Some thoughts only. The 500 watt amp is going to give you 7 dB or so more sound level over the 100, and assuming your speakers can take it will sound nearly twice as loud. The 100 watt even though it is class A just does not have the horsepower to match the 500 watt. The ability to deliver 1000 watts into 4 ohms is excellent as well, assuming your speaker does go down into this range of impedance.
That said the remaining specifications for the Emotiva are very average. I did not see any spec for intermodulation distortion, or damping factor.
That said the remaining specifications for the Emotiva are very average. I did not see any spec for intermodulation distortion, or damping factor.
IMD correlates with THD, so estimates can be made if other is known. I have measured both on my xpa-1, both in stock and after slight modifications. As stock the THD was approx 0,002% (to 4R@0,2-0,4W. Dummy load has 3,4µH of inductance.) rising to 0,01% 20khz, (2HD dominant) and IMD% little lower. With non-inductive dummy load the thd rise would be somewhat lower towards 20khz. With modified bias the THD drops to 0,000x% region and IMD follows. Measured performance is excellent even as stock (don't mind the home theater secrets' measurements that are very compromised because of ground loop and some other issues as well).
Damping factor/output impedance is a mystery, but thick foiled PCBs, high amount of parallel power transistors, 3 parallel output relays (that has silver alloy conductors by the way) and thick speaker wiring assures that the output impedance is low/typical for balanced bridged amp, assuming that used negative feedback level is typical. I would be prone to think that negative feedback level is not quite high, because of high-ish gain of 32dB and highly musical and unconstricted presentation, but I could be wrong.
By the way, it depends on application wether a high or low damping factor (voltrage or current drive) is preferred, while usually people understand that higher is better in every situation...
Regards,
Legis
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Why would you ever want a low damping factor? My understanding is that is the measure of how tightly the amp controls the physical movement of the speaker. In other words why would you want to decouple the speaker from the amp? Unless your speaker is short of bass and you want it to produce bass even after there is none left in the signal source.
Offtopic:
Current drive (= low damping factor = high output impedance) is usually preferred for example with full range speakers. FRs tend to get overdamped too easily with "normal" voltage drive amp: http://passdiy.com/pdf/cs-amps-speakers.pdf
I remember current drive reduces speaker's voice coil's inductance related nonlinearities (reduces THD) at middle and high frequencies. With heavy bass cone and low frequencies the voltage drive might be preferred almost always as you said. 🙂 Without electrical damping the cone's decay rate get's worse around Fs.
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Single number THD is a specification which has no correlation with sonics, one needs to see the data before it is collapsed and all the relevant information thrown out.
dave
There is an ideal amplifier output impedance (damping is an ugly way of specifyingoutput impedance) for every loudspeaker. There is a solid argument for making speakers that can be driver by a current output amplifier (damping factor << 1).
There are few absolutes in audio.
dave
i heard the jungson at a dealer in Beijing last summer. though the sound was powerful and smooth, there was an annoying glare at the top end that was unbearable.
the same system was much more listenable with a manley stingray.
the same system was much more listenable with a manley stingray.
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Sure, one needs also to see the FFT spectrum or some other information about the harmonics. I have pasted XPA-1's THD graph in this thread here. As stock, the harmonics H2 and H3 are visible in FFT, other harmonics are below noise floor (0,2-0,4W into 4R).
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If we confine the damping factor discussion to the conventional amps of dicussion in this thread (A or AB SS), and conventional speakers, and in particular the bass speaker, I would still maintain more damping factor is better. The whole purpose of reproducing an electrical signal to make a sound wave is to have the sound wave replicate the electrical signal as closely as possible. A bass speaker is heavy and behaves like any spring mass with moderate damping. It wants to vibrate at the fundamental frequency and keep going even when the amplitude of the signal has reduced or stopped. It is like a car with worn out shocks. But, with high amplifier damping, the amp can detect the undesired movement of the speaker and eliminate it, or at least significantly reduce it.
I think there is a common misunderstanding that you can over dampen a speaker. And yes that is true if you apply mechanical damping to the speaker. It would be like putting 8 shocks on your car instead of 4. But electrical damping does not work that way. It simply locks the signal to the speaker movement. When the signal decays as it should, the speaker follows in lockstep. It does not decay faster than the signal (but would with excessive mechanical damping).
