Hi Richard. I was out on a work trip and never ordered the OPA1655 I mentioned above but I have been looking at other opamps. Would most any single channel bipolar input opamp that is unity gain stable work for both positions? I saw the OPA1611 that has a bandwidth of 80Mhz but is unity gain stable. Would this be suitable for both opamp positions?
Thanks!
Thanks!
The OPA1611 would appear to be an excellent choice. You can use it in both positions.
I haven't tried it though.
Like most modern designs it is only available in SOIC or smaller so you'll need an adapter, or you can modify my board design to replace the DIP package with the SOIC package outline and fab the modified design yourself.
I haven't tried it though.
Like most modern designs it is only available in SOIC or smaller so you'll need an adapter, or you can modify my board design to replace the DIP package with the SOIC package outline and fab the modified design yourself.
Richard, thanks again for the excellent support on your project/design. I have several SOIC adaptors and I was thinking that some of then newest opamp designs might work well and sound good in the Emerald. Once I get the opamps ordered and installed I'll report back. Unfortunately I've got a few work trips lined up so it may be a while...
Thanks!
Thanks!
@arnold123
You can reach me by DM or email, but to answer your question here; using the Sapphire in the preamp build, you'll have 3-6-9 dB gain options, one or more of which should match to a 27 dB amp. What you'll end up with as the ideal really depends on your room / speakers so I can't say for sure.
The preamp build will drive any kind of normal amplifier input (600 ohms and up) but if it's a concern you can use the headphone amp build (30-600 ohms) which has significantly more quiescent current.
You can reach me by DM or email, but to answer your question here; using the Sapphire in the preamp build, you'll have 3-6-9 dB gain options, one or more of which should match to a 27 dB amp. What you'll end up with as the ideal really depends on your room / speakers so I can't say for sure.
The preamp build will drive any kind of normal amplifier input (600 ohms and up) but if it's a concern you can use the headphone amp build (30-600 ohms) which has significantly more quiescent current.
My version of Emerald phono preamp.
SUT MC input Lundahl LL1941-Ag (24dB gain). Because of it, IC's had to be tuned carefully. Best in IC1 was NE5534, best in IC2 was OPA627. Both IC are TO99. IC1 had its pins 5-8 decoupled with 22pF NP0 caps (just in case, it did not oscillate). IC1 is in unity gain. IC2 gain set to +/- 40dB. Both IC are biased in class-A with very low noise CRD.
All BD are original Philips from the 70ties, I had them in stock. EL caps. are Black Gate non polar (1000uF x 25V). All resistors (except R7) are Vishay Sfernice (S102C) @ 0.1%, found all of them on sale in an eBay shop in Poland. Riaa caps are 1% polystyrene but they actually measured 0.1%.
C3 / R10 were tuned since there is a balanced line transformer (Jensen JT-11-FLPCH) at the output. R10 are 7.5Ω, C3 are Black Gate (non polar) 470uF X 6V.
BTW, all the Black Gate are working in what they called "Super E-Cap" . . . it could be audiophile suggestion but I liked (very much) how this sounds.
PSU is also custom made with Avel-Lindberg split bobbin, Black Gate (non polar) EL and Teflon caps bypasses. The boards are working in +/- 15V.
PCB's for transformers were done by CNC. Parallel RCA in the back panel are used to fine tune cartridge damping. I am using this phono with a Lyra Titan-i and, for some reason, it had a big peak from 15-19Khz. We left it flat with a cap, then matched channels to within 0.1 dB with pink noise LP, ARTA through the DSP's I use as XO.
All measurements were done with AP, Stanford Research, Cronkite Instruments, LeCroy oscilloscope, etc. The technicians that made all this for me say that the performance in impressive. I had several phono pre-amps in my life, this is the best sounding and more silent of them all.
I had the idea how to assemble this package when I saw the PCB's. However, I'm not an audio technician so, somebody else had to do the job for me. For this same reason I am not prepared to answer complex technical questions.
Thank you Richard.
SUT MC input Lundahl LL1941-Ag (24dB gain). Because of it, IC's had to be tuned carefully. Best in IC1 was NE5534, best in IC2 was OPA627. Both IC are TO99. IC1 had its pins 5-8 decoupled with 22pF NP0 caps (just in case, it did not oscillate). IC1 is in unity gain. IC2 gain set to +/- 40dB. Both IC are biased in class-A with very low noise CRD.
All BD are original Philips from the 70ties, I had them in stock. EL caps. are Black Gate non polar (1000uF x 25V). All resistors (except R7) are Vishay Sfernice (S102C) @ 0.1%, found all of them on sale in an eBay shop in Poland. Riaa caps are 1% polystyrene but they actually measured 0.1%.
