my brain getting used to the arendals, took about a week, but i could tell how used i'd got to my q accoustics which had an extended treble so you could hear "detail", once i figured it was boosted i was determined to give more time n patience to my next speakers. I'd tried out at least 12 other speakers.
Its funny you mentioning that class d might be better, reading through Rich.b's thoughts and the thread about the ati class d, and having second thoughts about it.
Have been under the impression though that the added simbilance might not to my taste, leaness (which could be eq'ed out - so should'nt be concern) maybe worrying about it to much but don't want to make an exspensive mistake.
Thought 400w@4ohm would be best though, you confirmed my lingering concerns.

My concern with class AB amp for your speaker is in the range between 45-1000 Hz, where EPDR dips to around 2 ohms. There are tons of contents in music/movies in that range, so some class AB amps may struggle. In terms of current, lower EPDR than the impedance does not increase current, but could result in a lot more heat in the output devices so not a good idea.

This is a good example of using power, that is watts, is not the best way, as for people who are not familiar with EE principles may not realize that if an amp is rated say, 100 W 8 ohms, if that rating is limited by the rated current, then it is current limited at current = square root (100/8) = 3.53 A, then into 2 ohms, the "power" is only 3.53^2*2 = 24.92 W, that's not a whole lot! It is a reverse double down thing, so 100 W 8 ohms, 50 W 4 ohms, 25 W 2 ohms.

Simple math yet can confuse people right!

That's why I always want to calculate voltage and current requirement, not "power". Rule of thumb is, for higher impedance, voltage is more important and for lower impedance, current is, but that's just rule of thumb, there's always something in between, though the Ref 1, in the bass and midrange, it is current that they need, the tweeter do want voltage but it peaks at 16 ohm, that's not a concern.

As far as your concern about sibilance, lean, warm etc., I don't believe those things are due to power amps in the calibre of those you are looking at, if someone says they could hear the difference between ATI's class D and AB, I just smile, knowing full well, with confidence that they would not hear the claimed differences in a well controlled DBT, I respect enthusiasts like Richb, but I always just though they could imagine things better than I lol... I know people would say even their cats notice the difference when they change their amp, what can I say....sorry I digressed, should have just stick to EE principle and shut up on the rest.

 

[TLS Guy]

My concern with class AB amp for your speaker is in the range between 45-1000 Hz, where EPDR dips to around 2 ohms. There are tons of contents in music/movies in that range, so some class AB amps may struggle. In terms of current, lower EPDR than the impedance does not increase current, but could result in a lot more heat in the output devices so not a good idea.

This is a good example of using power, that is watts, is not the best way, as for people who are not familiar with EE principles may not realize that if an amp is rated say, 100 W 8 ohms, if that rating is limited by the rated current, then it is current limited at current = square root (100/8) = 3.53 A, then into 2 ohms, the "power" is only 3.53^2*2 = 24.92 W, that's not a whole lot! It is a reverse double down thing, so 100 W 8 ohms, 50 W 4 ohms, 25 W 2 ohms.

Simple math yet can confuse people right!

That's why I always want to calculate voltage and current requirement, not "power". Rule of thumb is, for higher impedance, voltage is more important and for lower impedance, current is, but that's just rule of thumb, there's always something in between, though the Ref 1, in the bass and midrange, it is current that they need, the tweeter do want voltage but it peaks at 16 ohm, that's not a concern.

As far as your concern about sibilance, lean, warm etc., I don't believe those things are due to power amps in the calibre of those you are looking at, if someone says they could hear the difference between ATI's class D and AB, I just smile, knowing full well, with confidence that they would not hear the claimed differences in a well controlled DBT, I respect enthusiasts like Richb, but I always just though they could imagine things better than I lol... I know people would say even their cats notice the difference when they change their amp, what can I say....sorry I digressed, should have just stick to EE principle and shut up on the rest.

It must have taken real work to deign a three way bookshelf speaker with an impedance curve like that. It is totally unnecessary apart from being design malpractice.

 

[highfigh]

Dr. Floyd Toole put it well in saying something like "It's the ears that got broken in", not the speakers, or electronic gear I guess..




In my opinion, your choice of going with amps rated 200 W 8 ohms, 300 W 4 ohms is about right for the Reference 1. When manufacturers say 50-200 W, you know it is better to go with 200 W, so peak would be 400 W, and that should get you the best out of those speakers, in terms of satisfying their voltage/current need, more may be better, say up to 400 W 4 ohms capable amps. There are good information in the linked review, but that's for the Reference 1 Meta, the non Meta version will be different but I am sure they would be similar enough in terms of current requirements.

Kef Reference 1 Meta Bookshelf Speaker Review

From the measurements, you can see that the Ref.1's loves currents, and it has rather low EPDR (a misleading spec, that says more about heat dissipation, than currents). That, from my understanding, you may be better off using class D amps such as the popular Hypex or Purifi modules based power amps. Class D amps seem less prone to low EPDR than class AB amps that would have to dissipate lots of heat in the output devices, but obviously the ATI signatures should be good with that too.

