[ROBSCIX]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif I posted the monstrosity a few days ago... http://www.head-fi.org/forums/f6/opa...ml#post6054301 I haven't tried the Class A with any modules in the past several days.

Sorry must have missed that. Must have to do with the pages of garbage being posted one after another.
I figured you had a dual To-99 adapter. I guess that would work also for testing. Post your impressions if you try class A on this unit.

 

[ecclesand]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif Sorry must have missed that. Must have to do with the pages of garbage being posted one after another. I figured you had a dual To-99 adapter. I guess that would work also for testing. Post your impressions if you try class A on this unit.

The kids aren't home from school yet and I'm done with work for the day so I decided to class A the 49710HA module. Forgive the crappy mounting, but it was my only option considering the opamps were already mounted on the adapter.

They get very warm, I can hold my finger on top of each can for about 5 seconds. The max temp for these is 85 degrees Celsius so who knows. They do sound livelier than the non biased module.

EDIT: The resistors are both 2.2k. I believe one is rated at 1/2W and the other at 1/4W. I only had one of each left. The bottom end is definitely tighter with the biasing...very snappy. Someone else should try this to see how much heat they get from these.

 

[leeperry]

Quote:

Originally Posted by extraordinary machine /img/forum/go_quote.gif BTW the OPA2132P is very decent... but I would go with 2x OPA132UA which sound veeery good.

considering how the 2134P is a major downgrade compared to the 2132P, I've got a hard time believing that 2*OPA132UA would sound better than 2*OPA132U(that totally lack the great bass response of the 2132P)

it seems that bass is very hard to output for an op-amp(compare the 49720NA w/ his inexistent low end bass to the 49720HA where it's overwhelming)....maybe the DIP package actually shields some EMI/RFI the browdog's simply don't

anyway the "magic" mids of the 2132P were very audible to me whatever on the DT770/600Ω and the STX/ST or the cd1k on the HD2...so it wouldn't appear to be that much environment dependent.

my hopes towards browndog's are very low, I'll try the 4*1363/1028 to replace my 2*1364 LPF...but from what Slash47 said my best option would be to replace the 2132P buffer by a burson. a burson is 50 EUR basically(and I already have fully gold plated DIP8 sockets), not too pricey

PS: maybe I'll try to replace the 2132P by the 2111KP, this one was less impressive but more balanced..and still a bit magic

 

[ROBSCIX]

Quote:

Originally Posted by extraordinary machine /img/forum/go_quote.gif I can't see why you keep overlooking the LME49723. It's the sweet spot - for me - between the different deviations (from transparency) of the various LME49720NA, LME49860NA, LM4562NA. Maybe because it's priced at $ 0.70. The LME49720HA does sound a bit more dynamic and smoother, but... well I need to compare directly. I have the feeling that it'll be interesting...

Have you tried a dual LME49710HA module yet?

 

[ROBSCIX]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif The kids aren't home from school yet and I'm done with work for the day so I decided to class A the 49710HA module. Forgive the crappy mounting, but it was my only option considering the opamps were already mounted on the adapter. They get very warm, I can hold my finger on top of each can for about 5 seconds. The max temp for these is 85 degrees Celsius so who knows. They do sound livelier than the non biased module. EDIT: The resistors are both 2.2k. I believe one is rated at 1/2W and the other at 1/4W. I only had one of each left. The bottom end is definitely tighter with the biasing...very snappy. Someone else should try this to see how much heat they get from these.

I may try it here soon but I am in the process of ordering a bunch of new parts for my parts bin so I will have to wait until I put in the next order.
I have been considering checking this out to hear the difference.
Thx for the info...

 

[levin]

is there a compliation of list of opamps people are using? would be nice if there was a breakdown of different companies opamp numbers and etc.

 

[SpudHarris]

Quote:

Originally Posted by extraordinary machine /img/forum/go_quote.gif DON'T DO THAT! What? You want to make the LME49710HA even smoother? Really, this is one of all those modern opamps for which that trick does only harm... Plus you completely screwed up the resistor value.

What resister value then? I've always used 2.2k as that's what Ron kerlin (Hiflight) told me to use. FWIW I don't get too much heat from mine in my P3+ headphone amp. Set up is different as I have 2 x single sockets so use 2 x 49710's in Class A adapters.

 

[ecclesand]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif What resister value then? I've always used 2.2k as that's what Ron kerlin (Hiflight) told me to use. FWIW I don't get too much heat from mine in my P3+ headphone amp. Set up is different as I have 2 x single sockets so use 2 x 49710's in Class A adapters.

I got my Lite DAC-AH yesterday and modded it by replacing some resistors, adjusting vref, and adding opamp sockets for rolling. I want to play with opamps before going to a passive output. Luckily the output stage consists of 2 single channel opamps. I'm currently waiting on some OPA627s. I will order some more LME49710HAs and bias them to class A but on single adapters and then test them on the Lite. On the module in the picture, I added a copper heatsink to the 2 49710s using some 3M thermal tape and it's working quite nicely.

