Re: HD 990
If I were to do a simple mod, yes it would be changing the OP275 for maybe a AD825 (my fav) they are singles so you would need 2 single to dual Browndog adapter board.
I was excited, until I picked it up, it was very light, I imdeatlty thought no they didn't!!!!! And yes they did, a dirty skinking rotten smp power supply and it's nearly double the price, they lost the beautiful Sony R-Core trany and nice power supplies and subsituted SMP junk.
I sent it straight back.
All it really has over the HD970 is quad diff dacs still the AD1955 just two of them, a little better SNR and DR figures that's all
Cheers George
banause said:
If I were to do a simple mod, yes it would be changing the OP275 for maybe a AD825 (my fav) they are singles so you would need 2 single to dual Browndog adapter board.
I had the HD990 here last month the first on into the country andJavin5 said:
I was excited, until I picked it up, it was very light, I imdeatlty thought no they didn't!!!!! And yes they did, a dirty skinking rotten smp power supply and it's nearly double the price, they lost the beautiful Sony R-Core trany and nice power supplies and subsituted SMP junk.
I sent it straight back.
All it really has over the HD970 is quad diff dacs still the AD1955 just two of them, a little better SNR and DR figures that's all
Cheers George
HD 990 / HD 980
Thanks for the info. Too bad, for their top of the line model. On the other hand, you can't always say that something is bad because it uses an SMPS, not all SMPS's are created equal. I also think, you will see them more and more in new products. Appearently, HK has obtained a good SNR, despite the SMPS.
(a) Any thoughts or experience with the HD 980?
(b) I still have a HD 760. Have you ever seen this model and any thoughts on modding? Would this even be worthwhile? It has the PMD100 chip, which should be quite good. Not a very common player, it was only sold for a short time, as far as I know. I bought it at the time because it can decode HDCD. Most of the newer players don't support this anymore.
Kurt
Thanks for the info. Too bad, for their top of the line model. On the other hand, you can't always say that something is bad because it uses an SMPS, not all SMPS's are created equal. I also think, you will see them more and more in new products. Appearently, HK has obtained a good SNR, despite the SMPS.
(a) Any thoughts or experience with the HD 980?
(b) I still have a HD 760. Have you ever seen this model and any thoughts on modding? Would this even be worthwhile? It has the PMD100 chip, which should be quite good. Not a very common player, it was only sold for a short time, as far as I know. I bought it at the time because it can decode HDCD. Most of the newer players don't support this anymore.
Kurt
Re: Re: HD 990
Hey Georgie Baby
Missed you Sunday 2 weeks ago when we had that blind amp shoot-out, it was a hoot. Was sitting next to Larry and said I missed you because it would have made it easier to do my score sheet, just look at yours and then reverse it. That got a laugh, but a good natured one. I just had trouble taking it seriously. The lower grade AKSA won and some modded DS (you know what DS stands for, right?, as is DSE) got second. Or was it the other way round? Think the Gryphon got last or second last, that was a bit of a shocker to all, I'd think. By the way, the Gryphon designer stole my brother's name: Flemming Rasmussen. Kid you not!
I've got somebody sending me up a 990 from Melbourne, might even get here this week. The smp worries me less than it does you, but I don't think it will be better than 970.
Re changing opamp, I know not all will agree, but I'd go for LM4562 (it's available from a company in Rhodes). I used one in a player as I/V converter and was impressed (it was a Rotel RD-990 - well worth finding cheap), even if that kind of opamp thing is not my cup of tea, but that was what he could afford.
But what should be tried on 970/990 is hot-wiring to a separate RCA sockets, via a coupling cap, straight of one side of the I/V converter. There may be some DC there, hence the cap. That is what I did with the LM4562/Rotel. For what was involved, it was terrific in $ terms. You may get a little less than 2V RMS out, but in this case I got near 1.8V - no probs.
That and Terra Firma, and you have a lower cost route.
For those who read this and don't know what Terra Firma is:
customanalogue.com/terra_firma.htm
www.audioasylum.com/audio/digital/messages/14/142994.html
Joe R.
georgehifi said:
Hey Georgie Baby
Missed you Sunday 2 weeks ago when we had that blind amp shoot-out, it was a hoot. Was sitting next to Larry and said I missed you because it would have made it easier to do my score sheet, just look at yours and then reverse it. That got a laugh, but a good natured one. I just had trouble taking it seriously. The lower grade AKSA won and some modded DS (you know what DS stands for, right?, as is DSE) got second. Or was it the other way round? Think the Gryphon got last or second last, that was a bit of a shocker to all, I'd think. By the way, the Gryphon designer stole my brother's name: Flemming Rasmussen. Kid you not!
