So you are recommending SI 990 . Are these 990EnH-Ticha pro Opamps.
I just asked VTV and they are recommending 995FET-Ticha Discrete Opamps.
Do you have experience of using 990’s or its just your opinion.
How do they differ from 995 .
And how do I select Unregulated power supply to the input boards. I am sure VTV must have set the power supply correctly when the amps were sent to me with Sparkos.
Or is it different setting for Sparkos and Sonic Imagery.
Yes I agree that it’s fun. But only if I was in USA. Sitting in Thailand I have to pay shipping and import taxes every time I import. I will let you know the outcome after I decide which way to go.
VTV is recommending Sonic Imagery 995.
choice...
The SMPS 1200, should be set for the unregulated output on the aux output. See the data sheet for the SMPS 1200 to see how the jumpers are set for regulated vs. unregulated output to confirm. You can download the data sheet from Hypex. I mention this because one amp, from a well known manufacturer, came to my workbench with the outputs from the the two SMPS 1200s set to regulated, when this amp used an input module with its own regulators, and expecting unregulated ~+/- 18 VDC input! Needless to say this amp was not working correctly, as the very nice discrete regulators were receiving 12 VDC input, and being asked to produce regulated 12 VDC output, of course they could not. If this was set wrong, it could explain why the amp is not sounding right to you...
As to SI 990 vs. 995, that would be up to you to decide. I would expect different sonic flavors from each, but which one you might prefer I would not know. The 990 appears to have the better objective performance, and I would choose the 990 for that reason. You seem to like the NC-400, it uses a discrete, all BJT input stage design (not FET), so you might prefer a non FET type OPA input stage, the 990...
I am running the Eval board on my Purifi amp, and it certainly does not sound bad, and I do not prefer the sound of my NC-400 amp to the Purifi.
BTW, you could also mount up the 1612 OPAs used in the Eval board with your VTV input boards, you just need to pick up some 1612 OPAs mounted to DIP 8 adapters, and these are pretty affordable to try. This way you could get a baseline for what the Purifi sounds like with the same OPA used in the Eval module. See the 1612 on adapter here:
OPA1612 Dual OPA DIP8 (Unit) - Audiophonics
The SMPS 1200, should be set for the unregulated output on the aux output. See the data sheet for the SMPS 1200 to see how the jumpers are set for regulated vs. unregulated output to confirm. You can download the data sheet from Hypex. I mention this because one amp, from a well known manufacturer, came to my workbench with the outputs from the the two SMPS 1200s set to regulated, when this amp used an input module with its own regulators, and expecting unregulated ~+/- 18 VDC input! Needless to say this amp was not working correctly, as the very nice discrete regulators were receiving 12 VDC input, and being asked to produce regulated 12 VDC output, of course they could not. If this was set wrong, it could explain why the amp is not sounding right to you...
As to SI 990 vs. 995, that would be up to you to decide. I would expect different sonic flavors from each, but which one you might prefer I would not know. The 990 appears to have the better objective performance, and I would choose the 990 for that reason. You seem to like the NC-400, it uses a discrete, all BJT input stage design (not FET), so you might prefer a non FET type OPA input stage, the 990...
I am running the Eval board on my Purifi amp, and it certainly does not sound bad, and I do not prefer the sound of my NC-400 amp to the Purifi.
BTW, you could also mount up the 1612 OPAs used in the Eval board with your VTV input boards, you just need to pick up some 1612 OPAs mounted to DIP 8 adapters, and these are pretty affordable to try. This way you could get a baseline for what the Purifi sounds like with the same OPA used in the Eval module. See the 1612 on adapter here:
OPA1612 Dual OPA DIP8 (Unit) - Audiophonics
Thanks barrows for such a detailed reply giving me various options.
I talked to VTV and he said SMPS 1200 are set correctly to unregulated power supply. Anyway I will check also as per your description and checking the technical details on their website.
As suggested I will should be first trying the OPA you mention are used on Eval board 1612. Thanks for sending me the link.
Will let you know the results.
I just saw that 1612 has 8 pins. But my Sparkos has 6 pins. How will I install 1612 in VTV board ?
I think this 1612 will go into the other socket of 4+4 pins in the middle of the board. So in that case will I be needing 4 OPA 1612 for two mono Amplifiers just like Sparkos. Will it need any other setting changes ?
I talked to VTV and he said SMPS 1200 are set correctly to unregulated power supply. Anyway I will check also as per your description and checking the technical details on their website.
As suggested I will should be first trying the OPA you mention are used on Eval board 1612. Thanks for sending me the link.
Will let you know the results.
I just saw that 1612 has 8 pins. But my Sparkos has 6 pins. How will I install 1612 in VTV board ?
I think this 1612 will go into the other socket of 4+4 pins in the middle of the board. So in that case will I be needing 4 OPA 1612 for two mono Amplifiers just like Sparkos. Will it need any other setting changes ?
Last edited:
The OPA 1612 is a dual opamp, so you only need one per input board. It mounts to the 8 pin DIP socket in the middle of the board. Whatever you do, make sure you mount it the right way, bad things will happen if the pins are not properly matched (find pin 1 on the socket and opamp) and make sure they align).
If you try the OPA 1612 this way, please report here what differences you hear in sound vs. the Sparks you have now. I am sure many will be interested in your comparison.
