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About Balcro

  • Birthday 08/12/1947

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  1. If you calculate upon a 100W input, nothing changes except the pressure within the port as I said previously. Remember Phil's comment about squeezing a balloon. The up-side:- if you change the smaller vent dimension to 3.8cm you are given a port length of 19.26cm i.e 19.3cm. You will need an air gap beyond the end of the port. If it's possible, make it equal to at least 3.8cm. The down-side:- the air velocity calculation shows a rise to 18m/s at 63Hz. Balloon squeezed, but still within recommended bounds.
  2. winISD calculates the tuning based upon speaker volume being linked to drive-unit parameters. It's giving an optimum result at one signal level only. As the amp signal/voltage increases, the speaker is pushed harder and increases the air pressure inside the cabinet. The tuning will stay the same, but the air pressure within the port rises and rises. Do you still only need to run the speakers at half your amplifiers rated output (150w)? I've run a variety of models with different amplifier inputs & enclosure volumes using your earlier rough guide to the speaker, and I 've found that with an 11.4L enclosure and a 75w signal from the amplifier, the 30Hz speaker output is at least -30dB below the output at 60Hz. With filters switched in, the difference is even larger; so large, it goes off the bottom of the scale. With a rectangular vent of 3.8 x 10cm (internal) and tuning set to 64Hz, the calculated port length is 19.26cm. Is this port length impracticable? The peak air velocity through the port is only 15.7 @ 63Hz. At the same frequency and with the 60Hz filter switched in, output from the speaker is down -4.6dB. Chuffing is not going to be an issue. With a 75w input the speaker is calculated to deliver 108dB from 80Hz & upwards, and with the 60Hz filter in the chain, xmax is not exceeded, even down to Zero Hz.
  3. The journey. In the early 70's I read too many magazines & caught the bug. Went to hi-fi shows, sat-in on listening panels, read more mags & dipped into hi-fi shops for a listen & drool - probably saw Bassaces' Quad. Lust but not enough cash. Started with a 10w per channel Amstrad!! Dad and I paired it with a Wharfedale Linton home built kit. 1976, a JVC cassette deck. 1977, an Alba UA 900 33w p/c amp, "a poor man's Sugden" (stil got it wrapped up in the loft). This was followed by another (bigger of course & on a stand) ) home built loudspeaker based on an 8" Dalesford speaker and a Shackman Electrostatic for mids &treble. Mmmm, nice. Went to Alex Shackman's house in Barnet for a personal audition. About '77, found Graham's Hi-fi in Islington. Really upmarket. Left with an Edinburgh Wireless FM tuner (Nytech in disguise) and a pair of PWB Electrostatic Headphones. Now we're motoring. Discovered Direct-Cut discs - Dave Grusin "Mountain Dance" was one. The PWB transformer failed in the 90's. Still in '78, bought an AR Sugden turntable & GH Hadcock tone arm. They're still parked in the hi-fi unit, loved but unused. Tweaked the platter with an anti-resonace damping pad. Married and moved. Walking to the car-park after work and spotted a Sugden A48 II in a record shop window!! It was a shop demo unit; I had to have it. It lasted about 12 years until I re-fitted the wrong plug into the wrong socket (hi-fi ffurniture re-fit) and blew an output transistor. Off to Sugden for £120 repair. I did a similar trick (with the mains extension socket thing on the back) early in the new century. There was a bang. Anybody want an old Sugden to fiddle with; A 48II, Serial No. 5723 awaits your screwdriver & soldering iron. Too embarrassed to send it back to Sugden again, so opted for a nice Denon 455 receiver which would have cost less than a major Sugden repair. Aiwa cassette deck bought in late 80's. Now parked and unused. I'm down to 20 cassettes. In the mid-late 90's CD's were the thing. More magazine articles. Marantz this, Marantz that - the best in it's class etc,. Went to Audio T in Enfield with my own CD's. "No sir, you don't need to spend extra on our extended warranties. These products are all very reliable." Auditioned Marantz ?67, a £600 Audiolab and a YamahaCDX 550. "The Marantz is a little more exciting" said the man. Thank you, said I. I started to become aware that I was listening to the eqipment (i knew the music backwards) but was the "excitement" accurate or was it showroom appeal? I came out with the Yamaha. I changed the cd-tray drive belt last year. If the electronics fails I'll change it, but not otherwise. Probably 24 years + amd counting. Circa 2015 bought a Van Den Huul interconnect for the CD player - a clear difference in both the revelation of detail & smooth presentation of the mids & high-mids. 70th birthday treat - Monitor Audio Bronze floor-standers. Great for cathedral organ music. Last year, Beyer Dynamics DT880's. Oh yes! LP's being phased out, the weak & unloved ones go to a local vinyl re-seller or Oxfam, the top one's are going to my grandson and many old/lesser CD's are being digitised. Maybe one day it'll all come down to a Brennan? Well, maybe one CD for the birthday & one for Christmas.
  4. Having read all the above posts it seems to me you may have a combination of weaknesses. Weakness 1. As others have said, the TC electronics form of compression is one thing and an average power-supply add up to a less than stellar sound at high volume probably regardless of the "D" class power module. Even so, 3-400 watts should good enough for most purposes. Weakness 2. In your post from about 13.13 you say you "struggle to hear the tone" and "the bass does not cut through the mix" at high volume. Well maybe you're also driving the speakers too hard as well. When driven in that state the drive units will also "compress" with increasing input power. That could be where you're losing the tone. Aside of whether you change the amp for a different class, why not try a temporary expedient. Cut the Bass. Turn up the low-mids and high-mids. Leave the treble where it is and re-try. If you need more definition turn up the high-mids a little more.
