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Budget Amp Suggestion for Heresy I


zcmckenna

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I recently inherited a set of Heresy 1s from my dad, and am pretty new to the hifi audio scene. I am looking for a solid budget amp to run them (Somewhere in the $200-$350 range). I am currently using an old pioneer reciever and would like an upgrade. Also if there is any other advice for the Heresy 1s that might be good for me to know, I would appreciate it. Thanks in advance.

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Get a receiver or integrated amp or preamp and amp combo first.  Put your ear down to the tweeter, midrange and woofer in turn with some music (with a lot of treble in it) to make sure all are working. 

 

Most speakers as old as Heresy 1s need new capacitors (unless your dad replaced them).  For advice on this, contact Bob Crites 

https://critesspeakers.com to see if he can either supply some new capacitors and instructions (if you are good at soldering) or some new crossovers at an affordable price (if you aren't good at wiring/soldering, or would rather have him do the work).

 

Enjoy!

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I have been mega impressed with the nobsound 10d mk11. I just set one up in my office and have been amazed at the quality of sound etc. not sure where they are sold as I bought mine locally at Berkeley Stereo  who I am pretty sure would ship you one 

 

my Bluetooth one was I think 365. 

 

https://quartzacoustic.com/shop/nobsound-ms-10d-mkii-hybrid-tube-amplifier/

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You can probably get an excellent used TOTL surround Receiver Yamaha or Pioneer or other for $200

Once the don't have the latest decoders, their value drops like a rock

Don't buy one that is Class D, stick with the Class ABs

100 WPC should do just fine

turn off all of the digital features, and try running in direct stereo aka bypass

The built in DAC will probably have TOTL chip sets like Burr Brown or other and a SN of 120db

You can add a sub later, since the system already supports it

Later if you go with 5 Heresies, you can run it in Surround 5.1 or 5.2 which would rock,

then turn off all of the processors and go direct to listen to music in stereo

The receiver will allow you to EQ both the room and the speakers if you wish.

 

I like the THX rated Pioneers with remote in excellent condition, you have to check for the HDMI interfaces, the new chip set is what Dolby Atmos ? The SC was the TOTL but you have to check for the reviews on line, some units are more lovable than others and reliable too.

https://www.ebay.com/itm/PIONEER-ELITE-VSX-33TX-THX-5-1-Receiver-EXCELLENT/202489839818?hash=item2f2555c0ca:g:wxwAAOSw3Zhbor0M:rk:2:pf:0

https://www.ebay.com/itm/Pioneer-Elite-VSX-54TX-AV-Receiver-7-1-Channel-THX-Orig-Price-1-500/323514746465?hash=item4b52fb4661:g:caAAAOSwrGlby5h5:rk:4:pf:0

https://www.ebay.com/itm/Pioneer-SC25-Elite-7-1-Channel-Digital-Home-Theater-THX-Receiver/332837602257?epid=97526440&hash=item4d7eaac3d1:g:0CsAAOSwNWhbtqcm:rk:6:pf:0

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Class D pluses:

High effiency

Switching power supplies, no giant transformers

Low Heat

Allow for greater channel density in surround amps where heat and power become big issues

 

Minus

Don't spec out against AB and A amps and sound quality has been an issue

 

"The power supply voltage directly amplitude-modulates the output voltage, dead time errors make the output impedance non-linear and the output filter has a strongly load-dependent frequency response. An effective way to combat errors, regardless of their source, is negative feedback. A feedback loop including the output stage can be made using a simple integrator. To include the output filter, a PID controller is used, sometimes with additional integrating terms. The need to feed the actual output signal back into the modulator makes the direct generation of PWM from a SPDIF source unattractive.[6] Mitigating the same issues in an amplifier without feedback requires addressing each separately at the source. Power supply modulation can be partially canceled by measuring the supply voltage to adjust signal gain before calculating the PWM[7] and distortion can be reduced by switching faster. The output impedance cannot be controlled other than through feedback. "

 

https://en.wikipedia.org/wiki/Class-D_amplifier

 

 

Class A is what all amps are compared to as the Reference

Can you have good and bad designs in each, sure.

