2006 vintage upgrade?
Printed From: Graham Slee Hifi System Components
Category: Headphone Audio
Forum Name: Graham Slee Headphone Amps
Forum Description: Questions, answers and product information zone for Graham Slee Headphone Amplifiers
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=398
Printed Date: 27 Mar 2026 at 2:11am
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Topic: 2006 vintage upgrade?
Posted By: jamescodway
Subject: 2006 vintage upgrade?
Date Posted: 06 Mar 2009 at 10:32pm
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Graham,
I seem to remember some mention... somewhere... maybe... of an option to have one's 2008-purchased unit (September 2006 vintage) upgraded to latest SRG spectacular specification. I (currently) have insufficient skill to risk the likely fatal damage from an attempted DIY mod... is it feasible and/or vaguely economic to return my unit for an upgrade? I already have a PSU 1. Doesn't it have to be worth at least a good % of the price of a new Novo... ? Kind regards, James |
Replies:
Posted By: mrarroyo
Date Posted: 07 Mar 2009 at 1:20am
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James, I can not speak for Graham but I will go out on a limb and say the it would not be cost effective if the mods are extensive. This because you would have to go into an amp that is a couple of years old and remove components. Then in some cases there might be jumpers and cutting of pcb traces. Lastly if extremely complex there would be components for which holes may have to be drilled into the board.
The only way this could be cost effective is if the individual user does the mod. Otherwise Graham and his staff may spend more time on the older unit than starting from scratch. I would sell the unit you have and buy a new one, you most likely will come out ahead. ------------- Miguel |
Posted By: jamescodway
Date Posted: 10 Mar 2009 at 9:17am
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Miguel,
given 'radio silence' from Yorkshire on the subject... thank you for your very specific comments and suggestion. 
Best wishes James |
Posted By: Graham Slee
Date Posted: 10 Mar 2009 at 10:44am
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We are doing the DIY (as well as factory fit) SRG upgrade for all 2004 onward silver case Solo's. It's just that it's been a bit difficult getting everything done lately thanks to our feckless Prime Minister pouring derision on the UK economy and all who try to sail in "her"... But the http://www.diy-audio-kits.com - www.diy-audio-kits.com website is online and developing nicely, and IT WILL FEATURE THE SOLO SRG UPGRADE KIT shortly. It will also give details on how to get your post 2004 Solo factory upgraded to SRG status. If you give it a few days more you will see it all at the above website. Thanks, Graham ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: jamescodway
Date Posted: 10 Mar 2009 at 2:26pm
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Excellent!
Thank you
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Posted By: faudrei
Date Posted: 24 May 2009 at 10:01pm
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Since the "Upgrade to SRG" posts are linking here - guess I'll have to revive this thread. By reading the reviews from fortunate users that have had the opportunity to compare "Green" (or other, pre-2008) and the latest SRG Solos I also have decided to upgrade my "Racing Green #69" to SRG. That is - once the upgrade kit will be available. So - an cortious "ping" to Graham on the "Upgrade to SRG kit" subject. ...and I would also kindly ask him a couple of questions:
------------- V3 |
Posted By: Charley Phogg
Date Posted: 25 May 2009 at 2:37am
Hi faudrei, I asked Graham about this in a pm when I first got my Green. Here is his reply. "I'd throw the question of gain open to the members. ..... the gain is 6 into a high impedance, falling to 3 into 30 Ohms phones (due to some output resistance dividing the output signal). Such load dependent gain variations being essential for flexibility in use. I tried to optimize it so that with most sources and headphones the "right" volume is selected between 9 and 3 settings. I treat the volume control differently to that of a power amp - instead of it being optimally parked somewhere between 9 and 11, the Solo's volume control positioning is much more flexible, and within the 9 and 3 positions will still give the same SQ. Because the volume control also acts as gain control in this sense, the amp always has plenty of headroom." You may quote me on the above, make suggestions or question me on it in the community sections - no problem. All of this is good feedback and it is gratefully received and often acted upon." Keep in mind that is in regard to the "Green" dated on feb 24th 2008 |
faudrei wrote:Posted By: faudrei
Date Posted: 25 May 2009 at 11:20am
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Thanks Charley, In fact, the things Graham stated are true - when I connect iPod as a source the volume is "usable" in "9 to 3" area. The problem arises when I connect, f.e., Paradisea + DAC which has "higher than iPod" output levels. ...the thing is - I somehow prefer Solo, Paradisea +, hagUSB and ThinkPad as my headphone listening source, and would therefore like, if possible, to lower Solo's gain. Regards, ------------- V3 |
Posted By: jamescodway
Date Posted: 25 May 2009 at 11:37am
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With due respect to our supportive friends at Audio Elevation, I find the Rothwell attenuators address the problem with no audible (to my cloth ears) loss of quality.
