Review: Jaycar 2x100Watt Intergrated Amplifer

Discussion in 'Audio Visual' started by mAJORD, Jul 8, 2006.

  1. mAJORD

    mAJORD Member

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    Review: Jaycar 2x100w Intergrated Amplifier.


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    As a commited DIYer when it comes to audio, and one who'd encourage anyone to get into themselves if they enjoy there music, it's almost scary to open up the box of a cheap, chinese amplifier, costing a mere $199 retail, and claiming 100x2 complete with remote. There is allways the chance something like this will represent better value for money than anything someone could DIY for the same price.

    But I was curious to see what this thing had to offer,So I Hope the following review is helpfull to those thining about buying this amp.


    Overview:

    With a flick through the manual, and a peek inside, it didn't take long to track down the manufacturer of this little number.

    It is infact a Fortex Ps-3038 http://www.fortex.com.hk/prodinfo.aspx?id=79 , made by themselves from what I can gather, and is part of a series of 'hifi' components including tuner, CD player, and *cough* cassette deck. All of which are designed to hook up to the receiver via specialised cables.

    It seems to be also distrubted by danish budg-o hifi company 'ELTAX' as the Acura series http://www.eltax.com/eltax/index.php?item=10&id=11270


    The reciever is fairly feature packed for It's price, and if you're allready interested in it, you'd know it features:

    *5 standard RCA inputs - Tape, Tuner, CD, AV1, AV2 plus one RIAA equalised PHono input, and one mic input, all selectable via front panel pushbuttons or remote.

    *tape rec out, plus external processor in/outs (is not a pre in/out however)

    *Bass and treble controls (unknown frequencies)

    *headphone jack

    *standby mode

    *4 equaliser presets, 'rock, pop etc etc'

    * and of course the remote.

    About the only thing it's missing is a tuner.


    Detailed description:

    -input/preamp section:


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    The input section consists of a set of philips HEF4052BP and 4066BP multiplexers / solid state input switches which are controlled by the front panel or remote. These simplify the design and allow remote controlled Source switching without the use of relays.

    The downside of this setup is it introduces it's own distortion and noise components to the signal. This will become apparent later on. However, this is a pretty common method for entry level AV receivers also. So It's to be expected on something like this given it has a remote.

    Volume/eq/tone preamp controls are provided by a single IC - The sanyo LC75392 http://www.ortodoxism.ro/datasheets/sanyo/ds_pdf_e/LC75392.pdf . which turns out to be an all in one, digitally contolled volume, tone, equaliser preset , and input selector. It would seem input selection is not priovided by this IC however, or if it is, the other ICs must serve a different purpose, but Havent traced this out, nor do I intend to!.

    All of these ICs are conrolled by a single microcontroller.

    Don't be confused by the fact the tone and volume controls are 'digital', that does not mean there are DACs onboard, these Chips simply use digital interfaces to control ANALOGUE signals. It is a quite different setup to that of the DSE amp for example, which uses traditional OPAMPs with Potentiometers to vary frequency (tone) , and volume.

    The downside to all this is, like any receiver using this method, is these controllers introduce there own distortion and noise into the signal, usually more so than the Opamps and switches/pots of traditonal setups.

    Being a budget setup the particular ICs (above) used for this job probably aren't the best.

    -Amplifer section.


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    As most allready know, amplificaiton is cortousy of 2 ICs or 'Chip amps', (SGS thompson TDA 7294) , http://www.st.com/stonline/books/pdf/docs/1057.pdf

    Which claims, Like the manufacturer, a maximum 100watt rms x2 @ 10% THD Short term.

    Being a chip-amp, The datasheet tells all, and it's pretty clear that it would be pushing it to expect anywhere close to 100watt continuous RMS, at reasonable distortion levels which more expensive Amplifiers are rated at.

    That aside, for chipamps, these are about as powerfull as the come, and there aren't many alternatives.

    Here is a snipit from the Datasheet, showing the claimed distortion vs power, and power versus supply voltage, which in this case, is +-39V with no load, but drops significantly under load as will be seen During measurments, which Ive pointed to with arrows, along with the maximum expected transient power levels.


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    Power Supply section:

    Power supply consists of a 30-0 30-0 Toroidal transformer of unknown VA rating, possibly 200-250VA going by it size, giving Rail voltages of +-39V.

