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Graham Slee's Solo SRG w/ PSU1

post #1 of 113
Thread Starter 
I had placed this observations as part of a larger thread. However my impressions took three days and do to the number of pictures I had to split the post. Thus I decided to start this new thread, hope it does not bother you the reader to see it in two places.


Part I:

On May 2, 2009 my Graham Slee Solo SRG and its PSU1 ( Solo SRG Headphone Amplifier: Solo Studio Reference Green Headphone Amplifier ) reached its 550th hour of burn in. Thus I decided to start some comparisons using various cans and music. You will notice that I will put a lot of picture and I hope they break the monotony of reading. Specifically for this round I used:

1.Ultrasone HFI-780 which has been re-cabled by Alex of APureSound ( APureSound - Where The Music Is Always Pure - APS Audio LLC. ) using a 7 foot long V3 silver plated wires covered in techflex and terminated in a ¼” Neutrik plug. The diode board in the HFI-780 has been removed and the pleather pads have been re-placed w/ a set of velour pads made by Beyerdynamic for the DT250/280.
2.Denon AH-D5000 that has been modded by MarkL ( Home ) including a pair of his V4 Bubinga wood cups installed. The cable is the stock one.

The music is stored via iTunes as Apple Lossless files on my Dell desktop. I use a glass optical cable to connect a Chaintech AV710 to a Monarchy NM24 DAC. Since most of you use SS DACs I used the SS DAC output of the Monarchy to feed the amps. As far as music for this first round I chose Diana Krall, specifically the following albums.

1.All For You: A Dedication to the Nat King Cole Trio
2.From This Moment On
3.The Girl In The Other Room

As of now I have three additional solid-state amps at the house. However one of these is a Graham Slee Novo powered by a switching wall wart. So I decided to use a highly modified Jaycar Amp (Australian based amp) and a highly modified Musical Fidelity X-Can V2. For those not familiar with the Jaycar it starts life as a kit sold by an electronics store in Australia. It is sold in two parts; the amp section and the power supply, to this you must add the transformer, case, volume pot, on/off switch, and rca’s.

Stereo Headphone Distribution Amplifier - Jaycar Electronics

Headphone Amplifier Power Supply Kit - Jaycar Electronics

The Jaycar I own was built by a very knowledgeable “old codger” who proceeded to highly tweak the unit by using better components, not necessarily boutique but definite upgrades. He also added a board to eliminate the ripples in the power supply, JLH board and a stepped attenuator. Note my unit uses a metal LM4562HA, pic below.

The internals of the finished Jaycar looks like.

The second amp I used started life as a basic Musical Fidelity X-Can V2. This amp has fallen out of favor and to be honest not many cared for it outside of Great Britain. This is IMO a pity because it is a killer amp with just a few mods, and what better mods than those developed by PinkFloyd (Mike Grierson). His mods have evolved over many years of tweaking followed by listening. The mods done to my V2 include:

1.Ultrafast Diodes
2.Panasonic FM/FC 105C capacitors
3.Evox Polypropylene capacitors
4.Since my sources do not output DC I removed the DC blocking caps w/ wires w/ ferrites (lowered floor noise)
5.Reduced the gain from about 9 to 5.7
6.Alps volume pot
7.Replaced power supply transistors w/ ZTX853/953
8.New Jalco ¼” headphone jack
9.Purple light (just for fun)
10.Dampen the bottom interior of the case with dynamat
11.Using Russian 6H23EB valves
12.Using the latest Little Pinkie V3i PSU

Lastly here are some beauty shots of the Graham Slee Solo SRG.

As you can see by the pictures the Solo SRG has two inputs that are user selectable via a toggle switch in the front panel. You will also notice there is a ground post on the back panel, this is meant mostly for those who use the switching wall wart. Although I have the upgraded power supply (PSU1) I still run a wire from the ground post on the back of the Solo SRG to a ground post on the back of my Monster HTS 3500 MkII. Lastly there is no on/off power switch, according to Graham the unit is intended to be kept on at all times, if this bothers you then it is easy to unplug the PSU1.