View attachment 74317

I think I would add 'mind' to the quote about ears breaking in- bias comes from the mind and the interface allows us to smooth out differences in sensed experiences. Then, we get to deal with the conflict that comes from "This can't possibly sound this good- it's not expensive, big, etc" due to education and preconceived notions. If a speaker produces killer bass and it's tiny, I think a lot of people will make sounds like a confused Scooby Doo.

 

[highfigh]

It must have taken real work to deign a three way bookshelf speaker with an impedance curve like that. It is totally unnecessary apart from being design malpractice.

Looks like they fixated on the frequency response and ignored the impedance.

 

[Sly]

My concern with class AB amp for your speaker is in the range between 45-1000 Hz, where EPDR dips to around 2 ohms. There are tons of contents in music/movies in that range, so some class AB amps may struggle. In terms of current, lower EPDR than the impedance does not increase current, but could result in a lot more heat in the output devices so not a good idea.

This is a good example of using power, that is watts, is not the best way, as for people who are not familiar with EE principles may not realize that if an amp is rated say, 100 W 8 ohms, if that rating is limited by the rated current, then it is current limited at current = square root (100/8) = 3.53 A, then into 2 ohms, the "power" is only 3.53^2*2 = 24.92 W, that's not a whole lot! It is a reverse double down thing, so 100 W 8 ohms, 50 W 4 ohms, 25 W 2 ohms.

Simple math yet can confuse people right!

That's why I always want to calculate voltage and current requirement, not "power". Rule of thumb is, for higher impedance, voltage is more important and for lower impedance, current is, but that's just rule of thumb, there's always something in between, though the Ref 1, in the bass and midrange, it is current that they need, the tweeter do want voltage but it peaks at 16 ohm, that's not a concern.

As far as your concern about sibilance, lean, warm etc., I don't believe those things are due to power amps in the calibre of those you are looking at, if someone says they could hear the difference between ATI's class D and AB, I just smile, knowing full well, with confidence that they would not hear the claimed differences in a well controlled DBT, I respect enthusiasts like Richb, but I always just though they could imagine things better than I lol... I know people would say even their cats notice the difference when they change their amp, what can I say....sorry I digressed, should have just stick to EE principle and shut up on the rest.

Thats actually some important info to have regarding what amp i should be looking out for. Going to have to swot up on the ee principles a bit, although i might be at a stretch to call it simple maths lol.
So really i should concentrate on currant rather than just power as a whole which in hindsight is a bit presumtous of the process.
Im leaning more towards ati's class d, although like you say cooling on those amps as a whole is quite good, but with the added perks of class d it weighs up favourably especially for this speaker.
Will have another good look although these companies can be very selective with the stats.
Thankyou again, you've been very helpful.

 

[Sly]

Looks like they fixated on the frequency response and ignored the impedance.

Tried to email them about it but seems impossible from a phone, won't scroll sideways.
Unless theres a simplified phone version, which i can't seem to access.

 

[PENG]

So really i should concentrate on currant rather than just power as a whole which in hindsight is a bit presumtous of the process.

You have very nice speakers, but it is a fact that their impedance/phase angle vs frequency curves are evident that supports they are not just so called hard to drive, but are in fact hard to drive, relatively speaking. That said, it is still important to consider the key factors that include listening habit and seating distance, as if those two conditions are "right", even a midrange AVR can do the job, if not, then amps rated 300 W/500 W 8/4 ohms such as the Hypex NC502MP, or ATI6000 or AT54XNC series. Great speakers deserve great amps!

 

[PENG]

It must have taken real work to deign a three way bookshelf speaker with an impedance curve like that. It is totally unnecessary apart from being design malpractice.

Agreed to a point only, because KEF probably considers impedance curves for their $7,500 a pair bookshelf speakers are not going to be a concern for their potential buyers who likely wouldn't mind spending at least $2,000 on a 200-300W/500W 8/4 ohm rated power amps. For those amps, they really don't care much about the impedance curves, again, for just bookshelf speakers.

 

[Sly]

You have very nice speakers, but it is a fact that their impedance/phase angle vs frequency curves are evident that supports they are not just so called hard to drive, but are in fact hard to drive, relatively speaking. That said, it is still important to consider the key factors that include listening habit and seating distance, as if those two conditions are "right", even a midrange AVR can do the job, if not, then amps rated 300 W/500 W 8/4 ohms such as the Hypex NC502MP, or ATI6000 series. Great speakers deserve great amps!

Will have, was going to buy straight the way but decided on avm90 (and better rc) and amp first hence me asking what amp would suit them.
Knew they were difficult but did'nt consider other factors like voltage/current and how low indepedence speakers react, especially when they have low curves like that.
Speakers will only be about 7ft away and listening is 75db avg.
Using a yamaha a8 at the mo, and gene measured the a6 at 150wx2, so there was some power but had huge doubts trying to power anything hard to drive, ie these.

 

[PENG]

Will have, was going to buy straight the way but decided on avm90

Decided on, or pull the trigger already? The AVM90 is nice, but if for better RC, I would have picked the AV20 and spend the $ on DLBC, though it is subjective to some extent.