Amp question

[tmurnin]

I have yet to witness any type of Audyssey room correction that didn't destroy what Dennis Murphy worked so hard to achieve with these speakers. Their mid-range is detailed and clear sounding, with very wide dispersion, creating a wide sweet spot.

Listening from either of those two blue chairs should be fine as they are shown in the photo.

The NAD isn't Audyssey equipped, so that's a non-starter regardless. I did run Dirac but can switch the correction off for now and see how it sounds.

 

[ryanosaur]

Dirac is supposed to be one of the best for room correction, but as I'm learning vicariously... it can still be problematic due to its complexity.

Unless you have reason to believe there is more significant problems to contend with, I would set a curtain to only correct below your Schroeder Frequency (usually around 200-300Hz).
I concur that you should pull the speakers out to a minimum of 18" from the front wall.
You should also do a Subwoofer Crawl in that space. It is large for a single sealed sub. I have a suspicion that you can get better bass response with that Sub if you moved it to the 1/2-way point on that long wall to your left as you are seated. (Looking at a more near-field placement may very well help with some depth in that room.)
Your speaker placement from left to right looks OK, but perhaps a little Toe-In is in order.

With any or all changes, you will need to redo Dirac if so inclined. Do as many test points as possible, and don't be afraid to spread them out a little more than is 'officially' recommended.

And based on my first reply, too... I fully agree with Swerd here... I think your NAD is a hindrance. FWIW, Outlaw just put the Monoblocks on sale. You can get 2 each for $539 as a bundle! The only better buy in amplification is if you needed to buy 3!

 

[ski2xblack]

Does Dirac offer a similar loudness compensation of some sort? If so, give it a try.

In spite of what Swerd said, the different loudness eq implementations I'm familiar with (DynamicEQ and YPAOvolume for Audyssey equipped kit and Yamaha respectively) can be implemented outside of 'room correction' eq, where I would agree that such automagic eq will do more damage than good. Song Towers don't need it. The OP's situation, however, can be improved with simple loudness eq.

 

[TLS Guy]

It's harder to find amps with high source impedance, and none mentioned by the OP exhibit that trait. I doubt source impedance of the amps is as relevant as the more basic power question.

He's trying to address what appears to be a tonal response deficiency, while trying to energize a 18x30 room with four 5.5" drivers. That's like using a Prius to pull a trailer up Loveland pass, not the right tool for the job.

I had not realized he was trying to fill an 18' 30' room with those speakers. That is insane. In that space he needs some potent speakers. His speakers have good drivers but will be no match for that space.

That is around the size of my space, and it takes really capable speakers and serious horse power. That space will "dwarf" those speakers for sure.

 

[TLS Guy]

Why don't you tell me what speakers you had whose sound you changed by adding watts?

Thanks

Honest, this thread is silly. If a guy does not like the sound of his speakers, he needs to change speakers.

Good grief.

No, I have changed the sound of speakers with different amps. This was especially true when we transitioned from tubes to speakers. Peter Walker founder of Quad, did a lot of research on that. It is absolutely true that amplifiers vary significantly in their ability to perform optimally under varying load conditions. So he put a lot of thought into making his designs as independent of load conditions as possible. The caveat is that an awful lot of speakers have so many defects that they dwarf the amp loading effects. But with better designs this is an issue. So in general you are correct if you don't like the sound, change the speakers. However upper end speakers do deserve higher quality amps for optimal results.

I did have a Denon receiver for a few years that I bought on eBay. I can tell you the Denon receiver driving my designs did not allow the speakers perform optimally, not withstanding the fact I go out of my way to avoid designing speakers presenting unduly difficult loads.

So amp designers can help with designs that perform optimally driving as wide a variety of loads as possible. And speaker designers can help by trying to avoid excessively adverse loads.

Just a piece of history. Peter Walker and Raymond Cooke founder of KEF were very good friends, and worked a lot together. Raymond Cooke was a great advocate of impedance compensated crossover designs, for this very reason. The problem is that doing that adds a complexity and increased component expense. Just to give you an idea, I designed the speakers in our family room as a tribute to Raymond. So I used his precepts. The two crossovers, cost $400.00 in components to build.

 

[Mikado463]

I had not realized he was trying to fill an 18' 30' room with those speakers. That is insane. In that space he needs some potent speakers. His speakers have good drivers but will be no match for that space.

