X3600/3CH or X3700/9Ch or XMC-2/9CH?

[RickyT]

Interestingly, this Behringer Km750 2 channel pro amp is rated at 200x2 or 750x1 bridged.

Behringer KM750 750W 2-channel Power Amplifier

750-watt 2-channel Power Amplifier with Accelerated Transient Response

www.sweetwater.com

 

[lovinthehd]

Too bad lab tests (From old print magazines) of these old Citation amps aren’t available online. Since my recently acquired Denon 4400h is driving my rears and atmos speakers, I now have open Citation channels and bridged 4 channels to 450x2 to drive Revel M106s that Amir tested around 85db efficiency at 8 ohms.

However, I think it’s more than 450x2 and I’m worried might damage my speakers. The 7.1 has a 2.2kva toroidal power transformer, and never feels more than slightly warm...which implies not too much class A bias. Most class A/B amps are 50-60% efficient. I think the 150x4 rating might really be 250x4...1000 watts would imply only 45% efficiency.

250x4 would imply 750x2 bridged into 8 ohms. Can this damage the Revels? Should I drive them with unbridged channels, if the output is really close to 250 watts? I usually listen between -10 and -20.

I suppose if you turned it up to 11 (as in Spinal Tap) you could damage them. Why bridge at all?

 

[everettT]

I suppose if you turned it up to 11 (as in Spinal Tap) you could damage them. Why bridge at all?

No practical reason.

 

[PENG]

The 7.1 has a 2.2kva toroidal power transformer, and never feels more than slightly warm...which implies not too much class A bias. Most class A/B amps are 50-60% efficient. I think the 150x4 rating might really be 250x4...1000 watts would imply only 45% efficiency.

Where did you get that info about the 2.2 kVA transformer? I downloaded the service manual, and based on the information in there, including fuse size, I doubt it is that big. 1.2 to 1.5 kVA would seem more believable. A 2.2 kVA 120/80V transformer would likely weight more than 40 lbs, the Citation weights 75 lbs soaked and wet with 4 robust power amps and beefy heat sinks, another indication it wouldn't be 2.2 kVA. If it is from online reviewers, I would consider that as unconfirmed, hearsay..

250x4 would imply 750x2 bridged into 8 ohms. Can this damage the Revels? Should I drive them with unbridged channels, if the output is really close to 250 watts? I usually listen between -10 and -20.

If the specs tell you it is 400 W into 8 ohm bridged, being an older HK product you should believe it, though I do believe it could do more on the test bench. You can ignore the owner's instruction manual and bridged it to drive your 4 ohms Revel (as it is obviously out of warranty anyway) as long as you are very careful and go easy on your preamp's volume dial, or risk shutdown, even damage to both the amp and the speakers.

Why do you need so much power, did you use the online calculator to figure out what your maximum power need really is? With that info, anything we suggest are pretty much based on guessimates, that is anecdotal at best.

Edit: The ownern's manual's info is a little difference than the service manual's no idea why, but here it is:

Download Harman Kardon CITATION 7.1 Owner's Manual | ManualsLib

www.manualslib.com

Just notice it specified power requirement of 2500 watts maximum, but you can't go by that as there is no standard that every manufacturer follows when specifying their power consumption, let alone maximum power consumption, that could be for a very short duration and at very high distortion level. The best rule of thumb is, as you alluded to, is to based on the rated output. In this case, 4X130 W, if the owner's manual is right, or 4X150 W if the service manual is right, and that at rated output, efficiency would be closer to 70% or higher.

So 600/0.7 = 870 VA, or if based on a very conservative efficiency of class AB amp, high bias, then it would be 1,200 VA.

 

[RickyT]

Where did you get that info about the 2.2 kVA transformer? I downloaded the service manual, and based on the information in there, including fuse size, I doubt it is that big. 1.2 to 1.5 kVA would seem more believable. A 2.2 kVA 120/80V transformer would likely weight more than 40 lbs, the Citation weights 75 lbs soaked and wet with 4 robust power amps and beefy heat sinks, another indication it wouldn't be 2.2 kVA. If it is from online reviewers, I would consider that as unconfirmed, hearsay..



If the specs tell you it is 400 W into 8 ohm bridged, being an older HK product you should believe it, though I do believe it could do more on the test bench. You can ignore the owner's instruction manual and bridged it to drive your 4 ohms Revel (as it is obviously out of warranty anyway) as long as you are very careful and go easy on your preamp's volume dial, or risk shutdown, even damage to both the amp and the speakers.

Why do you need so much power, did you use the online calculator to figure out what your maximum power need really is? With that info, anything we suggest are pretty much based on guessimates, that is anecdotal at best.