I've got somebody sending me up a 990 from Melbourne, might even get here this week. The smp worries me less than it does you, but I don't think it will be better than 970.
Re changing opamp, I know not all will agree, but I'd go for LM4562 (it's available from a company in Rhodes). I used one in a player as I/V converter and was impressed (it was a Rotel RD-990 - well worth finding cheap), even if that kind of opamp thing is not my cup of tea, but that was what he could afford.
But what should be tried on 970/990 is hot-wiring to a separate RCA sockets, via a coupling cap, straight of one side of the I/V converter. There may be some DC there, hence the cap. That is what I did with the LM4562/Rotel. For what was involved, it was terrific in $ terms. You may get a little less than 2V RMS out, but in this case I got near 1.8V - no probs.
That and Terra Firma, and you have a lower cost route.
For those who read this and don't know what Terra Firma is:
customanalogue.com/terra_firma.htm
www.audioasylum.com/audio/digital/messages/14/142994.html
Joe R.
The HD990 had the sound that typifies to my ear the sound of SMP, which was a thinner lifeless sound, good still in dynamics but in a squeezed and shot out of your speakers kind of way. The HD970 flowed out, sounding larger and more effortless.
In my opinion SMP's have no place in source equiptment yet. The only place they have been done properly that I've seen are in the massive Halcro DM88 power amps, at that end of the of the chain it's ok, but keep the dirty radiating stuff out of source equipment until they can better it.
Harman only used it to save money, it cost one third the price to manufacture the HD990's smp power supply than it did the HD970's R-core linear supply, yet the price has almost doubled, go figure.
They are just resting on the good name and publicty the HD970 got and decided to clean up on the HD990.
.
Cheers George
In my opinion SMP's have no place in source equiptment yet. The only place they have been done properly that I've seen are in the massive Halcro DM88 power amps, at that end of the of the chain it's ok, but keep the dirty radiating stuff out of source equipment until they can better it.
Harman only used it to save money, it cost one third the price to manufacture the HD990's smp power supply than it did the HD970's R-core linear supply, yet the price has almost doubled, go figure.
They are just resting on the good name and publicty the HD970 got and decided to clean up on the HD990.
.
Cheers George
Re: Terra Firma?
Hi Marc
Yes, it's a low cost solution IF you are stuck with opamps. Re Terra Firma, contact Vacuum State just or the border to Switzerland in Schaffhausen. This is their web site:
www.vacuumstate.com call them or email them. Ask Vacuum State for Terra Firma "Lite". Prices are here:
vacuumstate.com/fileupload/NewsletterFeb_2009_1.pdf
You can buy and it fit yourself, but if they do it, they can do the other suggestions I've made as well and it will benefit from a "program" that I can direct them to do.
TF is about reducing the worst kind of jitter - so it takes the form of a powered clock module a la LC Audio, SuperClock and all those others available. But TF goes way beyond what they do by giving the clocking extreme stability that is unmatched by our competitors. The proof is in the listening - it makes digital sound much less digital or more like analogue.
They could also, with my direction, fit LM4562 and extra RCA Sockets on the back panel, wiring directly to the LM4562 used as I/V converter. Based on the Rotel I did, I can be confortable in saying that the player you'll get back will be stunnnnn-ningly better in every respect. I have to say, the LM4562 is the opamp I want when I don't want an opamp but must still use one. A variation of what we down here call a "Clayton's".
An example of a Clayton's: "The mistakes we make are genuine, otherwise we wouldn't be making them." Comprehendo?
Cheers.
Joe R.
banause said:
Hi Marc
Yes, it's a low cost solution IF you are stuck with opamps. Re Terra Firma, contact Vacuum State just or the border to Switzerland in Schaffhausen. This is their web site:
www.vacuumstate.com call them or email them. Ask Vacuum State for Terra Firma "Lite". Prices are here:
vacuumstate.com/fileupload/NewsletterFeb_2009_1.pdf
You can buy and it fit yourself, but if they do it, they can do the other suggestions I've made as well and it will benefit from a "program" that I can direct them to do.
TF is about reducing the worst kind of jitter - so it takes the form of a powered clock module a la LC Audio, SuperClock and all those others available. But TF goes way beyond what they do by giving the clocking extreme stability that is unmatched by our competitors. The proof is in the listening - it makes digital sound much less digital or more like analogue.