That is around the size of my space, and it takes really capable speakers and serious horse power. That space will "dwarf" those speakers for sure.

he's not Doc, look at the pics he gave us, half the room actually. Regardless, I'm starting to think Swerd was right and as a 'retiring railroader' we've 'derailed' the thread ........

 

[Alex2507]

The only thing I would want to try is pulling the sub out to about where the tree is. I'm thinking that subwoofer range boominess from corner loading might overshadow midbass explaining the 'thin' thing.

 

[pcosmic]

Here’s some pics of the room from multiple angles. The three posters at the back of the room ( the Los Angeles, Miami and Hawaii ones) are actually acoustic panels from ATS Acoustics. I know it isn't much in terms of softening, but trying what I can....
View attachment 42661View attachment 42662View attachment 42663View attachment 42663

I have one of my setups (a hometheater+2 channel) hybrid setup in a basement sized similar to yours, save for a slightly taller ceiling. Man, I lost a acoustically wonderful vaulted ceiling in the house after the sorceress upstairs hoarded 2 floors all for herself and cursed/banished me into the basement. It looks like you’re losing access to the sweetspot in the middle because your wife wants an equal half with the 2nd seat. You could always get a love seat (seat for 2), and put it in the middle you know? It could bring the two of ya closer together (In equality/lovingly sharing a seat) and also get you in the sweet spot for sound when she’s not around.



Hmm, According to the ASR dudes, your NAD may have some funky things going on with the Class G n all. They’ve got a headless flailing panther over there. (https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-nad-t758-v3-avr.8912/). In general, if you need a good DAC in your things, you gotta go to the Japanese or the Chinese. Goofy ass Canadians (NAD, the fck?) are not bright enough to do things like DACs. But, it has enough power for starters and ya gotta work with what you got for now. Besides, you have got a powerful tool called parametric eq, right? Just make sure you don’t turn on any ECO mode or drop the speaker impedance setting or do anything to severely current limit the amp sections. Turn off any dynamic EQ, DRC setting, etc.

• You could pull the speakers forward a couple of feet away from the front wall. Toe them in towards you lovingly (after you get your loveseat, of course). I would also suggest that you experiment with reducing the distance between your speakers a bit. Forget the diffusion treatments for now (unless you can convince your wife that it’s some kinda “modern art” or something, Jackson Pollock stuff!).
• Turn OFF the sub first and remove its confoundance while you troubleshoot. You want your speakers to not sound ‘thin’ on their own. Always start with the fewest number of variables.
• Turn the volume up on your speakers a couple of db higher than your usual listening level.
• Now, work with with the EQ manually. Refer to my previous comment on how to start with it. Low Qs to begin with.
• Once you get your speakers to sound filled in, I would suggest that run the speakers full range. Try rolling the sub in ever so slightly at the low end (45ish to 50 hz?) or wherever your speakers start to roll off. Don’t overdo it with that sub in the corner (remember, ‘ever so slightly’ that you should barely be able to tell that your sub’s even on).

P.S

If you ever choose to get an amp in the future, don’t go all purist right away. I will suggest something like a Class AB Marantz PM8006. Why? It is a integrated with power amp direct in and also has tone controls for the bass, mids and treble. With your kinda speakers/room/setup restrictions, etc you may greatly appreciate things like that.

 

[TLS Guy]

Swerd has already lanced this boil. I have had other people NAD gear through my hands. May verdict is that is it awful stuff.

Thad NAD unit is going to be way under powered and I highly doubt it will give its rated power into those speakers.

Now thin sound does not solely mean lack of bass. It actually is a sign of inadequate BSC. Now those speakers are very narrow, so BSC is likely going to have to be applied below 600 Hz. As you can see in a previous thread, the impedance is dropped to do that. I highly doubt his amp is going to provide adequate power in the BSC range, hence in this case the thin sound.

I think he needs an amp that can deliver at least 150 watts into a four ohm load. If you look at just above 2 KHz where there is still a lot of demand for power, there is a -45 degree phase angle with an impedance of 4 to 5 ohms. That is just the sort of thing that sucks inferior amps dry.

