My original posts were buried in the Stax thread. This is the summery of some of the technical info. I will add the output cap test result by the end of next January (have to get those boutique caps first).
If you have done mods to your SRM-001 or have mod related info please contribute, some DIY'er might want to mod his/her SR-001 system to the "king of the portable" status.....
My mods/test will be done in five steps, related info/result will come out after each step is completed:
--A) General info about SRM-001 mods. This gives some idea what can be done to your little portable amp. (done)
--B) Opamp rolling. Info and test results of replacing opamps in the SRM-001. (done)
--C) Output capacitor testing. Different output capacitors can give very different sound, and you will notice it. (coming next spring. caps on order).
--D) Bias voltage test. Believe it or not, the circuit board has traces for an easy bias level change. We will see if lower bias will yield a super smooth sound for vocal....---- will skip this one due to the experiment in post #13, I will instead go toward modifications for driving SR-X.
--E) A tutorial with step by step pictorial instructions of how a full version mod is done. Apparently by then my SRM-001 will have too many extra test features and will be unfit for demenstrating how a general mod is done. I will need a fresh amp to complete the tutorial. So I have one slot open for an "full version (i.e. SuperFatCat) ", mod (8599, BlackGate eletrolytics, sonic/kimber output caps, etc). If you wish to get your SRM-001 modded and don't want to do it yourself, please PM me. The full mod package will be $150, it will also includ a RCA/mini adaptor made with Neutrik connectors and solid silver/teflon wire. Only accepting one amp, preferablely from within the US (for easy shipping). I will perform the mods and take pictures for the tutorial. Here are the conditions: 1)you Must also have a SR-003 and a stax 3XX series amp. 2) you must have a high grade CDP and silver IC's. 3) you will promise to provide a 500+ word feedback/report on how the modded SRS-001 compares to a SR-003/SRM-3XX combo. I know the SRM3xx should win but want to know the details.
--- update 1-13-08: there won't be a pictorial instructions, instead I will provide three to-do/parts-to-use list. The mod slot is still open, PM me if you are interested.
--- update 1-29-08: the mod slot has been taken by Larry the HeadphoneAddict
We still need reviewer with 003/3xx though, since Larry's amp is a SRM-1 which is too good for the SFC-001 to compete with. He will provide a report on the SFC vs. various $400 portable dynamic systems (phones+amp)
Where to find some of the info in this thread:
*Kevin Gilmore's info on 001's circuit layout (thanks a lot Kevin) -- post #8 (this page)
*info on battery power-- this post and post#71 (page 8)
*AC adaptor comparison-- post #23 (page 3)
*HeadphoneAddict's test of AA battery life on a stock 001 amp -- post #51-#55 (page 6)
*Heat dissipation of Q15 after SFC or UFC mod -- post #49 (page 5)
*opamp comparison test -- post #4 (this page)
*Interconnect to use -- post #40 (page 4)
*FC output cpacitor comparison test-- post #20 (page 2)
*FC input capacitor comparison test -- post #42 (page 5)
*FC to-do list -- post #47 (page 5)
*SuperFatCat input/output capacitor comparison test -- post #43 (page 5)
*SuperFatCat mod to-do list -- post #48 (page 5)
*FatCatUltra input/output capacitor comparison test -- post #44 (page 5)
*Ultra mod to-do list -- post #48 (page 5)
*sclee's modification to his amp -- post #29(page 3), #38 (page 4)
*Borisov's modification to his amp -- post #94 (page 10)
*SFC mod performed on HeadphoneAddict's 001-- post #74 (page 8).
*HeadphoneAddict's review on the modded 001 -- post #95 (page 10)
*catscratch's review on the 001 with SFC++RC mod (Rock/Classic)
some battery power info,for truely portable/on-the-go use:
The stock battery compartment configuration holds two AA Alkaline or NimH in series. There is quite a bit of sonic difference between using batteries and the 4.5V AC adaptor, the adaptor sound a lot sharper and a lot more detailed. If you want that clear sound while on the go (true portable, right?), you can convert the battery compartment from series to parallel configuration, and install two 14500 (AA size) Lithium-ion 3.7v rechargable in paralle. The voltage of lithium ion changes between 4.15V (full) to 3.3V (nearly empty), the 3,7V spec is kind of the average voltage. With two lithium ion in paralle you get 3.7V, 1500mAH~2200mAH (depends on the battery) power, which will give you at least a few hours of great sound (depends on whether you do the other mods and the kind of op-amp you use.).
Lithium batteries give the cleanest and most involving sound. This should be the first upgrade you want to consider, if you don't want to try anything thing else. Ultrafires 900mAH 14500's are less than $7 each and the charger is about $15. Get four batteries and one charger, convert the battery bay to parallel, then you will be all set
-- update 2-28-08: ****Caution!! DO NOT BUY the UltraFire protected 14500 li-ion rechargables, it will NOT fit into the 001's battery bay. After adding the protection circuit board, that battery is about 2mm longer than the standard AA, too long to use (strictly saying, the protected cells, being longer than 50mm, should not be called 14500 any more). The unprotected 14500, on the other hand, is the true AA size so can still be used. If you always use the dedicated charger for recharging and turn the amp off when the sound gets bad, the unprotected batteries should still be safe. Of course, the best and safest way to do it is find a open spot in the amp and add the protection board into the amp itself. ****
for more info, see post # 71
If you have done mods to your SRM-001 or have mod related info please contribute, some DIY'er might want to mod his/her SR-001 system to the "king of the portable" status.....
