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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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28th Jul 2020, 6:11 pm | #101 | |
Octode
Join Date: Nov 2013
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Re: Very low noise op amp recommendations?
Quote:
I lurk on a couple of audio fora and often end up biting my virtual tongue, especially when people advocate mass replacement of electrolytics because they might be time expired even if the equipment is working properly, as a for instance. That and the "signal path" capacitor arguments. and as you have mentioned elsewhere whether a caddock or a Shinto (Shinko?) or whatever resistor sounds best...………. I can't tell the difference between a standard Alps RK27 and a fancy switched attenuator so its wasted on me! I'm simply curious so this is all of interest to me. I have a very good phono stage in my regular solid state commercial preamp and I doubt whether I will find an improvement on that, its my normal everyday listening. As I said, I will be trying out the simple stage with a 5534 and I must get a good look at the Douglas Self design, I knew about Self a long time ago and completely appreciate his approach to design. I have fun playing around with different circuits and component technologies but I never expect to improve on proven and reliable designs. That's not the point for me. Thanks to all of you though. Very best regards. Andy. |
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29th Jul 2020, 12:18 am | #102 | |
Nonode
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Re: Very low noise op amp recommendations?
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Certainly, Bill Poel was refreshingly iconoclastic, but in this case he seems to have overlooked the adage that one should choose one’s target wisely. As far as I know, the HA12017 was more-or-less an improved version of the widely-used Toshiba TA7122 (which I think had a Hitachi counterpart with a four-digit number). This was essentially the three-transistor circuit in integrated form, intended primarily for the MM/RIAA job. I somehow doubt that it would or even could have done better than the NE5534 in that role, or even better than the erstwhile LM381, which was also included on the same Ambit page. The LM381 was also more versatile. But these low-noise preamplifier ICs were effectively made obsolete by the NE5534/2, which delivered about the best realizable MM/RIAA performance via an industry standard, multi-use opamp that could also be deployed for most other functions in a domestic audio control unit. Nonetheless the 1979 Signetics Applications, under stereo preamplifiers, referred not only to the NE5534, but also the NE542 and LM381 family. Cheers, |
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29th Jul 2020, 12:39 am | #103 |
Octode
Join Date: Nov 2013
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Re: Very low noise op amp recommendations?
Well that does get things in perspective.
I'd hazard a guess that in practice there'd be nothing to choose between that and a 5534 in a real world application. A. |
29th Jul 2020, 9:16 am | #104 | |
Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
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Re: Very low noise op amp recommendations?
Quote:
Baxandall also shows an inverse RIAA. You plug that into the RIAA input and use your favourite audio sweep generator (or audacity via your computer sound card) and you can check your RIAA accuracy. There is also a good paper on inverse RIAA here http://www.hagtech.com/pdf/riaa.pdf . Both Baxndall's and Hagerman's designs need careful value selection for accuracy of course. Craig |
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29th Jul 2020, 9:51 am | #105 | ||
Octode
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Re: Very low noise op amp recommendations?
Quote:
Andy Last edited by bikerhifinut; 29th Jul 2020 at 9:53 am. Reason: bad punktuashun |
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29th Jul 2020, 9:56 am | #106 | |
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Re: Very low noise op amp recommendations?
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The semiconductor industry was seduced by cellphones. Products that sell in zillions and have a production lifetime of about 6 months per model. The vinyl revolution will never compete with that, and the 5534 is good for other applications. Because the semiconductor industry is wholly concentrating on whatever the latest in gadget may be, there are whole areas of technology suffering neglect, and seeing the last devices suited to them going obsolete. All the Avago RF ICs and diodes got cancelled with a single stroke a few years ago. Almost all the varactors have gone, except those in cellphones. David
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29th Jul 2020, 10:00 am | #107 | ||
Dekatron
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Re: Very low noise op amp recommendations?
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29th Jul 2020, 1:37 pm | #108 | ||
Dekatron
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Re: Very low noise op amp recommendations?
