Amp for Manger drivers

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi Robert, it is more of a theoretical question. I am developing an active (digital) speaker using the Manger MSW above 250Hz or so and am wondering what amp to choose for it.

The claims by Manger that fast slew rate and rise time is important for the Manger seem odd in as much as the driver only goes to 35KHz so surely the amp only needs to as well. I wonder then, why many people claim a perceived improvement in amps with a faster slew rate and rise time with the Manger. My theory is that it is not in fact because the driver needs the fast rise time, but that the fast decay of the Manger reveals other distortions introduced by an amp approaching its slew rate limit more than a conventional driver would.

I wonder if anyone agrees with my theory or if they have another or can bring light to Mangers suggestion that it is the rise time which is important?
 
Thinking out loud... I think the question might be answered if someone has done an intermod test on the HF response of the Manger, and/or a raw THD vs. freq. vs. SPL. I don't know of it... anyone want to do a test??

As I noted, when I tried them - now quite a long time ago - they seemed "reticent" on the highs to me. Just so you know, at the time the comparison was to a Stage Accompany ribbon, which has unusually high efficiency, very low distortion and response out past 20Khz as well. My point in mentioning this is that often "lack of highs" is mistaken when the highs are significantly lower in distortion than is the typical "hi-fi tweeters" norm. Not the case here.

So, I would be curious about how they fare in the above tests.

My original thought is that what Manger really wanted was an amp with a little extra "zing" on the top, but maybe your theory has merit!?

_-_-bear
 
Hi,

What do you mean? "I am developing an active (digital) speaker". Is it a digital crossover or class D amplifier (mistaken for a "digital" amplifier) = PWM amplifier (is analogue)?

I haven't heard the Manger MSW, but I do not doubt that the sound is okay.
The only thing I can relate to at the moment is the advertising stuff:

"That the Manger® sound transducer in spite of its large frequency range of between 80 Hz and 35 kHz and its sensitivity of 91 dB 1W/1m can achieve the tremendously fast rise time of 13 µs is attributable to many design finesses.
And the future has also not been forgotten. The Manger sound transducer, with its fast rise time or even high cut-off frequency (these values can be mathematically converted internally ) of 35 kHz (-3 dB), and 60 kHz (-20 dB) respectively, is excellently suited for the future standards of DVD audio and SACD."

What? ?/µs - mathematically converted internally?:confused:

Al, thank you. It's not FIR filters, it's "only" IIR filters (biquads) - but it sounds okay.
 
Class AB vs. D

It's obvious that I will recommend my class AB amplifiers. But on the other hand I haven't heard ex. the Hypex Class D amps - I recon that if it's a PWM it will be a Hypex. From a theoretical point of view I see some problems with the Class D technology: Low Power Supply Rejection, high output impedance at high frequency, pretty high switch noise at the output, reliability caused by the high switching rate of the output stage making possible cross conduction and bad handling of reactive loads - have I forgotten any? Hypex solve the problems by using negative feedback in a genius way. I don't like the way the negative feedback is used just to get a decent amp. With the Class AB technology there are less problems and the negative feedback is used to improve the behaviour of the amp.

It's not that I don't like the Class D technology - actually I love the way and the sound of Class TD used in the Lab.Gruppen fP6400 and the previous models LAB4000, LAB2000 etc. It has a rock steady neutral controlled bass and I have made several A-B tests vs. Crown, Crest, C-Audio, QSC etc. over the years. The choice has always been Lab.Gruppen, but I would never use it in the high frequency area as it has a tendency to be aggressive/hard. There the choice has always been a Class AB. I would never ever use Class TD in a HiFi system.

Finally I will repeat I haven't heard the Hypex amps and I will recommend doing A-B tests it's so revealing.
 
Well, the time came when I needed to make a move so I ordered a pair of LC Audio 2.3SE amps today.

They seem a good price and have a good amount of power matched to 150KHz bandwidth. From an article about distortion in the Hypex UCD modules I am lead to believe that digital amps in general have many advantages in the form of linear feedback and linear distortion very close to the slew rate limit as well as a power bandwidth equal to the small signal bandwidth. I also know someone who is using them with Manger's and likes them.
 
Hi Robert,

I expect your amps would work well in this application but unfortunately my budget is beginning to run low so they are just a bit too pricey.

I think your digital crossover would have been good as well if it had a digital input. As it is, I have had to modify the DCX2496 for better sound. What I am not sure of at this point is how I will switch between digital or analogue input as I don’t want all the controls on display. Anybody got some ideas?
 
Tenson said:
Hi Bear, I'm not too sure about that. A high bandwidth surely wouldn't add more treble, just go higher.

I have THD measurments of the Manger but only up to 10Khz.




Tenson,

Thanks for posting...

What are we looking at there??

Is the yellow 2nd harmonic and the purple 3rd?? or???

Either way, they're between 30-40dB down max, and rising back at HF apparently...?

What power level?
Do you have the same test, same conditions, at say 1 watt and again at something like 3dB down from max??

_-_-bear :Pawprint:
 
bandwidth

john curl said:
Tenson, wider bandwidth is good, unless the amp is operating open loop. I doubt that you are considering that in this case.


Hi John n all,

I just read through this thread - I am thinking that my next speaker upgade will be to Mangers ( I current have JX92s covering the whole spectrum - :cheerful: )

My question is this - How high does bandwidth need to be, with feedback amps, before increasing it reaps no further benefit ?

I have a TVC in front of my amp so my bandwidth is limited to 100khz but I get the impression that the power amp being able to go higher than this will still be good because of feedback related issues

So what is an ideal -3db closed loop frequency response upper limit ?

1meg, 2meg, 5meg, 10meg ! ? !

some designs I have been playing around with in spice even exceed 10meg ( by quite a bit ) I'm not sure what to think about this ( apparently ) extreme internal bandwidth. ( But I seem to recall that I have read Jocko saying that 8 meg hz was desirable if one could achieve it )

what's the story on this ? - current perceived wisdom etc

mike
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.