This is what I have been pointing out. If you think an amp can be guaranteed to perform like that into a load like that compared to an eight or four ohm resistor, the I have the proverbial bridge to sell you in Brooklyn. Speakers like his do actually demand a better amp than he has. Amps do matter. There is a very good reason that I do not power any of my three systems with a receiver. You just can not rely on amps of that quality to do the job. The manufacturers only quote the minimum specs that they can get away with.

 

[tmurnin]

Alright, for now I’m going to get the Rotel amp and see how it performs - it’s not that much $ and I can always return it if it doesn’t do anything. Is there a compelling reason to go with the monoblocks over the rotel? One thing I’m concerned about is heat on the monos. The media cabinet has some ventilation at the back but I would probably need to stack the monos on top of each other to fit, and not sure that’s a great idea. The rotel is class D so shouldn’t get as hot anyway. I’ll pull the speakers further away from the wall and see if I can move the sub out a bit as well without the wife noticing. I’ll turn off the Dirac EQ as well at first and add it back to see if it helps/hurts.

any other immediate suggestion? Thanks for the advice and crazy long thread!

 

[mazersteven]

 

[tmurnin]

That’s in a rack, though. Would it make a difference if they are stacked directly on top—meaning they are sitting on each other, not racked?

 

[mazersteven]

That’s in a rack, though. Would it make a difference if they are stacked directly on top—meaning they are sitting on each other, not racked?

You tell me what would be the difference whether in a rack or not in a rack. Stacked is Stacked


I must be up too late

 

[pcosmic]

Alright, for now I’m going to get the Rotel amp and see how it performs - it’s not that much $ and I can always return it if it doesn’t do anything. Is there a compelling reason to go with the monoblocks over the rotel? One thing I’m concerned about is heat on the monos. The media cabinet has some ventilation at the back but I would probably need to stack the monos on top of each other to fit, and not sure that’s a great idea. The rotel is class D so shouldn’t get as hot anyway. I’ll pull the speakers further away from the wall and see if I can move the sub out a bit as well without the wife noticing. I’ll turn off the Dirac EQ as well at first and add it back to see if it helps/hurts.

any other immediate suggestion? Thanks for the advice and crazy long thread!

I have been a opponent of Class D for a long time. But, i'll let these qualified lads do the talking instead.

Bob Carver
"I built many of them right here in my own laboratory with the thought they could and would fulfill that final promise.... I was never able to build a Class D amplifier that sounded as good as a linear one."

John Curl (Parasound, CTC, Vendetta Research, Constellation)
"Some version of hybrid Class A/D looks like the future in optimum audio design."

Cyrill Hammer (Soulution Audio)
"If you want to have your product performing at the cutting edge it is not possible with today's known switching technologies. In order to come close to the performance of the best linear design we would need high-current semiconductors that provide switching frequencies of several MHz or even GHz."

Lew Johnson (Conrad Johnson)
"I tend to think that Class D circuit design is an approach best relegated to producing low-cost, physically manageable multichannel amplifiers where one might accept some compromise in sound quality for the sake of squeezing five, six, or seven 100 watt channels into one moderate-sized package for a budget home-theater installation."

Vladimir Shushurin (Lamm Industries)
"No, it is not. And I would like to respond to the second part of this question with an allegory. Any field of human activity defines a number of requirements which, when properly implemented, guarantee a positive outcome. For example, the basic requirement in the army and sports is an able-bodied individual. So, it would be quite natural to concentrate on searching for such an individual (especially as we know where to find him). However, out of the blue we decide to choose a feeble-bodied person who, on top of that, is encumbered by various diseases. Having made this decision (which is a priori improper) we start justifying it to ourselves and others by citing the great state of our medicine, which is capable of curing many ailments."

Fumio Ohashi (BAlabo)
"No. Class D can't really be considered for super-high-end performance in its present stage of development, although it can be fine for mid-market products."

Nelson Pass (Pass Labs)
"Does a $10 bottle of wine compete with a $100 bottle? Of course it does, and it often wins based on price. Right at the moment Class D designers seem to be still focusing on the objectively measured performance of their amplifiers. I expect that at some point the economics of the marketplace will encourage them to pay more attention to the subjective qualities, and then they will probably play a greater role in the high end."

Jürgen Reis (MBL)
"I have worked a lot lately with Class D. Ninety-nine percent of Class D circuits are not competitive with linear circuits. Most Class D sounds sterile. It's tricky to figure out what to do to compensate for that."