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There are a few glimmers of hope. There is a vibrant research group at TI who are progressively rewriting the collection of audio products - opamps of varying flavours and performance, and upcoming a range of audio DACs. Craig |
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29th Jul 2020, 2:22 pm | #109 |
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Re: Very low noise op amp recommendations?
What was Avago used to be HP's internal semiconductor group. After HP split up into HP computers and Agilent (instruments), Agilent sold off the semiconductor group principally to a financial investment consortium. Its name changed then to Avago.
Avago, then took over Broadcom, a semi firm much more into mainstream stuff. It looks like David eating Goliath, but Avago was just the front for a huge financial consortium. Broadcom didn't have a chance against that much clout. Avago now owned Broadcom and the rights to that name as well as their own. They thought Broadcom sounded more sensibe than 'Have-a-go' so they opted to change over to that name. They owned the rights and the web rights etc. so why not. As a result many people think Broadcom bought Avago. But it was the other way round. Which makes it all the more irritating that one of their first actions was to dump almost the entire Avago portfolio. It makes more sense when you realise it's the financial consortium's hand in the puppet. Broadcom got going with chips for digital TV. HP used some of them and I saw evidence that they didn't much understand phase locked loops. Since then they've become a big name in Wifi and other peripheral devices in computers, though they're probably known to more people for their devices instantiating ARM cores... the one in the raspberry pi for example. David
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30th Jul 2020, 9:15 pm | #110 |
Nonode
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Re: Very low noise op amp recommendations?
If I could only write here what I want to say...
The light is wan. They must have been wearing blinkers. |
30th Jul 2020, 9:31 pm | #111 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
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Re: Very low noise op amp recommendations?
If you want noise use MC1303.
It is possible to connect to a microphone input. Then the pre-amp output could be filtered actively using a graphic equaliser set to give the RIAA curve. |
2nd Aug 2020, 5:49 am | #112 | |
Nonode
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Re: Very low noise op amp recommendations?
The MC1303 must have been one of the earliest ICs developed for audio preamplifier use, dating from c.1968.
As far as I know the first such IC for which it was claimed to match discrete circuitry on the noise front was the LM381A of 1972. I am not sure that it was much used in domestic equipment, although I have a vague recollection that Hi Fi News published a suitable circuit when it was new. There is some evidence that it was used as a microphone preamplifier in professional equipment. Quote:
An irony was that the Mullard TDA1034 low-noise opamp (similar/identical to the NE5534) was announced in that same issue of WW. Also in that WW issue were announced a suite of Hitachi ICs, namely the HA1137 (CA3089 type), HA1196 (MC1310 type) and HA1197 (AM radio), supplied by Ambit. It gave the impression that Ambit was a main supplier of Hitachi ICs in the UK, which would explain its later enthusiasm for the HA12017 MM/RIAA IC. Perhaps the HA12017 was welcomed by the Japanese equipment makers, basis their prior use of the TA7122, but it was probably a difficult sell in geographies where the NE5534 had established itself. Cheers, |
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2nd Aug 2020, 6:25 am | #113 |
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Re: Very low noise op amp recommendations?
Hitachi ICs hadn't been seen on the UK scene until Ambit started offering them, and their wording was a bit pushy suggesting they were improvements on the incumbents in those particular slots.
My FM tuner at the time was a PW design because someone at work had laid out a PCB and made several. CA3089 and CA3090 pretty plain-vanilla flavour that worked as well as needed in a good signal area. My concentration was in trying to eliminate the spurs from a frequency counter I'd done for it. So I never tried the Hitachi ICs. If I'd needed higher performance, I'd have gone discrete or to individual ICs for limiter stages. At the time, the uA747 being a dual 741 had never been associated with low noise, and its gain.bandwidth product was a bit too limiting for best audio, so that WW article was just dismissed out of hand by all those I discussed it with. It was a bit odd that it got through their filter. David
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2nd Aug 2020, 12:57 pm | #114 |
Octode
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Re: Very low noise op amp recommendations?
And so the wheels turn, and the circle is completed and we end up where we started, ergo the 5534 and its equivalents really are as good, if not better than they need to be given the constraints imposed by source materials and transducers and noise from resistors etc.?
