Will my old Denon amp drive my new speakers?

[taize]

I've been fortunate to purchase some ATC SCM40s - a big step up from my 20yr old Jamo 98s. I've still got my old Denon PMA 1315R and Im wondering how it will go driving the ATC. Currently I'm running the speakers out of a LINN Sneaky DSM but it feel like the Sneaky is a little underpowered for the speakers. Is the Denon amp worth hooking up or just leave it as a large paper weight?

 

Kym

 

[andyr]

Looking at the specs for your SCM40s, it says:

• nominal impedance 8 ohms (with no mention of its lowest impedance over the frequ range)
• and recommended power 75 - 300w.

 

Your PMA 1315R is 115w into 8 ohms - with no mention of its output into 4 ohms.  However, as a Class A amp ... I would suggest it should sound marvelous with the ATCs.  Sure, it's at the lower end of the suggested power range ... but should be able to drive them well.  I suggest you would have to go to a seriously grunty power amp to get better sound - and as there are not many Class A power amps with more power than 115w that don't cost the price of a small car, you may find it difficult to get an amp which sounds better.

 

[taize]

  On 05/07/2022 at 10:40 PM, andyr said:

Looking at the specs for your SCM40s, it says:

• nominal impedance 8 ohms (with no mention of its lowest impedance over the frequ range)
• and recommended power 75 - 300w.

 

Your PMA 1315R is 115w into 8 ohms - with no mention of its output into 4 ohms.  However, as a Class A amp ... I would suggest it should sound marvelous with the ATCs.  Sure, it's at the lower end of the suggested power range ... but should be able to drive them well.  I suggest you would have to go to a seriously grunty power amp to get better sound - and as there are not many Class A power amps with more power than 115w that don't cost the price of a small car, you may find it difficult to get an amp which sounds better.

 

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Thanks for the feedback. I'll hook it up tonight and see how it sounds - limiting factor is going to be my input device as the sneaky DSM is in for repair

[Ken_Mc]

I bought a pma 915r new back in 1995, very similar to the 1315 but making about 25WPC.  
 

it’s far from being a paperweight but I don’t think it’s near enough amp to do those speakers justice.   If they are the ones I’m thinking of they are 85db efficient, the recommendation is for a minimum power of 75watts and a maximum of 300.   In my experience coming in close to the maximum power recommendation is where you want to be.   I ran my denon with a pair of dahlquist that were about 85db efficient, I blew a tweeter when I turned it up and the amp clipped.     

[taize]

  On 05/07/2022 at 10:54 PM, Ken_McAlinden said:

I bought a pma 915r new back in 1995, very similar to the 1315 but making about 25WPC.  
 

it’s far from being a paperweight but I don’t think it’s near enough amp to do those speakers justice.   If they are the ones I’m thinking of they are 85db efficient, the recommendation is for a minimum power of 75watts and a maximum of 300.   In my experience coming in close to the maximum power recommendation is where you want to be.   I ran my denon with a pair of dahlquist that were about 85db efficient, I blew a tweeter when I turned it up and the amp clipped.     

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I'm noticing the speakers are inefficient as any amp ive connected to them I've had to run at higher volumes. I'll give the Denon a go but its sounding like something with more grunt needs to be added to the wish list

[pete_mac]

  On 05/07/2022 at 10:40 PM, andyr said:

  However, as a Class A amp ... I would suggest it should sound marvelous with the ATCs.  

 

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It's not a true Class A amp - it has a fancy sliding bias circuit as found in many older Denons and Technics amps.

 

 

[andyr]

  On 06/07/2022 at 12:54 AM, pete_mac said:

 

It's not a true Class A amp - it has a fancy sliding bias circuit as found in many older Denons and Technics amps.

 

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Aah, OK - it's a pity that Denon put misleading definitions into their ad blurb.  

 

[pete_mac]

  On 06/07/2022 at 2:49 AM, andyr said:

 

Aah, OK - it's a pity that Denon put misleading definitions into their ad blurb.  

 

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Indeed, it's not particularly helpful!

 

[Ken_Mc]

  On 06/07/2022 at 12:54 AM, pete_mac said:

 

It's not a true Class A amp - it has a fancy sliding bias circuit as found in many older Denons and Technics amps.

