Thanks Carl. It just all seemed like a bit of an odd conversation since that post by Art M, anyway, that's nothing new on diyaudio!
Nothing odd. Doug Self asked which capas were electrolytics except the input coupling, and apparently this was too difficult a question to understand and people went off on all kinds of tangents. It has been clear to me for a long time that many here post first and then read the posts they are reacting to.
Jan
Forgive me Jan, but it's Doug's circuit, what am I missing. Also was it not published in Linear Audio magazine? Am I missing the plot?
My Reference Preamp
well after many months of operation, I am extremely happy with this preamp. Apart from the benefits of negligible noise, it sounds superb. And I remain a firm believer in tone controls to correct ...as far as possible..for the room, the speakers, the recording and the sound level. The preamp has revealed more detail than I knew was available and has turned out to be totally reliable. The only downside, probably not attributable to the preamp, is a turn-on thump which I have been able to cure, by inserting a 15-second delay in powering up the power amps (nCores).
The reliability of the design was expected as I have Doug Self's 1976 design under my desk as I type and it still works perfectly. I am wondering how long I have to wait for his next design?
Thnks to all for a great piece of work.
Hi Carl,
well after many months of operation, I am extremely happy with this preamp. Apart from the benefits of negligible noise, it sounds superb. And I remain a firm believer in tone controls to correct ...as far as possible..for the room, the speakers, the recording and the sound level. The preamp has revealed more detail than I knew was available and has turned out to be totally reliable. The only downside, probably not attributable to the preamp, is a turn-on thump which I have been able to cure, by inserting a 15-second delay in powering up the power amps (nCores).
The reliability of the design was expected as I have Doug Self's 1976 design under my desk as I type and it still works perfectly. I am wondering how long I have to wait for his next design?
Thnks to all for a great piece of work.
Forgive me Jan, but it's Doug's circuit, what am I missing. Also was it not published in Linear Audio magazine? Am I missing the plot?
Yes but Doug's circuit and BOM has been trough several 'improvements' here. It's like the telephone game
Jan
Yes but Doug's circuit and BOM has been trough several 'improvements' here. It's like the telephone game
Jan
Ha ha! Gotcha. "The telephone game" is a new one to me, is that like "Chinese whispers"?.....................
Forgive me Jan, but it's Doug's circuit, what am I missing. Also was it not published in Linear Audio magazine? Am I missing the plot?
Yes, the preamp is for the most part Doug's design and was published in Jan's Linear Audio magazine. At the time it represented his latest thoughts and evolution in tone control design. However what Doug published in Linear Audio v5 were the important building blocks and represented about 80% of what was required to realize the design in hardware. I filled in the missing pieces and after building a couple of prototypes presented the completed picture in this thread.
Along the way the PCB layout has evolved to improve aesthetics and ease of assembly. However the circuit cast on the PCB has remained largely unchanged, amounting mostly to a simplification of the BOM.
My latest incarnation that I have tagged 'v2 blue board' is again the same circuit and BOM. The only change is that the front panel pots have spread further apart to allow the use of bigger knobs. That was a request from builders.
There is no reason to use non-polar electrolytics anywhere except at the input.
Firstly, as remarked non-polars cost more.
Secondly, the circuitry was only tested with polar electrolytics, sized so that capacitor distortion would not occur even at full signal at 10 Hz. Whether non-polars of the same size will be equally free of that problem I do not know.
Firstly, as remarked non-polars cost more.
Secondly, the circuitry was only tested with polar electrolytics, sized so that capacitor distortion would not occur even at full signal at 10 Hz. Whether non-polars of the same size will be equally free of that problem I do not know.
Having built this preamp with NPs I am very satisfied with its performance.
I am about to embark on construction of a second one where only the input caps will be NPs. I don't have access to any measuring facility other than my ears but I will certainly be keen to try both versions out critically to see if I can hear any differences.
The preamp was very straightforward to construct using Carl's excellent boards and Doug's wonderful design. There were no problems with components not fitting or funny setup problems, and the layout is simple and elegant. I had no difficulty acquiring componentry mostly from Mouser although one must be patient with back orders!
I have yet to use the balanced inputs or outputs as my current inputs - phono preamp, cd player and tuner - are all unbalanced and my main amp has only unbalanced RCA inputs. Nevertheless there is no buzz or hum from the preamp even at full volume.
I am very, very pleased with this preamp. It has lifted the quality of reproduction of my whole system quite markedly. And going back to having tone controls after a very long time without has enabled corrections to balance and the effects of room furnishings etc.
