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-   -   Controlling transient response (http://www.diyaudio.com/forums/tubes-valves/104416-controlling-transient-response.html)

AdamZuf 30th June 2007 08:13 AM

Controling transient response
 
Hello guys,
I'm not really into electronics, but I have interest in DIY sometimes.
I have the Adam ANF-10 passive studio monitors for a test period. I have a Marantz Model 1150 running them. It's a '78 model IIRC, and looks very robust, at least it's heavy as hell. It's an 8 ohm amplifier, but the the ANF-10 are 4 ohm.
I really, really like the resolution and image I get from this combo, the sound is totally 3D, never heard anything quite like it. I don't drive the speakers to insane levels at all, only "quite loud" from about 1.5m listening when I listen for fun (and low levels when I monitor). Should I be afraid to damage the amp?

Anyway, to the point. I came to realize that both the ANF-10 and their active counterpart, the A7, has exaggerated transient response. This is obvious since percussive instruments are more forward, and because there is not enough "flesh" to the sound, which is actually meens that the transients don't blend into the decay well, and form a non natural time response. I put the Waves's TransX transient shaper on the stereo buss to tame the transients, and the impressions I've writen above were formed with the TransX, which I use now all of the time. I tuned the TransX to indentify transients on all frequencies down to about 100Hz. The natural transient response of the speakers below that is fine and taming that area hurts bass accuracy and does not give the pluses mentioned. However, I don't wish to keep on using the TransX, and look for a hardware solution.

My recording teacher (also an electronics engineer" told me that tubes has that "warm" sound because of a relatively low transient response. Do you think that it will solve my problem?
If it's ok that I'll keep using the Marantz, do you think that a tube preamplifier will do the trick? Or will an amplifier serve the cause better anyway?
It's still possible that I might go for the A7, I'll have to audition them, in that case it must be a preamplifier.
I would really like to have the option to tune the sound's transient by switching tubes, but maintain the bass's transient response, high resolution and keep low distortion figures and good S/N ratio.

How is this best achieved? ("and not too expensive....ni, ni")

Thanks
Adam

EC8010 30th June 2007 06:16 PM

Re: Controlling transient response
 
Quote:

Originally posted by AdamZuf
My recording teacher (also an "electronics engineer" told me that tubes has that "warm" sound because of a relatively low transient response.
Really? It's a bit more complicated than that and I'd be very wary of anyone who makes such catch-all simplified statements. It could be argued that all transistor amplifiers have a fatiguing brittle sound because of their Class AB output stage and distortion that rises with frequency, but that would be just as wrong since there are some perfectly decent transistor amplifiers.

I'd say it's a whole lot more likely that your amplifier is objecting to having to drive a 4 Ohm load when it was designed for 8 Ohms.

AdamZuf 30th June 2007 06:45 PM

My teacher didn't classify tubes as such and "that's it". He's a very knowledgable man. He says that the transient response ain't as good because of the time it takes electrons to travel through the tube, which contributes to rounder sound, some say "warm".

About my amp and its match to the ANF-10, they have the same transient behaviour with other amps as well, so does the active A7 monitors.
But is it likely that I'll damage the amp? I don't listen past 9 o'clock with the pot (it wakes up at 6:00 :D )

So... what do you think I should do?

Thanks
Adam

Frank Berry 30th June 2007 06:46 PM

Adam,

Your 1978 Marantz is probably in need of a tune up ... replacing power supply capacitors as well as all electrolytic capacitors in the audio stages as well as re-biasing the output stages.

Exxaggerated transient (square-wave) response could be a result of excessive high frequency distortion ... possibly because you are driving 4 ohm loudspeakers from an amplifier that is designed for 8 ohm loudspeakers.

Some of the best sounding amplifiers that I have heard are vacuum tube amplifiers. Properly designed (and with very good output transformers), they can produce a truly stunning audio experience.

rdf 30th June 2007 07:04 PM

Hi Adam. Another possibility is weak tubes or perhaps non-optimal subs, the added upper harmonic distortion content giving the impression 'speed' or exaggerated HF transients.

Re: the transit time impact on transient response, ask your teacher for me if a larger amplifier chassis also sounds warmer for the extra wiring it contains. One radio station I technically manage pounds 12,000 watts 24/7 at 100 MHz from a tube two feet tall and doesn't seem to have any issues with transients far above the audio range.
:joker:

EC8010 30th June 2007 07:06 PM

Quote:

Originally posted by AdamZuf
So... what do you think I should do?
Try the amplifier with some 8 Ohm loudspeakers. And if you have a diagram of the amplifier, post it.

