Nicwix
Survey says....
- Joined
- Aug 5, 2001
- Posts
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Exciting Times: Discussion on Portable amp for low impendence phones
The story so far ...
I started the Headwize thread thread on Headwize (id 2703): Best opamp-buffer combination for a portable multi-loop amp for low impedence phones assuming the multi-loop configuration was in fact the answer to my needs. I also placed a cross-reference thread in this Head-Fi forum - thread 12157 ).
The only real variables that I was concerned about were which opamp and buffer and buffer would be best to use.
This developed into a discussion on well various chips performed at lower voltages (as per datasheets or actual testing) and the associated current requirements, and hence battery capacity needs and options.
At that point PRR replied with a few helpful comments, such as:
Quote:
Aghast to discover my requirements were unsynergistic
, I restated the design goals as:
1. high-end sound quality
2. small, portable package (board and battery)
3. good battery life (say 20 to 40 hours)
3. high current capability
4. as minimalist as possible (I like to know what each component is there for)
5. reasonable cost and easy to source components
6. relatively easy to build and package
PRR also seemed to be questioning the need for loops.
In his response, PRR went then on record saying he was "not convinced it [the multi-loop topology] is best". No wilting violet is our PRR.
PRR then suggested some simplified output configurations (not full designs) and later suggest that the LMH6642/6643/6644 3V, Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers might be worth trying.
I expressed my concern about the output impedence of buffers (specifically the EL2001) without feedback - which led to PPR suggesting that the EL2001 was an old design that had limitations - this pricked some holy cows indeed.
At that point Morsel though her hat into the ring (
- Morsel sans hat), then ppl weighed in big time.
The discussion continues hotly in the Headwize thread.
We look forward to the ongoing debate - anyone else willing to venture an opinion?
In the meantime, tangent has kindly pointed out that the META42 does meet the stated requirements pretty well (at least in the opinion of some)!!!
Nix
ps (Added after tangent's post below) The various smilies in this post (actually I maxed out the smilies) are intended to clarify that this whilst poking a bit of fun around, only goodwill is felt towards all participants - and though we may have heated debates, we will still remain friends.
All the best - Nix
The story so far ...
I started the Headwize thread thread on Headwize (id 2703): Best opamp-buffer combination for a portable multi-loop amp for low impedence phones assuming the multi-loop configuration was in fact the answer to my needs. I also placed a cross-reference thread in this Head-Fi forum - thread 12157 ).
The only real variables that I was concerned about were which opamp and buffer and buffer would be best to use.
This developed into a discussion on well various chips performed at lower voltages (as per datasheets or actual testing) and the associated current requirements, and hence battery capacity needs and options.
At that point PRR replied with a few helpful comments, such as:
Quote:
"I don't know what "multi-loop" is doing in there; you want good sound, not a certain number of loops." "Your requirements are not synergistic." and "You can get ample speed and current with 2V total supply, IF you design for it. Putting on more voltage to overcome losses in a circuit not optimized for low voltage speed/current is just wasteful." |
Aghast to discover my requirements were unsynergistic
1. high-end sound quality
2. small, portable package (board and battery)
3. good battery life (say 20 to 40 hours)
3. high current capability
4. as minimalist as possible (I like to know what each component is there for)
5. reasonable cost and easy to source components
6. relatively easy to build and package
PRR also seemed to be questioning the need for loops.
PRR then suggested some simplified output configurations (not full designs) and later suggest that the LMH6642/6643/6644 3V, Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers might be worth trying.
I expressed my concern about the output impedence of buffers (specifically the EL2001) without feedback - which led to PPR suggesting that the EL2001 was an old design that had limitations - this pricked some holy cows indeed.
The discussion continues hotly in the Headwize thread.
In the meantime, tangent has kindly pointed out that the META42 does meet the stated requirements pretty well (at least in the opinion of some)!!!
Nix
ps (Added after tangent's post below) The various smilies in this post (actually I maxed out the smilies) are intended to clarify that this whilst poking a bit of fun around, only goodwill is felt towards all participants - and though we may have heated debates, we will still remain friends.
All the best - Nix