C3 / R10 were tuned since there is a balanced line transformer (Jensen JT-11-FLPCH) at the output. R10 are 7.5Ω, C3 are Black Gate (non polar) 470uF X 6V.
BTW, all the Black Gate are working in what they called "Super E-Cap" . . . it could be audiophile suggestion but I liked (very much) how this sounds.
PSU is also custom made with Avel-Lindberg split bobbin, Black Gate (non polar) EL and Teflon caps bypasses. The boards are working in +/- 15V.
PCB's for transformers were done by CNC. Parallel RCA in the back panel are used to fine tune cartridge damping. I am using this phono with a Lyra Titan-i and, for some reason, it had a big peak from 15-19Khz. We left it flat with a cap, then matched channels to within 0.1 dB with pink noise LP, ARTA through the DSP's I use as XO.
All measurements were done with AP, Stanford Research, Cronkite Instruments, LeCroy oscilloscope, etc. The technicians that made all this for me say that the performance in impressive. I had several phono pre-amps in my life, this is the best sounding and more silent of them all.
I had the idea how to assemble this package when I saw the PCB's. However, I'm not an audio technician so, somebody else had to do the job for me. For this same reason I am not prepared to answer complex technical questions.
Thank you Richard.
Attachments
Thank you Richard.
The Signetics 5534 in metal TO99 were the NE5534AH, NE5534H and there is some other from Philips. I found 4 in UK and 4 in The Netherlands. I decided to use those from The Netherlands because they had the S from Signetics. I'm afraid the IC from UK could be generic.
The gain measured with AP was not 64dB as calculated but 62.5dB, not a problem whatsoever. BTW I was told that I misspelled one of the instrument in my first post, correct name is Krohn-Hite.
The phono was optimized and finally presented to the cartridge a impedance of 20Ω. Lyra recommends 10Ω max. when using a SUT, but do this was too complicated and IMO unnecessary.
I couldn't be more satisfied.
The Signetics 5534 in metal TO99 were the NE5534AH, NE5534H and there is some other from Philips. I found 4 in UK and 4 in The Netherlands. I decided to use those from The Netherlands because they had the S from Signetics. I'm afraid the IC from UK could be generic.
The gain measured with AP was not 64dB as calculated but 62.5dB, not a problem whatsoever. BTW I was told that I misspelled one of the instrument in my first post, correct name is Krohn-Hite.
The phono was optimized and finally presented to the cartridge a impedance of 20Ω. Lyra recommends 10Ω max. when using a SUT, but do this was too complicated and IMO unnecessary.
I couldn't be more satisfied.
Hi folks, I've been following along on this thread for a while and finally pieced together my Emerald. I'm currently working on the power supply and am having difficulty finding a proper cable for the umbilical. I found a post earlier that said an unshielded, 3 conductor cable is the way to to go but after a few days of searching all I'm finding is this cable off Amazon.
What are other folks using for their umbilicals? Do I need to be worried about quality of materials here or will any conductor material do?
What are other folks using for their umbilicals? Do I need to be worried about quality of materials here or will any conductor material do?
@Calvdart
I find a spare 18 AWG or 16 AWG power cord and chop off the plugs at each end. Back in the day I'd buy the same 3-wire power cable by the meter at my local electronics store, cut from a spool, but sadly that's no longer an option for most people anymore myself included.
The thinner 18 AWG cable should work with most XLR connectors.
I find a spare 18 AWG or 16 AWG power cord and chop off the plugs at each end. Back in the day I'd buy the same 3-wire power cable by the meter at my local electronics store, cut from a spool, but sadly that's no longer an option for most people anymore myself included.
The thinner 18 AWG cable should work with most XLR connectors.
A dual mono supply could require as many as 8 wires, (V++/COM) x2 and (V--/COM) x2.
The COM of V++ and V-- combine eventually on the boards, so not a big deal to go down to 6 wires (V++/COM/V--)x2
If COM is shared between channels it's not a dual mono supply anymore, and this arrangement might require some tweaking of the grounding layout to get working. I expect the phono stage chassis would have to be connected to COM at the place where they join up, rather than using the GND pads...
The COM of V++ and V-- combine eventually on the boards, so not a big deal to go down to 6 wires (V++/COM/V--)x2
If COM is shared between channels it's not a dual mono supply anymore, and this arrangement might require some tweaking of the grounding layout to get working. I expect the phono stage chassis would have to be connected to COM at the place where they join up, rather than using the GND pads...