Thorsten Loesch (iFi - AMR)
"I have yet to hear a pure class D Amp I’d rate above "below average for solid state" (which is not very high performance). In a little update of my classic 'Valve Analogue Stages for DACs' I wrote: "Perhaps more crucially, so called Class D Amplifiers, which have in recent times sprouted up like mushrooms after a warm rain, continue to use the straight two or three level modulation scheme described above. And thus they still require the use of heavy handed noise shaping to attain anything like acceptable 16 Bit Audio performance.The clock frequencies for these amplifiers are usually at 300 KHz to 1MHz in the best cases. That is 3,000 to 10,000 times lower than what is required to attain 16 Bit / 44.1 KHz performance without noise shaping and other forms of signal manipulation! And again, one is baffled and perplexed by the rave reviews many Class D amplifiers receive, as baffled as one was about the late 90s reviews of timeslicing DACs. The best of breed I have auditioned were certainly not bad; however in direct comparison to the best available valve and solid state amplifiers they do not produce a very good sound. Well, at least they offer novelty and the reviewers something to write about other than another (however good sounding) 8 Watt valve amp. Incidentally, the best sounding Class D amps tend to be really low power single chip devices (putting out little more than the 8 watt valve amps), presumably because they are faster AND because they always work near what one might call a full scale, if they would be DACs. On second thought, they of COURSE are DA Converters and where a Class D amplifier accepts analogue input directly it is an A2D converter followed by a power D2A converter! What an insight!?"

Mark Levinson
"Interleaving of multiple Class D Amplifiers is potentially a step in the right direction, but does not go far enough.Personally I think that the best option would be something that combines a Class D Amplifier for the heavy lifting with something Class A for fine detail. Probably implemented in the style I did for AMR’s AM-77 "Jikoda" Style. In this case both of the circuits involved can operate fully open loop. In many ways the problems in Class D Amplifiers are analogous (but not identical to) those in Class B Amplifiers (but without an option to implement Class AB or Class A) so similar solutions apply. All Class D amplifiers are essentially delta-sigma DAC’s. If the input is not digital PWM signals (aka "DSD") but analogue audio then it is also a Delta Sigma Analogue to digital converter...Now DSD (aka SACD) which to my ears fails to come close, never mind equal true PCM CD Replay in most aspects of sound quality, operates at 2.8MHz switching, or around 10 times as fast as common Class D Amplifiers...Why anyone would want to listen through an A2D followed by an D2A Converter that are around 10 times worse than single speed DSD is beyond me. But with enough hype and snazzy naming it cannot help but sell high and wide."

And, don't worry, we haven't forgotten:

Jeff Rowland
"I consider Class D to be highly competitive in the present, and to offer an evolutionary pathway of audio design that may produce even more astonishing results in the future."

 

[PENG]

Normally I ignore it when threads derail. But this thread has gone beyond the deep end.

When it comes to Salk SongTowers, I cannot ignore it when people suggest that room EQ will solve lack of bass. EQ, unless it is limited to frequencies below 200-250 Hz, will suck the life out of these very good sounding speakers.

I don't know about this particular model of NAD receiver, but NAD has long had the reputation of producing receivers and amps that, despite their rated power, have underwhelming power. Depending on the speaker being driven, this can easily translate to poor bass performance.

As I previously said, I know from first-hand experience that greater power will greatly improve the bass performance of these speakers. FWIW, here is the impedance curve of SongTowers. Red is impedance magnitude in ohms, and green is impedance phase angle in degrees.

SongTowers are clearly 4 ohm speakers. Look at the red trace in the 200-300 Hz range. Their mild phase angle changes, less than 90° in that range, are what makes them relatively easy to drive – for a 4 ohm speaker.
View attachment 42664

People are suggesting EQ to the 20-200 or may be up to 200 Hz range only because he seems to want to thicken the sound. Also, that thing has Dirac Live, that should make it not too difficult to customize the curve for that range of frequencies. My BMR are also designed by Dennis, and I found Dirac Live (was using the trial version at the time) did improve the low to lower mid range. With Dirac, like Audyssey+App, you can limit the range for EQ, so no harm needs to be done. Based on what I can see, yes the room is big but he's seating close enough to the Song Tower for me to say his issues with "thin" sound is not due to not having enough power for the Song Towers, but the room acoustic conditions that could benefit from Dirac Live and setting crossover higher, in case there are cancellation going on between the sub and the bass capable Song towers that may be a little too tricky for even Dirac, at certain frequencies.