    Filter capacitors are 2x 4700uF so there is definatly a lack of smoothing ability if it is to produce it's claimed figures at low frequencies especially.



    Build Quality:

    This is actually a pretty solidly built Chassis, of reasonable quality. The only complaint here is the poorly moulded tone and volume controls, which don't spin true.


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    Internal Build is above par for a cheap peice of gear like this. Phenolic board as expected, but all PCBs are quite smartly layed out, and well secured. Ribbon cables and connectors are standard fair. No complaints here. soldering quality is good.

    Connections:


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    No gold plated RCA connectors to be seen. They are mounted well though. Very solid, and I don't expect them to cause connection troubles from flexing the internal PCB.

    Speaker connectors are Quite cheap and nasty. I had some trouble getting a solid connection with 8 gauge speaker cable, but are at least a reasonable size banana plug / screw type. I would have had no hope with spring type connectors, so Again, can't complain too much. And once connected, there are no problems.

    All in All a pretty smartly designed and built little unit. If it wern't for the wonky and horrible tone and volume controls Id give it 4/5 for for build quality at this price.

    Operation:

    Operation of the Amp is simple and fuss free. There is no need to read the manual here ;). All inputs are selected with a touch button press. Volume control, being a digital type moves indefinately left or right. One complaint here is the step size for volume increments, It's rather large with only 25 steps from 0 to full noise, which, at normal listenting levels, and with your average source, equates to about 10 points from 0 to quite 'loud' volume. not enough IMO. If you're hooking this up to a computer or other source with a better volume control, it shouldn't prove to be an issue.

    The remote operates from approximatly 90deg in all directions, and to a distance somewhere over 15M straight on. (The hallway is not long enough :) )




    Sound Quality:


    Now comes the hard part. and the part most people are interested in. I say it is hard, because I am a firm beliver that Amplifiers contribute a lot less to
    the SQ of the system than speakers do, hence unless they're suffering major flaws, nitpicking trends in there sound can be irritating to put into words :).

    I could evalutae speakers all day on the other hand, as there sonic signature is much more obvious.

    Ive chosen to do perceived SQ tests first, because measurments only serve to sway ones feelings if not doing blind tests comparing other equipment. (which I was unable to do).

    Test Setup - Listening.


    Source: music PC, running Silent W/C setup, EM-U 404 soundcard, Foobar 2000 kernal streaming, all media Ripped from CD with CD-EX-paranoia to FLAC.

    For direct comparsion I've chosen 2 Amps to run along side it.

    Firstly, an amp I'm most happy with at the moment, a Tripath 2020 Based Class D (T) reference/ amp. putting out approximatly 50watt/chan@8ohm.

    Secondly, my ESP 101A based class AB monoblock of 150watt/chan into 8ohms. A good reference amp, as it has very low distortion, plenty of Power, and a very beedfy power supply.

    I would have loved to also throw the DSE 2x80 watt amp into the mix, but I am unable to. Hopefully someone is, and will be able to give there comparisons.

    Speakers consisted of 2x Proac 2.5 clone, DIY floorstanders. A bassy, rich sounding speaker, which will bring out the worst in any recording or amp. It is
    noted for having a very smooth musical sound and has a rating ot 70watt RMS / speaker.

    First Impressions:

    I First listend to some music with my standard setup for some time to 'desensitize myself' (lets face it, listening to your main system after being at work all day, and listening to the car radio for hours makes it sound like heaven)

    Upon switching over the Jaycar amp, the first thing I noticed was the presence of some backround noise (hiss / white noise).

    There is no real denying it here, the noisefloor level is not the best, but in all honesty It's no worse than a lot of cheap receivers, (up to $500 mark).
    If you are a bit of an audiophile, and listen to detailed music in a quiet environment, at nearfeild position, then perhaps forget this Amp, and move up to something much more expensive, OR consider a mod to bypass some of the input switching and volume circuirty. I see no point in doing that however.

    IF however this is not you, and you either have an audible fan in your computer's PSU, or intend to use the amp in a living room where your head isn't jammed against the speaker do not let the noisefloor deter you, as you won't hear it, so you're not missing out on anything.