Class A can be used to heat the room

 

Excellent write up on Amp Types, I can't read it too many times

https://en.wikipedia.org/wiki/Power_amplifier_classes

 

 

 

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Worth reading from the chip set and board level makers, goes over the issues.

Actually, highly recommended reading........

 

class_d-fig-07.jpg?la=en

 

https://www.electronicdesign.com/analog/can-class-d-amplifier-audio-performance-get-any-better

 

http://www.irf.com/product-info/audio/classdtutorial606.pdf

 

https://medium.com/@EPC_Corp/egan-fets-in-high-performance-class-d-audio-amplifiers-11e94d78c4d2

 

 

The differences in power dissipation and efficiency widen at moderate power levels. This is important for audio, because long-term average levels for loud music are much lower (by factors of five to 20, depending on the type of music) than the instantaneous peak levels, which approach PLOAD max. Thus, for audio amplifiers, [PLOAD= 0.1 × PLOAD max] is a reasonable average power level at which to evaluate PDISS. At this level, the Class D output-stage dissipation is nine times less than Class B, and 107 times less than Class A.

For an audio amplifier with 10-W PLOAD max, an average PLOAD of 1 W can be considered a realistic listening level. Under this condition, 282 mW is dissipated inside the Class D output stage, vs. 2.53 W for Class B and 30.2 W for Class A. In this case, the Class D efficiency is reduced to 78%—from 90% at higher power. But even 78% is much better than the Class B and Class A efficiencies—28% and 3%, respectively.

These differences have important consequences for system design. For power levels above 1 W, the excessive dissipation of linear output stages requires significant cooling measures to avoid unacceptable heating—typically by using large slabs of metal as heat sinks, or fans to blow air over the amplifier. If the amplifier is implemented as an integrated circuit, a bulky and expensive thermally enhanced package may be needed to facilitate heat transfer. These considerations are onerous in consumer products such as flat-screen TVs, where space is at a premium—or automotive audio, where the trend is toward cramming higher channel counts into a fixed space.

 

https://www.analog.com/en/analog-dialogue/articles/class-d-audio-amplifiers.html

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On 10/30/2018 at 11:00 PM, zcmckenna said:

looking for a solid budget amp to run them (Somewhere in the $200-$350 range)

Welcome to the forum :D 

I suggest going the vintage amp road.   You can find a nice Yamaha CR-620 for about $150 ... or a better CR-1020 for about $350.  Or look for a Kenwood ... usually "underpriced" but with pretty good sound. I prefer Marantz, but they have been getting more and more expensive ... Check your local CraigsList and OfferUp so you can hear the amp before handing over your money. :D 

Good luck with the search :) 

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30 minutes ago, Emile said:

Welcome to the forum :D 

I suggest going the vintage amp road.   You can find a nice Yamaha CR-620 for about $150 ... or a better CR-1020 for about $350.  Or look for a Kenwood ... usually "underpriced" but with pretty good sound. I prefer Marantz, but they have been getting more and more expensive ... Check your local CraigsList and OfferUp so you can hear the amp before handing over your money. :D 

Good luck with the search :) 

+ 1 to what he says....I definitely like the vintage idea.

 

George

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5 hours ago, Bubo said:

Class D pluses:

High effiency

Switching power supplies, no giant transformers

Low Heat

Allow for greater channel density in surround amps where heat and power become big issues

 

Minus

Don't spec out against AB and A amps and sound quality has been an issue

 

"The power supply voltage directly amplitude-modulates the output voltage, dead time errors make the output impedance non-linear and the output filter has a strongly load-dependent frequency response. An effective way to combat errors, regardless of their source, is negative feedback. A feedback loop including the output stage can be made using a simple integrator. To include the output filter, a PID controller is used, sometimes with additional integrating terms. The need to feed the actual output signal back into the modulator makes the direct generation of PWM from a SPDIF source unattractive.[6] Mitigating the same issues in an amplifier without feedback requires addressing each separately at the source. Power supply modulation can be partially canceled by measuring the supply voltage to adjust signal gain before calculating the PWM[7] and distortion can be reduced by switching faster. The output impedance cannot be controlled other than through feedback. "

 

https://en.wikipedia.org/wiki/Class-D_amplifier

 

 

Class A is what all amps are compared to as the Reference

Can you have good and bad designs in each, sure.