In the end all it really comes down to is a very low output impedance which is not reduced by excessive impedance in the speaker cable, cable connections, and speaker internal wiring and crossover. Without electrical damping the speaker will take the remaining energy after the signal stops and continue to vibrate and make sound at the fundamental vibration frequency of the bass driver. If you like to hear that bass frequency in your music, even though it is not there in the source material, then perhaps you will like a low damping factor amp. Many would just call it a "tubby" sounding system, and a distortion of true music reproduction.
I think there is a common misunderstanding that you can over dampen a speaker. And yes that is true if you apply mechanical damping to the speaker. It would be like putting 8 shocks on your car instead of 4. But electrical damping does not work that way. It simply locks the signal to the speaker movement. When the signal decays as it should, the speaker follows in lockstep. It does not decay faster than the signal (but would with excessive mechanical damping).
In the end all it really comes down to is a very low output impedance which is not reduced by excessive impedance in the speaker cable, cable connections, and speaker internal wiring and crossover. Without electrical damping the speaker will take the remaining energy after the signal stops and continue to vibrate and make sound at the fundamental vibration frequency of the bass driver. If you like to hear that bass frequency in your music, even though it is not there in the source material, then perhaps you will like a low damping factor amp. Many would just call it a "tubby" sounding system, and a distortion of true music reproduction.
You will not get aftersale service from Jungson.
I purchased my Jungson JA-99D's from the North American Distributor Grant Fidelity, not cattylink.
Grant Fidelity apparently facilitated the sale between the factory and us (due to language barrier), so we actually did the transaction with them.
We did find that one of the units currently still with our technician was in fact worked on and they were dry joints all over the place and poorly soldered transistors. We even emailed them pics and they decided to remain quiet on the issue.
Guys PLEASE BEWARE - STAY AWAY FROM JUNGSON, you will be seriously let down.
We will publish a warning in our local audio visual magazine that no dealers or client are to come close to this brand. Our aim now will be to protect anyone in this country purchasing this brand. We are also planing on aproaching the Chinese Consumer Protection dpt to have JungSon fully investigated.
I purchased my Jungson JA-99D's from the North American Distributor Grant Fidelity, not cattylink.
Grant Fidelity apparently facilitated the sale between the factory and us (due to language barrier), so we actually did the transaction with them.
We did find that one of the units currently still with our technician was in fact worked on and they were dry joints all over the place and poorly soldered transistors. We even emailed them pics and they decided to remain quiet on the issue.
Guys PLEASE BEWARE - STAY AWAY FROM JUNGSON, you will be seriously let down.
We will publish a warning in our local audio visual magazine that no dealers or client are to come close to this brand. Our aim now will be to protect anyone in this country purchasing this brand. We are also planing on aproaching the Chinese Consumer Protection dpt to have JungSon fully investigated.
I'm sorry for your bad luck. Could you post the pictures also here?
Do you mean that somebody had done something to the amp, that was with the technician, after it came from the factory, or that it came from the factory in a condition like it was. Why was the amp with the technician anyway?
I think one should not make hasty conclusions and go into extremes. Jungson is, I think, after all one of the most respected manufaturers among the chinese people, and they ought to know local manufacturers better than westerns. All manufaturers have bad samples.
Also some western hifi dealers have been known to have a "querilla war" agains chinese manufacturers, maybe in order to hope to sabotage their reputation. Bells should ring if a poster has registered recently and has only1 post that mocks chinese brands. This description applies also to you by the way, I'm just saying.
I don't own Jungson by the way.
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Recommended power
Great discussion 🙂. I learnt a lot especially about a couple amps (Emo XPA-1, XPA-2 and Jungson 99d) that I have under consideration.
I am no longer interested in the Jungson because mainly of the inefficiency of a pure class A design.
My speakers are 88 db/w, are currently set up in a smallish room (3x5 m) and generally I listen at relatively low levels (well at least compared to my offspring).
I have never owned a muscle amp and I not too worried about the expenditure. I can also make after market changes if needed (ie DIY if needed).