The Solo SRG w/ PSU1 sells for 425.11 PB plus 39.37 PB with expedited SH to the USA. The price has remained relatively stable, however the BP has regained some of its strength. Thus an amp, which could have been bought for well under $600, a couple of months ago will now set you back close to $700. I wish I had a $650-$800 solid state amp to compare with the Solo SRG so I could comment on value, sadly I will only be able to comment on its sound.

However I have asked three members of Head-Fi and it appears two have already agreed to put the solo through its paces, I know one owns a solid-state amp that retails for over $1,250. This brings the question if it is “fair” to compare an item with another that retails for almost twice as much. Personally I would feel more comfortable if it was closer to 20% difference but I also know we go crazy in this hobby and what started as a $100 headphone ends up in a $2,500 expenditure.

So over two pages of “stuff” and yet nothing on how the Solo SRG w/ PSU1 sounds? So where should I start? I think with the soundstage, it is very wide and deep w/ openness to the presentation that keeps you coming back for more. The music is presented in such a way that every note has its place and makes for a very engaging and enjoyable listening experience.

Although people talk about bass and treble extension the reality is that most of the music is in the mids. This is one area where the Solo SRG excels at; it is very clear and detailed w/ lots of air in between the notes. As stated earlier the soundstage is wide and deep, this makes for a very easy exercise to place the instruments as well as allowing the singer “the room” to strut his/her stuff. All of this allows you to pick-up the start and end of notes, for example cymbals and hi-hats. In other words it is very musical and it presents the material with excellent control and micro detail. All of this IMO makes for non-fatiguing listening sessions, yes it keeps you tied listening to your favorite music.

There is excellent treble extension this allows for notes to cut through and for the listener to place the various instruments. The amp kept its composure and remained tight and articulate.

The bass is tight and goes deep, although at times it is a bit light. What it has is very clean and punchy while staying in control. I found that once I stopped listening to the bass as compared to other amps it did not seem lean at all, actually it was at times a bit much with the Ultrasone headphone.

More to come.
post #2 of 113
Thread Starter 
Part II:

I am back, hoping to provide meaningful feedback on the Solo SRG. Today is Sunday, May 03, 2009 and I will be using my trustworthy Grado RS-1. It will be accompanied by a Denon AH-D2000, which has had the MarkL mods and one of his V4 Bubinga wood cups. But wait! Isn’t this the same as the D5000 used yesterday? Well, I left a piece of information out … the D2000 has been re-cabled by HiFLYiN9. He used a 24 gage silver-plated copper cable, it is a 10 foot long and it is terminated in a ¼” plug. You can read more about the Xev cable at: Zynsonix - Headphone Recabling Service

Here are some “beauty shots” of the two headphones used today.

As far as music goes I decided to use different artist, although all are in the jazz genre. These are:

1.Modern Jazz Quatet – Pyramid
2.Moss – Moss
3.Najee – Share My World

The rest of the music chain remained unchanged from yesterday. Hopefully this will allow for some consistency in this process. Although I did forget to mention the Monarchy NM24 DAC is being fed power via a Monarchy AC Regenerator.

One thing I did not mention yesterday is that I listen at very low volumes. Rarely do the peaks in the headphones play reach 75 dB with over 95% of the time below 70 dB. As you can imagine the “average” music passages are in the low to mid 60’s dB. This measured with a sound pressure meter I purchased at Radio Shack. I hope the low level listening does not produce results significantly different from those who listen at LOUD levels. As stated yesterday I hope the other testers will be able to add their feedback including how “loud” they listen.

Today’s comparison pretty much validated all I heard yesterday, except one characteristic I will discuss later. As you can tell by my music selection I listen mostly to jazz, although occasionally I listen to classical, new age, and easy listening. I believe that all this genres of music will benefit from the Solo SRG. This because of its ability to have a wide and deep soundstage which when combined with the airy and detailed presentation envelops the listener. Also this types of music are by nature extended and fast, abilities which IMO the Solo SRG has a plenty.

I have not spoken of how quickly the Solo SRG responds, as the various jazz passages get more complex or revert to a solo rendition it demonstrates its ability to quickly transition and portray the music in a cohesive and engaging way. The word “musical” keeps coming back and it truly describes the sound I hear.