Edit: The ownern's manual's info is a little difference than the service manual's no idea why, but here it is:

Download Harman Kardon CITATION 7.1 Owner's Manual | ManualsLib

www.manualslib.com

Just notice it specified power requirement of 2500 watts maximum, but you can't go by that as there is no standard that every manufacturer follows when specifying their power consumption, let alone maximum power consumption, that could be for a very short duration and at very high distortion level. The best rule of thumb is, as you alluded to, is to based on the rated output. In this case, 4X130 W, if the owner's manual is right, or 4X150 W if the service manual is right, and that at rated output, efficiency would be closer to 70% or higher.

So 600/0.7 = 870 VA, or if based on a very conservative efficiency of class AB amp, high bias, then it would be 1,200 VA.


View attachment 38169

Sorry, I mispoke, it's 2.2Kw, not 2.2kVA. I got the 2.2Kw from AVS member who quoted Steve Mantz, the designer of the amps. Steve is still an active poster at diyaudio.com. I emailed him this morning at his company Zed Audio's email contact. Steve quickly replied and confirmed the 2.2Kw number.

citation 7.1

Greetings, My friend and I determined that the inputs are all functioning properly and that the power supply is fine. We then traced the input signal to the large rectangular transistor on the top of the board Q30/Q31 [all seems fine up to there] just before the large amplifying transistors...

www.diyaudio.com

Harman Kardon Citation 7.1

www.avsforum.com

Steve Mantz on the Citation 7.1 -

"We did design and build the Citation 7.1 and the smaller 5.1. We built a lot of these for Harman International. The amplifiers are flat from DC to 270KHz where the response is about 1dB down. Harman wanted this silly specification, why I do not know because we are not bats and cannot hear that high. The original specification was that they wanted the amplifier to go out to 600KHz, but the first prototypes were NOT happy out there and so we 'compromised' at just under 300KHz.

Each channel uses 10 Toshiba 20MHz output devices with a theoretical dissipation of 1,500 watts. The circuitry is fully complementary from input to output and it has some very unique features. Each channel has 6 power supplies which are separate from the other channels. The only common item between channels is the power transformer, which is a 2.2Kw toroid. This 2.2Kw rating is at 25 deg C and it can put out upwards of 3Kw at higher temperatures.

The input complementary differential pairs are driven by temperature compensated constant current sources, which ensure almost zero drift of the DC conditions with each channel. These are also cascode connected for maximum bandwidth. The main gain stage is also cascoded for increased bandwidth and is also Darlington configured for high current gain.

The output stage is a triple Darlington with ultra fast turn off delay. The main power emitter resistors are non inductive types. No coils are used in the speaker circuit and the amplifier is stable into reactive loads with a phase angle of over 45 degrees. It has the usual plethora of protection circuits which by the way are not in the audio path. The amplifier can be turned on with a remote trigger or by the rocker switch on the rear. It can be changed to run from 100v to 240 AC 50/60Hz.

I have the last two production amplifiers at home, one of which I use in my own system for the subs. I run it in bridge mode into a 2 ohm load, and I get out 1Kw per pair of bridged channels. I did modify the protection circuit to allow me to run each channel into 1 ohm!
I have used the amplifier for 8 years now and it has run flawlessly." - Steve Mantz

Back in 2003, Gene's review of the Aragon Soundstage "enticed" me to buy a Soundstage too (great prepro!)...along with Palladium II monoblocks (fully balanced, XLR only, 100+ watts in Class A...they ran like space heaters) and the 8008x3 amp....all used on Audiogon.

Aragon Soundstage Processor Review

The Aragon Soundstage Processor represents the pinnacle of Aragon's success at producing a sophisticated digital preamp processor capable of decoding Dolby Prologic, Dolby Digital and DTS.

www.audioholics.com

Different reviewers have stated that both Aragon models use 2.0 kVA transformers. Do you think they are both wrong about these 65-70 lb amps?

Product Review

http://hbassociates.us/AragonPalladiumII.pdf

I just did the online spl calc. If I listen to at -10, my Revel M106s would only need ~ 110 watts to achieve 95 db peaks. So I don't need to bridge for them...thanks guys! I will keep two channels bridged on my Earthquake Supernova 15inch subwoofer though (a rare one in passive form).

 

[lovinthehd]

Sorry, I mispoke, it's 2.2Kw, not 2.2kVA. I got the 2.2Kw from AVS member who quoted Steve Mantz, the designer of the amps. Steve is still an active poster at diyaudio.com. I emailed him this morning at his company Zed Audio's email contact. Steve quickly replied and confirmed the 2.2Kw number.

citation 7.1

Greetings, My friend and I determined that the inputs are all functioning properly and that the power supply is fine. We then traced the input signal to the large rectangular transistor on the top of the board Q30/Q31 [all seems fine up to there] just before the large amplifying transistors...

www.diyaudio.com

Harman Kardon Citation 7.1

www.avsforum.com

Steve Mantz on the Citation 7.1 -

"We did design and build the Citation 7.1 and the smaller 5.1. We built a lot of these for Harman International. The amplifiers are flat from DC to 270KHz where the response is about 1dB down. Harman wanted this silly specification, why I do not know because we are not bats and cannot hear that high. The original specification was that they wanted the amplifier to go out to 600KHz, but the first prototypes were NOT happy out there and so we 'compromised' at just under 300KHz.