Which amp (XPA-2 or XPA-1) can you recommend
regards
Great discussion 🙂. I learnt a lot especially about a couple amps (Emo XPA-1, XPA-2 and Jungson 99d) that I have under consideration.
I am no longer interested in the Jungson because mainly of the inefficiency of a pure class A design.
My speakers are 88 db/w, are currently set up in a smallish room (3x5 m) and generally I listen at relatively low levels (well at least compared to my offspring).
I have never owned a muscle amp and I not too worried about the expenditure. I can also make after market changes if needed (ie DIY if needed).
Which amp (XPA-2 or XPA-1) can you recommend
regards
Sulphur, XPA-1 is very good amp even as stock condition.
What comes to my modding project of XPA-1, it has finally come close to and end. Some pictures along the way...
Input's DC blocking caps changed to Clarity caps (250V ESA series)
Figured that old 4,7µF Sounders could be soldered to PSU section between the rails to offer more low pass to get somewhatr cleaner DC (as stock there is only one 0,47µF caps accross the rails on the amp module card). Notice also the empty fuse holders.
One amp board finished with new components and a stock board for comparison on the top:
On the right side board, 16ga UP-OCC rails (soldered with wonder solder signature) to squeeze off all the extra resistance from the PSU rails and output impedance. Cleaning off the flux after all that solder was a pain in the @ss 😀
Two finished boards
Changed the relays of the inrush current limiter boards to 16A (Finder brand), to sustain the slightly higher inrush at startup due to higher bias and lower resistance of the lines due to by-passed fuses and soldered contacts, and to give lower contact resistance.
Starting to mod the case to breath better to support the increased heat generation of higher than stock bias. On left window there is a steel wire net for demoing purposes to see how it looks.
Then there were more holes...
Some temperature comparison with new holes in the case (temperature measuring prod under the white tape)
Measuring temperature control in the "rack" with the modded cases. The temps are just below 50 degrees celcius, approx. 23 degrees higher than room temperature.
After shooting the pics I have sanded the edges smoothier. I have not yet installed the steel nets so I cannot show how it looks finished. However I have demoed it, and it did look quite nice. I was thinking that maybe at some point the nets could be changed to aluminum or stanless rounded hole perforated sheets, so I'm not planning to install the nets with permanent solution like epoxy at this point.
Complete mod list I have done to my XPA-1s along the way (not in any particular order), hold on to your hats!
- Snubbed the main PSU's diode bridge (0,1µF poluprops + 1000R resistors)
- Snubbed the secondary of the tranny (with low just loss 0,1µF polyprop capacitor)
- Snubbed the diodes (8pcs) of the front end with 0,1µF polyprop caps
- Strengtened the star grounding on the PSU/input board. Originally the star has 2mm2 of copper in each string, now it has 10mm2 in each.
- Streghtened the grounding wires of the amp modules (also from 2mm2 to 10mm2)
- Added couple of polyprop bypass caps to filter sections of main PSU and pre amp PSU
- Added 2x4,7µF Sounders between the PSU rails
- Strenghtened the PSU rails on the PCBs with 16ga UP-OCC
- Have soldered every solderable apico etc. connector inside the amp to minimize series resistance and make the amp more age proof
- Bypassed all the 5 fuses inside the amp to minimize series resistance (fuses are quite unnecessary anyway because they don't burn fast enough almost always.) The microprosessor controlled fault protection works very good anyway.
- Added snap on ferrites to the PSU rail wires after rectification
- Emitter resistors changed from 0,5R "white coffins" to 0,15R Mills low-inductive wirewounds
- Changed the three axial polyprop caps on amp modules to Clarity caps
- Input DC blocking caps changed to Clarity caps
- Removed the two NTC thermistors on the inrush current limiter board, and installed a 10R 50W aluminum covered power resistor with leap wires neatly on the chassis itself. This doubled the series resistance of the limiter, it limits better the inrush.
- Changed the three <16A relays on the inrush current limiter boards to 16A to minimize series resistance of the contacts
- Changed the internal speaker wiring to Neotech 14ga solid core, teflon insulated UP-OCC
- Upped bias from 480mA to 1,6A, keeping the same bias voltage as stock because it was found to be optimal bias voltage with THD measurements. This increased the idle consumption from ~70w to ~135W per amp.
