aparatusonitus said:Hi George,
Have you managed to get HD980/990 service manuals....I've tried the to download from HK site using all combinations I can think off, but no cigar.
Yeah you need a password to enter the file site.
Sorry, I was promised one if I kept the HD990 they gave me to play with, I wouldn't feel right to ask for one now that I've given it back to them.
Cheers George
Joe Rasmussen said:
This new HD990 is a grab for money by Harman after the success and good reputation of the HD970.
It's almost double the price. Doesn't sound as good, and even with those mods, you still have the dac, filter, input receiver & transport all still running on the filthy dirty SMPS. Instead of very well regulated/smoothed linear supplies, fed by a lovely Sony R-Core transformer which they (Harman) prided themselves in that they could use such an expensive trany in a budget machine as the HD970
It is not worth the money to buy, or the time and money to mod. Bring back the HD970 as it was!!!
Cheers George
georgehifi said:
George, most of the filthy and worst noise actually come from the "dac, filter..." etc, and not from the smps. But I know I won't budge you no matter what arguments I put forward. I don't regard "smps" as a four-letter-word, linear power supplies are not without fault as well and also produce "filty" noise of one or many sorts. Current surges and depletion into reservoir caps are not exactly an ideal world, translating AC into DC will always be a dirty business. Just a different set of compromises.
BTW, the 990 actually sounds quite good and maybe just a little better due to separate twin Dacs per channel. Is it worth more money, probably not, but the 970 is gone and the 990 is here.
Joe R.
This is NOT value.
There are others you just have to look. This is over priced crap (four letter word), and I'm not afraid to say it.
And with your mods over $2,000.00 if your true to the same price for the same mods on the HD970.
It was direct coupled from dac to output standard, now it is capacitor coupled, where's the value in that.
Cheers George
There are others you just have to look. This is over priced crap (four letter word), and I'm not afraid to say it.
And with your mods over $2,000.00 if your true to the same price for the same mods on the HD970.
It was direct coupled from dac to output standard, now it is capacitor coupled, where's the value in that.
Cheers George
tvicol said:
I've been trying to find one too.
I did the work on the 990 here without service manual, but the post DAC circuit is based on the 970 for which the service manual is available. The clock circuit is capable driving 50 Ohm (ICS83905 chip) and cannot tell whether it takes advantage of that.
Joe R.
tvicol said:
If you want to use Tent clock with PS, then you will need to feed clock signal into ICS83905, remove Xtal and little caps as per usual. You can download the pdf file for ICS83905 at www.alldatasheet.com .
Joe R.
I got a HD970. My impression is that the unit sounds good, but not excellent. German HiFi magazines rate it somewhere in the midrange, if that means anything at all. Not sure if I should still wait with modding for the one year warranty to expire, but here are some questions anyway:
(a) Has anybody succeeded slaving the transport to the DAC-clock? How could this be achieved in this unit? This is really the way it should be done, it would get rid of the jitter generating PLL. A Tent clock could then really show its full potential.
(b) The analog output stage appears to be well designed, fully discrete class A. Georgehifi, you are changing that in your mods, what is wrong with the present design?
(c) A spectrum analysis with FFT reveals that the noise background shows some discrete lines and is not as clean as, e.g. the HD 760. I'm not sure what causes this. However, the digital and analog supplies are not as well separeted as I would wish. Maybe using an extra transformer for the analog supply, with better regulators, would clean this up. Unclear at this point if the R-core should then be used for the digital or for the analog supply.
(d) I'm also bothered that the unit cannot really be fully switched off; I don't need to be able to switch it on with the remote, pressing a key on the unit would be ok.
Any thoughts?
Kurt
(a) Has anybody succeeded slaving the transport to the DAC-clock? How could this be achieved in this unit? This is really the way it should be done, it would get rid of the jitter generating PLL. A Tent clock could then really show its full potential.
(b) The analog output stage appears to be well designed, fully discrete class A. Georgehifi, you are changing that in your mods, what is wrong with the present design?
(c) A spectrum analysis with FFT reveals that the noise background shows some discrete lines and is not as clean as, e.g. the HD 760. I'm not sure what causes this. However, the digital and analog supplies are not as well separeted as I would wish. Maybe using an extra transformer for the analog supply, with better regulators, would clean this up. Unclear at this point if the R-core should then be used for the digital or for the analog supply.
(d) I'm also bothered that the unit cannot really be fully switched off; I don't need to be able to switch it on with the remote, pressing a key on the unit would be ok.
Any thoughts?
Kurt
Javin5 said:
I go one better, solid state discrete single ended direct coupled class A for the output, and discrete direct coupled transimpeadance for the I/V, circuit attached.
But like I also said it is a very good output stage, and for a simple mod I would do just the I/V stage with my fav opamps the AD825's.
The standard XO clock is also very good, better than most, it will benifit from power supply improvements, a Tent XO 2.2 with it's own galvanicly isolated supply would be better.
Cheers George
PS: stay away from the HD990
Attachments
The 970 has a clock frequency 24.576MHz, this is integer related to 48Kz (512x), 96KHz (256x) and 192KHz (128x) - these are DVD frequencies.
On the other hand, the 990 is 22.5792MHz which is integer divisible to 44.1KHz (512x).
This is in both cases dedicated CD players. In the 970 some fancy sample rate conversion needs to take place that is 557.278911564626x , whereas in 990 it just 512x.
Do I need to elaborate?
BTW, the Harman Kardon HD990 will make an appearance this Sunday at Audiophile Society of NSW (ASoN) meeting, held at Haberfield (same building as the Library, ground floor) in Sydney, 3PM. All are welcome, not just members.
George, will you be there? Hope to see you.
Joe R.
On the other hand, the 990 is 22.5792MHz which is integer divisible to 44.1KHz (512x).
This is in both cases dedicated CD players. In the 970 some fancy sample rate conversion needs to take place that is 557.278911564626x , whereas in 990 it just 512x.
Do I need to elaborate?
BTW, the Harman Kardon HD990 will make an appearance this Sunday at Audiophile Society of NSW (ASoN) meeting, held at Haberfield (same building as the Library, ground floor) in Sydney, 3PM. All are welcome, not just members.
George, will you be there? Hope to see you.
Joe R.
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