    Music Sound quality -low to medium power levels:

    material played:

    I have a couple of albums I like to use for this sort of testing from artists: Fiona Apple, Gomez and Cat empire.

    Tracks of particular interest:

    The cat Empire - all that talking
    Fiona Apple - Limp.

    Initial impressions were surprising. The amp did not sound flat in direct comparison to either amp, as some commercial AV receivers sometimes do, especially those utlising cheaper IC amps.

    In the gentle start to both tracks it performed very well, It has plenty of dynamics and attack for percussion, equalling that of the tripath (not the TP's strongest point however) , and not far off the very dynamic monoblock.

    Midrange Detail is good, except in the below mentioned scenario. Bass was reasonably accurate, not quite a match for either of the comparison amps here though - a bit sloppy and lacking in the very bottom end. Highs were plentifull and quite smooth. A rising THD with frequency is good for that.

    Audibly, frequency reponse seems flat, but slightly lacking in the very bottom end like I said.

    Complex sections of tracks is where it falls down a tiny bit, the differences between It and the Tripath are quite minor here, but there is an apparent lack of stereo imaging during complex peices of music, along with this, some detail is lost, and sounds tend to get bit muddled and recessed.
    Compared to the monoblock amp however, there really wasn't any difference, apart from it being a bit bright in comparison. (measurments later on show not so good stereo seperation, which the ESP amp also suffers due to a preamp problem may be the cause)

    Music sound quality - high power:

    Placebo - Commercial for Levi.
    Gomez - Love is better than a warm trombone.

    Again, here I was fairly impressed. audibly, it had plenty of grunt in comparison with the 50watt tripath, as it should.
    Next to the ESP monoblock, it's limitations were found, even on the relativly low power handling floorstanders. It certainly did not seem to have the
    overhead of a 100watt amp. Percussion becomes compressed at higher volumes in comparison, but in the context of it's actual power capability as measured below, It copes well. A beefing up of the power supply would go a long way here.

    If there is one thing that is for certain, the Chipamp is in no way a limiting factor here for perceived sound quality. It is an overal good sounding amp, It
    is not weak within the limits of it's power levels, which I'll go into shortly, and while I havent had the ability to compare it to the DSE (what I see as
    it's alternative) I would be very surprised to hear anyone say it was lacking in this area.

    Having had other DIY Class AB chipamps such as gainclones using the more favoured National semi Chips, this amp compares favourably.

    Anyone of the belief Chip amps cannot compare to Discrete designs at sub 100W power levels might want to spend some time with this amp, if they're unwilling to build a gainclone :)


    It should also be remembered the shortfalls are minor, and would pale into insignifcance compared to the differences bettween ordinary and Decent speakers in this 0-1K mark.

    So to summarise perceived tests:

    Strengths: Accurate, dynamic reporoduction, on par with just about any amp in, and somewhat above its class, escpecially multichannel receivers.

    Weaknesses:
    Noisefloor
    slight lack of transparency and imaging on complex music
    Is no match for an amp with a plentifull Power supply.

    Measurments Continued next post!:
     
    Last edited: Jul 8, 2006
  2. OP
    OP
    mAJORD

    mAJORD Member

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    Measurments:


    High power Sine Measurments:

    The following was done using resistive dummy loads, In an attempt to determine maximum peak output, and continuous output. Plus to check the behaviour of the PSU at high power.

    8ohm tests:

    Dummy loads: 8.3ohms each - wet.

    Firstly, the unladen rail voltage was measured at +- 39.5v. the CRO showed approximatly 40v on the trace, This was used to ensure continuity between
    multimeter and CRO.

    Continuous Sine waveforms 8ohm:

    Click on Images to Enlarge


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    Figure 1 - 50Hz - Showing onset of clipping: approximatly 58v peak-peak. power supply droop to about +-32V - calculates to approximatly 55WRMS into 8ohms



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    Figure 2&3 - prior to, and onset of clipping at 500Hz. Not much different



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    Fig3. - 1Khz.




    Continuous Sine waveforms 4ohm:



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    Fig 4&5. 100hz - Showing onset of clipping. Approximatly 48v peak-peak after power supply droop, calculates to approx 70WRMS into 4ohm




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    Fig 6. 1Khz





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    Fig 7: Power supply Droop and ripple @ 4ohm, and onset of clipping. (very top division=40v center=0 , 10v per division)

    High power - Music Tests.