- Modded the case with better ventilation
I have not yet measured the performance with the latest mods, since my sound card (E-MU 0404 USB) has been at the warranty repair for 6 weeks now. I will post some measurements once I have been able to done them.
Judged by the ear, the sound took a leap forward with higher bias. The upper end is now just as ultra smooth as with the Shengya PSM-300's. The sound is sweet, exciting, powerfull and also the same musical nature, that the amp exhibits also as stock, is there. The bass, regardless everything I did to reduce the resistance of the PSU rails and the output impedance, is not quite as controlled and snappy as with Shengya. It's however a bit more fuller and "airier" if one may say so, and this sacrifices the freakiest feeling of control that the Shengyas exhibit. Pick you poison which one you like better. 🙂
Regards,
Legis
What comes to my modding project of XPA-1, it has finally come close to and end. Some pictures along the way...
Input's DC blocking caps changed to Clarity caps (250V ESA series)
An externally hosted image should be here but it was not working when we last tested it.
Figured that old 4,7µF Sounders could be soldered to PSU section between the rails to offer more low pass to get somewhatr cleaner DC (as stock there is only one 0,47µF caps accross the rails on the amp module card). Notice also the empty fuse holders.
An externally hosted image should be here but it was not working when we last tested it.
One amp board finished with new components and a stock board for comparison on the top:
An externally hosted image should be here but it was not working when we last tested it.
On the right side board, 16ga UP-OCC rails (soldered with wonder solder signature) to squeeze off all the extra resistance from the PSU rails and output impedance. Cleaning off the flux after all that solder was a pain in the @ss 😀
An externally hosted image should be here but it was not working when we last tested it.
Two finished boards
An externally hosted image should be here but it was not working when we last tested it.
Changed the relays of the inrush current limiter boards to 16A (Finder brand), to sustain the slightly higher inrush at startup due to higher bias and lower resistance of the lines due to by-passed fuses and soldered contacts, and to give lower contact resistance.
An externally hosted image should be here but it was not working when we last tested it.
Starting to mod the case to breath better to support the increased heat generation of higher than stock bias. On left window there is a steel wire net for demoing purposes to see how it looks.
An externally hosted image should be here but it was not working when we last tested it.
Then there were more holes...
An externally hosted image should be here but it was not working when we last tested it.
Some temperature comparison with new holes in the case (temperature measuring prod under the white tape)
An externally hosted image should be here but it was not working when we last tested it.
Measuring temperature control in the "rack" with the modded cases. The temps are just below 50 degrees celcius, approx. 23 degrees higher than room temperature.
An externally hosted image should be here but it was not working when we last tested it.
After shooting the pics I have sanded the edges smoothier. I have not yet installed the steel nets so I cannot show how it looks finished. However I have demoed it, and it did look quite nice. I was thinking that maybe at some point the nets could be changed to aluminum or stanless rounded hole perforated sheets, so I'm not planning to install the nets with permanent solution like epoxy at this point.
Complete mod list I have done to my XPA-1s along the way (not in any particular order), hold on to your hats!
- Snubbed the main PSU's diode bridge (0,1µF poluprops + 1000R resistors)
- Snubbed the secondary of the tranny (with low just loss 0,1µF polyprop capacitor)
- Snubbed the diodes (8pcs) of the front end with 0,1µF polyprop caps
- Strengtened the star grounding on the PSU/input board. Originally the star has 2mm2 of copper in each string, now it has 10mm2 in each.
- Streghtened the grounding wires of the amp modules (also from 2mm2 to 10mm2)
- Added couple of polyprop bypass caps to filter sections of main PSU and pre amp PSU
- Added 2x4,7µF Sounders between the PSU rails
- Strenghtened the PSU rails on the PCBs with 16ga UP-OCC
- Have soldered every solderable apico etc. connector inside the amp to minimize series resistance and make the amp more age proof
- Bypassed all the 5 fuses inside the amp to minimize series resistance (fuses are quite unnecessary anyway because they don't burn fast enough almost always.) The microprosessor controlled fault protection works very good anyway.