Each channel uses 10 Toshiba 20MHz output devices with a theoretical dissipation of 1,500 watts. The circuitry is fully complementary from input to output and it has some very unique features. Each channel has 6 power supplies which are separate from the other channels. The only common item between channels is the power transformer, which is a 2.2Kw toroid. This 2.2Kw rating is at 25 deg C and it can put out upwards of 3Kw at higher temperatures.

The input complementary differential pairs are driven by temperature compensated constant current sources, which ensure almost zero drift of the DC conditions with each channel. These are also cascode connected for maximum bandwidth. The main gain stage is also cascoded for increased bandwidth and is also Darlington configured for high current gain.

The output stage is a triple Darlington with ultra fast turn off delay. The main power emitter resistors are non inductive types. No coils are used in the speaker circuit and the amplifier is stable into reactive loads with a phase angle of over 45 degrees. It has the usual plethora of protection circuits which by the way are not in the audio path. The amplifier can be turned on with a remote trigger or by the rocker switch on the rear. It can be changed to run from 100v to 240 AC 50/60Hz.

I have the last two production amplifiers at home, one of which I use in my own system for the subs. I run it in bridge mode into a 2 ohm load, and I get out 1Kw per pair of bridged channels. I did modify the protection circuit to allow me to run each channel into 1 ohm!
I have used the amplifier for 8 years now and it has run flawlessly." - Steve Mantz

Back in 2003, Gene's review of the Aragon Soundstage "enticed" me to buy a Soundstage too (great prepro!)...along with Palladium II monoblocks (fully balanced, XLR only, 100+ watts in Class A...they ran like space heaters) and the 8008x3 amp....all used on Audiogon.

Aragon Soundstage Processor Review

The Aragon Soundstage Processor represents the pinnacle of Aragon's success at producing a sophisticated digital preamp processor capable of decoding Dolby Prologic, Dolby Digital and DTS.

www.audioholics.com

Different reviewers have stated that both Aragon models use 2.0 kVA transformers. Do you think they are both wrong about these 65-70 lb amps?

Product Review

http://hbassociates.us/AragonPalladiumII.pdf

I just did the online spl calc. If I listen to at -10, my Revel M106s would only need ~ 110 watts to achieve 95 db peaks. So I don't need to bridge for them...thanks guys! I will keep two channels bridged on my Earthquake Supernova 15inch subwoofer though (a rare one in passive form).

Well of all the amps that you could bridge, the Citation does seem like the one to use! You have a 20A circuit for it?

 

[PENG]

Steve Mantz on the Citation 7.1 -

"We did design and build the Citation 7.1 and the smaller 5.1. We built a lot of these for Harman International. The amplifiers are flat from DC to 270KHz where the response is about 1dB down. Harman wanted this silly specification, why I do not know because we are not bats and cannot hear that high. The original specification was that they wanted the amplifier to go out to 600KHz, but the first prototypes were NOT happy out there and so we 'compromised' at just under 300KHz.

Each channel uses 10 Toshiba 20MHz output devices with a theoretical dissipation of 1,500 watts. The circuitry is fully complementary from input to output and it has some very unique features. Each channel has 6 power supplies which are separate from the other channels. The only common item between channels is the power transformer, which is a 2.2Kw toroid. This 2.2Kw rating is at 25 deg C and it can put out upwards of 3Kw at higher temperatures.

Actually that's worse than I thought. Transformer's output power rating should be in VA, kVA, or MVA, not watts, kW, MW.

Why Transformer Rated In kVA, Not in KW? - Electrical Technology

Transformer Always Rated In kVA instead of KW. Why Motor rated in kW instead of kVA? Why AC (Air-condition) rating in Ton, not kW or kVA? Why Alternator rated in kVa, not in kW? Why Battery rated in Ah and not in VA? Why Power Plant Capacity Rated in MW and not in MVA?

www.electricaltechnology.org

.

If Steve Mantz is right that the toroid is rated 2.2 kW, then the kVA rating would likely be a little higher because:

kW = kVA X PF, and PF is power factor that is 1 for resistive load, i.e. phase angle between V and I is 0 degree, so for reactive load such as moving coil loudspeaker, PF is less than 1 for the most part of the audio band frequency range. kW = kVA only if the load is a resistor. So if the transformer is rated 2.2 kW for a reactive load with say PF = 0.8, then the transformer will have to be rated for 2.2/0.8 = 2.75 kVA.

