Harmon Kardon HD-970 modded, a world beater?

[georgehifi]

Originally posted by dw8083
I wish the HD990 played SACD's. -David

For those who want to know David and I both have the hard to get rare as hens teeth Analog Devices AD-1955 Evaluation Reference Board which also sounds very good and can do many different things, with the switch of the many onboard dips, it can even input sacd, it's just that David and I need a transport that plays and outputs sacd, attached are just some of the options it can do.
To view right click and "save as" to your desktop

http://www.diyaudio.com/forums/attac...amp=1192777835

Cheers George

[Tolu]

Hi George

any news on the HD 980 and HD 990. The HD 990 seems to have a discrete output stage.

[georgehifi]

Yes they have dual dif AD1955 in this one, as for the I/V and output stage, still no answer, Harman said they will send a service manual to me as soon as they get them, but it will come with the delivery of the HD990, and that is to be at the end of the year.

Cheers George

[georgehifi]

Wait a minute they are already dual dif, I should have said quad dif, which will make life interesting for the Transimpedance amp hook up.

[Tolu]

Please keep me informed about further developments. I think I'll buy one and test is out-of-the-box. They are already available in Germany. But you have to use a magnifier to find one.

[georgehifi]

Yes in Europe, never in USA. just like the HD970 (unfortunately not available any more anyway), I think it has something to do with the R-Core transformer they use, maybe no 120v version available? Which is strange because is Harman not an American company?
Anyway here is a link to do some reading on the HD990.
http://www.convoy.com.au/harmankardo...nts/HD990.aspx

Cheers George

[Tolu]

HD 970: How many do you need for about 250€?

How much cost your mod?

[georgehifi]

I do two mods, depending on use, (stand alone player) which most of my customers get or (D/A convertor use only)
The stand alone player get both mods which are $600aud each.
1: Transimpedance, discrete, direct coupled, I/V amp, a discrete direct coupled (with dc servo) class A single ended output amp, these are powered by shunt regulated power supply and additional toroidal transformer, the Harmans R-Core is then utilized only for the digital and transport section.
2: A Tentlabs XO2.2 clock circuit module and XO Galvanic isolated power supply and low leakage mains transformer.

Then if you plan to use the Harman as a Dac only with your own transport, then stage 1 of the above is done, stage 2 can also benifit because it is a better clock for the D/A section as well.

We found that when both mods are done to the Harman no matter how good an external transport was it could not better using the Harman as a stand alone unit even thou the Harmans transport/laser is nothing to write home about a (Sanyo SF-HD65 mech and laser)

Cheers George

[sq225917]

quad diff, 1955, AD black fin, sounds like the inside of the Cambridge audio 840c to me...

Could Harman be licensing ip from Anagram Technologies?

[georgehifi]

Originally posted by sq225917
quad diff, 1955, AD black fin, sounds like the inside of the Cambridge audio 840c to me...

Could Harman be licensing ip from Anagram Technologies?

Funny you should mention the Cambridge 840c, we compared the modded Harman to it, and it made the Cambridge sound like it was dynamically challenged, the Harman walked all over it (these are the Transimpdance Amps strengths). I had no idea that it used quad AD1955's, they obviously did not pay too much attention to the rest of it.
And yes I remember when the Harman won the best Euro product award in 2005 there was mention of the Anagram similarities in the blurb.

Cheers George