- Added snap on ferrites to the PSU rail wires after rectification
- Emitter resistors changed from 0,5R "white coffins" to 0,15R Mills low-inductive wirewounds
- Changed the three axial polyprop caps on amp modules to Clarity caps
- Input DC blocking caps changed to Clarity caps
- Removed the two NTC thermistors on the inrush current limiter board, and installed a 10R 50W aluminum covered power resistor with leap wires neatly on the chassis itself. This doubled the series resistance of the limiter, it limits better the inrush.
- Changed the three <16A relays on the inrush current limiter boards to 16A to minimize series resistance of the contacts
- Changed the internal speaker wiring to Neotech 14ga solid core, teflon insulated UP-OCC
- Upped bias from 480mA to 1,6A, keeping the same bias voltage as stock because it was found to be optimal bias voltage with THD measurements. This increased the idle consumption from ~70w to ~135W per amp.
- Modded the case with better ventilation
I have not yet measured the performance with the latest mods, since my sound card (E-MU 0404 USB) has been at the warranty repair for 6 weeks now. I will post some measurements once I have been able to done them.
Judged by the ear, the sound took a leap forward with higher bias. The upper end is now just as ultra smooth as with the Shengya PSM-300's. The sound is sweet, exciting, powerfull and also the same musical nature, that the amp exhibits also as stock, is there. The bass, regardless everything I did to reduce the resistance of the PSU rails and the output impedance, is not quite as controlled and snappy as with Shengya. It's however a bit more fuller and "airier" if one may say so, and this sacrifices the freakiest feeling of control that the Shengyas exhibit. Pick you poison which one you like better. 🙂
Regards,
Legis
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Great mods
Well done Legis.
More courage than me especially with upping the ante on the bias (with the extra heat and in rush current etc). I admire your work . It is a more than I would attempt without your example to follow.
I think I would change the signal caps to better quality if I felt the need.
If the XPA-1 is good in stock form (and significantly better than the XPA-2) then I will probably buy them.
Thanks for your advice.🙂
regards
Well done Legis.
More courage than me especially with upping the ante on the bias (with the extra heat and in rush current etc). I admire your work . It is a more than I would attempt without your example to follow.
I think I would change the signal caps to better quality if I felt the need.
If the XPA-1 is good in stock form (and significantly better than the XPA-2) then I will probably buy them.
Thanks for your advice.🙂
regards
Thanks! I think XPA-1 is very good amp indeed as stock. It also makes a good base for mods, if one is into that, but there aren't any real need to mod anything. I have never heard XPA-2, but would presume it gives nice performance also.
Some pictures with the steel nets installed. Nets are installed temporarily with hot glue, to test temperatures with them in the rack.
XPA-1 HC-edition 🙂
XPA-1 HC-edition 🙂
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Hi Legis,
Incredible work. Great job.
I took some courage and changed all the caps to Sonicaps, removed the toggle switch connecting direct to balanced input and changed the stock XLR to Cardas CMF-XLR chassis connector.
Sound has improved quite a bit. There seems to be more space between the instruments and the base is much tighter than before. I tried it on one amp and compared it to the unmodified amp on one channel. Swapping between the amps really did show quite a noticeable difference.
I'm now considering changing the caps to Mundorf Silver in Oil from the Sonicaps. Any advice?
Incredible work. Great job.
I took some courage and changed all the caps to Sonicaps, removed the toggle switch connecting direct to balanced input and changed the stock XLR to Cardas CMF-XLR chassis connector.
Sound has improved quite a bit. There seems to be more space between the instruments and the base is much tighter than before. I tried it on one amp and compared it to the unmodified amp on one channel. Swapping between the amps really did show quite a noticeable difference.
I'm now considering changing the caps to Mundorf Silver in Oil from the Sonicaps. Any advice?
Here's a post from another ex agent from South Africa... Bad experience with Jungson Audio | whathifi.com
If in doubt, I will get my technician to post pictures later. By the way, I buy other Chinese audio equipment from reputable manufacturers, so I am not generalizing, I am singling out JungSon who by the way also claim to sell a pure
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