By the way, an electron accelerated through 150V will hit the anode at 7.26 x 106m/s. That means it will require 275ps to travel from the cathode (at 0V) to the anode (at 150V) if they are separated by 1mm (pretty typical distance for a small-signal audio valve). Transit time isn't significant in audio...

AdamZuf 30th June 2007 08:14 PM

Quote:

Originally posted by Frank Berry
Adam,

Your 1978 Marantz is probably in need of a tune up ... replacing power supply capacitors as well as all electrolytic capacitors in the audio stages as well as re-biasing the output stages.


Well to me it sounds awesome. It was very well kept.

Quote:

Exxaggerated transient (square-wave) response could be a result of excessive high frequency distortion ... possibly because you are driving 4 ohm loudspeakers from an amplifier that is designed for 8 ohm loudspeakers.
But as I said, this behaviour is typical for the speakers, not my amp.

Quote:

Some of the best sounding amplifiers that I have heard are vacuum tube amplifiers. Properly designed (and with very good output transformers), they can produce a truly stunning audio experience.
I have no doubt of that.

Quote:

Originally posted by rdf
Hi Adam. Another possibility is weak tubes or perhaps non-optimal subs, the added upper harmonic distortion content giving the impression 'speed' or exaggerated HF transients.

Didn't get it, what case are you talking about?

Quote:

Re: the transit time impact on transient response, ask your teacher for me if a larger amplifier chassis also sounds warmer for the extra wiring it contains. One radio station I technically manage pounds 12,000 watts 24/7 at 100 MHz from a tube two feet tall and doesn't seem to have any issues with transients far above the audio range.
:joker:
I won't ask him in such a disrespectful manner but I'll sure talk to him about the issue again. It seems no one confirmes that tubes are less fast then SS, and by EC8010's explanation it's logical. However, specs aside, my teacher is a 20 experienced sound engineer and electronic engineer. He wouldn't say something unless his ears verified.

Quote:

Originally posted by EC8010
Try the amplifier with some 8 Ohm loudspeakers. And if you have a diagram of the amplifier, post it.

I sure did try it with other speakers, it's a great focused amp.

Quote:

By the way, an electron accelerated through 150V will hit the anode at 7.26 x 106m/s. That means it will require 275ps to travel from the cathode (at 0V) to the anode (at 150V) if they are separated by 1mm (pretty typical distance for a small-signal audio valve). Transit time isn't significant in audio...
Thanks, I'll quote you for my teacher and see what's his answer.

So, how CAN I reduce the transient sensitivity of my speakers?

Thanks
Adam

rdf 30th June 2007 09:09 PM

Sorry Adam, no disrespect was meant to your teacher. The theory just makes little sense. If transit time is important then, on its face, the device shouldn't matter: 'short' transistor vs. 'long' tube, small enclosure vs. large. The difference in circuit path length between a typical small signal tube and an opamp (today's most popular SS audio device) is easily swamped by circuit board layout.

My hobby stock contains 50+ year old radar tubes with application data advising how best to keep them stable around 1 GHz. Radio, TV and radar came well before the general application of solid state and tubes had by then long since demonstrated bandwidth and transient capabilities many orders of magnitude greater than any required for audio reproduction.

Johan Potgieter 30th June 2007 09:16 PM

Adam,

OK, honest questions by you. But again as is often the case, there are several possibilities, quite difficult to pinpoint without being there. I would first start very basic, if possible for you, by using a signal generator and scope to find whether the amplifier actually delivers a constant signal voltage to the loudspeaker. That will sort out whether the problem lies with the speaker or amplifier.

Too high a h.f. output into the loudspeaker would be curable in the amplifier, or if the output voltage is constant but the sound too bright, then you could try with a h.f. attenuating network.

Also, as was said, driving 4 ohm loudspeakers with the same signal amplitude as an 8 ohm unit will accentuate their response by 6dB where the amplifier can maintain a constant outputvoltage into all of this.

AdamZuf 30th June 2007 10:33 PM

I tried the speakers with other amps as well, even one capable of 2 ohm, and the Marantz ain't brighter then any of them. I really don't see a reason to check with a scope that I don't have.

If it work ok now, then can I keep on using the amp or not?

I thank all of trying to "troubleshoot" my problem, but really guys, I've noticed the transient thing in the store before I took them to demo! And exagerated transient response doesn't have to meen bright! I know the difference, I'm a sound engineer (well I'm on my way). The exagerated transient goes down to the midbass. I see it as a problem and not as a plus because I'm trying to have a reference system that translate mixes well to other systems. if it was for pure enjoyment then I might not have started this thread, the ANF-10 sound awesome either way.

So, please help, what the heck can I do to reduce dynamic response other then processors?


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