http://www.audioelevation.co.uk/CartV3/Details_options.asp?ProductID=97 - http://www.audioelevation.co.uk/CartV3/Details_options.asp?ProductID=97
I even use them to attenuate ipod line out signal to get a real 9-3 useable range (depending on mastering level). To my ears, 11-1 o'clock has more 'power/control' than 9 o'clock - esp. w/closed back HD25/HD250.
Anyone say 'placebo'?... pah !!
 Regards,
James ------------- Voyager - HD25 |
Posted By: mrarroyo
Date Posted: 25 May 2009 at 1:21pm
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You could also contact the manufacturer of the Paradisea to find out if you could replace the OPA2604 w/ a lower gain op-amp. ------------- Miguel |
Posted By: faudrei
Date Posted: 25 May 2009 at 3:01pm
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Miguel, Paradisea + (plus) that I have came with LM4562 in place. At the moment I'm evaluating LM6172 there (makes Paradisea+ IMO a Paradisea++ or "broadband" Paradisea). The thing is - IF there is an easy/elegant gain adjustment option on Solo and IF Graham is willing to share it with us - I am really interested to try it out. If not - I pretty much know my other gain lowering options and, in the bottom line, can live with "standard" Solo Green gain. ------------- V3 |
Posted By: jamescodway
Date Posted: 14 Jun 2009 at 2:53pm
Graham, hello. Are we any nearer to 'a few days more'? My 701s/RS-1s are pestering me
 James ------------- Voyager - HD25 |
Posted By: Graham Slee
Date Posted: 14 Jun 2009 at 10:20pm
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Hi James, A very helpful American friend asked me if I could drive a tad more bass into the K701. Well you know just how difficult the K701 likes to be..................? Virtually anything else works well, apart from the K701 and that bit more bass, which admittedly is hard to drive to the depths. I took it as a challenge, so rather than having "service pack 5437" I thought if I just took a little longer... Well time flies doesn't it, especially when you're "sweating on the top-line" ... And the burn-in takes such a long time (no I don't do long burn-in on purpose  )So if after the next 4 days (the usual length of time a mod takes to burn-in - even a single component change) then I can release the "service pack 5436" tad extra bass revision - we are talking of less than an acoustic decibel but if it helps the K701 it's worth doing. Graham ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: jamescodway
Date Posted: 16 Jun 2009 at 8:59pm
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Graham,
this sounds like a quest... a quest for 701 heaven.
I'm guessing your supporters will consider it well worth the wait.
I didn't pass on this piece of news to my (currently in the drawer, I'm enjoying the HD250s too much) AKGs... they just might not be able to contain themselves with the exciting anticipation.