I am sure Mr. Mantz is a designer, but I am not sure if he also has a stronger background in EE theory especially on the power side. Based on collaborative information provided in your quote though, it now seems believable that he over designed (so the general rule of thumb for kVA transformer /W wouldn't apply) that particular Citiation 7.1 amp. It then begs the question why it is rated only 4X130 W 8 ohms, and 4X210 W 4 ohms. The 4 ohm rating looks much more reasonable, but the 4X130 W 8 ohm is ridiculously low given that it has such as large transformer and apparently high (80 V) bridge rectifier output voltage. May be you can email him that question for me. Note: I don't think it has a whole lot to do with just being conservative but to some extent, yes I suppose, but not by a factor of 2.

Back in 2003, Gene's review of the Aragon Soundstage "enticed" me to buy a Soundstage too (great prepro!)...along with Palladium II monoblocks (fully balanced, XLR only, 100+ watts in Class A...they ran like space heaters) and the 8008x3 amp....all used on Audiogon.

Aragon Soundstage Processor Review

The Aragon Soundstage Processor represents the pinnacle of Aragon's success at producing a sophisticated digital preamp processor capable of decoding Dolby Prologic, Dolby Digital and DTS.

www.audioholics.com

Different reviewers have stated that both Aragon models use 2.0 kVA transformers. Do you think they are both wrong about these 65-70 lb amps?

I have no reason to doubt those because they are class A amplifiers so it is possible that such a 400 W rated monoblock would have a 2 kVA transformer and weighs 70 lbs, though 1.5 kVA should have been more than adequate.

I just did the online spl calc. If I listen to at -10, my Revel M106s would only need ~ 110 watts to achieve 95 db peaks. So I don't need to bridge for them...thanks guys! I will keep two channels bridged on my Earthquake Supernova 15inch subwoofer though (a rare one in passive form).

If you don't mind telling me your distance from the M106, I would like to check your 110 W number. If your calculation is correct, that at -10 the amp outputs 110W, to achieve 95 dB, then to achieve the 105 dB peak THX specified as reference, you are going to need 1,100 W (1.1 kW) per channel. So you can see why I would like to check your number, or you double check it yourself. The M106's specs say recommended amplifier power 50-150 W, so you follow what I am saying right?

 

[RickyT]

Actually that's worse than I thought. Transformer's output power rating should be in VA, kVA, or MVA, not watts, kW, MW.

Why Transformer Rated In kVA, Not in KW? - Electrical Technology

Transformer Always Rated In kVA instead of KW. Why Motor rated in kW instead of kVA? Why AC (Air-condition) rating in Ton, not kW or kVA? Why Alternator rated in kVa, not in kW? Why Battery rated in Ah and not in VA? Why Power Plant Capacity Rated in MW and not in MVA?

www.electricaltechnology.org

.

If Steve Mantz is right that the toroid is rated 2.2 kW, then the kVA rating would likely be a little higher because:

kW = kVA X PF, and PF is power factor that is 1 for resistive load, i.e. phase angle between V and I is 0 degree, so for reactive load such as moving coil loudspeaker, PF is less than 1 for the most part of the audio band frequency range. kW = kVA only if the load is a resistor. So if the transformer is rated 2.2 kW for a reactive load with say PF = 0.8, then the transformer will have to be rated for 2.2/0.8 = 2.75 kVA.

I am sure Mr. Mantz is a designer, but I am not sure if he also has a stronger background in EE theory especially on the power side. Based on collaborative information provided in your quote though, it now seems believable that he over designed (so the general rule of thumb for kVA transformer /W wouldn't apply) that particular Citiation 7.1 amp. It then begs the question why it is rated only 4X130 W 8 ohms, and 4X210 W 4 ohms. The 4 ohm rating looks much more reasonable, but the 4X130 W 8 ohm is ridiculously low given that it has such as large transformer and apparently high (80 V) bridge rectifier output voltage. May be you can email him that question for me. Note: I don't think it has a whole lot to do with just being conservative but to some extent, yes I suppose, but not by a factor of 2.



I have no reason to doubt those because they are class A amplifiers so it is possible that such a 400 W rated monoblock would have a 2 kVA transformer and weighs 70 lbs, though 1.5 kVA should have been more than adequate.



If you don't mind telling me your distance from the M106, I would like to check your 110 W number. If your calculation is correct, that at -10 the amp outputs 110W, to achieve 95 dB, then to achieve the 105 dB peak THX specified as reference, you are going to need 1,100 W (1.1 kW) per channel. So you can see why I would like to check your number, or you double check it yourself. The M106's specs say recommended amplifier power 50-150 W, so you follow what I am saying right?

I sit 9 feet away. If I listen at -10 below THX reference, wouldn't the peak would be 95dB, not 105dB?

Steve designed the amps for Madrigal Audio Labs (which was now part of Harmon Specialty Group, and had the Mark Levinson/Lexicon/Revel brands), but I don't think he was involved in their marketing. By the time I bought the amps (a few years after they were on the market), I was told the initial 130x4 was restated by Madigral to 150x4 (see below). And the weight changed from 70 to 75 lbs. They didn't change the original owners' manuals.