My mods/test will be done in five steps, related info/result will come out after each step is completed:
--A) General info about SRM-001 mods. This gives some idea what can be done to your little portable amp. (done)
--B) Opamp rolling. Info and test results of replacing opamps in the SRM-001. (done)
--C) Output capacitor testing. Different output capacitors can give very different sound, and you will notice it. (coming next spring. caps on order).
--D) Bias voltage test. Believe it or not, the circuit board has traces for an easy bias level change. We will see if lower bias will yield a super smooth sound for vocal....---- will skip this one due to the experiment in post #13, I will instead go toward modifications for driving SR-X.
--E) A tutorial with step by step pictorial instructions of how a full version mod is done. Apparently by then my SRM-001 will have too many extra test features and will be unfit for demenstrating how a general mod is done. I will need a fresh amp to complete the tutorial. So I have one slot open for an "full version (i.e. SuperFatCat) ", mod (8599, BlackGate eletrolytics, sonic/kimber output caps, etc). If you wish to get your SRM-001 modded and don't want to do it yourself, please PM me. The full mod package will be $150, it will also includ a RCA/mini adaptor made with Neutrik connectors and solid silver/teflon wire. Only accepting one amp, preferablely from within the US (for easy shipping). I will perform the mods and take pictures for the tutorial. Here are the conditions: 1)you Must also have a SR-003 and a stax 3XX series amp. 2) you must have a high grade CDP and silver IC's. 3) you will promise to provide a 500+ word feedback/report on how the modded SRS-001 compares to a SR-003/SRM-3XX combo. I know the SRM3xx should win but want to know the details.
--- update 1-13-08: there won't be a pictorial instructions, instead I will provide three to-do/parts-to-use list. The mod slot is still open, PM me if you are interested.
--- update 1-29-08: the mod slot has been taken by Larry the HeadphoneAddict
Where to find some of the info in this thread:
*Kevin Gilmore's info on 001's circuit layout (thanks a lot Kevin) -- post #8 (this page)
*info on battery power-- this post and post#71 (page 8)
*AC adaptor comparison-- post #23 (page 3)
*HeadphoneAddict's test of AA battery life on a stock 001 amp -- post #51-#55 (page 6)
*Heat dissipation of Q15 after SFC or UFC mod -- post #49 (page 5)
*opamp comparison test -- post #4 (this page)
*Interconnect to use -- post #40 (page 4)
*FC output cpacitor comparison test-- post #20 (page 2)
*FC input capacitor comparison test -- post #42 (page 5)
*FC to-do list -- post #47 (page 5)
*SuperFatCat input/output capacitor comparison test -- post #43 (page 5)
*SuperFatCat mod to-do list -- post #48 (page 5)
*FatCatUltra input/output capacitor comparison test -- post #44 (page 5)
*Ultra mod to-do list -- post #48 (page 5)
*sclee's modification to his amp -- post #29(page 3), #38 (page 4)
*Borisov's modification to his amp -- post #94 (page 10)
*SFC mod performed on HeadphoneAddict's 001-- post #74 (page 8).
*HeadphoneAddict's review on the modded 001 -- post #95 (page 10)
*catscratch's review on the 001 with SFC++RC mod (Rock/Classic)
some battery power info,for truely portable/on-the-go use:
The stock battery compartment configuration holds two AA Alkaline or NimH in series. There is quite a bit of sonic difference between using batteries and the 4.5V AC adaptor, the adaptor sound a lot sharper and a lot more detailed. If you want that clear sound while on the go (true portable, right?), you can convert the battery compartment from series to parallel configuration, and install two 14500 (AA size) Lithium-ion 3.7v rechargable in paralle. The voltage of lithium ion changes between 4.15V (full) to 3.3V (nearly empty), the 3,7V spec is kind of the average voltage. With two lithium ion in paralle you get 3.7V, 1500mAH~2200mAH (depends on the battery) power, which will give you at least a few hours of great sound (depends on whether you do the other mods and the kind of op-amp you use.).
Lithium batteries give the cleanest and most involving sound. This should be the first upgrade you want to consider, if you don't want to try anything thing else. Ultrafires 900mAH 14500's are less than $7 each and the charger is about $15. Get four batteries and one charger, convert the battery bay to parallel, then you will be all set
-- update 2-28-08: ****Caution!! DO NOT BUY the UltraFire protected 14500 li-ion rechargables, it will NOT fit into the 001's battery bay. After adding the protection circuit board, that battery is about 2mm longer than the standard AA, too long to use (strictly saying, the protected cells, being longer than 50mm, should not be called 14500 any more). The unprotected 14500, on the other hand, is the true AA size so can still be used. If you always use the dedicated charger for recharging and turn the amp off when the sound gets bad, the unprotected batteries should still be safe. Of course, the best and safest way to do it is find a open spot in the amp and add the protection board into the amp itself. ****
for more info, see post # 71