Now I just have to work out how I'm gonna cope when the day comes for my '06 vintage to make that long trip from London to Yorkshire for its SRG upgrade ------------- Voyager - HD25 |
Posted By: mrarroyo
Date Posted: 17 Jun 2009 at 11:36pm
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This is great news! The Solo SRG w/ PSU1 I have is making the rounds w/ members of Head-Fi. So far three have listened to it w/ positive comments, one more reviewer to go. I hope the mod is simple to implement. Thanks.------------- Miguel |
Posted By: Graham Slee
Date Posted: 02 Jul 2009 at 10:24am
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Hi Miguel, I've been reading your updates and although I'm very pleased how your fellow head-fiers have been enjoying the Solo SRG, I have felt frustrated that I'd not delivered to their full expectations - the comment similar to "I could have used a little extra bass" as you know, I not only take on board, but jump through hoops to correct. Unfortunately I am unable to make a simple modification to deliver the tad required. Instead it's been the usual case of a few hundred hours research and development, and the same again regarding burn-in time. The result should actually be known as a completely different model because there is only the faintest similarity to the SRG, that being that it's still an op-amp voltage amplifier with a transistor output stage. So what had to be changed? It would be easier to list the things that were not changed. At this point I will have to leave you all in suspense for a little longer as the days chores are pressing right now, but very soon I want to be able to offer all Solo users since spring 2004 a full upgrade service, or a DIY upgrade card. More info to follow in this thread sooner than it's been going so far. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: mrarroyo
Date Posted: 03 Jul 2009 at 2:24pm
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Isn't it amazing that what at first may seem like a simple thing becomes not only a major project but a complete re-design? I wish I was technically competent so I could come up w/ some suggestions, specially since you have had to spend so many hours to make this happen. I sit back and look forward to your next masterpiece, thanks. ------------- Miguel |
Posted By: faudrei
Date Posted: 21 Jul 2009 at 1:44pm
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...while we are waiting for Solo upgrade kit... There is quick&dirty way of squeezing more bass from Solo driven K701: Get the AD823 out and swap in AD8397 (heatsinked and mounted on SOIC to DIL adapter). ------------- V3 |
Posted By: mrarroyo
Date Posted: 22 Jul 2009 at 12:56am
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Graham will have to chime in if all the Solo's specially the Solo SRG has an AD823. He will also have to indicate if the AD8397 could oscillate. Personally I rather use the LM6172 or the LM4562 but I do not know if they would work. ------------- Miguel |
Posted By: Graham Slee
Date Posted: 22 Jul 2009 at 2:16am
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http://www.gspaudio-community.activeboards.net/forum_posts.asp?TID=561&PID=4191#4191 - Please see this link Although announced to the contrary at the time (some 6 months ago) a rumour has emerged that we still use the AD823 in the SRG. The AD823 was dropped early in production as the financial crisis threatened to wipe out Analogue Devices Inc. (please feel free to look up ADI stocks quotes history). Since then things recovered but the AD823 has not been used in the SRG since. As a responsible manufacturer (unlike some I could mention) we are highly equipped on the test and measurement gear front. Unlike Mr Pease ex of National Semiconductor who frowns on simulators, I use one of the best on the market and even without modelling in parasitics it can easily be seen that some op-amps are unsuited to some applications. Even without any test gear or simulation it can be seen what it says on Data Sheets and for the LM4562 and LME49860 which is the same in every respect apart from its supply voltage, both data sheets clearly show a 16% overshoot for a 100pf capacitive load. Although no capacitors can be seen between the output of the Solo opamp and its output transistors they exist! Those who don't see them don't know electronics, and shouldn't really be making any performance claims (sorry to be so harsh - you'll have to forgive this blunt Yorkshireman). Bipolar, FET or valve, they all have input capacitance, and even in follower mode feature Cie or the equivalent notation. This is because all devices have a transition frequency at which their gain falls to unity. The result I'm afraid to say, is oscillation if the equation doesn't balance and if an opamps overshoot is 16% into 100pf, what is it at 10 times that capacitive load? Yes gross distortion at HF (quite possibly beyond our hearing but there is a phenomenon known as mixing which brings in alias frequencies). Now, place that inside a negative feedback loop and even Mr Pease will tell you it oscillates because he knows his stuff! Edit: I don't really like pulling rank because I'm not arrogant - blunt maybe but not arrogant. Well before the internet and all these opinions my job was to design line drivers and receivers. They were used to transmit live feeds via a BT line from an outside venue back to the studio for FM stereo broadcasting. The BT line from one of these venues was a mile long (Peace Gardens to the Star newspaper building top floor where Radio Hallam in Sheffield lived at the time). Because of the galvanic isolation required by BT (British Telecommunications) there were 1:1 audio transformers either end, but these were essentially transparent to the devices driving them (apart from the excitation current) - they "saw" the 1 mile cable. Those devices were NE5532's!