Power Output

4 x 150 watts @ 8 Ohms,

4 x 240 watts@ 4 Ohms

2 x 150 watts + 1 x 450 watts @ 8 Ohms

2 x 450 watts @ 8 Ohms bridged

FTC: 20 Hz - 20 kHz, .03% THD, All
channels driven
HCC 130 Amps/channel in dual mono mode
Frequency Response < 3 Hz - 200 kHz ?3 dB at rated output
THD/IMD Less than 0.03% at rated output
Power Bandwidth 5 Hz - 130 kHz
Input Impedance 22k Ohms
Input Sensitivity 1.1 volts for rated output
Dimensions (HxWxD) 7 1/2 x 17 15/16 x 17 1/2"
191 x 456 x 445 mm
Weight 75 lbs / 34 kg
Power Requirements 120/230VAC, 50 - 60 Hz; 2500 watts,
maximum

 

[PENG]

I sit 9 feet away. If I listen at -10 below THX reference, wouldn't the peak would be 95dB, not 105dB?

Thank you, my calculations show to achieve 95 dB from 9 ft, you only need 48 W, not 110 W. That's based on Revel's sensitivity spec of 87 dB/2.83V/1m and 4 ohm impedance. If their spec is based on 87 dB/1W/1m, then the power required would be halved, that is, 24 W.

At volume position 0, the Denon should be outputting about 100 W into 8 ohms, or 200 W into 4 ohms, so at -10, it should be about 10 W into 8 ohms, or 20 W into 4 ohms. That's just ball park figures, can't be more accurate without more information.

The calculations shown in the table below should be quite accurate under the stated conditions, and based on the M106's specs, the 9 ft distance, and the other stated assumptions as show in the table.

Calculator A: To calculate amplifier power output requirements:
Input data required:	Input data	Unit
1) Speaker nominal impedance (Ohms)	4.00	Ohm
2) Sensitivity in dB/W at 1 Meter		dB
3) Sensitivity in dB/2.83 V at 1 Meter	87.00	dB
4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)	2.74	Meter
5) Room gain for speaker placement near walls/corners, enter 0 to 3 dB max., to err on the conservative side	3.00	dB
6) Desired additional amplifier headroom (dB) Recommended minimum is 3		dB
7) Target SPL - THX reference is 85 dB, with 20 dB of headroom	95.00	dB
Calculated values from the input data:	Calculated values
Sensitivity loss at seating distance (dB)	8.77	dB
SPL/W at seating distance calculated from the input data	81.23	dB
Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter	2.00	Watt (W)
Power increase in multiples needed to achieve target SPL	23.81
Power increase in dB needed to achieve target SPL	13.77	dB
Calculated amplifier output power required:
For the target SPL at seating distance	47.67	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

 

[RickyT]

Thank you, my calculations show to achieve 95 dB from 9 ft, you only need 48 W, not 110 W. That's based on Revel's sensitivity spec of 87 dB/2.83V/1m and 4 ohm impedance. If their spec is based on 87 dB/1W/1m, then the power required would be halved, that is, 24 W.

At volume position 0, the Denon should be outputting about 100 W into 8 ohms, or 200 W into 4 ohms, so at -10, it should be about 10 W into 8 ohms, or 20 W into 4 ohms. That's just ball park figures, can't be more accurate without more information.

The calculations shown in the table below should be quite accurate under the stated conditions, and based on the M106's specs, the 9 ft distance, and the other stated assumptions as show in the table.

Calculator A: To calculate amplifier power output requirements:
Input data required:	Input data	Unit
1) Speaker nominal impedance (Ohms)	4.00	Ohm
2) Sensitivity in dB/W at 1 Meter		dB
3) Sensitivity in dB/2.83 V at 1 Meter	87.00	dB
4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)	2.74	Meter
5) Room gain for speaker placement near walls/corners, enter 0 to 3 dB max., to err on the conservative side	3.00	dB
6) Desired additional amplifier headroom (dB) Recommended minimum is 3		dB
7) Target SPL - THX reference is 85 dB, with 20 dB of headroom	95.00	dB
Calculated values from the input data:	Calculated values
Sensitivity loss at seating distance (dB)	8.77	dB
SPL/W at seating distance calculated from the input data	81.23	dB
Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter	2.00	Watt (W)
Power increase in multiples needed to achieve target SPL	23.81
Power increase in dB needed to achieve target SPL	13.77	dB
Calculated amplifier output power required:
For the target SPL at seating distance	47.67	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

Where do you get 4 ohms from? Revel rates the M106 at 8 ohms and 87. Amir measured it at 86, with min 4.6 ohms....and between 70-2000 hz, the impedance curve spends some time between 8 and 20/30 ohms.