 

 

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I was down the product line a bit from the 1315  but from what I’ve experience with the PMA series of the era is a bit suspicious as far as their technical claims. Class A is heavy, with large transformers, an energy hog that puts out a bunch of heat. That in no way describes a denon PMA. Not to mention it sounds entirely different.     I believe the watts claimed are peak and not RMS.    There is good reason an amp from before 1980 that claims 100wpc will cost three to four times as much as one from 1995 that makes the same claim.   One is giving usable power and the other a momentary peak.    
 

all of this can result in clipping as I learned the hard way.   This was 30 years ago and I had never heard the word “clipping”  much less knew what it was or knew what to listen for.    I remember it vividly, I was playing a cd of a miles Davis concert from 1966.  It sounded great and I was pushing the volume pretty hard but without any distortion.   Someone else in the band was taking a solo and  when miles came in his horn was much louder and the tweeter instantly failed.    
 

So to the thread starter,  your denon is  very close to the minimum watt (rms) recommendation of the manufacturer.  The full bloom of those speakers isn’t going to happen but you will get closer as you push the volume and if you do, a sudden spike in levels on the recording could put you in a bad spot.     I’m sure it will be fine but be aware and cautious. 

[andyr]

From @Ken_McAlinden's comments (given that Denon appears to have mis-led customers - both in claiming the amp is Class A and by over-stating its power), @taize, I'm afraid I withdraw my suggestion that your Denon should be suitable for your SCM40s.  

 

Andy

 

[pete_mac]

  On 05/07/2022 at 10:54 PM, Ken_McAlinden said:

I bought a pma 915r new back in 1995, very similar to the 1315 but making about 25WPC.  
 

it’s far from being a paperweight but I don’t think it’s near enough amp to do those speakers justice.   If they are the ones I’m thinking of they are 85db efficient, the recommendation is for a minimum power of 75watts and a maximum of 300.   In my experience coming in close to the maximum power recommendation is where you want to be.   I ran my denon with a pair of dahlquist that were about 85db efficient, I blew a tweeter when I turned it up and the amp clipped.     

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I'm confused as to where your claim of 25PC for the 915R comes from... it's clearly spec'd at 80WPC and the schematics and design of the amp back this up. She's not a 25WPC amp, that's for sure.

 

Blowing a tweeter due to clipping the amp into 85db efficient speakers isn't the fault of the amp outright.

 

  On 06/07/2022 at 1:12 PM, Ken_McAlinden said:

I was down the product line a bit from the 1315  but from what I’ve experience with the PMA series of the era is a bit suspicious as far as their technical claims. Class A is heavy, with large transformers, an energy hog that puts out a bunch of heat. That in no way describes a denon PMA. Not to mention it sounds entirely different.     I believe the watts claimed are peak and not RMS.    There is good reason an amp from before 1980 that claims 100wpc will cost three to four times as much as one from 1995 that makes the same claim.   One is giving usable power and the other a momentary peak.    

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The 1315 (and 915) are entirely capable of producing its rated power by design - there's no fudging going on.

 

As I noted above, the amp runs a sliding bias design which vary the class of amp operation depending upon output level. This is why the amps are able to produce the rated power output without acting as a small room heater The somewhat sneaky use of the words "Class A" in the description of that design (e.g  "Super Stable A MOS Plus",  "Optical Class A",  and in the case of Technics, "New Class A" unfortunately confuses the matter, but the nature of the design is explained in the advertising and brochures of the era.

 

Now, I'm not suggesting that these amps are the 'bees knees", but I'd be somewhat wary in stating that Denon has overstated the power output by a large margin, versus stating that the amps provide insufficient headroom to deal with the dynamics of some music without clipping when driving inefficient speakers (which is essentially an amp/speaker mismatch, and not the amp's fault). These are two different things entirely.

 

Edited July 6, 2022 by pete_mac

[pete_mac]

  On 06/07/2022 at 9:14 PM, andyr said:

From @Ken_McAlinden's comments (given that Denon appears to have mis-led customers - both in claiming the amp is Class A and by over-stating its power),

 

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I'm not convinced that Denon has done either of these things. Admittedly, the use of the letter 'A' in the amp typology description isn't helpful, but it's explained in the literature of the day.

Edited July 6, 2022 by pete_mac

[taize]

FWIW I connected the speakers to the Denon last night and it sounds good (my source is terrible since I don't have the Sneaky DSM anymore). I didn't need to turn it past 4/10 to get a reasonable volume that didn't disturb the neighbours. Does it sound better than being driven by the Linn Sneaky DSM? I'm not sure. I definitely had to turn the sneaky up higher to get the same volume. Would a more powerful, modern amp sound better - only time will tell as I don't have one to compare (anyone in Sydney want to drop in with the amp so we can compare  ) .

