[burdie]

  Hi again, 
 
Looks like I did it after all.
 

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PROS:
- BURSON V5-D are definitely having a lower noise than original HPA-3B's op-amps, so great job BURSON! These are definitely the lowest noise op-amps I ever tested.
- I liked women voices and instrument separation a lot.
- Cymbals sound a bit more clean and natural with V5s.
 
NEUTRALS:
- Details are about the same as LME49860, with just a slight advantage for V5s (BURSON V5 did a great job in revealing more details and clarity with my Objective2 amplifier: http://www.head-fi.org/t/616331/o2-amp-odac/4965#post_12382477).
- Sound-scene is about the same as original op-amp, but I'll test this again the next days and get back to you.
 
CONS:
- Need to replace power regulators for decreasing the voltage from +/-18V to +/-15V, otherwise lifetime of V5s will decrease.
- Height is 2 mm more than it should be to perfectly fit inside HPA-3B, so you'll need to remove the DIP-8 sockets and solder V5s directly onto motherboards to fit the case
- A bit pricey (about 25% of the price of Matrix HPA-3B).
 
Note: Many thanks to BURSON for providing these solid-state op-amps for this test!
 
Will get back here when I'll have the time to compare more op-amps and more songs,
Raul.

Raul, you did it again. Any further update on the listening?
Since you got very good soldering skill, would you mind to do one more thing on V5? since V5 is 2mm taller even you remove the dip-8 socket, will it be able to fit in the case if you diy a L shape dip-8 socket (extend the pins and bend it down for 90 degress) and lay the V5 to the left and right. or may be relocate the 2 big cap...

 

[burdie]

Raul, I am talking about this right angle dip-8 socket, which can be found on 
http://www.digikey.com/product-search/en?mpart=299-93-308-10-001000&v=54

 

[raoultrifan]

In case you intend to get rid of existing DIP8 sockets and solder 2 x SS V5s inside HPA-3B there will still remain about 4-5 mm of space left on top of each V5, so no worries about it. In the below pictures you can see a V5 standing on the PCB and HPA-3B case is completely closed top/bottom.
 

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No flash​	With flash​

 
burdie, thanks for the 90 degrees angled DIP8 socket. I don't think would be winner for HPA-3B, but I might try something like that inside my Objective2 headamp.

 

[Bruch]

Really what's needed is a DIP-8 socket extender via a short ribbon cable so that the V5 can be fixed somewhere convenient. I think that I saw something like that once but I can't find anything now - not even to make yourself.

 

[burdie]

  In case you intend to get rid of existing DIP8 sockets and solder 2 x SS V5s inside HPA-3B there will still remain about 4-5 mm of space left on top of each V5, so no worries about it. In the below pictures you can see a V5 standing on the PCB and HPA-3B case is completely closed top/bottom.
 

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No flash​	With flash​

 
burdie, thanks for the 90 degrees angled DIP8 socket. I don't think owuld be winner for HPA-3B, but I might try something like that inside my Objective2 headamp.

If the clearance is about 4 to 5mm, may be still possible to put a dip8 socket to ease opamps swapping. The shortest i can find is 4.4mm to 4.5mm (above pcb), and if still out by 0.X mm, then have to consider removing the red case?

 

[raoultrifan]

  Really what's needed is a DIP-8 socket extender via a short ribbon cable so that the V5 can be fixed somewhere convenient. I think that I saw something like that once but I can't find anything now - not even to make yourself.

I really don't think there's enough room for extenders. Now honestly, removing the DIP8 sockets is easy, the only downside I can see would be no more op-amp rolling possible (well, at least not without resoldering again). What I am thinking right now is to use a drilling machine with a 1 or 1.5 mm spiral and increase PCB holes diameter so I can get both DIP8 sockets inside the PCB with few mms. This is how DIP8 sockets look like: http://g01.a.alicdn.com/kf/HTB1aIzEKVXXXXcbXXXXq6xXFXXXr/20pcs-DIP8-8-Pin-Gold-Plated-Socket-for-DIP-8-round-hole-8-pin-Op-Amp.jpg & http://www.retroamplis.com/WebRoot/StoreES2/Shops/62070367/4B99/037E/6882/C75B/0F91/C0A8/28BA/3F8A/DIP8.jpg. Now I don't know if PCB traces are big enough to accomodate these bigger holes.
 