Revel M106 Bookshelf Speaker Review

This is a review and detailed measurements of the Revel M106 bookshelf speaker. It was kindly purchased and drop shipped to me. It is not a new sample but came to me with full packaging and protective wrapper. The M106 costs US $1,000 each or $2,000 for a pair. It is only sold through dealer...

www.audiosciencereview.com

General Specifications

Height	15" (38.1 cm) Note
Width	8.3" (21 cm)
Depth	11" (27.8 cm)
Weight	19 lb (8 kg) Note
Crossover Frequencies	2.3 kHz
Enclosure Type	Bass-reflex via Rear-firing Port
Finishes	Piano Black or High Gloss Walnut
High-frequency Driver Components	1” (2.5 cm) Aluminum Tweeter with Acoustic Lens Waveguide
Nominal Impedance	8 Ohms
Input Connections	Binding Posts
Low Frequency Extension	10dB@39Hz -6dB@54Hz -3dB@59Hz
Low-frequency Driver Components	6.5” (16.5 cm) Aluminum Cone, Cast-frame Woofer
Recommended Amplifier Power	50-150
Sensitivity	87 dB

 

[RickyT]

Well of all the amps that you could bridge, the Citation does seem like the one to use! You have a 20A circuit for it?

Yep! No, I do not have a 20 amp circuit.

 

[PENG]

Where do you get 4 ohms from? Revel rates the M106 at 8 ohms and 87. Amir measured it at 86, with min 4.6 ohms....and between 70-2000 hz, the impedance curve spends some time between 8 and 20/30 ohms.

I find Soundstage's curve, basically the same as Amir but better scale so easier on my eyes.
It spent quite some time in areas where you typically get a lot of contents, that is between 40-70 Hz, 130 to 300 Hz, then again between 2500 and 10K at about 6 ohms average, just eyeballing.

Also, the measured sensitivity was only 85.6dB vs the Revel specified 87 dB (averaged 300Hz-3kHz on Listening Window, 2.83V/1m) . You mentioned Amir measured 85 dB, that's close enough too. So the overall results would be much different if I plugged in 6 ohm or even 8 ohm, but also reduced the sensitivity from the specified 87 dB to 85/86 dB, say 86 dB.

SoundStageNetwork.com | SoundStage.com - NRC Measurements: Revel Performa3 M106 Loudspeakers

www.soundstagenetwork.com

But fair enough, let me use 6 ohms and 86 dB/2.83 V/1m and then you should get more accurate results instead of me trying to give you a conservative number:

Calculator A: To calculate amplifier power output requirements:
Input data required:	Input data	Unit
1) Speaker nominal impedance (Ohms)	6.00	Ohm
2) Sensitivity in dB/W at 1 Meter		dB
3) Sensitivity in dB/2.83 V at 1 Meter	86.00	dB
4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)	2.74	Meter
5) Room gain for speaker placement near walls/corners, enter 0 to 3 dB max., to err on the conservative side	3.00	dB
6) Desired additional amplifier headroom (dB) Recommended minimum is 3		dB
7) Target SPL - THX reference is 85 dB, with 20 dB of headroom	95.00	dB
Calculated values from the input data:	Calculated values
Sensitivity loss at seating distance (dB)	8.77	dB
SPL/W at seating distance calculated from the input data	80.23	dB
Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter	1.33	Watt (W)
Power increase in multiples needed to achieve target SPL	29.97
Power increase in dB needed to achieve target SPL	14.77	dB
Calculated amplifier output power required:
For the target SPL at seating distance	40.01	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

So 40 W for 95 dB based on 6 ohms nominal, or 30 W if you prefer to use 8 ohms, not a whole lot of difference.
The good news is, you can get almost 101 dB, only 4 dB below reference and still in the safe zone of the 150 W maximum specified for the M106.

 

[PENG]

250x4 would imply 750x2 bridged into 8 ohms. Can this damage the Revels? Should I drive them with unbridged channels, if the output is really close to 250 watts? I usually listen between -10 and -20.

I wouldn't bridge those amps for at least two reasons:

1) The specs didn't provide a bridging spec for 4 ohms so that should tell you something.
2) The M106 has dips below 6 ohms.
3) Revel recommended 50-150 W amplifier power, that matches the Citation's 4X130/150 W 8 ohms, 4X240 W 4 ohms power output specs very well already.

Bridging will likely add distortions, and may endanger your speakers if you are not careful.

Is it a HT system or just two channel? If it is HT, I would suggest using two channels for the FL and FR and consider using the remaining two channels to biamp the center speaker, depending on what kind of center speaker you have.

 

[RickyT]

I find Soundstage's curve, basically the same as Amir but better scale so easier on my eyes.
It spent quite some time in areas where you typically get a lot of contents, that is between 40-70 Hz, 130 to 300 Hz, then again between 2500 and 10K at about 6 ohms average, just eyeballing.

