diyAudio (
-   Digital Source (
-   -   Harmon Kardon HD-970 modded, a world beater? (

Nigel Page 2nd June 2008 04:08 AM

Harmon Kardon HD-970 modded, a world beater?
I am definitely not a tech when it comes to hifi systems my paramount interest being my desire to hear the music as it was originally created. How this is accomplished is not of great interest .
When I was recently looking to upgrade my DAC within my system I had an extraordinary stroke of luck for after looking at a range of off the shelf medium priced DACS's, I was gven the name of George Stantscheff and was told what he could do with a Harmon Kardon HD-970.
I my youth Harmon Kardon was considered OK but in recent times with the way things have gone with of so many of the big names it didn't even come on the radar. Well at below $600 how could it rate with the $2000 to $3000 units I was looking at.
Well after a few more enquiries I purchased on and sent it to George for his initial modification comprising the discrete transimpedace amps and their shunt regulated power supply and toroidal transformer.
Well after receiving the modded unit the difference is STUNNING.
This unit compares with units I have heard way beyond my price range and far beyond my affordability.
You name it has it - it is open, transparent, full bodied. It has all the attributes for me to be able to say that IT IS THE NEAREST SOUND I HAVE EVER HEARD TO THE REAL THING. I was surprised at the unmodded HK in that it was better than I expected and obviously has a basic quality but with the mods it is something else.
Unfortunately the second phase of mods with the Tentlabs clock
coming from Europe, with the thing called ROHS means that as yet this cannot go ahead. Having said that I am so pleased with the first stage of the mods that it is not a problem to live with it as it is - not by any measure. Everbody out there revere this chap called George - he has given me what I thought I would never achieve within any system I could ever afford
For all those techs out there George explains what he does at

georgehifi 3rd June 2008 10:38 AM

Hi Nigel, glad to see that it's is doing the same for you as other owners have expressed to me, and what I also feel is it's strengths, thank you for your kind words.

I have to elaborate on what you said a little. in that it is not just the discrete I/V direct coupled Transimpedance Amp that is making the differences that your hearing, but also a discrete direct coupled Single Ended transistor Class A amp on the output after the Transimpedance Amp that's helping things along a little. As well as a massive Shunt Regulated power supply to power both these amplification stages.
In all the standard HD-970 used to consume around 12watts, now with these mods it's more like 40watts, not what you would call a "Green Machine" but then the majority of products I have always had a liking for have always consumed more power than their green "Switch Moded/Class D amped" cousins. Which I have never been able to get excited about.

And it looks like the new batch of Tentlabs clocks are just around the corner if you look at the web site, I sent an email off to Guido for an update on availability, no doubt I'll get a reply later than sooner, "Guido Time" you see, I'll let you know when he's all back in production again.

Cheers George

Audionutz 8th June 2008 09:04 AM

Noted this subject when it came up on one of my "Googles" and thought I'd add my 2 cents worth. As a relatively long time user of the "George Modded" HD 970 (12 months plus - which is a lifetime in my system !), I feel I can fairly comment on the strengths of this unit. Also, as those who know me will attest, I'm in the enviable position of having a constant stream of hi-end gear through my system as it comes in for sale or trade. Whilst this does not necessarily qualify me more highly than anyone else (No Golden Ears here), it does allow me to compare a lot of different gear.

The Harmon was originally recommended by George, following my ownership of his previous benchmark DAC - a highly modded Musical Fidelity A3.24. I had been extremely happy with the MF and saw absolutely no reason to change it. It had great synergy with both my standard Teac VRDS 10SE and also my Forsell Air Reference CDT. However, George convinced me to try the Harmon and whilst not keen to let the MF go, I agreed to find a standard unit and get him to mod it. I did at first try it in it's unmodified form and while I thought it was good for what it was, it was still far below the MF unit. I kept the MF meanwhile as George modded the Harmon, so when finished I had the chance to A-B them both.

The difference was not subtle. Where the MF had been supremely competent in bass weight and definition, the Harmon absolutely slaughtered it in every other area and was its equal in the bass department. What I immediately discovered with the Harmon was its ability to show up any weaknesses in the audio chain (A bit like George’s Lightspeed Attenuator in that regard). I found myself going through my Digital Cable collection and making comparisons between them. Small changes in isolation, speaker cables and positioning were far more audible with the Harmon than before. Amp and Transport changes were immediately apparent, with the Harmon allowing the correct character of each component to shine through unhindered.