  5. In a reply to one of my posts elsewhere, Bill Fitzmaurice used the words "keep the velocity below 18m/s within the pass-band". From that, I assume he meant the pass-band for bass generally, would be something "above" 40 / 50Hz, with most (average) bass speakers managing a flattish frequency response down to 80Hz and then declining perhaps -7dB by 40Hz. So for example, if the port velocity rises at frequencies at or below e.g 40Hz, then air-velocity wouldn't be an issue. If you're aiming to keep velocity below 17m/s then you only need to do that over the pass-band, which, with the little Faital-Pro's is about 50Hz & upwards. As you have stated that you have use of a 50/60Hz HPF, I would use the filter/graphic equaliser all the time. It pulls down the air velocity over 4m/s in the 50/60Hz region. I've seen some fairly extreme home hi-fi set-ups with curving pipes, and it may be usable in your circumstances, but in doing that you need to make the enclosure bigger to accomodate the larger volume of internal pipework. As port calculations seem to be based upon the cross-sectional area x length I expect that "middle of port" is the answer. I can't comment on the use of the drainpipe or the ventilator duct, apart from to say that a right-angle will cause some turbulence. Over to Stevie on that one.
  6. After coming across quite late to your post and playing with the various options available under winISD I've found what I think is a compromise you might care to look at, but only for an input signal of 80 watts. As Stevie has said, getting good venting with high-powered small speakers in compact lightweight enclosures is very difficult. In my opionion it's a real P.I.A. Set the volume to 11.30 litres and tuning to 64Hz (same as the Fs). Following your references to a 3:14 ratio between port height and width I went back and checked my own figures which I had calculated earlier, but they didn't match. I found that using 3.8cm x 11.6cm I could get the air velocity down to 20m/s @55Hz. Port length is down to 23cm. With the 3:14 ratio for the port, the air-velocity is 1m/s higher. Without a filter, the frequency response is down - 4.9dB @ about 55 Hz. Put in a high-pass filter set to 50Hz and the 55Hz response drops to - 7.2dB. In these circumstances I think that is for the better as it is acting at the point where the air velocity is highest. With a 150 watt input, like you, I found it impossible to achieve good air velocity figures which ever way I changed the enclosure volume. At 150 watt input there is a small dip in power handling between 80 - 115 Hz (the xmax / cone excursion figure corresponds) so I would consider limiting your input to about 110 watts. Best of luck.
  7. I'm still open to it even at the fully ripe age of 72, but I must admit I want it to come to me. I never listen to the radio even though we have 2 digital radios. Occasionally I'll pick something up on youtube and I'll hit on say 1 track, like this for example. https://www.youtube.com/results?search_query=anouar+brahem+blue+maqams Then I'll bemoan the lake of anything new and classy. Singer-songwriters and anything vaguely M.O.R are out, boring; rap & club crap are definity out - doesn't meet my idea of music and I'm too old for swallowing chemicals to make the noises acceptable (might interfere with the statins). Where are the new class acts with well written songs? Are there new "Steve Miller" or Robert Cray" bands out there? As SimonEdward says above "well crafted music". I even enjoyed the acceptable face of electronic music way back when - anyone remember Isao Tomita "Snowflakes are Dancing" (Debussy). I've tried Spotify and as an example looked for "New Jazz". Gave up after endless utterly obscure variations on an unknown theme from a hallucinatory western. Even wacky can be fun, especially if it's done well. When "San plein pour moi" comes on as backing to a commercial we're grinning our heads off and I take to air guitar! Yes, I'm still open for accepting new stuff, but please help!!!
  8. Replacing the drivers with bass units can work and I assume the 4x10 is a closed box and the gross internal volume of the cab is about 95 litres. The Celestion Pulse 12-200 fits quite well. The Eminence Beta 12a-2 works a little less well and may be a touch "boomier" in the low-mid bass (see coments above from "Beer of the Bass").
  9. Guess who they've been listening to? Another way of "Making America Great Again !!"
  10. THIS! + rigger gloves @ work.
  11. I get a lovely tone on my Cort GB74. No complaints. have a look at the videos on youtube - https://www.youtube.com/results?search_query=ghs+precision+flats+
  12. stringsdirect.co.uk are considered to be very reliable. They're stocking GHS. I think I bought mine from there. If it's not listed on the web-site, phone them. They can usually get hold of strings in a few days.
  13. Wow! What a collection: 5 drivers. The K.140 is quite adaptable. BFM's post from May 2015 will give a long smooth roll-off at the bottom end. If you want more low bass, then a single K140 will still work happily in a 2cu.ft (56 litre) enclosure. So two K.140's will require 112 litres or thereabouts. Port size and length are dependent on your choice of enclosure size. For example, with 2 x K.140's in a 112litre enclosure, winISD suggests a 12.5cm square duct but only 4.5cm long. The 2123 bass /mid works in a closed box of 7 - 14 litres. Frequency response is from 80Hz to 6K, although the recommended crossover is 3K. The Altec 808 compression driver works from 500Hz - 20KHz. You'll certainly need an attenuator to match it to the bass and bass/mid. Whether you need the 2402 and the 2405 is questionable with the 808 extending to 20K. Whatever size you choose, you need to reserve 15litres for the separate midrange box, 6 litres for the internal volume taken up by the two K.140's, 1 litre for the 808 compression driver and 0.5litre for the internal space taken up by the duct.
  14. Pauline Moran - For many years the demure but sharp Miss Lemon in the Poirot TV progs . From '65-70 played bass in a band called The She Trilogy. These days she's an astrologer.
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