As I recall many aficionados to headphone listening have stated on many occasions that Grado headphones do best with tube amps or warm solid-state amps. Otherwise they will sound shrill and the treble will be too energetic to be a pleasurable experience. I also remember reading that if a solid-state amp is properly designed and built it will produce beautiful music. Thus it would reproduce the music in such a manner that it would not be shrill or fatiguing to the user.

Until recently I have felt the same that is that Grado headphones need a tube amp. Thankfully I have had an opportunity to listen to a few solid-state amps that have changed my opinion. Since I do not have those solid-state amps on hand to do a side by side I will not mention their brand, although I will say that few have all the characteristics of the Solo SRG: wide & deep soundstage, airy & detailed mids, clear & extended highs, and an organic presentation which combine to a very musical and engaging amp. No I lied, I will mention the name it was a Blue Circle Amp belonging to a friend. His unit was modified by the vendor for his particular needs. BTW this unit sells for quite a bit more than the Solo SRG, perhaps I could borrow to do a side by side. I also hope you all understand that what may be good to me may not be to you, we all hear differently and have different expectations of what good sounds like.

Well, back to the one characteristic that I was not able to validate: bass. Today marks the 24th consecutive day of burn in, or over 575 hours. You would think any amp would have stopped changing; well it appears that is not the case. The available bass continues to be deep, tight, and punchy. However there appears to be more of it, do not know if the perceived change is due to the two headphones being used today, 24 hours of additional burn in, different music, or just getting used to the sound signature. I will report back on my last installment, using a much harder to drive can (AKG K501 w/ a 10 foot V3 APureSound re-cable terminated in a ¼” Furutech plug).

More to come.
post #3 of 113
Thread Starter 
Part III:

Well, it is Saturday, May 09, 2009 and here I am back writing on the Solo SRG w/ the PSU1. I believe this will be my last time writing specifically on this amp. I may add a comment or so on other forums/post as I see fit. Anyways, the write up today will not be a comparison type. Instead I will write of my listening experience over the last few days.

Most of the time I was using an AKG K501, which as stated above has been re-cabled by Alex of APureSound. Here is a picture.

The amp has continued to evolve, but the changes have been IMO very subtle and the sum of all of them over the last week has been small compared w/ the changes since I received the unit or even over the last 100 hours of burn in. IMO the change over the last 25-50 hours have resulted in smoothing out the overall presentation, this has been followed by a bit more depth/width of the soundstage, and the bass amount has increased a bit. Do not expect the Solo SRG to shake the windows, it will not. However the bass is reproduced in a very tight, deep, and realistic way thus making this unit fantastic for jazz and classical users. I should also restate that the unit has amazing extension both ends.

It is apparent to those who have heard a lot of gear that some units may emphasize a frequency over others. Many of us compensate by getting an opposing headphone or source. For example, if the headphone is energetic in the top end we get a warm amp to tame the highs. No need to do so here, I find the Solo SRG to be very even in the way it present the overall frequency range, and it does so in a smooth controlled way.

For those wanting to know, I have used a variety of jazz music over the last week or so. For example:

2.Mark Whitfield
3.Mark Antoine
4.Melody Gardot

My plans are to ship the unit out to a couple of aficionados so they can spend a couple of weeks with the amp and post their impressions. Even if they have a totally different opinion after listening to the Solo SRG it is IMO very good because it provides both the designer/builder as well as potential customers with valuable feedback. On one end the designer/builder can improve the product and on the other end the potential customer has a different take on the amp. To me this translates to a win-win situation.

Thanks for taking the time to read my ramblings.
post #4 of 113
Thanks for the impressions Miguel. I really enjoyed my Solo Green and hated parting with it. But now that I am settled--heck, I even bought a turntable this week--I may have to pick up another Solo. Thanks for reminding me of what I've been missing. I'll be sure to send you a strongly worded letter when I end up spending cash on this amp for the second time.
post #5 of 113

If only I didn't live in the UK - I could write up on your Solo too - it would be interesting to compare it to my older one.
post #6 of 113
Ah Part III finishes it. Great review and I am pretty sure I will end up buying one in the future.
post #7 of 113

SRG is Great With Grados, Denons and ATHs, as Well as Senns

Thanks to “mrarroyo’s” generosity I demoed the GS Solo SRG recently to see how it compared to my Millett MiniMax. I tested it with my Marantz SA8001, and Monarchy M24 and my Senn MHD580s, MD5000s, RS-1s, and AD2000s with a variety of jazz CDs.