They could also, with my direction, fit LM4562 and extra RCA Sockets on the back panel, wiring directly to the LM4562 used as I/V converter. Based on the Rotel I did, I can be confortable in saying that the player you'll get back will be stunnnnn-ningly better in every respect. I have to say, the LM4562 is the opamp I want when I don't want an opamp but must still use one. A variation of what we down here call a "Clayton's".
An example of a Clayton's: "The mistakes we make are genuine, otherwise we wouldn't be making them." Comprehendo?
Cheers.
Joe R.
banause said:
Because it's safe and they had to meet RBCD standards that we DIY'ers don't. Also they are highly influenced by conservative engineering practice and not taught to think laterally. Just take almost a PDF file on any DAC chips (published by the DAC maker) and look at the recommended post DAC audio circuit, then compare that to what is used in low to middle (and often high) cost players and there is little difference. Only when you get to more expensive or special dedicated companies' models, will you start to see more innovative thinking. The stock 970 is actually a little better than usual. Not by much though.
I have seen no CD player using hot-rodded I/V converter outs. It cuts down on available filtering (and probably non-RBCD because of it), and is single ended (half the output is 'wasted') and they use a second stage to sum the two, so on paper is so-called "correct." But when was "correct" always "right." No flexible thinking and it doesn't occur that "right" might sound awfully better than "correct."
Finally, you have the role of the bean counters. Very few accountants are audiophiles. Stock engineering practice is cheap and requires no real concern for quality parts or innovative thinking. The most common IC used in post DAC audio is the "State of The Past" 5532 opamp designed in the 70's. Still used and today along with its Jap cousin 4558, are everywhere! Enuff said?
Joe R.
banause said:
It did'nt win the European Product of the year award for nothing, it's sound quality is superb, it's I/V is a OP275 (nice opamp) better than what most use (NE5532), but it can still be much better with a discrete direct coupled Transimpedance I/V stage that has true all most zero ohm input impedance, which is what the HK's AD1955 dac would dearly love to see.
The standard discrete class A Diamond Differential output stage is very good, and can be left alone.
The AD1955 is a current output dac if loaded correctly down to nearly zero ohms, it's output will be miniscule, hence the need for an active Transimpedance amp that has the low, zero input impedance yet can because being active still get the output back up again within it's self.
The only opamp version Transimpedance amp I know worth using is the AD844 (attached) note how the + & - inputs go to the emitters of the input transistors and not the bass, as most opamps, this is a true Transimpedance Opamp for I/V use, it is not a direct sub for the Harmans OP275 I/V quite a bit of surgery needed to get it going in there, that's why I preferred to go discrete Transimpdace for the I/V duties same amount of work but even better again.
Cheers George
Attachments
georgehifi said:
Right George, which is what I do too, but it's also about the cost. For your less affluent clients who can't afford the real McCoy, using LM4362 hot-rodded is them getting something that they would not otherwise get and also get you a job and both sides be happy. Quite willing to pass on the details to you and if you make use of it, good for you.
The LM4562 is anything but my preferred solution, but HUGELY better than OP275 which it directly replaces. Indeed you can even hot-rod OP275 now and that alone would be better than stock. Take the output from Pin 7 and feed to 3.3uF coupling cap, then series with 390R to new RCA socket centre pin. Across the RCA fit 2n2 cap. Finally a wire back from RCA ground to suitable player ground, close to opamp. Do to both channels, both new RCA sockets that must not be grounded to the case, use insulators that usually comes with the sockets. The original outputs will work as before but sound nowhere near as good. The new outputs might be a bit down in volume level, but not too severely. But use LM4562 as a job worth doing is worth doing well. Not as good as the expensive solution, but great nevetheless, and this is from an anti-opamp preacher.
Cheers.
Joe R.
This is taken directly from the AD1955 data sheet, these guys know, they designed it. I have tried it and they are right, it sounded distorted, it wants to see almost zero ohms load.
" Audio Outputs
Active I/V converters should be used, which will hold the DAC
outputs at a constant voltage level. Passive I/V conversion should
not be used, since the DAC performance will be seriously degraded."
Cheers George
" Audio Outputs
Active I/V converters should be used, which will hold the DAC
outputs at a constant voltage level. Passive I/V conversion should
not be used, since the DAC performance will be seriously degraded."