 

To be honest, all I can say is the Denon+ATCs sounds much better than the Denon+my old Jamo speakers and better than an old Onkyo AV amp.  Beyond that I can't really comment as I don have much experience comparing different setups.

[sir sanders zingmore]

  On 06/07/2022 at 10:17 PM, taize said:

I didn't need to turn it past 4/10 to get a reasonable volume that didn't disturb the neighbours. Does it sound better than being driven by the Linn Sneaky DSM? I'm not sure. I definitely had to turn the sneaky up higher to get the same volume.

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just to confuse things, the position of the volume knob is not about the power of the amp, it’s about the gain. 
My personal preference is to be able to turn the volume control more as it gives much finer control (if 4/10 is ear splitting then imho you have too much gain)

[taize]

  On 06/07/2022 at 11:47 PM, sir sanders zingmore said:

just to confuse things, the position of the volume knob is not about the power of the amp, it’s about the gain. 
My personal preference is to be able to turn the volume control more as it gives much finer control (if 4/10 is ear splitting then imho you have too much gain)

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So much I still need to learn

[pete_mac]

  On 06/07/2022 at 11:47 PM, sir sanders zingmore said:

just to confuse things, the position of the volume knob is not about the power of the amp, it’s about the gain. 
My personal preference is to be able to turn the volume control more as it gives much finer control (if 4/10 is ear splitting then imho you have too much gain)

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Agreed in principle, but this assumes that "a reasonable volume that didn't disturb the neighbours"  equates to "ear-splitting" volume levels. Perhaps @taize could clarify, as I get the feeling that the listening levels are well below "ear-splitting"? 

[Ken_Mc]

  On 06/07/2022 at 9:32 PM, pete_mac said:

 

I'm confused as to where your claim of 25PC for the 915R comes from... it's clearly spec'd at 80WPC and the schematics and design of the amp back this up. She's not a 25WPC amp, that's for sure.

 

Blowing a tweeter due to clipping the amp into 85db efficient speakers isn't the fault of the amp outright.

 

 

The 1315 (and 915) are entirely capable of producing its rated power by design - there's no fudging going on.

 

As I noted above, the amp runs a sliding bias design which vary the class of amp operation depending upon output level. This is why the amps are able to produce the rated power output without acting as a small room heater The somewhat sneaky use of the words "Class A" in the description of that design (e.g  "Super Stable A MOS Plus",  "Optical Class A",  and in the case of Technics, "New Class A" unfortunately confuses the matter, but the nature of the design is explained in the advertising and brochures of the era.

 

Now, I'm not suggesting that these amps are the 'bees knees", but I'd be somewhat wary in stating that Denon has overstated the power output by a large margin, versus stating that the amps provide insufficient headroom to deal with the dynamics of some music without clipping when driving inefficient speakers (which is essentially an amp/speaker mismatch, and not the amp's fault). These are two different things entirely.

 

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I’m saying the 915 is about 25wpc less than than yours, not that it’s only 25 wpc.

I’m not saying the WPC is a lie as much as I’m saying they way manufacturers measure changed around 1980 or so.  It’s the peak wpc compared RMS (continuous power handling).  https://techformusic.co.uk/rms-and-peak-watts/

A bit like a new car might say it gets 30 miles per gallon but from tank to tank you only get 20. What is technically possible and what happens under normal operation are just two different things. 

clipping happens with every amp that you push too hard.  A solid state amp has a much harder clip than a tube and it can blow a tweeter.  That’s the reason a speaker manufacturer publishes  a minimum power requirements, to prevent damaging the speaker.   It is much easier  to damage a speaker with an amp that makes too little power than too much.   With too much power it starts to sound bad before it breaks, you get lots of fair warning and have to make bad choices.   With a speaker that isn’t getting enough power it sounds better as you turn it up and then suddenly falls off a cliffs.

 

But I digress, use the Denon.  It’s a good amp, not enough to get the best out of those speakers but a fine starting point. if you start to get that volume knob past 12 o’clock , you might want to be concerned about clipping. 

all the best 

 

[taize]

Pete - not sure exactly how to quantify this for you. 

 

4/10 is a volume I would be happy to sit down and listen or watch a TV show. Definitely not ear splitting but above background volume levels that would use if I was working or studying.

 

We live in a duplex with a common wall so the volume needed to not disturb the neighbours is less that would it would be if we were in a stand alone house

[sir sanders zingmore]

  On 07/07/2022 at 12:08 AM, pete_mac said:

 

Agreed in principle, but this assumes that "a reasonable volume that didn't disturb the neighbours"  equates to "ear-splitting" volume levels. Perhaps @taize could clarify, as I get the feeling that the listening levels are well below "ear-splitting"? 