 

[PENG]

I have been a opponent of Class D for a long time. But, i'll let these qualified lads do the talking instead.

Bob Carver
"I built many of them right here in my own laboratory with the thought they could and would fulfill that final promise.... I was never able to build a Class D amplifier that sounded as good as a linear one."

John Curl (Parasound, CTC, Vendetta Research, Constellation)
"Some version of hybrid Class A/D looks like the future in optimum audio design."

Cyrill Hammer (Soulution Audio)
"If you want to have your product performing at the cutting edge it is not possible with today's known switching technologies. In order to come close to the performance of the best linear design we would need high-current semiconductors that provide switching frequencies of several MHz or even GHz."

Lew Johnson (Conrad Johnson)
"I tend to think that Class D circuit design is an approach best relegated to producing low-cost, physically manageable multichannel amplifiers where one might accept some compromise in sound quality for the sake of squeezing five, six, or seven 100 watt channels into one moderate-sized package for a budget home-theater installation."

Vladimir Shushurin (Lamm Industries)
"No, it is not. And I would like to respond to the second part of this question with an allegory. Any field of human activity defines a number of requirements which, when properly implemented, guarantee a positive outcome. For example, the basic requirement in the army and sports is an able-bodied individual. So, it would be quite natural to concentrate on searching for such an individual (especially as we know where to find him). However, out of the blue we decide to choose a feeble-bodied person who, on top of that, is encumbered by various diseases. Having made this decision (which is a priori improper) we start justifying it to ourselves and others by citing the great state of our medicine, which is capable of curing many ailments."

Fumio Ohashi (BAlabo)
"No. Class D can't really be considered for super-high-end performance in its present stage of development, although it can be fine for mid-market products."

Nelson Pass (Pass Labs)
"Does a $10 bottle of wine compete with a $100 bottle? Of course it does, and it often wins based on price. Right at the moment Class D designers seem to be still focusing on the objectively measured performance of their amplifiers. I expect that at some point the economics of the marketplace will encourage them to pay more attention to the subjective qualities, and then they will probably play a greater role in the high end."

Jürgen Reis (MBL)
"I have worked a lot lately with Class D. Ninety-nine percent of Class D circuits are not competitive with linear circuits. Most Class D sounds sterile. It's tricky to figure out what to do to compensate for that."

Thorsten Loesch (iFi - AMR)
"I have yet to hear a pure class D Amp I’d rate above "below average for solid state" (which is not very high performance). In a little update of my classic 'Valve Analogue Stages for DACs' I wrote: "Perhaps more crucially, so called Class D Amplifiers, which have in recent times sprouted up like mushrooms after a warm rain, continue to use the straight two or three level modulation scheme described above. And thus they still require the use of heavy handed noise shaping to attain anything like acceptable 16 Bit Audio performance.The clock frequencies for these amplifiers are usually at 300 KHz to 1MHz in the best cases. That is 3,000 to 10,000 times lower than what is required to attain 16 Bit / 44.1 KHz performance without noise shaping and other forms of signal manipulation! And again, one is baffled and perplexed by the rave reviews many Class D amplifiers receive, as baffled as one was about the late 90s reviews of timeslicing DACs. The best of breed I have auditioned were certainly not bad; however in direct comparison to the best available valve and solid state amplifiers they do not produce a very good sound. Well, at least they offer novelty and the reviewers something to write about other than another (however good sounding) 8 Watt valve amp. Incidentally, the best sounding Class D amps tend to be really low power single chip devices (putting out little more than the 8 watt valve amps), presumably because they are faster AND because they always work near what one might call a full scale, if they would be DACs. On second thought, they of COURSE are DA Converters and where a Class D amplifier accepts analogue input directly it is an A2D converter followed by a power D2A converter! What an insight!?"

