Pundit
Post by peter0c on Jul 25, 2023 12:28:01 GMT 12
The acrylic was a deliberate choice. Wood is hydroscopic. There is a lot of engineering behind the steel including absorbent coating. Too hard for me to debate.
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Post by michaelw on Jul 25, 2023 13:39:37 GMT 12
Acrylic is also relatively cheap and easily malleable to whatever shape you desire.
Depending on the wood, hygroscopicity is not a factor.
Everything has a signature sound, at this level A wouldn't be my first choice
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Pundit
Post by stuzzo on Jul 25, 2023 14:51:59 GMT 12
Was Double Blind mentioned or would that start a punch-up!
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Pundit
Post by peter0c on Jul 25, 2023 15:18:47 GMT 12
No double blind but the difference was startlingly obvious. Damn. Another prejudice bites the dust.
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Pundit
Post by peter0c on Aug 25, 2023 11:37:15 GMT 12
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Pundit
Post by peter0c on Sept 20, 2023 13:04:42 GMT 12
FYI "Meetings: 4th Monday of the month at 7.30pm, February to November
info@aas.org.nz
AAS SEPT MEETING - MONDAY SEPTEMBER 25 7.30 pm at Softball clubrooms, Cornwallis Street, St Lukes.
This month/Sept President John Simpson presents his …wait for it … super amp. Some time in gestation it is an Ultra low distortion amplifier module originating from Silicon Chip magazine.
They say it is their latest and best performing amplifier module. “Not only have we reduced the distortion from Mk3 to this Mk4 version, but it is smaller and has more features. LEDs for the supply rails and blown fuses, etc.”
“We haven’t called this amplifier series Ultra-LD for nothing. The Mk3 module already had extremely low distortion levels of 0.001% up to a few kilohertz and just 0.002% at 10khz. Very few commercial amplifiers would beat that. In fact the distortion of this amplifier module is so low we had to develop new techniques to measure it”.
The power of this Mk4 is 135W continuous into 8ohms and 200W into 4ohms.
We look forward to President John telling us more of the overall thinking of this amp.
Sec"
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Post by michaelw on Sept 20, 2023 14:38:28 GMT 12
Hello 1970s as we chase vanishing low distortion again Is this an analogue amp ? Or some fancy digital/switched-mode thingy ?
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Pundit
Post by peter0c on Sept 20, 2023 17:30:38 GMT 12
Analogue. Comments welcome after a listen.
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Post by RdM on Sept 20, 2023 20:30:12 GMT 12
I haven't been able to attend even as a visitor the last few times, and I'm not sure yet about next Monday, but you never know... until it happens. I have an Auckland VHF Club meet on the 2nd Monday of the month, which I made, and an NZVRS meet and auction on the 3rd Monday last, I had to skip that. I'm a bit stressed out preparing for a move in the next few or 6-8 weeks max, apart from underlying health issues which are slowing me down. Multitasking slowly.
A simple search shows some links and forum posts, scrolling down, on the amp modules, pcbs & similar kits still available. Although I don't need new amps myself!
Regards!
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Pundit
Post by peter0c on Jan 12, 2024 11:23:00 GMT 12
Auckland Audio Society Meeting 7.30pm, Monday 22 1 24, Ramblers Softball Clubrooms, Cornwallis St, St Lukes The first meeting for the Society is scheduled for 7.30pm on Monday 22 1 24 and will feature Steve Prothero's refurbished (by John Simpson) Quad 33/303 pre and power amp and his personally refurbished Bowers and Wilkins DM2a speakers. The Quad combo is a classic which will be well known to older audiophiles. The power amp uses one of the earliest higher powered NPN transistors (2N3055), commonly used in a push pull capacitor-coupled configuration as a non complementary pair in many 1960's and 1970's amplifiers before the matching PNP transistor (MJ2955 ) became available, allowing a center-tapped power supply and direct coupled output. The Bowers and Wilkins DM2a are equally famous and have the same Celestion HF1300 mid range and Coles 2000 super tweeter as the well-known Spendor BC1 but better bass, as expected from a transmission line design. The HF 1300 and Coles 4001 pair has probably (still) the flattest mid range response of any consumer speakers. John Simpson's ‘Ultralow Distortion Mk 4” (Silicon Chip 2016) amplifier will be available (the old and the new) for comparison. This amplifier produces 200wpc, has a damping factor of 450 (the highest damping factor that I have seen), uses surface mounted parts and the output devices (MJL3281A & MJL1302A ) are continuously monitored for heat and have an integral diode for automatic bias adjustment. Here are some links if you want to know more. www.siliconchip.com.au/Issue/2015/August/Ultra-LD+Mk.4+200W+RMS+Power+Amplifier%2C+Pt.1www.siliconchip.com.au/Issue/2015/September/Ultra-LD+Mk.4+200W+RMS+Power+Amplifier%2C+Pt.2Suffice to say it is a thoroughly modern design and useful to have available to the club as a baseline. Please bring along any of your friends as we would like the Society to grow. Out-of-town visitors are particularly welcome as this might enable us to form links with clubs in other cities. Peter Coleman Secretary
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Pundit
Post by peter0c on Feb 16, 2024 8:11:44 GMT 12
Audio Society Meeting, Ramblers Clubrooms, Cornwallis St, St Lukes at 7.30 pm on 26 2 24
I trust that you have all had a good break and are looking forward to the second meeting of the year which will feature John Simpson's refurbished late 1970's Magnepan SMGa speakers. These Planar-Magnetic-Driver speakers were heralded in the day as having low mass (.0005 inch) diaphragm, a bi-polar design (no cabinet to color the sound) and direct coupled (no transformer). They are also mirror-imaged (they are 2 way), have a linear power response and flat impedance, and an accurate phase response. They are said to be flat from 50hz to 18khz, have an efficiency of 90db and a purely resistive loading of 4 ohms. They should therefore be able to be driven by relatively modest amplifiers of 40 watts or more. These are the speakers (along with the gigantic 30 series) that put Magnepan on the map. We will have available to power them the Society's Krell 300i amplifier and John's new low distortion amplifier that we heard last week.