The SRG appears to be clearly improved over the Solo 2007, which I tried last year. It seems much better with low impedance phones like Grados, Denons, and ATHs. The SRG seems much smoother, and less harsh with those phones. Though - I should note... my impressions of the Solo 2007 were based on an amp that was "right out of the box" and not fully burnt in, which may not have been fairly representative of the fully matured amp.

The SRG is especially great with Denons, in that it does a good job of controlling their bass, and smooths their highs, while bringing out their mids a bit more. It sounds very much like the X-CAN v8 with the Denons, though maybe a bit better. But… the SRG is also still great with Senns, which the v8 is not.

The overall sonic character of the Solo SRG is very much like that of the Solo 2007 – which is powerful, rich, full bodied, weighty, organic, textured and smooth. Bass and treble are nicely extended, and the mids are rich and warm. The bass is bold with impact, extending up into the lower mids a bit imparting a weighty sound, though not overpowering. The highs are clear, detailed, smooth and refined. The resolution is good, presenting all the details and nuances of the performance and venue, providing a good sense of the positioning of the performers. The soundstage is fairly wide and deep, though the overall sound is somewhat forward within the soundstage. The PRAT is fast and quick, though the leading edges are not as sharp as my MiniMax, or some other SS amps.

Compared to my MiniMax, the SRG has a very slightly warmer, richer, more weighty sound – which complements Grados, Denons and ATHs very well. Though, the PRAT and detailed highs of the MiniMax may complement the Senns a bit better.

The power output / gain of the SRG is similar to that of the MiniMax – fairly loud (about as much as you can stand) at about 11-12 O’clock with Grados, Denons and ATHs, and at about 2-3 O’clock with Senns. This is with output levels from the sources of about the standard 2 volts.

This SRG was well burnt in with over 500 hrs of use prior to my demo. Even so, I noted that the SRG sounded warmer and richer, during the first 2-4 hours of use – during which time it was especially good with Denons, Grados and ATHs, though not so good with Senns. After about 18+ hrs it seemed to brighten up a bit, sounding much better with Senns, and a bit less warm and rich with Denons, Grados, and ATHs – though still great. I'd almost say... the AD2000s may sound the best of the lot with the SRG, possibly the best I've heard them - its certainly a great combo.

Both the SRG and MiniMax compare very well to my WA6 SEM – though, the WA6 SEM does sound a bit better in most respects, though the difference is small. I think most folks would be very pleased with any of these amps – though the real values are the Minimax and SRG. Its hard to deny the fact that once you get past about the $400-800 threshold... you realize only very subtle improvements in sound quality relative to the disproportionate investment required. It is far more important to carefully match the source to the amp to the phones to optimize their sound, than to simply "throw money" at equipment, expecting it to sound much better because it costs a lot - it doesn't.

The sound of the SRG is so good with all my phones, that I may actually get one. Though, I’m still trying to decide if I prefer the SRG to my MiniMax – probably with Grados, Denons and ATHs, maybe not with Senns. Its too close to call. Or, so it seems to me.
post #8 of 113
Wow you really make me want to hear one some day. I have the 2007 but your description may seem to indicate it can be the perfect amp for the Pro 900. the older Slee Solo already being very good but the improvements just plays right into them it seems.
post #9 of 113


Originally Posted by oqvist View Post
Wow you really make me want to hear one some day. I have the 2007 but your description may seem to indicate it can be the perfect amp for the Pro 900. the older Slee Solo already being very good but the improvements just plays right into them it seems.
Please note... my impressions of the Solo 2007 were with a "new out of the box" amp, which had not been burnt in - which could make a difference in how well it sounds with low impedance phones.