By the way, this DAC-AH sounds very good modded. I'm running it with two LT1357s until the 627s arrive.

 

[ROBSCIX]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif I got my Lite DAC-AH yesterday and modded it by replacing some resistors, adjusting vref, and adding opamp sockets for rolling. I want to play with opamps before going to a passive output. Luckily the output stage consists of 2 single channel opamps. I'm currently waiting on some OPA627s. I will order some more LME49710HAs and bias them to class A but on single adapters and then test them on the Lite. On the module in the picture, I added a copper heatsink to the 2 49710s using some 3M thermal tape and it's working quite nicely. By the way, this DAC-AH sounds very good modded. I'm running it with two LT1357s until the 627s arrive.

So both you and Spudharris are using them in class A config?
I like the 627's and I am considering building a matched pair of TO-99's for both the 627's and 637's. I wonder if the extra heat is because of the dual config or if there is extra heat when using in single channel module also. Will have to ask.

 

[ROBSCIX]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif What resister value then? I've always used 2.2k as that's what Ron kerlin (Hiflight) told me to use. FWIW I don't get too much heat from mine in my P3+ headphone amp. Set up is different as I have 2 x single sockets so use 2 x 49710's in Class A adapters.

Your using the LME49710HA in a single channel circuit and the heat is acceptable? I know the class A bias would generally produce more heat and all opamps produce heat anyway.
The questions is, is this heat from normal operation or is there some other issue?
Your using them baised to class A in a single channel circuit position and you say the heat is not too excessive.
Ecclesand, is using a dual channel module biased to class A and says there is quite a bit of heat.
Just wondering if the heat is from the dual channel module. I am going to have to do some testing....

 

[SpudHarris]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif Your using the LME49710HA in a single channel circuit and the heat is acceptable? I know the class A bias would generally produce more heat and all opamps produce heat anyway. The questions is, is this heat from normal operation or is there some other issue? Your using them baised to class A in a single channel circuit position and you say the heat is not too excessive. Ecclesand, is using a dual channel module biased to class A and says there is quite a bit of heat. Just wondering if the heat is from the dual channel module. I am going to have to do some testing....

I don't have any dual channel converters like that one as my P3, P3+ and my PPA are all single channel sockets. Unfortunately I only have one OPA627 which was ground in my PPA, I have 4 x 637's but they are unstable in my favourite amp (P3+). Nothing gets overly hot with Class A chips in my P3+.

Started listening to the Ultimae Fahrenheit Project Collection last night and rolled some Opamps to suit this Genre (Ambient Trance), the LT1028's are all over this genre and then some

 

[ROBSCIX]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif I don't have any dual channel converters like that one as my P3, P3+ and my PPA are all single channel sockets. Unfortunately I only have one OPA627 which was ground in my PPA, I have 4 x 637's but they are unstable in my favourite amp (P3+). Nothing gets overly hot with Class A chips in my P3+. Started listening to the Ultimae Fahrenheit Project Collection last night and rolled some Opamps to suit this Genre (Ambient Trance), the LT1028's are all over this genre and then some

The 637 don't have internal compensation so they need fairly high circuit gain to operate properly. They are one of my favorites and I am considering building matched sets of both 627 and 637 TO-99 modules.
So if you don't notice any excess heat in single channle circuit perhaps the issue is the dual channel module. Really though, looking at it as a circuit; the only thing that is shared between the two LMR49710HA chips is the power and gnd rails.
Maybe it is not the biasing and is something else.
I have the LT1028's on my list of opamps to test.

 

[ROBSCIX]

Quote:

Originally Posted by ecclesand /img/forum/go_quote.gif I got my Lite DAC-AH yesterday and modded it by replacing some resistors, adjusting vref, and adding opamp sockets for rolling. I want to play with opamps before going to a passive output. Luckily the output stage consists of 2 single channel opamps. I'm currently waiting on some OPA627s. I will order some more LME49710HAs and bias them to class A but on single adapters and then test them on the Lite. On the module in the picture, I added a copper heatsink to the 2 49710s using some 3M thermal tape and it's working quite nicely. By the way, this DAC-AH sounds very good modded. I'm running it with two LT1357s until the 627s arrive.

When you tested the LME49710HA module without the biasing, did you notice any excess heat?

 

[leeperry]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif rolled some Opamps to suit this Genre (Ambient Trance), the LT1028's are all over this genre and then some

any chance for a 1028<>1364 shootoot for vocals? the 1678 stinks compared to the 1364 on that point..

 

[lu-chen-chan]

Hello in the future i will certainly buy ibasso D10 to my Livewires , and i will want to switch OPA, to make sound more warm and bassy , can you advice me some good OPAs?