The committee has decided to invite members to bring along an amplifier of their choice (contact John the SMGa's owner first) to try with these speakers, and to a similar invitation at subsequent meetings. Club members probably quite often wonder how a particular profiled amplifier or speaker might sound with their gear and so this is an attempt to solicit a greater involvement. The same invitation is extended regarding DAC's, turntables and so on. In the same vein you will find attached to this email the minutes of the last two but one (the last is still in draft form and needs to be accepted as a true and correct record) committee meetings from 13 11 23 and 11 12 23. This will assist members in keeping up-to-date with what is happening and proposed for future meetings and of course prompt your involvement.
Another way in which the committee would like to enhance members involvement is to have an open forum at each club night so that members can ask technical questions about something that interests them (e.g. problems with their own gear) and suggest what sort of equipment or music that they would like to have featured or bring along themselves at our monthly meetings.
So I hope that we will see you all at the next meeting, possibly bringing a bit of equipment with you. Visitors are also welcome, particularly from interest groups in other cities or paddocks.
Peter Coleman Secretary
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Post by michaelw on Feb 16, 2024 9:42:47 GMT 12
Classic Maggies. I had a pair back in the 80s but my room was too big so moved up to MG1b's, III's (not 30) were too big, too expensive. Fortunately Maggies came in all sizes, there was sure to be a Goldilocks model They are more accurately described as dipolar - figure 8 dispersion pattern - rear out of phase with front. Bipolar - as popularised by Mirage - are also figure 8 but front and rear waves are both in phase. They work well with grunty SS amps like Krells.
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Pundit
Post by peter0c on Mar 14, 2024 16:08:47 GMT 12
AAS Meeting 7.30pm on March 25th at Ramblers Softball Club, Cornwallis St, St Lukes
This month's meeting at St Lukes will feature my Ecofan 6N7 preamp, Ecofan SE6A3 power amp and 12 inch wide-range Goodmans 301 speakers. Members are invited to bring along any other compatible pieces of gear to try with these amplifiers or speakers, and of course we can always give the club amplifier or speakers an outing.The evening should therefore provide members with a bit of an idea as to how a nearly 100 year old amplifier design and 70 year old speaker designs compare with modern equipment. (Quite well is the answer!)
ECOFAN amplifiers (a contraction of Ecological Fanatic) were made by the late Murray Dick and are relatively well known in Auckland. Murray made about 50 pre amps and phono amps and about 150 power amps of wildly different designs (P-P, SE and OTL), over a 30 year period. They all feature DC filaments, direct coupled circuitry (i.e. no capacitors in the signal path) and zero negative feedback.
The SE6A3 although one of the lowest powered is regarded by aficionados as being the best of his power amps. It is a two stage design (like the direct coupled 1928 Loftin White, the much later Dan Garber Fi2A3 amps from New York and Yamamoto Type 45 and 2A3 amps from Japan, but quite unlike the very conventional 3 stage Audio Note capacitor-coupled designs), and has dual-mono valve rectification. Unusually, the power transformer has one primary and two secondaries to fulfill the 'more iron' transformer approach that Murray Dick favoured. The SE6A3 has a flat frequency response from well below 20 hz to well over 65 khz and is quite capable of driving inefficient speakers (e.g. Shahinians). The matching 6N7 preamp (according to Murray, the 6N7 - which is not related to the better known dual triode 6SN7GT tube - has the flattest transfer curve of any triode valve), similarly has dual valve rectified power supplies. This combination ought to drive the Goodmans 301 wide range speakers of 97db efficiency - supplemented by Aarum Cantus ribbon super tweeters cutting in at 10khz - to a satisfactory level.