DIYAudio and Linear Audio have opened my eyes (and ears) to what is possible in the audio high quality end without needing to be a millionaire. Thank you Douglas for making this exceptional design freely available through Jan Didden's great publication and thanks to Carl for his work on the pcbs design and distribution.
I must say that I am a great believer in the dissemination of knowledge through publication and peer review, and with the Self books and others such as Morgan Jones, Bob Cordell etc., Linear Audio and with the DIYAudio forums knowledge in the audio sphere is in good hands and well served.
Graeme
I am about to embark on construction of a second one where only the input caps will be NPs. I don't have access to any measuring facility other than my ears but I will certainly be keen to try both versions out critically to see if I can hear any differences.
The preamp was very straightforward to construct using Carl's excellent boards and Doug's wonderful design. There were no problems with components not fitting or funny setup problems, and the layout is simple and elegant. I had no difficulty acquiring componentry mostly from Mouser although one must be patient with back orders!
I have yet to use the balanced inputs or outputs as my current inputs - phono preamp, cd player and tuner - are all unbalanced and my main amp has only unbalanced RCA inputs. Nevertheless there is no buzz or hum from the preamp even at full volume.
I am very, very pleased with this preamp. It has lifted the quality of reproduction of my whole system quite markedly. And going back to having tone controls after a very long time without has enabled corrections to balance and the effects of room furnishings etc.
DIYAudio and Linear Audio have opened my eyes (and ears) to what is possible in the audio high quality end without needing to be a millionaire. Thank you Douglas for making this exceptional design freely available through Jan Didden's great publication and thanks to Carl for his work on the pcbs design and distribution.
I must say that I am a great believer in the dissemination of knowledge through publication and peer review, and with the Self books and others such as Morgan Jones, Bob Cordell etc., Linear Audio and with the DIYAudio forums knowledge in the audio sphere is in good hands and well served.
Graeme
Hello M. Self,
Thanks for sharing your design with us.
Do you mean populating all the board with bi-polar is not mandatory (but the caps in serie with the signal and not the shunt ones) ?
Is there some area where the caps must be Non-polar on the main board ?
I believe it diserves some others caps at power positions on the pre pcb for a "less" thin sound !
I saw some used Nichicon FK serie for the biggest caps of the pre board, I believe there is better to do .
YMMV, my amp and speakers are very on the clear side already !
Nich. KG for the PS board is a very good decision; I will change the others 100 uF caps of the the Power boards ! But it's a detail and I had no time to tweak the sound for my tastes/own system...
Last outrages to drosophiles as the design is good enough
Thanks to Doug & Carl
I saw some used Nichicon FK serie for the biggest caps of the pre board, I believe there is better to do .
YMMV, my amp and speakers are very on the clear side already !
Nich. KG for the PS board is a very good decision; I will change the others 100 uF caps of the the Power boards ! But it's a detail and I had no time to tweak the sound for my tastes/own system...
Last outrages to drosophiles as the design is good enough
Thanks to Doug & Carl
I should have mine up and running in the next few days. I'm waiting on some pcb screw terminals for the I/O link, I didn't like the 20way idc connectors specified in the BOM. I was thinking of hard wiring between the boards but this is impossible with them in situ and tricky otherwise. Also I'm going to use a supply that's already powering my active crossover. Do you think you'd be able to hear the difference with polarized caps? It will be interesting to see what graemed says after he's built his.
That's what I did between the main and I/O board : copper silver plated with PFTE suround! More by faith than benchmark, as most of the time it is what I use for my diy dacs.
My understanding is the flat cable for the select board rotary pot is not seing any signal ! Just for selecting the relays.
My understanding is the flat cable for the select board rotary pot is not seing any signal ! Just for selecting the relays.
I have a capacitor placement question. Looking at the schematic I see that the pins of C42 and C43 seem to be directly connected to a 3K3 resistor. C42/43 have multiple holes in the board. In the BOM I have the capacitors in both of these locations are the same. Unfortunately I am about 3000 miles away from my board this week so I am unable to confirm/check but either C42L or C43R (sorry can't remember which one) when I flip the board over it does not seem to directly connect to the R42 (or R45) resistor.
It seems like the board hole alignment for one of these capacitors is not how I would expect it to be. Am I mistaken in my understanding or is the marking on the circuit board not correct?
It seems like the board hole alignment for one of these capacitors is not how I would expect it to be. Am I mistaken in my understanding or is the marking on the circuit board not correct?
As the designer I think I have the right to say that this is a waste of time & money.
Last outrages to drosophiles as the design is good enough
Thanks to Doug & Carl
Last outrages to fruitflies ??? Lost on me.