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“ear splitting” was a term used to illustrate (not very well) my general point. That being, the OP seems to be confusing volume knob position with power (I may be wrong about that too of course) 

[taize]

  On 07/07/2022 at 1:03 AM, sir sanders zingmore said:

“ear splitting” was a term used to illustrate (not very well) my general point. That being, the OP seems to be confusing volume knob position with power (I may be wrong about that too of course) 

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so many things about hifi still confuse me so you are probably correct

[pete_mac]

  On 07/07/2022 at 12:59 AM, Ken_McAlinden said:

I’m saying the 915 is about 25wpc less than than yours, not that it’s only 25 wpc.

I’m not saying the WPC is a lie as much as I’m saying they way manufacturers measure changed around 1980 or so.  It’s the peak wpc compared RMS (continuous power handling).  https://techformusic.co.uk/rms-and-peak-watts/

 

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Ah, understood re: 25wpc - this wasn't clear in your earlier post.

 

Regarding the power rating of amps moving from RMS to peak after 1980, I think that's a rather loose generalisation and I'm not sure of its basis. The FTC's "amplifier rule" for measuring amplifier output (introduced in 1974 to help regulate the industry) was still place at that time. Reputable manufacturers of two channel amps, regardless of their price point, continue to rate the output of their amps based upon a continuous output, both channels driven, across a particular bandwidth, and at a particular distortion level. 

 

As an example:

• The 1315R is a minimum of 115 WPC into 8 ohms, two channels driven, 20hz to 20khz, at 0.02% THD.
• The 915 is a minimum of 80WPC into 8 ohms, two channels driven, 20hz to 20khz, at 0.02% THD.

These are not what I'd consider to be "peak" outputs. There are separate figures provided for this in the manuals which are slightly looser, albeit consistent with the German DIN criteria (i.e. the 1315R is 200W into 4 ohms, DIN, 1khz, 0.7% THD DIN and the 915 is 130W - as you can see, the DIN criteria is less onerous)

 

The only thing that likely changed since the introduction of the FTC requirements in 1974 was the rather strict amplifier pre-conditioning requirements, which caused many an amp to overheat and consequently required the de-rating of the power output. I can't find any facts on if/when this occurred, but if it did, this would prove less taxing on an amp and make it easier to achieve higher 'continuous' power output ratings.

 

Home theatre amps, sound bars and the like are a different kettle of fish altogether though -  it seems to be the wild, wild west as far as power ratings go. Some mass-market items include a proper power output into one channel only, or with the two front channels driven, but rarely a proper measurement for all speakers driven simultaneously. The FTC seem to have dilly-dallied on how to mange it!

 

 

 

 

 

 

 

 

 

[Ken_Mc]

  On 07/07/2022 at 1:36 AM, pete_mac said:

 

Ah, understood re: 25wpc - this wasn't clear in your earlier post.

 

Regarding the power rating of amps moving from RMS to peak after 1980, I think that's a rather loose generalisation and I'm not sure of its basis. The FTC's "amplifier rule" for measuring amplifier output (introduced in 1974 to help regulate the industry) was still place at that time. Reputable manufacturers of two channel amps, regardless of their price point, continue to rate the output of their amps based upon a continuous output, both channels driven, across a particular bandwidth, and at a particular distortion level. 

 

As an example:

• The 1315R is a minimum of 115 WPC into 8 ohms, two channels driven, 20hz to 20khz, at 0.02% THD.
• The 915 is a minimum of 80WPC into 8 ohms, two channels driven, 20hz to 20khz, at 0.02% THD.

These are not what I'd consider to be "peak" outputs. There are separate figures provided for this in the manuals which are slightly looser, albeit consistent with the German DIN criteria (i.e. the 1315R is 200W into 4 ohms, DIN, 1khz, 0.7% THD DIN and the 915 is 130W - as you can see, the DIN criteria is less onerous)

 

The only thing that likely changed since the introduction of the FTC requirements in 1974 was the rather strict amplifier pre-conditioning requirements, which caused many an amp to overheat and consequently required the de-rating of the power output. I can't find any facts on if/when this occurred, but if it did, this would prove less taxing on an amp and make it easier to achieve higher 'continuous' power output ratings.

