The original Preamp 96 version, or the current version as advertised on the Signal Transfer website?
Don't believe all that you read.
A lot of the info on that site seems very selective and the opamp based headphone amp is not suitable for a TLO72.
The switches are available from Signal Transfer.
Digikey do the 4-pole types:
401-1226-ND and
401-1227-ND (gold contacts.... nice!)
The 6-pole 6-switch interlocking assembly was a custom part.
The only place that the TL072 is used in the Precision Preamp is as a DC integrator in the Moving Coil amplifier. All other op-amps are NE5532 and NE5534 types.
Digikey do the 4-pole types:
401-1226-ND and
401-1227-ND (gold contacts.... nice!)
The 6-pole 6-switch interlocking assembly was a custom part.
The only place that the TL072 is used in the Precision Preamp is as a DC integrator in the Moving Coil amplifier. All other op-amps are NE5532 and NE5534 types.
Precision Preamp tone controls automated?
Hi,
Wonder if this thread is still alive? If so, anyone try to make this tone control automatic by means of replacing the mechanical pots with a electronic pot using a serial I/F? I understand that the digital pots will add some degree of colouration, but I am willing to live with this. Would also be using a PGA2320 and PGA4311 in a 7.1 channel preamp, so already committed to electronic control and lazy as well.
Any suggestions as what parts to use for digital pots?
Discussion has come up that Doug Self has a new version as well, can't wait for publication. Doug. I'd offer to lay it out for you since I have it done already!!
Managed to PSPICE the preamp circuit and did layout of it out, what a mess to deal with
, yet to fab however, so looking at my options here.
Thanks
Rick
Hi,
Wonder if this thread is still alive? If so, anyone try to make this tone control automatic by means of replacing the mechanical pots with a electronic pot using a serial I/F? I understand that the digital pots will add some degree of colouration, but I am willing to live with this. Would also be using a PGA2320 and PGA4311 in a 7.1 channel preamp, so already committed to electronic control and lazy as well.
Any suggestions as what parts to use for digital pots?
Discussion has come up that Doug Self has a new version as well, can't wait for publication. Doug. I'd offer to lay it out for you since I have it done already!!
Managed to PSPICE the preamp circuit and did layout of it out, what a mess to deal with
, yet to fab however, so looking at my options here.Thanks
Rick
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Wher can I get more information on this preamp
This seems like just the right preamp I need. I am looking for an all "Analogue" preamp with parametric tone control (3 band minimum, 6 band maximum), and with an active loudness having an amplitude control (pot type). Also I am looking for exceptional SNR and THD characteristics. So where can I get more information and where can I purchase the parts for it?
Thanks Ben
This seems like just the right preamp I need. I am looking for an all "Analogue" preamp with parametric tone control (3 band minimum, 6 band maximum), and with an active loudness having an amplitude control (pot type). Also I am looking for exceptional SNR and THD characteristics. So where can I get more information and where can I purchase the parts for it?
Thanks Ben
The whole preamp ran as a series of articles in Wireless World magazine. There is (not sure if its still available) a kit for the whole preamp which is extremely comprehensive and was available from "The Signal Transfer Company".
This tone stage is Bass and Treble with adjustable turnover frequencies.
This tone stage is Bass and Treble with adjustable turnover frequencies.
I guess not quite yet what I am looking for
Thanks Mooly, you just saved me lots of time researching which, in the end, would not do the trick for me. I still appreciate your suggestion. I do need at least Base, Mid, and Treble.
This is just the beginning of my search. I yet did not expect to be right on target on first post. But your suggestion is definitely in the right direction; please stay in tune.
Million thanks, Ben
Thanks Mooly, you just saved me lots of time researching which, in the end, would not do the trick for me. I still appreciate your suggestion. I do need at least Base, Mid, and Treble.
This is just the beginning of my search. I yet did not expect to be right on target on first post. But your suggestion is definitely in the right direction; please stay in tune.
Million thanks, Ben
Hi Ben,
There are a couple of parametric EQ designs around in the DIY marketplace (Group DIY is one possible source).
Another solution is to get hold of a couple of EQ modules or sub-assemblies from mixing consoles:
... Neve 51-Series is a 4-band sweep frequency EQ with switchable bell/shelf on the HF and LF bands.
... Neve VR is 4 band parametric with variable Q, sweep frequency and HF/LF bell/shelf.
... Calrec M-Series or Q-Series modules offer a wide variety of options that would take up several paragraphs to adequately describe!
The Neve and Calrec EQs all benefit from some additional circuitry to provide balanced inputs & outputs (if this is what you need).
Send me a PM if you need any further info.
Best regards,
Gareth.
There are a couple of parametric EQ designs around in the DIY marketplace (Group DIY is one possible source).
Another solution is to get hold of a couple of EQ modules or sub-assemblies from mixing consoles:
... Neve 51-Series is a 4-band sweep frequency EQ with switchable bell/shelf on the HF and LF bands.
... Neve VR is 4 band parametric with variable Q, sweep frequency and HF/LF bell/shelf.
... Calrec M-Series or Q-Series modules offer a wide variety of options that would take up several paragraphs to adequately describe!
The Neve and Calrec EQs all benefit from some additional circuitry to provide balanced inputs & outputs (if this is what you need).
Send me a PM if you need any further info.
Best regards,
Gareth.