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Pause for the "WI ladies" to vomit.... What a shock! How could that be? Technique! It's not the opamp but the way it's used. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: mrarroyo
Date Posted: 22 Jul 2009 at 10:22pm
Boy it is good to be right ("do not know if they would work") even though I do not know anything!  ------------- Miguel |
Posted By: faudrei
Date Posted: 22 Jul 2009 at 11:39pm
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I do not know electronics. Therefore I can not and will not argue any given technical argument. I trust my ears though. Even with the possibility that my hearing may be defective and/or my subjective audio quality scale may be wrong too, I tend to evaluate SQ according to that scale of mine. Not going into details, I percieve LM4562, LM6172 and AD8397 to be overall sonically better in Green Solo than stock AD823. Even more evidently so after "speed modding" the output transistors. ------------- V3 |
Posted By: Graham Slee
Date Posted: 23 Jul 2009 at 12:51am
It is difficult for me to explain without being technical. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: jamescodway
Date Posted: 09 Aug 2009 at 9:52am
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Graham, hello.
As I wait with rising anticipation for the 'tad more bass' SRG that I hope will take the 701s & RS1s to a higher level, I had a thought... is the 'tad' going to be too much for the HD250s that are currently enjoying about 90% of my head-time?
Best
James
------------- Voyager - HD25 |
Posted By: Graham Slee
Date Posted: 09 Aug 2009 at 1:19pm
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I guess if I were one of my competitors I would be saying "James, you really need one of these!", but you all know me better than that. It is possible that some could say I should be saying things like that and wishing I would, but if your'e getting 90% "up time" with the HD250 - a seemingly difficult headphone to drive, then the 2006 vintage Solo still looks a very viable amp. In the old days when the BBC was still a British company, BBC Stores AKA Canford Audio had persuaded Sennheiser to bring back the much beloved HD250 because nothing could match its neutrality in balancing the EQ controls for the "best average" radio performance. The result is the HD250 linear II you, I and a few others still use. After many years of being heavily influenced (and I make out that nobody influences me...) by the 120R series resistor of the DIN and IEC audio matching system was absolute tripe! I had a wise and common sense realisation: with Sennheiser being Deutsche (the D in DIN) there could be some sense in the DIN/IEC audio matching system - after all, it had it right for phono stages. So there's a clue to where the extra bass was found... The SRG still features the secondary negative feedback loop that corrects for the comb effect many have found while testing all kinds of headphones - something that the 120R was criticised for emphasizing - but with this secondary negative feedback loop in place, the 120R becomes, dare I say it? Blameless! So, for SRG (non i or II) owners, is it just a matter of swapping two 33R resistors for two 120R resistors? Well, I did a lot more than that before arriving at such a conclusion, but if the Spirited DIYer wants to give it a try, that single change may do the trick... Now, the really technical may want to know how I justify such an allegiance with DIN/IEC? The answer can be read above by Mr jamescodway. But really, it is just transmission line stuff - the stuff that makes it possible for the telephone network to exist - the stuff that makes it possible to send RF up a transmitter pole - the stuff that makes DMX lighting cable runs work, and in actual fact it is also known as maximum power theorem. What it isn't is someone else's say so. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: jamescodway
Date Posted: 09 Aug 2009 at 5:35pm
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Thank you very much for the prompt response Graham. I confess I only get the gist of the technical story but I know others will get the specifics. I interpret your remarks as (insert tongue in cheek)...
"James, your 2006 Solo/PSU1 will continue to sound as good with the 250 LII as it ever has and if you want that tad more bass (& other possible 'benefits') for your 701/RS1 you'll have to run to a good dealer with a run-in SRG in due course and see if it makes enough of difference with those cans to add to your (growing) collection of GS products..."
FWIW, I am rapidly falling out of any love with the HD650s...