One thing I get great pleasure from is the discovery that so much of my vintage equipment really does cut it in the modern world, given that its maintained and fettled to the condition it would have been in when new. But I do enjoy very much the learning process and benefiting from the professionals on here insight and experience. And a bit of experimentation. It would appear that Armstrong used the HA12017 in their 700 series amplifiers. Lovely workmanship too. http://www.audiomisc.co.uk/Armstrong/700/700page5.html A. Last edited by bikerhifinut; 2nd Aug 2020 at 12:58 pm. Reason: grammatical error |
2nd Aug 2020, 4:17 pm | #115 |
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Re: Very low noise op amp recommendations?
There was plenty to like in those last Armstrong amplifiers and tuners, but the company's name had been on the wane for some time before them and they came out just as the audio world was starting to go silly. So they never succeeded in the market to the extent they deserved.
Some vintage equipment wasn't so good, but some was genuinely excellent and trying some shows that there may have been lots of technology changes, but there has been relatively little progress in the prime purpose, of reproducing sound. To put this in perspective ask yourself how much progress human hearing has made in the same period The people back in the fifties and sixties weren't stupid and they knew what violins, voices and electric guitars sounded like. They could sort the good stuff from the crap. Loudspeakers are where some useful progress has been made. David
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2nd Aug 2020, 5:52 pm | #116 |
Octode
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Re: Very low noise op amp recommendations?
I can't add anything to the excellent theoretical & practical posts in this thread, other than the following peripheral tip.
Back in my youth I made an RIAA preamp which was housed in a tin can (for screening) and located up under the turntable. With all that gain down at 50Hz it's very easy to end up with hum issues, and I'd decided to remote the RIAA stage close to the cartridge. Now, the problem of supplying ultra-clean DC supplies? I used simple (decoupled) zeners on the RIAA board, and fed the unit from constant current sources back at the main amplifier. Hence no ripple DC current in the earth lead. It worked a treat. John |
2nd Aug 2020, 6:02 pm | #117 | |
Octode
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Re: Very low noise op amp recommendations?
Quote:
John |
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2nd Aug 2020, 6:20 pm | #118 |
Dekatron
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Re: Very low noise op amp recommendations?
The Armstrong last gasp of the 7000 series was a truly spectacular swan song.
They only come up for sale very occasionally. Amazingly the 521 seems to fetch £80 to £120; the world has gone truly bonkers. I have one in the attic, and it measures truly badly. RIAA off by a mile, noisy and a really bad distortion power amp section. I only keep it for nostalgia's sake. The 600 series was a different kettle of fish. Looks great, slimline, nice feel to the controls and switches, and measures reasonably. But the 700 series was in a different class entirely. I'd like a set, but think they are likely to fetch good money on the rare occasion one comes up for sale. Craig |
2nd Aug 2020, 7:30 pm | #119 |
Nonode
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Re: Very low noise op amp recommendations?
Seriously I did look into low noise for microphone pre-amps a few years back I seem to
get good results from Ferranti ZN459, and OP-27, PMI I think. When we were building RIAA amps as a classroom project, we settled on the inexpensive RC4558 / 4559 and went on to plot the frequency/gain a response close to ideal. These might not meet your s/n but they were popular in audio mixers. If anything tape head preamps are more critical as the levels can be very low. |
3rd Aug 2020, 6:41 pm | #120 |
Pentode
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Re: Very low noise op amp recommendations?
I have a PW Winton amp with toroidal transformer and fet output transistors which I built in 1979. It’s pre stages were tlo72s.It has been in continuous use with sme3009 arm connoisseur bd1 deck and Nagaoka MP110 cartridge, and Telefunken 710s. I had slight hiss with the volume control at about 11 o’clock.
A few weeks ago I replaced the first stage with a surface mount OPA1642 dual jfet and stage 2 and 3 with OPA2134. I Can now turn it up to about 2 o’clock before I hear any hiss. This set up sounds just as good as a new Denon PMA600NE with Dali spektor2s. |