Cheers George
georgehifi said:
I take that with a grain of salt. Passive does work, but it must be as low Z as an imperfect virtual earth (a perfect one would be zero ohms, but I have not seen one and they don't exist in my book), this means sub 10 Ohm balanced (5 Ohm or less per side).
The trick is two-fold, it must 'float' unlike normal Passive (which will probably destroy the chip - seen that happen) and bleed off the DC current to + rail.
Then the actual AC load should be say 6 Ohm (2 x 3R), the signal then is very tiny and need to use extremely low noise gain a la what you would need for a Moving Coil cartridge (turntable) to get
up to 2V RMS. This actually does work and I know somebody who does just that to good effect. I would think it would work OK in the 970 using a discrete phono stage sans the RIAA EQ components. Now, how is that for an idea - use your favourite phono stage for your CD player. That'd be lateral thinking and some.
Joe R.
HD 980
Since the HD 970 may not be available much longer, I think that the current HD 980 may be of some interest to the modders here. Small reviews appeared recently in the german magazines STEREO and AUDIO, I hope this info is useful. Here is what they had to say:
- The HD 980 converts the CD-signal to 24/176.4.
- The DAC is a Wolfson 8740, not an AD1955.
- Uses a 32 Bit DSP. Probably the same Blackfin DSP with the Anagram technology?
- Excellent error correction (i.e. it can read damaged CDs better than most).
- Jitter is 165 ps.
- AUDIO thinks that the sound is even more precise than with the HD 970 (whatever that means).
- STEREO thinks that the sound is almost on par with the Cambridge Azur 640C V2.
- The HD 980 has also an SMPS, as georgehifi found in its more expensive brother, the HD 990.
- From the picture, it appears that there is plenty of space to replace the SMPS with a linear supply. The SMPS is on its own board with a single flat cable to the main board.
I have not seen a review of the HD 990 yet..
Kurt
Since the HD 970 may not be available much longer, I think that the current HD 980 may be of some interest to the modders here. Small reviews appeared recently in the german magazines STEREO and AUDIO, I hope this info is useful. Here is what they had to say:
- The HD 980 converts the CD-signal to 24/176.4.
- The DAC is a Wolfson 8740, not an AD1955.
- Uses a 32 Bit DSP. Probably the same Blackfin DSP with the Anagram technology?
- Excellent error correction (i.e. it can read damaged CDs better than most).
- Jitter is 165 ps.
- AUDIO thinks that the sound is even more precise than with the HD 970 (whatever that means).
- STEREO thinks that the sound is almost on par with the Cambridge Azur 640C V2.
- The HD 980 has also an SMPS, as georgehifi found in its more expensive brother, the HD 990.
- From the picture, it appears that there is plenty of space to replace the SMPS with a linear supply. The SMPS is on its own board with a single flat cable to the main board.
I have not seen a review of the HD 990 yet..
Kurt
Re: HD 980
Too many different voltages, it would be a hard task. J
Just get a new or second hand 970 it sounds better than the 980 and has more potential for modding than the 990.
I had the 990 for a while before sending it back, and it is a sad step backwards in sound quality compared to the 970 and almost double the price and "half the weight".
Cheers George
Javin5 said:
Too many different voltages, it would be a hard task. J
Just get a new or second hand 970 it sounds better than the 980 and has more potential for modding than the 990.
I had the 990 for a while before sending it back, and it is a sad step backwards in sound quality compared to the 970 and almost double the price and "half the weight".
Cheers George
Javin5 said:
Don' worry. I wouln't use what manufaturers do as a good yard stick for what is good or bad.
Two answers to your question. Rebuilt hundreds of players and never had muting problems - just make sure your Volume Control is down (or anything that stops the sound to get to the speakers) when turning the player's power on and off.
If you disable the old outputs (there is usually 100-470 Ohm resistor) before it gets to the muting, just connected the new outputs to the muting point, and voila! I do this to the HKs I've done.
But really, don't need it that much. BTW, there are some who would argue that solid state muting can introduce non-linear effects and also that mechanical relays shorting to ground is the way to go.
But I repeat, muting is not absolutely necessary in 95% of players, you don't get much noise or clicks, if any at all. Trust me! Otherwise I would have been inundated with complaints.
BTW, the huge majority of DIY NOSDACs out there, they don't have muting because, if memory serves me correctly, the muting function is usually in the Digital Oversampling Filter, which they have deliberately omitted. I have built about a dozen of them and there is no option to include Muting. They work just fine.
Joe R.
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