Burdie, inside the SS V5 there's something yellow inside that looks like a melted plastic and I believe it has thermal conductivity. Without cutting the red case out I don't see how to get to inside electronic parts...and I don't want to get rid of the beautiful red case.

 

[raoultrifan]

As I reduced recently rail voltages from +/-18V to +/-15V so I can test BURSON V5 op-amps now I need to find out what's max. power of my HPA-3B. I was able to connect my HPA-3B to a single-ended cable (left over from my 600 ohms DT880 Beyers) and 3 resistors, each having 10 ohms and I measured a total of 34.5 ohms resistance (cable included).
 
Here are my scope graphs for single-ended output only (can't find my spare balanced plug/cable, sorry):

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32 ohms - non-clipping (1.33 Watts)​	32 ohms - clipping  (1.45 Watts)​
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32 ohms - FFT shows no strange harmonics @ 1.33 Watts​	500 ohms - non-clipping (185 mWatts)​
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60 ohms - non-clipping 1.07 Watts (8.042 V RMS)​

 
Comparing with my old values from http://www.head-fi.org/t/770610/introducing-the-matrix-m-stage-hpa-3u-and-hpa-3b-review-to-follow/60#post_12250417 looks like lowering voltage with +/-3V also lowered output voltage & power to about 75%. For example for 60 ohms now I have about 1.1 Watts and initially I had about 1.45 Watts.
 
Anyway, HPA-3B has plenty of power even when powered from +/-15V on rails.
 
The main advantages for lowering voltage rails:
- ability of testing almost all op-amps from Earth
- temperature inside HPA-3B drops with a couple of degrees, perhaps increasing internal components life
 
Disadvantage:
- power reduces to about 75% of initial values

 

[canthearyou]

As I reduced recently rail voltages from +/-18V to +/-15V so I can test BURSON V5 op-amps now I need to find out what's max. power of my HPA-3B. I was able to connect my HPA-3B to a single-ended cable (left over from my 600 ohms DT880 Beyers) and 3 resistors, each having 10 ohms and I measured a total of 34.5 ohms resistance (cable included).

Here are my scope graphs for single-ended output only (can't find my spare balanced plug/cable, sorry):

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[TD][/TD]​

[TD][/TD]​

[TD]32 ohms - non-clipping (1.33 Watts)[/TD]​

[TD]32 ohms - clipping  (1.45 Watts)[/TD]​

[TD]32 ohms - FFT shows no strange harmonics @ 1.33 Watts[/TD]​

[TD]500 ohms - non-clipping (185 mWatts)[/TD]​

[TD] [/TD]​

[TD] [/TD]​

[TD][/TD]​

[TD]60 ohms - non-clipping 1.07 Watts (8.042 V RMS)[/TD]​

Comparing with my old values from http://www.head-fi.org/t/770610/introducing-the-matrix-m-stage-hpa-3u-and-hpa-3b-review-to-follow/60#post_12250417 looks like lowering voltage with +/-3V also lowered output voltage & power to about 75%. For example for 60 ohms now I have about 1.1 Watts and initially I had about 1.45 Watts.

Anyway, HPA-3B has plenty of power even when powered from +/-15V on rails.

The main advantages for lowering voltage rails:
- ability of testing almost all op-amps from Earth
- temperature inside HPA-3B drops with a couple of degrees, perhaps increasing internal components life

Disadvantage:
- power reduces to about 75% of initial values

That's awesome!

 

[raoultrifan]

I found my "magic" 4-pin XLR plug and I was able to measure HPA-3B's max. power in balanced operation when 60 ohms resistors & headphones cables are attached.
 

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60 ohms BALANCED - non-clipping 3.5 Watts (41.41 V peak-to-peak, 14.55 V RMS)​

 
Looks like this little headamp still remains a little beast, even after lowering power rails to +/-15V; a decrease with about 20% over the initial 4.5 Watts is quite OK. After all, 3.5 Watts should be OK for most balanced headphones, even for Hifiman HE5 & HE6 I'd say.

 

[canthearyou]

I found my "magic" 4-pin XLR plug and I was able to measure HPA-3B's max. power in balanced operation when 60 ohms resistors & headphones cables are attached.