But... the SRG does sound good with low impedance phones, no matter how the Solo 2007 sounds with them.
post #10 of 113
The Solo SRG keeps calling me I was amazed to have looked through my documents recently and found it's been over a year since I bought the 740C... it really deserves a higher level amp to compliment it, and now I have the funds to buy the PSU1 version of the Solo SRG too, I should just stop reading about it and press the damn buy button
post #11 of 113
Thanks to Miguel for the loan of the SRG, and thanks to Gradofan2 for cutting his time short to squeeze me in. I'm really glad I got the chance to compare the Green Solo with the SRG/PSU-1 combo. I also compared the smsp wallwart with the PSU-1 on my Green Solo.

Let me preface this with I don't have experince with other amps or headphones, other then TotalBitHead and HD-555's.

My dac is the OMZ 4.1 and my phones are the HD-580's.

My first hour with the SRG I spent a/b'ing my already warmed up Green,which I always leave on, to the cold (temp wise, not sound wise) SRG. Right out of the box it was apparent that the SRG was more detailed then the Green. The sound signature was the same, but with the SRG having the better soundstage. At this point it was hard to tell how exactly, or was it just from the better detail?

Using the Ultrsone cd as an example... on the first track the banjo was a little more up front, more even in the mix then with the Green Solo. Not night and day different, I remeberthinking that if I wasn't a/b'ing them, it would take an experienced person to be able to tell the difference.

About 5 or 6 hours in, the greater detailing really started showing in the SRG.

Using Jeff Beck Live at Ronnie's scott's 2007 .........

Amazon.com: Performing This Week: Live at Ronnie Scott's: Jeff Beck: Movies & TV

Was simply amazing. I could almost feel JB bending the strings. When JB played the guitar just by tapping the strings up the neck, it was like you could hear the individual strands of the string on JB's fingertip. Joss Stone, doing "People Get Ready" her voice made my ears hard , not to mention Imogen Heap's sultry bedroom voice doing "Blanket" about finished me off

The contrast between JB's playing and the soulfoul,sultriness of Joss Stone and Imogen Heap was amazing.

Even after a little more then 6 hours of the SRG warming up, the difference in the detail was now night and day and growing.

I left the SRG on over nite and about cried when I had to ship it off this am, but over night the sound had gone more towards neutral, I sposse, then being close to the Green's the night before. I can't imagine how it would sound after 72 hours,as this is when Miguel says it really comes on full song.

So after only having it for 20 some hours I can say this about the SRG compared to my Green Solo......

I was expecting the SRG to be better, natuarly, I didn't expect this amout of difference. The ampunt of detail blew me away. Soundstage was better,fuller, was to hard for me to try to nail down any more then that in the short time. Positioning was much better too. Also more upfront. High's are more extended. I didn't get the impression that is why it was more upfront then the Green, your also closer,almost on stage with the SRG. I found this paticularly true with regards to the actual recording. Sometimes you're between the musicians on stage, other times at the stage,. or a row or two away.

Listening to

Grateful Dead
Amsterdam, Netherlands

Chappell's matrix sick bits vol. 27 for all you heads outthere ...

1st set is acoustic, and it was heavenly. I was right in the middle of the boys and their acoustic guitars and bongo's, and I thought the Green SOlo sounded good with drums and bongos and stuff. Hard for me to say if the SRG's PRAT, impact and bass is faster,deeper, but I can tell that it is better.

This hobby is funny, you never know what you're not hearing until you hear it. If you haven't heard some of the top end amps, you think you know what it sounds like, because that's all you know. Before I thought the Green Solo had a fair amount of detail and resolution... now I'm ruined

Hope that made some sense, I feel like I'm getting lost.

Thanks again Miguel
post #12 of 113
"the AD2000s may sound the best of the lot with the SRG, possibly the best I've heard them - its certainly a great combo."

music to my ears!
post #13 of 113
great review btw.
can you loan a set of ath-ad2000 from someone and give us your opinions with the solo?
would be interested in your comments.
post #14 of 113
Thread Starter 
oldson, the ATH AD2000 is a great can, last time I listen to one was a couple of years ago. Will see what I can do, but it will be hard to pull me from my MarkL Modde D2000 or D5000. These are the bomb!
post #15 of 113
Hi. I am going to buy the Graham Slee Solo and in my country is Solo with PSU1
1/3 more expensive than without it. Do you think (or have some experience) the Solo with PSU1 is so much better?
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