Keep up the good work in the cause of keeping our ears 'warm'  ------------- Voyager - HD25 |
Posted By: mrarroyo
Date Posted: 13 Aug 2009 at 12:07am
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Nice post to read Graham! For those not technically competent will you be providing them w/ an sketch on which resistors to change? Yes I am technically challenged. ;) ------------- Miguel |
Posted By: faudrei
Date Posted: 14 Aug 2009 at 12:31am
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That would be easy... even for me... The two 33R are the only two resistors that are bigger than other resistors in Solo (rated 0,5 W, all other resistors are rated 0,25 W). ...perhaps a pair of 120R 0.5W Takman carbon films in their place ( http://www.hificollective.co.uk/components/takman_resistors.html - http://www.hificollective.co.uk/components/takman_resistors.html )? ------------- V3 |
Posted By: mrarroyo
Date Posted: 14 Aug 2009 at 2:07am
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I bet that Graham has an specific resistor in mind, if I recall correctly his designs are finicky to changing component brands. ;) ------------- Miguel |
Posted By: Graham Slee
Date Posted: 14 Aug 2009 at 9:42am
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Faudrei has spotted the right resistors - the only two larger ones on the board. They are roughly in line with one another in the direction of the length of the board and their location is between the op-amp section and the transistor section. I'll try and find a picture. The original type was a carbon film sourced from Radio Spares in the 80s. I had over ordered and still had a few thousand on stock when the Solo came into being. It then changed to Welwyn 0.75 watt MFR5 and I think that's the type fitted in the 2007. We recently discovered more stock of the carbon film Radio Spares ones (I hadn't realised John had re-ordered a load of the RoHS compatible ones) and will be using these up as well - I can't tell any sonic difference between them and the Welwyn metal films. The problem is now that Welwyn are "subbing" out manufacture having closed their UK facility and I can't stand the sound of the new Welwyns. The only other option seems to be the Brazilian Philips resistors which are now Vishay Sfernice. I have to strike a balance between what I want to hear and what I can afford: I have to buy tens of thousands of resistors a month and so the finicky or speciality audio resistors offered at out of this world prices are out - we'd really have to pump our prices up to cover the cost and that's the last thing I would want to do. My test of a good resistor is its effect on instrumental decay - the "new" Welwyns came to a full stop whereas the old ones held on to the natural decay right to the release - so they did music. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: mrarroyo
Date Posted: 14 Aug 2009 at 1:33pm
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Graham, any source to buy the Welwyns? " ... Welwyns came to a full stop whereas the old ones held on to the natural decay right to the release - so they did music. " ------------- Miguel |
Posted By: Graham Slee
Date Posted: 14 Aug 2009 at 6:28pm
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I'd go for the Vishay Sfernice - the good old Welwyns will be like rocking horse sh*t by now (rare). Digikey or Newark should have them The only way to tell the old Welwyns from the new Welwyns is to listen to piano note decay and release - if it releases early they're the new ones. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: mrarroyo
Date Posted: 14 Aug 2009 at 8:26pm
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Would this work?: http://www.newark.com/welwyn/mfr5-120r-1/resistor-0-75w-1-120r/dp/97K4948 - http://www.newark.com/welwyn/mfr5-120r-1/resistor-0-75w-1-120r/dp/97K4948 ------------- Miguel |
Posted By: Graham Slee
Date Posted: 15 Aug 2009 at 10:19pm
It says it's a Farnell UK direct ship which could suggest they're the new ones from A.N Other resistor Co. If anything like the smaller MFR4's, I bought up all Farnell's remaining original ones months ago, so maybe somebody bought up all the old MFR5's? Better to go for the Vishay. Or a bog standard 0.5W carbon film. Or sit tight and wait for the Solo SRGII.... (yes, I know it's taking some time, but I don't want to be doing any more tweaking on it this year if I can help it and I'm just making sure it plays everything in my collection perfectly... well, not quite, it would take till 2011...) ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: mrarroyo
Date Posted: 15 Aug 2009 at 10:33pm
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I shall be a good boy and wait! ------------- Miguel |