So I connected my DAC through my DCB1 buffer instead of the LDR3x (passive LDR) since as per LC, the input impedance of the FO is too low for a passive such as LDR. For me, it made a night and day difference in the bass section (still not exactly where I want it to be but adding the extra caps on the power supply will surely get me there. Soundstage is quite nice. I have to run a few listening sessions but it is quite good as it is.
The only thing I don't love about the DCB1, even though it has a great soundstage and details it adds its own sound signature and you can tell, compared to the LDR which is very transparent. So I will try and find another preamp to test. I am thinking of LC's preamp, the Salas DCG3, BPBP, etc... Just looking for something that disappear between the DAC and amplifier...
Thanks
Do
The only thing I don't love about the DCB1, even though it has a great soundstage and details it adds its own sound signature and you can tell, compared to the LDR which is very transparent. So I will try and find another preamp to test. I am thinking of LC's preamp, the Salas DCG3, BPBP, etc... Just looking for something that disappear between the DAC and amplifier...
Thanks
Do
The dcg3 is quite a bit better than the dcb1.. I have both.
It just "gives more" and at the same time disappear more.. 🙂
It just "gives more" and at the same time disappear more.. 🙂
ok nice!
I bought the PCBs and matched transistors so I'll order the parts and assemble it.
Thanks
Do
Hi Do !
so, seems the diyaudio experience is about seeking for the cleaner dac and best ever amp and then finally adding preamp which suits our ears and taste 😕 I m (we are) not finished then
lolI recently saw the same approach around the ncore by NordOne, adding a classA preamp inside... then my conclusion would be : lets go with FO and invest the money saved in other component of the audio chain 😉
cheers
Yesterday we had a party with FO L and I was blown with the bass authority given by the DAC having (each channel) OPA1632 plus two LT1010 (both LT1010 in OPA1632 feedback) on DAC's output. For volume control we were using Roon's -80-0 dB DSP volume slider. Definition and mass of the bass were unearth like.
L.C.
L.C.
Hi LC,
I take it it was 2 LT1010 to drive only one output, and not two outputs.
In that case, two LT1010 in parallel configuration must be terrific re drive, given one can already drive almost anything we need.
Your feedback is interesting, as I would have expected the LT1010 to colour the sound quite a bit of the OPA1632.
LC, it seems for whatever reason that the FOs are very sensitive to the preamp's output impedance. I was surprised to read that people who carried tests with 2.5k or even much less preamp output impedance (passive 10k resistive volume control, or even simple active buffer) where struggling, apparently even when increasing the FO's low imput impedance to 20k.
That's a bit strange (as with short suitable cables inside an integrated amp it should still be OK on the paper with a ratio less than the 1:10 "blindly" recommended). It is also sad : a nice passive pre can be so nice sounding for such little money compared to active preamps. And makes more sense than boosting again a signal... to attenuate it afterwards.
Can anything be done to help the FO cope suitably (without any sonic quality loss) with a 10k resistive pre, when having say less than 60cm total cable /connection length between them (from attenuator ouput pin to FO board input) ?
Thanks for the interesting feedback and perhaps that gives you ideas re your planned (?) DAC/pre...
Claude
I take it it was 2 LT1010 to drive only one output, and not two outputs.
In that case, two LT1010 in parallel configuration must be terrific re drive, given one can already drive almost anything we need.
Your feedback is interesting, as I would have expected the LT1010 to colour the sound quite a bit of the OPA1632.
LC, it seems for whatever reason that the FOs are very sensitive to the preamp's output impedance. I was surprised to read that people who carried tests with 2.5k or even much less preamp output impedance (passive 10k resistive volume control, or even simple active buffer) where struggling, apparently even when increasing the FO's low imput impedance to 20k.
That's a bit strange (as with short suitable cables inside an integrated amp it should still be OK on the paper with a ratio less than the 1:10 "blindly" recommended). It is also sad : a nice passive pre can be so nice sounding for such little money compared to active preamps. And makes more sense than boosting again a signal... to attenuate it afterwards.
Can anything be done to help the FO cope suitably (without any sonic quality loss) with a 10k resistive pre, when having say less than 60cm total cable /connection length between them (from attenuator ouput pin to FO board input) ?
Thanks for the interesting feedback and perhaps that gives you ideas re your planned (?) DAC/pre...
Claude
Oh, just noticed the OPA1632 wasn't a usual op amp, but a differential one with 2 outputs - understand better the 2 LT1010 now: one at each end, hence full differential from the DAC chip's output to the DAC's unit output...
Guys,
When you have done all your mods and matched the F.O. with suitable equipment and when you are happy with the sound (bass, sound-stage...etc) do yourselves a favor and google for "symmetrical power" or "balanced power" and check at equitec.com the feedback from the pro users.
Sorry to insist but clean, unlimited power is essential.
Cheers,
M.
When you have done all your mods and matched the F.O. with suitable equipment and when you are happy with the sound (bass, sound-stage...etc) do yourselves a favor and google for "symmetrical power" or "balanced power" and check at equitec.com the feedback from the pro users.
Sorry to insist but clean, unlimited power is essential.
Cheers,
M.
I finally decided to purchase the following :
4x Kemet ALS30A103DE063
10000uF 63V
ESR = 17 mOhm @ 100Hz
Ripple Current = 10.8A @ 100Hz
Impedance = 14 mOhm
Lifetime = 5000 Hrs @ 85°C
Keep you posted!
Do
4x Kemet ALS30A103DE063
10000uF 63V
ESR = 17 mOhm @ 100Hz
Ripple Current = 10.8A @ 100Hz
Impedance = 14 mOhm
Lifetime = 5000 Hrs @ 85°C
Keep you posted!
Do
Yes, for the extra cap bank. I'm using 2x Cresnet SMPS which are actually doing a very good job with the FirstOne (once I added the DCB1 buffer instead of the LDR due to the very low input impedance of the FO 1.4) but I want to experiment with additional caps and hear the difference.
Thanks
Do
Guys, sorry for the slightly off topic post (but hey, it's for the better sake of the F.O.)
Today I finally swapped my old balanced power transformer (BPTx; only 1KVA from local technician) for my new 2,5KVA BPTx ordered from a national maker of repute. As you may know the most important feature is that the dual secondaries (0-110/0-110 in my case) must be strict bifilar windings.
(see equitec.com for technical info and expected results)
The Tx plus the iron box must weigt around 50Kg 😱
The improvement is significant to say the least, scarry sometimes. Best USD $300 spent in ages.
You haven't heard your amp yet if you connect it to the wall...
The amp is sounding better and better without direct intervention, only by improving the supplied energy...great work Lazy Cat.
I run the source with another smaller balanced power Tx in series. Now I will use the old 1KVA Tx to isolate the sources. 😎
I hope this helps.
M.
Where did you buy these things for 300$ USD? They seem to only sell stuff at 2000$ USD and more... Which model did you buy?
Thanks
Do
Do,
Are you using Cresnet SMPS-600? Please check following post from Cresnet on max capacitance support for SMPS-600:
http://www.diyaudio.com/forums/vend...-mosfet-amplifier-module-359.html#post4950368
I believe someone has done it with the Cresnet, worst case scenario, I'll cut the capacitor in half for 5000uF... 😉
As I explained, find a reputed local maker, ask him to custom build you an isolation TX for "medical equipment" with split dual secondaries strictly bifilar windings and see how much you can save. Then wire as per equitec's instructions and voilà! In my case 2.5KVA, 220 to 2*110V.
Maybe not exactly the same as the inventor's but great anyway... 😎
Good luck.
M