We will again have a 10 to 15 minute open forum just before we break for tea and biscuits. This is to enable members to ask questions about issues with their own equipment, advice on possible new acquisitions / tweaks and suggest what they would like featured at subsequent meetings. Whilst we have some tasty items to feature at the next few meetings, it is helpful to have the assistance of members in suggesting and locating other interesting pieces. For example, does anyone have access to a classic McIntosh 275 valve amplifier or a well-reviewed solid state pre-power amp?
Finally, please bring your favourite CD's (music or sound effects) along to the March meeting. Visitors welcome
Peter Coleman Secretary
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Post by foveaux on Mar 15, 2024 9:03:51 GMT 12
Wish I could be there for your Ecofan session Peter! I bet the listeners will be well satisfied.
I treasure the day when timing and good fortune intersected for me to own a 6A3 power amp from Murray.
(S/N: 00480 )
"I see music as a lifetime affair." [Rory Gallagher]
"Free - I miss that band, but when I look back, we were very young" [Paul Rodgers]
848 posts
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Pundit
Post by peter0c on Mar 15, 2024 12:00:28 GMT 12
I have belonged to the Auckland Audio Society for about a year and recently put my name forward as secretary. One of the features of the audio world is tribalism (analogue v's digital, s-s v's valves, p-p v's se and so on and we haven't even talked about speakers!) which holds everyone back because we turn up at noses at things we are ideologically opposed to. For example I have been putting AAS stuff on Dark Lantern from the time that I joined and have NEVER been successful in encouraging any Auckland based DL respondents to one of our meetings, rather only a few snide comments. I suspect it is because the core DL respondents are turntable guys (which is fair enough) and although we have a turntable (Rega 3), we have mostly used CDs and recently streaming. I want to encourage the featuring of all kinds of equipment including modern stuff because it is only by listening a range can we really have an informed opinion. News break - most amplifiers and nearly all speakers sound wildly different from each other and guess what, none of them are anywhere near perfect. Tribalism like religion is silly and might be the death of DL.
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Post by michaelw on Mar 15, 2024 12:56:24 GMT 12
Tribalism on DL ? I know of at least one member who has attended AAS and decided it wasn't for him.
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Post by Citroen on Mar 15, 2024 15:30:33 GMT 12
Do we even have enough active members to form a tribe? 🤣
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Post by foveaux on Mar 15, 2024 16:16:56 GMT 12
Do we even have enough active members to form a tribe? 🤣 Maybe we're all just 'rank strangers' ?
"I see music as a lifetime affair." [Rory Gallagher]
"Free - I miss that band, but when I look back, we were very young" [Paul Rodgers]
848 posts
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Pundit
Post by peter0c on Mar 15, 2024 16:26:33 GMT 12
Taking Michael's response first, voluntary societies are what you make them. If every prospective member decided "it's not for me" because they didn't like what was currently on offer, then AAS and DL would cease to exist. Voluntary societies only exist because members put their time, money and thought into it. The claim "it's not for me" could reasonably be reinterpreted as "I'm not going to contribute", "I've got nothing to offer" or much more likely, "I can't be bothered". Members make it what it is and tribalism doesn't help. Citroen's comment that DL doesn't have enough members to form a tribe could similarly be reworded as "it is already tribal-based". Subsequent to Owen Young's untimely departure from DL, a large proportion of posts have related to "What I Am Listening To" on vinyl, which I now ironically applaud. I say now applaud because in the past it could have informed what vinyl I don't want to spend vast amounts of money on and await for several months the couriered arrival of a warped LP. Now I can rapidly have a listen on Tidal. Thanks guys!
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Post by Citroen on Mar 15, 2024 16:48:58 GMT 12
"The claim "it's not for me" could reasonably be reinterpreted as "I'm not going to contribute", "I've got nothing to offer" or much more likely, "I can't be bothered". Members make it what it is and tribalism doesn't help."
'It's not for me' can't REASONABLY be interpreted as what you purport!
'Its not for me' could be for a multitude of other reasons rather than what you say. The meeting topic may not have been of interest, the vibe of the group might not have been to their liking, the people may not have been their crowd, the day/time might not have been convenient, the gear of no interest, the topics on discussion of no interest. Who knows.
I have no idea what that member's reasons were but would be interesting to know.