Also, the measured sensitivity was only 85.6dB vs the Revel specified 87 dB (averaged 300Hz-3kHz on Listening Window, 2.83V/1m) . You mentioned Amir measured 85 dB, that's close enough too. So the overall results would be much different if I plugged in 6 ohm or even 8 ohm, but also reduced the sensitivity from the specified 87 dB to 85/86 dB, say 86 dB.

SoundStageNetwork.com | SoundStage.com - NRC Measurements: Revel Performa3 M106 Loudspeakers

www.soundstagenetwork.com

View attachment 38177

But fair enough, let me use 6 ohms and 86 dB/2.83 V/1m and then you should get more accurate results instead of me trying to give you a conservative number:

Calculator A: To calculate amplifier power output requirements:
Input data required:	Input data	Unit
1) Speaker nominal impedance (Ohms)	6.00	Ohm
2) Sensitivity in dB/W at 1 Meter		dB
3) Sensitivity in dB/2.83 V at 1 Meter	86.00	dB
4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)	2.74	Meter
5) Room gain for speaker placement near walls/corners, enter 0 to 3 dB max., to err on the conservative side	3.00	dB
6) Desired additional amplifier headroom (dB) Recommended minimum is 3		dB
7) Target SPL - THX reference is 85 dB, with 20 dB of headroom	95.00	dB
Calculated values from the input data:	Calculated values
Sensitivity loss at seating distance (dB)	8.77	dB
SPL/W at seating distance calculated from the input data	80.23	dB
Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter	1.33	Watt (W)
Power increase in multiples needed to achieve target SPL	29.97
Power increase in dB needed to achieve target SPL	14.77	dB
Calculated amplifier output power required:
For the target SPL at seating distance	40.01	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

So 40 W for 95 dB based on 6 ohms nominal, or 30 W if you prefer to use 8 ohms, not a whole lot of difference.
The good news is, you can get almost 101 dB, only 4 dB below reference and still in the safe zone of the 150 W maximum specified for the M106.

That's awesome! I will drive my M106s and C205 (hopefully the C208 later) with 3 un-bridged Citation 7.l channels. I love these amp's' low 1.1V sensitivity to happily pair with the Denon receivers like the 4400H.

btw, which spl calc site did you use? I only used this one:

Peak SPL Calculator

 

[RickyT]

I wouldn't bridge those amps for at least two reasons:

1) The specs didn't provide a bridging spec for 4 ohms so that should tell you something.
2) The M106 has dips below 6 ohms.
3) Revel recommended 50-150 W amplifier power, that matches the Citation's 4X130/150 W 8 ohms, 4X240 W 4 ohms power output specs very well already.

Bridging will likely add distortions, and may endanger your speakers if you are not careful.

Is it a HT system or just two channel? If it is HT, I would suggest using two channels for the FL and FR and consider using the remaining two channels to biamp the center speaker, depending on what kind of center speaker you have.

Steve Mantz says the amps are stable into 2 ohms, but I don't need to bridge them on these Revels.

It's a 5.2.4 system. Denon 4400H drives two Revel M8 onwall rears and 4 Focal sib (mounted on ceiling) atmos speakers. One Citation 7.1 will drive the LCR: Revel M106 and C205. 2nd Citation 7.1 is bridged to drive two passive subs: Earthquake 15inch and NHT W1 12inch (rated at high 94 db).

Years ago, I originally used them in bridged mode to drive big, full range NHT 3.3 towers that are rated 87db into 6 ohms (can dip to 3.2 ohms). These citations never feel more than slightly warm.

NHT 3.3 loudspeaker

When Ken Kantor helped to found Now Hear This, Inc. (most commonly referred to by its initials, NHT) in 1986, he brought with him a wealth of design and production experience learned from stints with NAD and Acoustic Research. He also brought a desire to build and market products that a wide...

www.stereophile.com

I also have a 3rd Citation 7.1 in the closet, for back up

 

[PENG]

Steve Mantz says the amps are stable into 2 ohms, but I don't need to bridge them on these Revels.

It's a 5.2.4 system. Denon 4400H drives two Revel M8 onwall rears and 4 Focal sib (mounted on ceiling) atmos speakers. One Citation 7.1 will drive the LCR: Revel M106 and C205. 2nd Citation 7.1 is bridged to drive two passive subs: Earthquake 15inch and NHT W1 12inch (rated at high 94 db).

Years ago, I originally used them in bridged mode to drive big, full range NHT 3.3 towers that are rated 87db into 6 ohms (can dip to 3.2 ohms). These citations never feel more than slightly warm.

NHT 3.3 loudspeaker

When Ken Kantor helped to found Now Hear This, Inc. (most commonly referred to by its initials, NHT) in 1986, he brought with him a wealth of design and production experience learned from stints with NAD and Acoustic Research. He also brought a desire to build and market products that a wide...

www.stereophile.com

I also have a 3rd Citation 7.1 in the closet, for back up

So you have over 200 lbs of citations!
I wish I have one, such seemingly amazing amp. Still, as you said, you don't need to bridge to drive this little Revels. So put them to better use..