    For this test I played the album Seven dust - home at maximum output (monitored on the CRO for clipping), transients into 8 ohms were seen up to 35V or so. Inot 4ohm, about 28volts. For music use therefore, you may see closer to 70Watts@8 and 100watts@4 short term.

    A digital anayliser or scope would be needed to get decent figures.

    One thing that I suggest may happen with 4ohm loads is Current limiting cutting in at high power. I didn't really witness this however.



    The Cooling Fan kicked In after about 5mins with 8ohm loads, and stayed on a low speed for the whole Album.

    During the same test with 4ohm load, it was on after

    only 2mins, and at full speed the entire time.

    at lower listening levels, I wouldn't expect the fan to cut in at all.


    Calculated Power Outputs:

    Continuous power, both channels driven into 8 ohms @ onset of clipping:
    55Watts RMS / channel
    Continuous power, both channels driven into 4 ohms @ onset of clipping:
    72Watts RMS / channel


    Peak RMS (tranisents) into 8 ohms -Estimated from 100ohm load:
    80Watts RMS @ onset of clipping
    Peak RMS (tranisents) into 4 ohms -Estimated from 100ohm load:
    100Watts RMS @ onset of clipping


    These are all give or take around 5watts.



    Power measurments Summary:

    It is evident here that the Power supply is the weak link in preventing this amp from making the75-80watts continuous RMS it should be capable of.

    Somewhat Ironicly, it is this 'weak' power supply that allows the amp to drive 4 ohm loads without going into to current overload protection.

    Providing one is happy to only drive 6-8ohm loads, a beefing up of power supply filtering would allow a higher output. As it stands though, it is capable of providing clean output up to the limitations found.


    Noise, dynmaic range, and distortion measurments - A comparison with other amplifiers.



    Unfortunatly, My 1/4" jack - RCA adapters have gone AWOL, so these tests were Performed using my DCD1015 Denon CD player as a source, as such there is a bit more noise, and distortion components in the test signal than there would be using my EM-U card in loopback.

    All measurments were made with a purely resistive voltage divider (no op amps, I like to live dangerously in a nerd kind of way) and under typical load of the test speakers.


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    The full Report can be found here: http://www.users.on.net/~majord/Comparison-8-7-06-jaycar2x100.htm



    The results show quite reasonable performance from the little Jaycar amp.

    Whilst none of the figures quite match the other 2, The real world differences are minor. It does show however the effect the input stage has on results such as these, It is quite likely the chip-amps themselves would perform better on there own, and come close to the other 2.

    One thing of note is the Rolloff at the bottom end - my monoblock is also rolling off at the same rate, which is disapointing. I belive it's an input cap issue. with the preamp.

    Conclusion:


    Despite the lower than Hoped power output capability, and not so good noise floor, this amp still represents good value for money. If you can get it at trade prices (OCAU group buy) it's brilliant value.

    If you require a remote control, and multiple inputs then it's hard to go past it in comparison to the DSE, as it still provides similar power output.

    If however you're a bit of an audiophile, and demand the best in low distortion, dynamics, and a super low noise floor.. probably not the amp for you. But in it's defence, you probably should be looking to save some more dosh, or make some comprimises in features and go a DIY route.

    Those hoping this amp would provide an effortless 100watt RMS/channel may be disapointed.


    Pros: Great sound Quality for the $, heaps of inputs, Remote.
    Cons: noise-floor, Doesn't quite meet power claims, volume control step size a little large.


    Overall: 4/5 from me :)
     
    Last edited: Jul 9, 2006
  3. Greg Erskine

    Greg Erskine Member

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    Thanks mAJORD, excellent work. :) I do appreciate your efforts.

    BTW: I have a DSE A2760 here and maybe we could swap for your P101. :D I've been meaning to build one to keep my P3A company.
     
  4. ChaoticBob

    ChaoticBob Member

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    What's the headphone jack like, i'm not expecting anything amazing, but is it reasonably clean and listenable? This and no remote are the main reasons I'm hesitant about a dse amp. So i'd be interested in your experience.
     
  5. Goth

    Goth Grumpy Member

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    Now this is my idea of an amplifier review. With audio hardware, you can't really be sure what you're getting without a screwdriver, and decent testing of distortion and power output. Nice work.
     