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Post by RdM on Mar 15, 2024 17:44:15 GMT 12
AAS Meeting 7.30pm on March 25th at Ramblers Softball Club, Cornwallis St, St Lukes This month's meeting at St Lukes will feature my Ecofan 6N7 preamp, Ecofan SE6A3 power amp and 12 inch wide-range Goodmans 301 speakers. Members are invited to bring along any other compatible pieces of gear to try with these amplifiers or speakers, and of course we can always give the club amplifier or speakers an outing.The evening should therefore provide members with a bit of an idea as to how a nearly 100 year old amplifier design and 70 year old speaker designs compare with modern equipment. (Quite well is the answer!) [ ... ] Finally, please bring your favourite CD's (music or sound effects) along to the March meeting. Visitors welcome Peter Coleman Secretary Thanks Peter, and for the continuing updates. I've never had any concerns or considerations about so-called 'tribalism', or whatever is being imaginatively referred to... I've simply had health and stressful busy moving episodes that have prevented me from attending yet so far, that's all. I'd like to make it that night, and will make a serious effort to do so. It's only a couple of bus trips from my new place, not difficult. It'd be very nice to meet you after all these years, and also other members and guests on the night. Perhaps I'll bring a CD or two for a track from each too. I hope I won't be too rank a stranger after said couple of bus trips! ;=})) Meanwhile, for your entertainment, I just found this after spinning off that... Keith Richards - I'm Waiting For The Man (Lou Reed Cover) Ross Matheson _
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Pundit
Post by peter0c on Mar 15, 2024 18:37:51 GMT 12
I'll make sure that you get a lift home Ross.
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Post by RdM on Mar 15, 2024 18:51:12 GMT 12
I'll make sure that you get a lift home Ross. That's very kind of you Peter. I do so look forward to catching up! We'll see what happens! ;=}) Cheers !!!
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Post by rmc001 on Mar 18, 2024 9:06:47 GMT 12
[quote author=" peter0c" source="/post/37934/thread" timestamp="1710389327". It is a two stage design (like the direct coupled 1928 Loftin White, the much later Dan Garber Fi2A3 amps from New York and Yamamoto Type 45 and 2A3 amps from Japan, but quite unlike the very conventional 3 stage Audio Note capacitor-coupled designs), [/quote] A question: the Audio Note Kit One has a high-sensitivity input (I think it takes only 125 milli-volt to drive to full output. That means it doesn't need a pre-amp. So - do all 2-stage valve amps such as the Ecofan need a pre-amp.? (I see in the SET and full-rangers thread earlier on some two-stage valve amps seem to have volume control - like the Kit One. So - maybe not.?
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Pundit
Post by peter0c on Mar 18, 2024 11:52:35 GMT 12
No two stage amps don't absolutely need a preamp but it does help. The Audio Note Kit 1 has more gain however and I think has a valve for input and volume control duties but would still work okay with with a passive volume control. I hope to see you at the next meeting Rob.
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Post by rmc001 on Mar 18, 2024 12:22:23 GMT 12
Thanks.
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Post by Citroen on Mar 28, 2024 16:20:23 GMT 12
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Post by RdM on Mar 28, 2024 20:10:02 GMT 12
OMG I completely forgot! Maybe a post or email the night before might be a good idea for old forgetful fogeys like me... I'm so sorry, Peter. Looking back through emails to see what I might have been doing on the 25th instead, I see I wrote a long email re moving in and a phono stage I'd just bought. Well, I sincerely hope that we can catch up some time before we all die! ;=}) Let's try again for next time. Maybe we'll even be able to meet privately some time as well. Best regards still;- I hope to do better next time!
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Pundit
Post by peter0c on Apr 13, 2024 17:54:26 GMT 12
Auckland Audio Society Meeting 7.30 pm, 22 April at Ramblers Softball Club, Cornwallis St, St Lukes
This month's meeting is scheduled for 7.30 pm on Monday 22nd April at our usual venue alongside St Lukes Mall. It will feature Mark Farrell's two vintage English valve amps together with Bob Harvey's classic Celestion 25 speakers.
One of the valve amps is a Radford ST25 and the other are PYE HF 25 monoblocks. Both are push-pull ultralinear amplifiers offering 25 watts per channel using respectively, EL34 and KT66 output valves. The frequency response of the PYE's are given as 2hz to 160khz, they have 26db of negative feedback and variable damping from 35 to infinity! I will negotiate a preamp selection with the owners of both if they don't have one, and members are welcome to bring along some speakers - or a preamp - that they would like to try.
Bob's Celestion HF 25 speakers have a 12 inch bass, two Celestion HF 1300 midranges and a Coles 4001 super tweeter. (These widely-used midrange speakers and tweeters are identical to those on Steve Protheroe's B & W DM2a speakers which we heard a couple of months ago). Both amps would be capable of driving the club speakers. I will have my Goodmans 301's on standby for this or the next meeting and Bob Harvey is also keen to try his Leak TL10's (KT61 output tubes) on high efficiency speakers again. Please bring some of your favourite CD's and we will again have an open 15 minute forum (suggestions or offers for the future, handy hints or hifi questions) just before breaking for tea and biscuits. Visitors and friends are welcome.
Peter Coleman Secretary
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