Class A can be used to heat the room

 

Excellent write up on Amp Types, I can't read it too many times

https://en.wikipedia.org/wiki/Power_amplifier_classes

 

 

 

 

What is the current status of TIM (Transient Intermodulation Distortion)?  In the late '70s and later, too much negative feedback got the blame.  Some audiophile amplifiers are advertised with "0 feedback."   Otala did a follow up paper in 2013, but I can't find it.  The Google citation for the 2013 paper sends me to the 1977 paper.   When Matti Otala came up with it in 1977, PWK said it should be named Otala distortion, in Matti's honor.  

 

I think John Curl still gives TIM figures in the spec sheets for his Parasound amplifiers, on the ground that there is little correlation between listening tests and either THD or ordinary intermodulation distortion, but there is between TIM and listening test results?  Yeah, here we go for the Halo jc5:  http://www.parasound.com/jc5.php under Specs (not Features): TIM Unmeasurable

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On 11/4/2018 at 6:35 PM, garyrc said:

 

What is the current status of TIM (Transient Intermodulation Distortion)?  In the late '70s and later, too much negative feedback got the blame.  Some audiophile amplifiers are advertised with "0 feedback."   Otala did a follow up paper in 2013, but I can't find it.  The Google citation for the 2013 paper sends me to the 1977 paper.   When Matti Otala came up with it in 1977, PWK said it should be named Otala distortion, in Matti's honor.  

 

I think John Curl still gives TIM figures in the spec sheets for his Parasound amplifiers, on the ground that there is little correlation between listening tests and either THD or ordinary intermodulation distortion, but there is between TIM and listening test results?  Yeah, here we go for the Halo jc5:  http://www.parasound.com/jc5.php under Specs (not Features): TIM Unmeasurable

1977 PDF

http://www.jockohomo.net/data/7470.pdf

 

 Nice write up by Olin Lathrop

Transient Intermodulation distortion (TIM) is usually measured by putting a burst of a fixed frequency into a amplifier and then measuring what actually comes out. By Fourier analisys, you can see that changing amplitude of a frequency actually implies additional frequencies. This is why AM radio stations can't be spaced too close together. They don't just radiate at the carrier frequency, but some range on either side of the carrier frequency.

The additional frequencies of a single-frequency burst cause particular trouble to some types of amplifiers, and the resulting distortion appears more noticable to human listeners than more general distortion. Put another way, audio quality isn't just about total distortion level, but the type of distortion too. Different types of distortion are more objectionable than others, and TIM is of the more objectionable type. This is why there is sometimes a separate spec for TIM in addition to the overall distortion spec.

TIM seems to be exacerbated by amplifiers that don't have much frequency headroom above the highest desired frequency, and a high global feedback ratio. Design techniques to minimize TIM include:

 

  1. Making the internal signal path of the amplifier still have gain well above the highest frequency of interest. For example, for a "HiFi" audio amp that must work up to 20 kHz, you may want individual stages to be reasonably flat to 100 kHz.
  2. A simple passive low pass filter in front of the amp that limits incoming signals above the specified operating range. This together with point 1 means that the active part of the amp will only see frequencies for which it's gain is relatively flat. This can be as simple as a one or two stage R-C filter.
  3. The gain of each stage should be stable and well-defined. Do not rely on global feedback to deal with high and unrestrained gain of individual stages.
  4. Keep the global feedback fairly low, which is the same as saying keep the open-loop gain of the overall amp only somewhat above the final desired gain of the whole amp. 10-15 dB seems to be a reasonable range. If all the stages individually have reasonably flat gain, then not much feedback will be needed to guarantee overall flat and predictable gain anyway.

https://electronics.stackexchange.com/questions/156643/what-is-transient-intermodulation-distortion

 

Decent write up, beat is one of the RF items I could learn more about, Radio the final frontier.

https://en.wikipedia.org/wiki/Intermodulation

 

A frequency spectrum plot showing intermodulation between two injected signals at 270 and 275 MHz (the large spikes). Visible intermodulation products are seen as small spurs at 280 MHz and 265 MHz.

 

576px-RF_Intermodulation_at_280_MHz.jpg

 

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