If you try the OPA 1612 this way, please report here what differences you hear in sound vs. the Sparks you have now. I am sure many will be interested in your comparison.
I confirmed with SMPS1200 data sheet. It’s set at unregulated position 2&3 in J6 and J7
Attachments
Thanks for this important information about connecting 1612 . Pin 1 to socket 1. I hope numbering is their both on OPA and socket.
I have already sent a mail to audiophonics about 1612.
If you are sure than I can order straight away on the website.
I will need 4 of them just like 4 Sparkos in my two monoblocks.
Ok thanks a lot. It means I will be needing only 2 pieces of 1612 to replace 4 pieces of Sparkos. That’s even better.
Yes I checked the input buffer just now and there is scope for only one 1612 on each board.
It works out much cheaper option and who knows better also.
Will definitely let you know the results.
Yes you are correct . I checked the input board and there is scope for one 1612 per buffer board. Thanks.
Will order tonight only and will let you know the results.
Already ordered 2 pieces of 1612 shipment by TNT. May be another5/6 days due to week end.
Last edited:
I checked the VTV buffer board, there is no numbering on the 8 hole socket . But I see a V shape marking on the socket and V or U shape cut on the 1612 OPA. May be these are meant for proper alignment. Just check it out on VTV buffer photo and 1612 photo on Audiophonics website.
Waiting arrival of 1612 OPA , I tried one more thing on the VTV buffer board.
I changed the Jumper setting to get extra 7 dB gain there by getting higher gain.
To my surprise this helped me getting little bit improvement in sound quality and some of the smoothness appears to have gone.
But I have to do some more listening before jumping to any conclusion.
I changed the Jumper setting to get extra 7 dB gain there by getting higher gain.
To my surprise this helped me getting little bit improvement in sound quality and some of the smoothness appears to have gone.
But I have to do some more listening before jumping to any conclusion.
Now after running the amps for almost 24 hours, I am sure by increasing the gain by 7db most of my problems appears to have been solved. Though sound is still a bit on the smoother side but there is no loss of dynamics anymore. Images are well defined and there is air around instruments and voices. Huge sound stage and big smooth dynamic sound. I would prefer a bit more reduction in smoothness. May be the change in jumper setting has changed some circuit of the signal which might need some burn in time. .
Normally change in gain should not impact the sound so much. I am surprised too.
Now the amplifiers are much better and listenable.
Normally change in gain should not impact the sound so much. I am surprised too.
Now the amplifiers are much better and listenable.
That is interesting. Perhaps this allows the front-end circuits in the op-amp to operate in a more linear region since the input voltage swing (for the same output) would be lower.
I've decided to start with the Neurochrome buffer for my build. I have been collecting parts, but haven't ordered the two chassis yet, so it will be late this year before they are making music.
I'm building them with a very beefy linear power supply, starting with a Toroidy 1500VA Supreme Audio Grade transformer for each monoblock. The transformers just arrived yesterday. These are pretty impressive with polished stainless steel cases, weighing in at 14Kg (31lbs) each.
Once I have them working, I'll start work on designing a couple more front-end boards to try. I'm thinking of something similar to the WHAMMY design (op amp driving a class A MOSFET stage) in a balanced configuration, and also a triode based design.
I've decided to start with the Neurochrome buffer for my build. I have been collecting parts, but haven't ordered the two chassis yet, so it will be late this year before they are making music.
I'm building them with a very beefy linear power supply, starting with a Toroidy 1500VA Supreme Audio Grade transformer for each monoblock. The transformers just arrived yesterday. These are pretty impressive with polished stainless steel cases, weighing in at 14Kg (31lbs) each.
Once I have them working, I'll start work on designing a couple more front-end boards to try. I'm thinking of something similar to the WHAMMY design (op amp driving a class A MOSFET stage) in a balanced configuration, and also a triode based design.
Today I got OPA1612 and have installed in my mono amplifiers.
These amps are really interesting very tiny in size, marked 1 near upper left pin and 8 near upper right pin and the notch is in the middle.
My initial impressions are very encouraging. Sound appears to be cleaner than Sparkos while maintaining the same warmth and soundstage. Let me put on some more hours to make a final conclusion.
My initial impressions about increasing the gain of Buffer board with Sparkos was not very correct. Some how I was not yet satisfied despite some improvements. Sound was not involving.
Jaytor nice to read about your project. Using Toroidy 1500VA audio grade transformer is really interesting. Few days back I read a review in Stereophile or May be TAS of an Amplifier for $10,000 using audio grade transformers with excellent results.
Do keep us posted about your project.
I have a feeling that may be 1612 OPA are better suited for Purifi.
I will have to wait and see.
These amps are really interesting very tiny in size, marked 1 near upper left pin and 8 near upper right pin and the notch is in the middle.
My initial impressions are very encouraging. Sound appears to be cleaner than Sparkos while maintaining the same warmth and soundstage. Let me put on some more hours to make a final conclusion.
My initial impressions about increasing the gain of Buffer board with Sparkos was not very correct. Some how I was not yet satisfied despite some improvements. Sound was not involving.
Jaytor nice to read about your project. Using Toroidy 1500VA audio grade transformer is really interesting. Few days back I read a review in Stereophile or May be TAS of an Amplifier for $10,000 using audio grade transformers with excellent results.
Do keep us posted about your project.
I have a feeling that may be 1612 OPA are better suited for Purifi.
I will have to wait and see.