 

Home theatre amps, sound bars and the like are a different kettle of fish altogether though -  it seems to be the wild, wild west as far as power ratings go. Some mass-market items include a proper power output into one channel only, or with the two front channels driven, but rarely a proper measurement for all speakers driven simultaneously. The FTC seem to have dilly-dallied on how to mange it!

 

 

 

 

 

 

 

 

 

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Ever pick up a denon AVR that’s rated for  150 wpc for five or seven channels?  That would be a total of 750 watts being made.  The whole thing weights about 30-40lbs.  A Sansui 9090 that makes 110wpc (total of 220) weighs about twice that and it’s not the metal face plate, it’s the power transformers.  I’ve opened the chassis on both and seen it for myself. They publish the peak power possible not the RMS.  It’s a marketing gimmick. 

[sir sanders zingmore]

  On 07/07/2022 at 2:08 AM, Ken_McAlinden said:

Ever pick up a denon AVR that’s rated for  150 wpc for five or seven channels?  That would be a total of 750 watts being made.  The whole thing weights about 30-40lbs.  A Sansui 9090 that makes 110wpc (total of 220) weighs about twice that and it’s not the metal face plate, it’s the power transformers.  I’ve opened the chassis on both and seen it for myself. They publish the peak power possible not the RMS.  It’s a marketing gimmick. 

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  On 07/07/2022 at 1:36 AM, pete_mac said:

 

Home theatre amps, sound bars and the like are a different kettle of fish altogether though -  it seems to be the wild, wild west as far as power ratings go. Some mass-market items include a proper power output into one channel only, or with the two front channels driven, but rarely a proper measurement for all speakers driven simultaneously. The FTC seem to have dilly-dallied on how to mange it!

 

 

 

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careful not to take comments out of context

[stereo coffee]

  On 07/07/2022 at 1:36 AM, pete_mac said:

 

Ah, understood re: 25wpc - this wasn't clear in your earlier post.

 

Regarding the power rating of amps moving from RMS to peak after 1980, I think that's a rather loose generalisation and I'm not sure of its basis. The FTC's "amplifier rule" for measuring amplifier output (introduced in 1974 to help regulate the industry) was still place at that time. Reputable manufacturers of two channel amps, regardless of their price point, continue to rate the output of their amps based upon a continuous output, both channels driven, across a particular bandwidth, and at a particular distortion level. 

 

As an example:

• The 1315R is a minimum of 115 WPC into 8 ohms, two channels driven, 20hz to 20khz, at 0.02% THD.
• The 915 is a minimum of 80WPC into 8 ohms, two channels driven, 20hz to 20khz, at 0.02% THD.

These are not what I'd consider to be "peak" outputs. There are separate figures provided for this in the manuals which are slightly looser, albeit consistent with the German DIN criteria (i.e. the 1315R is 200W into 4 ohms, DIN, 1khz, 0.7% THD DIN and the 915 is 130W - as you can see, the DIN criteria is less onerous)

 

The only thing that likely changed since the introduction of the FTC requirements in 1974 was the rather strict amplifier pre-conditioning requirements, which caused many an amp to overheat and consequently required the de-rating of the power output. I can't find any facts on if/when this occurred, but if it did, this would prove less taxing on an amp and make it easier to achieve higher 'continuous' power output ratings.

 

Home theatre amps, sound bars and the like are a different kettle of fish altogether though -  it seems to be the wild, wild west as far as power ratings go. Some mass-market items include a proper power output into one channel only, or with the two front channels driven, but rarely a proper measurement for all speakers driven simultaneously. The FTC seem to have dilly-dallied on how to mange it!

 

 

 

 

 

 

 

 

 

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Just putting us all in the picture,  there is a wrong presumption here that figures of ohms, somehow,   represents a actual speaker... This is not true, rather ohms in such measurements,  represents a lovely linear resistance. .  Just about as  far removed as you can get ,  from what occurs when. a loudspeaker is connected to a amplifier  

[pete_mac]

  On 07/07/2022 at 4:11 AM, stereo coffee said:

Just putting us all in the picture,  there is a wrong presumption here that figures of ohms, somehow,   represents a actual speaker... This is not true, rather ohms in such measurements,  represents a lovely linear resistance. .  Just about as  far removed as you can get ,  from what occurs when. a loudspeaker is connected to a amplifier  

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Absolutely! However, for the purpose of undertaking measurements of an amplifier's output to enable 'like for like' comparisons, I would think that using fixed resistance of an agreed nominal value (or set of values) is the only practical option.  

Edited July 7, 2022 by pete_mac