[TD][/TD]​

[TD]60 ohms BALANCED - non-clipping 3.5 Watts (41.41 V peak-to-peak, 14.55 V RMS)[/TD]​

 
Looks like this little headamp still remains a little beast, even after lowering power rails to +/-15V; a decrease with about 20% over the initial 4.5 Watts is quite OK. After all, 3.5 Watts should be OK for most balanced headphones, even for Hifiman HE5 & HE6 I'd say.

Yup, this will be my next purchase.

 

[raoultrifan]

  Wow, well done, you have done such a neat job of that soldering.
 
When you remove the DIP8 socket does the V5 fit straight into the mother board without any further modification? It looks like a perfect fit from the pictures. But for 2mm I think I would be more inclined to drill a couple of holes in the roof!
 
From you description it sounds like it raises the HPA-3B up to the next level.
 
I also note that on other mods you are not afraid to say that you can't tell any difference in sound quality, which is a good thing. It gives us confidence that the differences that you do describe are real.

Thanks Bruch!
 
I can tell you for sure that the best mod for this amp was shielding the transformer and also grounding the shield. I also changed input caps because technically speaking polypropylene is better than polyester, at least in audio field (well, best cap is no cap, I know).
 
Changing op-amps in HPA-3B was not something like night & day difference in trebles, bass, clarity or scene, instead the changes are quite subtle here, because LME49860 is already one of the best in class op-amp. For example OPA2604 had a little bit less clarity and details than all others tested in HPA-3B, but at least this op-amp was not heating so much like all the others tested.
 
With BURSON V5s the best improvement was perhaps related to HPA-3B internal noise, though HPA-3B already has a low SNR, when using high-gain (+20dB) and low impedance/high sensitivity headphones there's some noise coming up (especially in balanced mode). Perhaps my amp upgraded with V5s is having now a SNR of -116dB instead of original -114dB, but most people will really not notice this change unless max. power + sensitive headphones are used.
 
Also, BURSON sound character pleased my ears when women voices were present. Instruments spacing is better too, but we're speaking about a very small margin here (LME49860 is a very good op-amp as well).
 
P.S.: Other op-amps I liked would be MUSES8820 and MUSES8920.

 

[raoultrifan]

Yup, this will be my next purchase.

MATRIX HPA-3U is about the same as AUDEZE DECKARD: http://www.head-fi.org/t/749486/audeze-deckard-class-a-amp-usb-dac/150#post_12160801.
 
Also, HPA-3B is around the same electronic schematic as well, so I really believe that both HPA-3U and HPA-3B are "the best bang for the buck".

 

[Bruch]

Thanks for your feedback Raoul,
 
My 3B should be coming this week and I already have a pair of LME49720HA's to try. I don't have any Grain Oriented Silicon Steel f​or shielding but I do have some lead sheet which I will try. I note your point about grounding.
 
Although the V5 route does seem like quite a lot of trouble for what you describe as subtle changes in sound quality it is probably something that I will try at some stage. I also want to try the V5's in an EHP-O2 amp (I note that you had success with that) so my thoughts are to buy 2xV5 singles with a DIP-8 doubler for the O2. If I like what I hear I will buy a V5 Double for the O2.
 
Well done for leading this mod thread. It takes someone like you with knowledge and a bit of courage to lead so that the rest of us can follow!
 
Kind regards
 
Bruch.

 

[raoultrifan]

  [...] so my thoughts are to buy 2xV5 singles with a DIP-8 doubler for the O2. If I like what I hear I will buy a V5 Double for the O2.

 
Hi Bruch, 
 
Why single V5s? I used one double V5 in my O2 and my next step would be to get out the batteries, remove the metallic battery connectors so I can get a 90 degrees DIP8 socket adapter to install a dual V5 for good (will get me more details and the great BURSON sound).
 
Note: Perhaps many times I wrote V5s, so my bad...but I actually meant the plural for V5 and not V5-single...sorry. So, I only tested V5-dual op-amps in both Objective2 and Matrix HPA-3B amplifiers.
 
Raul.

 

[Bruch]

  Note: So, I only tested V5-dual op-amps in both Objective2 and Matrix HPA-3B amplifiers.
 
Raul.

 
Sorry, although I realised that you were using a double in the O2 I had thought that you were using a pair of singles in the HPA-3B. A pair of doubles does add to the price quite considerably but I'm one of those people who will still probably end up doing it anyway!