Not looking for a full blown equalizer unit
Actually, a full 11~31 band equalizer becomes unmanageable on-the-fly. at times, even a 11 band equalizer would require 4 to 5 hands to operate, but even if I had the ability to use a bunch of fingers to control the sliders or rotary pots, the finesse of execution would be hindered by the awkwardness of manipulation. Although a slider type of potentiometers would be more manageable. Nonetheless, a parametric 5 way would be a limit requiring yet 10 operations to be executed simultaneously. Some passages require a fast yet very precise manoeuvrings; like enhancing the harmonics of a drum hammer "after" its peak to give it a reverb hall effect. I am not going to go in detail all the enhancing possibilities here; for every song/music, and every interpretation of every song/music lends to an endless variety of mood alterations. This is like playing a musical instrument; one can finger note a guitar with soul, while another thinks that he does but only makes scratching noises.
Actually, a full 11~31 band equalizer becomes unmanageable on-the-fly. at times, even a 11 band equalizer would require 4 to 5 hands to operate, but even if I had the ability to use a bunch of fingers to control the sliders or rotary pots, the finesse of execution would be hindered by the awkwardness of manipulation. Although a slider type of potentiometers would be more manageable. Nonetheless, a parametric 5 way would be a limit requiring yet 10 operations to be executed simultaneously. Some passages require a fast yet very precise manoeuvrings; like enhancing the harmonics of a drum hammer "after" its peak to give it a reverb hall effect. I am not going to go in detail all the enhancing possibilities here; for every song/music, and every interpretation of every song/music lends to an endless variety of mood alterations. This is like playing a musical instrument; one can finger note a guitar with soul, while another thinks that he does but only makes scratching noises.
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This sounds interesting - you should start a thread on this and post a recording of 'before' and 'after' you have added your skills to it - so we can appreciate what you are hearing and we are not.
Actually I whish I could but withour the preamp...
Sadly I whish I could, but without the preamp and parametric EQ, I am left without the possibility. This is the reason for my inquiry about a DIY unit that would satisfy my needs. This unit (instrument preamp) is quite specific, and it seems as though very few audiophile lend to the practice, since, to be labeled an audiophile, one thinks he/she must not change the source; yet they do not realize that the whole purpose of music is feeling, the rush it can give you. Apart from the chest inflateds, If you love every note, seek every instruments, vocals, foreground and background sounds, even unintentional recording impurities, you are an audiophile to my eyes (or ears). It is great time the term audiophile be revised. If the purity, clearness, and separation of instruments and vocals are unsatisfiably important to you, always seeking for better and better, this is what it's all about. I have been an avid audio enthusiast for over 45 years making my own equipment because what I am after does not exist or is prohibitively expensive. But I cannot stop looking for better, and I think that is part of my drive.
Sadly I whish I could, but without the preamp and parametric EQ, I am left without the possibility. This is the reason for my inquiry about a DIY unit that would satisfy my needs. This unit (instrument preamp) is quite specific, and it seems as though very few audiophile lend to the practice, since, to be labeled an audiophile, one thinks he/she must not change the source; yet they do not realize that the whole purpose of music is feeling, the rush it can give you. Apart from the chest inflateds, If you love every note, seek every instruments, vocals, foreground and background sounds, even unintentional recording impurities, you are an audiophile to my eyes (or ears). It is great time the term audiophile be revised. If the purity, clearness, and separation of instruments and vocals are unsatisfiably important to you, always seeking for better and better, this is what it's all about. I have been an avid audio enthusiast for over 45 years making my own equipment because what I am after does not exist or is prohibitively expensive. But I cannot stop looking for better, and I think that is part of my drive.
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Paid Member
I am also considering the merits of an analogue EQ (vs DSP) and one idea I came across which interested me is based on a very simple topology but requires inductors (which may be hard to source if you can't make them). See attached - there's a thread somewhere which claims this is a well regarded approach and is known as the 'East German EQ', and takes this concept a bit further, suggesting the use of an op-amp based gyrator to replace the large inductors. this approach is OT for this thread though.
Attachments
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Precision Preamp
I built the precision preamplifier in 2014 and it's remarkable. I also built his LOAD INVARIANT amplifier in a BIAMP configuration to drive speaker in separate amp (bass&Treble). For this I use a frequency separator before attacking the 4 amps. And the precision preamp is driving the frequency separator. The result is just stuning. The MC-MM turntable board that goes with the precision preamp is undergoing construction. The PCB will also include the Devinyliser describe in Linear Audio Volume 11. Here the key is how you're doing the PCB. Once done I will comment how the whole precision preamp sounds with amplifiers. It's a total Douglas Self project!!
Wondered if anyone had built and or listened to Doug Selfs precision preamp published in August and September 1996 in Electronics World ?
The Signal Transfer Company: Precision Preamplifier
Dougs tone controls with adjustable turnover frequencies look interesting.
The whole design uses NE5532's and does have a fair few electroylitics in the audio path, mainly to keep any offset current out of the pot wiper as it uses NE5532's. Using FET opamps looks a possibilty and would enable these to be ommited.
Anyone any experience of the design in practice
I built the precision preamplifier in 2014 and it's remarkable. I also built his LOAD INVARIANT amplifier in a BIAMP configuration to drive speaker in separate amp (bass&Treble). For this I use a frequency separator before attacking the 4 amps. And the precision preamp is driving the frequency separator. The result is just stuning. The MC-MM turntable board that goes with the precision preamp is undergoing construction. The PCB will also include the Devinyliser describe in Linear Audio Volume 11. Here the key is how you're doing the PCB. Once done I will comment how the whole precision preamp sounds with amplifiers. It's a total Douglas Self project!!
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