  6. OP
    OP
    mAJORD

    mAJORD Member

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    NP Greg.

    Chaotic Bob: Unfortunatly I have no decent headphones, so I kind of overlooked the headphone output.

    I have now checked them with what I have, and whilst I can't determin how good the SQ is (no obvious degredation) there IS still some backround noise from the preamp, just like at the speaker outputs.

    Again, This may or may not bother you depending on your expectations. :cool:

    Others who have the amp now may have good headphones, and good comparions to make there.
     
  7. ChaoticBob

    ChaoticBob Member

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    that's alright, thanks anyway for the great review
     
  8. <pRo>ToSs

    <pRo>ToSs Member

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    at the end of the day majord, is it that much better than the DSE, if you dont look at the extra inputs and remote? I'm realli having a hard time deciding between the two, and the Jaycar is $100 more exxy i think.... cant make up my friggin mind :(
     
  9. OP
    OP
    mAJORD

    mAJORD Member

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    Well at no point would I say it's 'better' than the DSE amp, you'd need someone with both to do a direct comparison.

    If anything it's slightly less powerfull and refined sound quality wise than the DSE amp, so It's key advantage is features.

    If you need multiple inputs, and a full function remote, it's an obvious choice IMO.


    At full retail price, the choice is harder as the DSE amp is so much cheaper now.
     
  10. <pRo>ToSs

    <pRo>ToSs Member

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    sweet.. spanks majord.. u rock

    Edit:- top notch review mAjord. Major respect from me. :D
     
    Last edited: Aug 10, 2006
  11. silenthunter

    silenthunter Member

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    mAJORD, if someone could lend you a DSE amp could you do a comparison?
     
  12. OP
    OP
    mAJORD

    mAJORD Member

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    yeah, fine with me.

    Happy to do vis versa if no one wants to though :)

    Be interesting to run something like an RMAA test on both as a comparo too.
     
  13. Freedom_

    Freedom_ Member

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    I guess this doesn't have S/PDIF in/out. If it did, I'd be interested in buying one....
     
  14. L0che

    L0che Member

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    Thats was a great review. Amazing detail. You should do them more often. :D
     
  15. richan3185

    richan3185 Member

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    There was some testing done of the DSE Amp (i think its in teh phat thread) but nothing of this kinda of caliber.
     
  16. Grimace22

    Grimace22 Member

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    you deserve a sticky for your efforts:) you definetley take the saying "If a jobs worth doing its worth doing right" by heart. Nice work:p
     
  17. Ulan

    Ulan Member

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    Top notch review.. extremely thorough and with lots of usefull info.. thanks and I hope to read a review of more amps in the future from you, as i'm now in the market for a new amp since the right channel died on my NAD :(
     
  18. kieran

    kieran Member

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    A group buy is good suggestion for a cheap & dirty amp. If it could be had for $150++ it would be a sweet deal. Jaycar have it for $158.95 for 10+ orders, $179 for 4-9, or $199 for 1.
    My old marantz is at the point where it could be replaced. Its not a home theatre amp, and that is not its role - its for my xbox and ipod to play party tunes more than anything. This is the sort of amp that can sit out in the shed to keep me grooving while I brew. :)
     
  19. OP
    OP
    mAJORD

    mAJORD Member

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    Thanks for the CC all, first review so I didn't know if it was a bit long.

    Kieran:

    Bryn has allready run one group buy. but has kindly offered to run another if theres enough numbers, so register interest here:


    Group Buy: http://forums.overclockers.com.au/showthread.php?t=483020&page=5


    Freedom_ : no S/PDIF unfortunatly. I am curious though as to why you need it for only 2 channels?
     
  20. Dr feelgood

    Dr feelgood Member

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    Nice review, its good to hear how people evaluate audio gear.
    Some quick Q's:

    do you think lifting the level of the inputs (using a small pre-amp) will help remove the noise input stage? I ask because most cheap P.A amps have very noisy pre-amps and simply putting a little higher signal into them and turning the pre-amp control down (essentially making it redundant and act more like a buffer) drops the noise quite considerably.

    Whats the max. I/p voltage of your CRO? I was thinking of getting a new one but so far the range I can afford only allows 30v p/p?

    Cheers.
     

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