 

[PENG]

That's awesome! I will drive my M106s and C205 (hopefully the C208 later) with 3 un-bridged Citation 7.l channels. I love these amp's' low 1.1V sensitivity to happily pair with the Denon receivers like the 4400H.

btw, which spl calc site did you use? I only used this one:

Peak SPL Calculator

I use the one I showed you in the tables. I did it myself using Excel. It allows you to enter any impedance values.

 

[RickyT]

So you have over 200 lbs of citations!
I wish I have one, such seemingly amazing amp. Still, as you said, you don't need to bridge to drive this little Revels. So put them to better use..

I actually have 280 lbs of citations! As I also have the smaller 5.1 (100x4 or 300x2, 55 lbs) augmenting a Denon 5200W in a 7.2 family room setup with NHT bookshelves and subwoofers.

These Citation amps original retail was $2800 and $2200 and can be found used $700-900 and $400-600 these days. They were part of a modular THX system with Citation 7.2 LCR speakers, 7.3 rear dipoles, and 7.4 passive subwoofers (with the highly regarded LE14H-1 14inch driver) with these specs:

7.4 Specifications
General Description
Front-firing Subwoofer, THX Certified

Frequency Response
21 Hz - 100 Hz ±3 dB

Driver Complement
14" Woofer with Cast Frame Basket

Nominal Impedance
6 Ohms

Sensitivity
92 dB SPL / 1 watt @ 1 meter

Power Handling Capability
Over 300 watts

Dimensions (HxWxD)
20 5/8 x 24 x 17 3/8" (not including feet)

81.5 lbs / 37 kg

Hence, the Citation amps were designed to drive these subs in bridged mode, with each bridged amp channel seeing 3 ohms (nominal).

The brains of this system was Jim Fosgate's Citation 7.0 analog surround prepro, with his splendid 6-Axis that eventually became Dolby Pro Logic 2 (and made him a rich man!). The 7.0 is still regarded on Audiogon as a sweet sounding analog preamp (even for 2 channel). I used the 7.0 for a few years before getting the Aragon Soundstage prepro.

Nice AH article on this:

History of Surround Sound Processing: The Battle for Dolby Pro Logic II

This is a historical perspective on 6-Axis surround originally developed by Jim Fosgate (who recently passed away) and how it battled Harman's very own Logic 7 format to become Dolby Pro Logic II.

www.audioholics.com

 

[ParleyW]

I actually have 280 lbs of citations! As I also have the smaller 5.1 (100x4 or 300x2, 55 lbs) augmenting a Denon 5200W in a 7.2 family room setup with NHT bookshelves and subwoofers.

These Citation amps original retail was $2800 and $2200 and can be found used $700-900 and $400-600 these days. They were part of a modular THX system with Citation 7.2 LCR speakers, 7.3 rear dipoles, and 7.4 passive subwoofers (with the highly regarded LE14H-1 14inch driver) with these specs:

7.4 Specifications
General Description
Front-firing Subwoofer, THX Certified

Frequency Response
21 Hz - 100 Hz ±3 dB

Driver Complement
14" Woofer with Cast Frame Basket

Nominal Impedance
6 Ohms

Sensitivity
92 dB SPL / 1 watt @ 1 meter

Power Handling Capability
Over 300 watts

Dimensions (HxWxD)
20 5/8 x 24 x 17 3/8" (not including feet)

81.5 lbs / 37 kg

Hence, the Citation amps were designed to drive these subs in bridged mode, with each bridged amp channel seeing 3 ohms (nominal).

The brains of this system was Jim Fosgate's Citation 7.0 analog surround prepro, with his splendid 6-Axis that eventually became Dolby Pro Logic 2 (and made him a rich man!). The 7.0 is still regarded on Audiogon as a sweet sounding analog preamp (even for 2 channel). I used the 7.0 for a few years before getting the Aragon Soundstage prepro.

Nice AH article on this:

History of Surround Sound Processing: The Battle for Dolby Pro Logic II

This is a historical perspective on 6-Axis surround originally developed by Jim Fosgate (who recently passed away) and how it battled Harman's very own Logic 7 format to become Dolby Pro Logic II.

www.audioholics.com

I just received my repaired LE14H-1 woofers today. I’ve got two mint Citation 7.4 subs now in operation. Lovely things.

 

[ParleyW]

I’m surprised at the efficiency of the LE14. I’ve got both subs running off a RBH SA-400 sub amp. I have the gain all the down to 8 o’clock, boost button off. They have a very beautiful sound, quite unique compared to my other reference class subs. I doubt that I’ll sell these. Their keepers…plus my recone tech did a beautiful job restoring the woofers for little coin. Thx again for the data.