In case you read this and think that the Harmon is purely an analytical, unmusical tool, well nothing could be further from the truth. When your system is right and "on song", the Harman just gets out of the way of the music and presents what’s there - purely and simply without exaggeration or coloring. If it has one feature or characteristic that stands out, I would say that its the snap and impact of the leading edge of transient sounds. Something that usually comes in with a bang, now comes in like a whip crack on steroids. I suspect that it's a combination of the HD's ability to present the space and "blackness" between notes, followed by its percussive accuracy. This combination has startled me on more than one occasion, even on well known tracks.

Now, before someone asks, or insinuates, "he must be related to George" or "he must have received a freebee" - I can assure you I paid the same as anyone else and consider it an absolute no-brainer of an Audiophile Bargain. Period.

Is it perfect - no, but then what component is ? Will it improve your system - yes, but make sure that improvement is what you want. Having this kind of accuracy and transparency in your system is a real double-edged sword. It makes you lift your game in almost every other area of your setup as well - something not everyone wants to undertake.

Put it this way, if George wanted to make a lot of money from this unit in its modified form, it'd be quite easy. A thick milled aluminum fascia, some dark Perspex and a bit of "bling" here and there. Add about 20kg extra weight and you'd have a $10,000 CD/DAC Combo - easy. A buyer would never know that it had started out as a lowly Harmon Kardon HD970 and the sound would never give away the secret !

I'm just waiting 'till these blasted clocks get here and I can get one installed in mine - 'cmon George, where are they !

stoolpigeon 8th June 2008 09:43 AM

2 Dorothy Dixers - should this be in Market Place?


Audionutz 8th June 2008 10:11 AM

A "Dorothy Dixer"? ... sorry but your masterful grasp of the English language has put your meaning beyond us mere mortals - can't undestand if this is a compliment or an insult ?

Joe Rasmussen 31st August 2008 11:39 PM

Hey Georgie Baby

Were you there when they kicked us out early yesterday?

But that is not what this post is about.

The new replacement HD-990 was supposed to have Wolfson DACs, right? Not so sure anymore.



Twin AD1955:

This also says it uses AD Blackfin DSP - and likely will then also use the same AKM receiver chipset as it also states it's got digital input - stand-alone DAC. So the 990 may yet turn out to be son of 970 after all and seems to double up on AD1955?

Anybody else been able to find anything that shines some more light on this?

Now if we could get our hands on a service manual...?

Joe R.

georgehifi 31st August 2008 11:45 PM

The 980 has Wolfson dac, but the new 990 will have twin AD1955 dacs in dual dif mode, but the cost is going to be nearly $900aud!! Already have the first one on order but the cost is too big.

hifimaker 1st September 2008 12:01 AM

I wish the HD990 played SACD's. -David

Joe Rasmussen 1st September 2008 03:22 AM


Originally posted by georgehifi
The 980 has Wolfson dac, but the new 990 will have twin AD1955 dacs in dual dif mode, but the cost is going to be nearly $900aud!! Already have the first one on order but the cost is too big.

Hi George

Yeah, I just received an email that pointed out much the same. But try the 980 with a passive output stage, should give 1V RMS with a bit of luck. Then do the other bits as well. It should sound quite nice indeed, maybe not to the same degree, but also without the cost of Lars' module.

Hmm... maybe 1V RMS not enough with the Lightspeed? Maybe time to get a real preamp? :D

Or up the gain of whatever power amp you use. That works for me.


Joe R.

PS: The 980 won't have the AD Blackfin DSP or AKM receiver chipset - I suspect. That will also help account for the price difference other than choice of DAC chip.

infinia 1st September 2008 03:58 AM


Originally posted by Audionutz
A "Dorothy Dixer"? ... sorry but your masterful grasp of the English language has put your meaning beyond us mere mortals - can't undestand if this is a compliment or an insult ?

Dorothy Dixer, a widely-used phrase in Australia meaning a question from the floor that enables the speaker to make or strengthen a point he wanted to get across.

All times are GMT. The time now is 09:21 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 18.75%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio