[theory_87]

Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif The pic shows imbalanced bypassing. Also what are you using on G_CH? Why I didn't solder R19 (wideband mode resistor for G_CH) is, I couldn't find merit for using it;( And as you know, OPs on there should be higher output current type. I don't always recommend 4ch architecture, so that produces DC, and I received massages from Japanese users who says 4ch architecture will give hiss. BTW, I think stacked 634 won't go with the wideband mode (SW1 ON) when portable use, of course will get warmer than LT1210. Wideband mode will make it effective with single 634P and 634U.

Sorry, which part is imbalanced bypassing
ad8397 is used in the ground channel.
My dad is the user of the amp and he think it sounds better with wide band width and 4ch. I can't have a proper test as all my iem is not with me till next week

 

[ryuzoh]

Quote:

Originally Posted by theory_87 /img/forum/go_quote.gif Sorry, which part is imbalanced bypassing ad8397 is used in the ground channel. My dad is the user of the amp and he think it sounds better with wide band width and 4ch. I can't have a proper test as all my iem is not with me till next week

Wwwwait....AD8397 is dual channel OP, which COULDN'T be used on the G_CH socket where is for single OP only.
I think this seems to be cause of the hiss, so should be removed and requiring to be changed immediately.

Imbalanced parts are left side FX....seems to be using 100uF and 47uF,
They should be in same capacitance.

 

[theory_87]

Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif Wwwwait....AD8397 is dual channel OP, so COULDN'T be used on the G_CH socket there is for single only. I think this seems to be cause of the hiss, so should be removed and changed immediately.

My bad... will do it then. I thought I should use dual channel op there just like Xin SuperMacroIV

 

[ryuzoh]

Quote:

Originally Posted by theory_87 /img/forum/go_quote.gif My bad... will do it then. I thought I should use dual channel op there just like Xin SuperMacroIV

In GND is driven by LT1210 as like PRII and Portaphile V2^2.
Out GND is changeable btwn Standalone single OP or common connection to In GND.

But actually this amp can achieve 110dB+ SNR with 3ch architecture

 

[SpudHarris]

Ryuzoh, sorry to bombard you with 'another'. I still use your recommended set up with the P3+ and have yet to better the SQ this set up puts out. If you are using ADA4267's in L/R what buffer and ground set up do you recommend? Also I find big hiss with 4 channel compared to 3......

 

[ryuzoh]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif Ryuzoh, sorry to bombard you with 'another'. I still use your recommended set up with the P3+ and have yet to better the SQ this set up puts out. If you are using ADA4267's in L/R what buffer and ground set up do you recommend?

As your 1st, for OPA637s, I always use 3ch architecture.
Given with 4 channel, I'll use with R19 as 100 ohms and single 634P on G_CH, no stacking.

L/R buffers what I'm using now for ADA4627 are HA-5002 adapter (we'll release later) on above, 2-stacked BUF634Us on bottom side.

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif Also I find big hiss with 4 channel compared to 3......

I'm thinking this as caused by arrangement of LT1210.
Can you get rid of R20 and jumper it?
Let me know result of your trial

Added----
Also, are you using default caps on C1-C2?

 

[jamato8]

You don't think that stacking the 634U on the underside will get the 634U too warm as thee wouldn't be any real air gab between the stacked buffers?

Ryuzoh, what do you think is the max wattage output for the fi.Q?

 

[ryuzoh]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif You don't think that stacking the 634U on the underside will get the 634U too warm as thee wouldn't be any real air gab between the stacked buffers? Ryuzoh, what do you think is the max wattage output for the fi.Q?

I'm going to use stacked 634s without wideband mode (SW1 OFF) as like newest Supermacro IV.
So, they won't get warm, needless to give air gaps.
Because stacking is used for achieve lower distortion as making afford to give more currents to load.
Why I don't simultaneously use wideband mode and stacking will be understood when you actually use.

This is measuring THD+N and 12 ohms loading wattage

 

[jamato8]

Then you could also stack two on an adapter on top or use two adapter that are socketed, like some I have from Xin and have 4 stacked BUF634U with none under the board.

The THD is very low. That is 1 watt into 12 ohms. There are so many variables in frequency and load. I wonder what to expect as an average wattage or current with a voltage of 18 or 24?

 

[SpudHarris]

Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif The switches on above side will set for...... SW1; BUF634 Wideband mode ON/OFF with 200 ohm connection btwn 1-4 pin. SW2; Output impedance changing switch (aka A47), and will improve stability for unstable OPAMPs, also changes proportion of output currents from buffers and OPAMPs.(Highly recommended to set this ON) Output current proportion When ON, OPAMP : BUF on front : BUF on bottom = 1 : 1 : 1 (OPAMP works 1/3), can achieve less distortion, stability. When OFF, OPAMP : BUF on front : BUF on bottom = 1 : 5 : 5 (OPAMP works 1/11), can provide more driveability for low efficient headphones. If you mind the hiss, are you using with default setting?

Man so many questions to ask............

My amps is standard, I assume the missing caps will be added when maxxed out?

Can you not use switch one with stacked 634's? (top/bottom or both) or is that a preference thing.

I have 4 x 634U's and may well stack them underneath at some point today. However as this is a somewhat perminent mod I wondered how this would limit what type of buffers are used above?

I still prefer 4 channel to 3 but havent got rid of R20 and jumpered it yet I'll try this if the hiss bugs me but when the musics on I don't hear hiss, just beautiful 'Full Bodied' glorious tunage

 

[slwiser]

Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif I already tried ADA4627-1(A and B), which gives precise sound stage and focusing 3D sound...I think this is so suitable with E8. And LME49710/20 always go with this amp

These are the two opamp that I was thinking of listening to when I get around to changing the default configuration. Do either of these or both require something more than a change out of the default opamp to implement them; i.e., different buffers, resistors or internal settings? Does it require more than a simple insertion to change the opamps?

I will be using this primarily with my UE9s.

Have you shown an internal picture of the default amp yet? I have seem various configurations but have not seen one that seems to be the default. I have yet to open my amp up, BTW.

Thanks

 

[qusp]

boxing day at the beach was pretty nice

sound is powerful yet articulate and wide with 2 x OPA827 on this adapter its decoupled with silmic II bypassed with vishay COG 0.1uf, just wrapped the silver ground wire around the ground terminal of the power rail caps for now

I have a silmic II on the other side as well, but for these pics hadnt sorted out how I would fit it in the amp with both. i'm still running stock caps in the amp bar the UTSJ 10000uf, will be installing a few nichicons tomorrow and when everything else arrives i'll go to town on the amp and power supply/wall-wart. I
also have this 2 x OPA211 with blackgate and vishay COG, with custom cryo silver pins, but the BG wont fit like this and also the 22uf NXHQ is only rated to 6.3v, thought I would show it anyway as it shows what is possible with these adapters

and the underside with silver pins

and these are the diamond buffers with sanyo oscon SVP SMD, with temporary adapters on the end till I work out placement properly. i'll still leave the sockets in the amp to allow me to keep fiddling, but will simply push the SCSCAg directly into the sockets to save a little space

as you can see I dont mind a little cardas flux for SMD soldering

its noclean so its no drama, will clean it up soon, when I can be bothered, as the white PCB certainly shows it off

here they are fitted bar the grounding

as you can see its a little tight, but doable and i'll still be able to fit the upgraded caps in the amp. If things get really squeezy I have some lower profile organic polymer caps from AVX, not cheap either; I have a few spare from my ackodac build. I built another 2 pairs of these buffers as well; a pair with 100uf Nichocon FG and another pair with some pansonic bypassed with 0.1uf BG; no chance those ones will fit though. I could probably fit the Nichocon ones with some coaxing and with just plugging the wires directly into the sockets. the input filter has been omitted for now, will leave it out unless needed

and the gaggle of parts for my (not so) discrete rig and a ring-in

i'll find a way to fit the Burson discrete opamp in there somehow, but not for a little while

so Ryuzoh, i'm assuming this rather errrmm 'star-like' formation on the underside of the board at the UTSJ is the star-ground? certainly would seem right and it couldnt look more like a star if you tried

I flipped the board over to have a look and that kind-of stood out to me. I wasnt expecting anything so 'X marks the spot' if its not the star-ground for the whole amp, it surely is for the power supply

so yeah loving the amp with OPA827 in OP and 2xstack of BUF634P in buf (till I work out the SSB01 grounding) i'l stick some 634u on the bottom even if i'm running the discrete buffers. thinking I may even whack some OPA211AID on the bottom there actually. really want that much of a fan of the LME49720HA in there myself. having to use the amp in high gain just wasnt doing it for me. on low gain it was for lack of a better word; a little dull. bass was really lacking IMO. sounded grea5t in high gain, but thats just not practical, pity because I really like that chip. will see what its like in ground and give it another try when the buffers are installed.

for the moment OPA827 wins hands down

so can I confirm that the switches are ON when the switch is pushed towards the word ON? or away from ON? if towards the amp came supplied without the BUF in high current mode.

and what you said to Theory87 regarding the unbalanced bypasses. you just meant that the supplies to each chip needed to be the same in value yes? not that each pair of C2/CP2 C3/CP3 C4/CP4 had to be identical caps, only that C2=C3=C4 and CP2=CP3=CP4 etc correct?

i'm withholding my detailed impressions until I get my head around the sound some more and do a bit more tweaking. then i'll compare against a certain other portable in my stables

 

[ryuzoh]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif My amps is standard, I assume the missing caps will be added when maxxed out?

Sure.
Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif Can you not use switch one with stacked 634's? (top/bottom or both) or is that a preference thing.

No. because that's meaningless.
And just pulling out 634Ps can achieve it.
Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif I have 4 x 634U's and may well stack them underneath at some point today. However as this is a somewhat perminent mod I wondered how this would limit what type of buffers are used above?

I'll do it for you when I max it out.
Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif I still prefer 4 channel to 3 but havent got rid of R20 and jumpered it yet I'll try this if the hiss bugs me but when the musics on I don't hear hiss, just beautiful 'Full Bodied' glorious tunage

I think that should be fixed immediately.

Quote:

Originally Posted by slwiser /img/forum/go_quote.gif Do either of these or both require something more than a change out of the default opamp to implement them; i.e., different buffers, resistors or internal settings? Does it require more than a simple insertion to change the opamps?

No, they don't require any changing from current circuit

Quote:

Originally Posted by slwiser /img/forum/go_quote.gif Have you shown an internal picture of the default amp yet? I have seem various configurations but have not seen one that seems to be the default. I have yet to open my amp up, BTW.

Sorry, I didn't received any default setting amps.
Because iBasso said several FG caps had damaged and required to be omitted, then I proposed to get omitted version.
So, if you could, uploading from you will be pleased.

Thanks

 

[ryuzoh]

Quote:

Originally Posted by qusp /img/forum/go_quote.gif so Ryuzoh, i'm assuming this rather errrmm 'star-like' formation on the underside of the board at the UTSJ is the star-ground? certainly would seem right and it couldnt look more like a star if you tried

Yes, that's it.
Quote:

Originally Posted by qusp /img/forum/go_quote.gif so can I confirm that the switches are ON when the switch is pushed towards the word ON? or away from ON? if towards the amp came supplied without the BUF in high current mode. and what you said to Theory87 regarding the unbalanced bypasses. you just meant that the supplies to each chip needed to be the same in value yes? not that each pair of C2/CP2 C3/CP3 C4/CP4 had to be identical caps, only that C2=C3=C4 and CP2=CP3=CP4 etc correct?

Towards the word ON, and default is set as OFF both.

Rail section
C1=C6=CP4=C10
C2=C5=CP3=C11

Isolated OPAMP section
C3=CP1=C13
C4=CP2=C12

 

[SpudHarris]

Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif I think that should be fixed immediately

Thanks Ryuzoh,

Do you mean that will fix it immediately? OR I think that should be fixed immediately? (as in if you don't there will be a problem). The hiss isn't bad enough to effect my listening experience but if you are sure removing and jumping R20 will cure it then I'll do it. Thanks for assisting Ryuzoh, much appreciated