Mark Levinson
"Interleaving of multiple Class D Amplifiers is potentially a step in the right direction, but does not go far enough.Personally I think that the best option would be something that combines a Class D Amplifier for the heavy lifting with something Class A for fine detail. Probably implemented in the style I did for AMR’s AM-77 "Jikoda" Style. In this case both of the circuits involved can operate fully open loop. In many ways the problems in Class D Amplifiers are analogous (but not identical to) those in Class B Amplifiers (but without an option to implement Class AB or Class A) so similar solutions apply. All Class D amplifiers are essentially delta-sigma DAC’s. If the input is not digital PWM signals (aka "DSD") but analogue audio then it is also a Delta Sigma Analogue to digital converter...Now DSD (aka SACD) which to my ears fails to come close, never mind equal true PCM CD Replay in most aspects of sound quality, operates at 2.8MHz switching, or around 10 times as fast as common Class D Amplifiers...Why anyone would want to listen through an A2D followed by an D2A Converter that are around 10 times worse than single speed DSD is beyond me. But with enough hype and snazzy naming it cannot help but sell high and wide."

And, don't worry, we haven't forgotten:

Jeff Rowland
"I consider Class D to be highly competitive in the present, and to offer an evolutionary pathway of audio design that may produce even more astonishing results in the future."

Are those comments dated, or recent?

 

[PENG]

I have yet to witness any type of Audyssey room correction that didn't destroy what Dennis Murphy worked so hard to achieve with these speakers. Their mid-range is detailed and clear sounding, with very wide dispersion, creating a wide sweet spot.

Listening from either of those two blue chairs should be fine as they are shown in the photo.

Too bad you weren't in my room when I was testing my BMRs extensively, with and without Dirac or Audyssey. No night and day difference for me, but nothing got destroyed either, not even close. I guess a lot depend on how they are run/used.

 

[VMPS-TIII]

Alright, for now I’m going to get the Rotel amp and see how it performs - it’s not that much $ and I can always return it if it doesn’t do anything. Is there a compelling reason to go with the monoblocks over the rotel?

If the Rotel is cheaper I would get it. The mono block design should not provide much difference.

 

[mazersteven]

If the Rotel is cheaper I would get it. The mono block design should not provide much difference.

What about the Monoblock design makes you say that?

 

[PENG]

Alright, for now I’m going to get the Rotel amp and see how it performs - it’s not that much $ and I can always return it if it doesn’t do anything. Is there a compelling reason to go with the monoblocks over the rotel? One thing I’m concerned about is heat on the monos. The media cabinet has some ventilation at the back but I would probably need to stack the monos on top of each other to fit, and not sure that’s a great idea. The rotel is class D so shouldn’t get as hot anyway. I’ll pull the speakers further away from the wall and see if I can move the sub out a bit as well without the wife noticing. I’ll turn off the Dirac EQ as well at first and add it back to see if it helps/hurts.

any other immediate suggestion? Thanks for the advice and crazy long thread!

The Outlaws will run cool even if you stack them. I only issue with that Rotel is that if they didn't even pay attention to their specs, what else would they have not paid attention to?

Their specifications for input sensitivity and gain are contradictory and neither one makes sense. If I were interested in buying one, I would talk to their engineering/tech support and ask them what the input sensitivity really is for the rated output of 250 W/Ch 8 Ohms. It is definitely not 1.5 V if the gain is 27.1 dB, it should be almost 2 V, in order to output 250 W 8 ohms or 500 W 4 ohms if the gain is 27.1 dB

Also, if the input impedance is really 8.3 k ohms, that is a little low even for a standalone preamp, let alone for a mid range AVR such as your NAD that does not have preamp mode so the preamp has to feed the internal amp and the external amp (two in parallel).

I used to be quite impressed with the details Rotel provided for their amps, not in this case, it is really sloppy/vague on their part.

Unless you can get this cleared up, my recommendations would be to go with the Outlaw, or the Monolith if you don't mind the ridiculous weight. Aside from the concerns I highlighted above, the power output of the Rotel is really impressive though.

Input Impedance/Sensitivity Input Impedance/Sensitivity:

RB-1562-1572 ML OC - b.indd (rotel.com)

RB-1562 - 8.3 k ohms / 1.25V
RB-1572 - 8.3 k ohms / 1.5V

Gain
RB-1562 - 27.2 dB
RB-1572 - 27.1 dB

For non EEs not familiar with gain/input sensitivities, here are the formula and calculators:

Decibels to Voltage Gain and Loss convert calculation conversion amplification amplifier electronics - sengpielaudio Sengpiel Berlin

dB calculator for amplification gain and damping (loss) factor of an audio amplifier calculation decibel dB ratio - sengpielaudio Sengpiel Berlin