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Post by karatestu on Mar 24, 2018 19:05:20 GMT
I started my hifi journey with Marantz & Wharfedale back in the 1990's. Nothing spectacular and it was enough for me until i heard some Naim & B&W equipment at a dealers. I came away with a CD3.5, Nait3 and a pair of B&W P4 transmission line speakers. Suited me down to the ground and the music i was playing at the time. A friend sold me a Linn LP12 and Lingo (£150 )and i had never heard one before. My system stayed much the same (except for an amp change to Nac72 & Nap140 and a couple of hicaps were added) for about 10 years (unheard of nowadays) until the fateful day that i joined the Naim forum. I then discovered PFM (2007) and the Naim forum was quickly forgotten. The next stage of my journey involved reading the pfm diy room from top to bottom, learning lots of stuff and plucking up the courage to learn how to solder and have a go. Much modification of my system followed and the discovery of Avondale Audio. My amps and psu's quickly turned fully Avondale except the cases. I then realised that the cases were not big enough for what i wanted to do so they were abandoned and i built four mono block amps on 60cm2 sheets of 20mm chipboard. No shielding or bugger all. CD3.5 morphed into something really special with all the mods i could think, 4 psu's and lots more besides. However, i was still not truly satisfied even after going mostly Avondale. I had remembered reading Richard Dunn's rants on pfm (2007?) and quite enjoying them. I looked up his company and read lots of things on his website that interested me. I then found HFS, quickly joined, read lots of the archive and decided to try out some of the ideas there. Speakers were first. What started as a simple doc mod project turned in to a semi omni experiment and then a 12" bass cube was added. That quickly turned into an isobaric bass cube. Awesome. I then bought an AP20, phono1, BMU and some cables. Loved what i heard and so started modding my psu's and amps more in the nva direction. Filters removed and psu's modified. Tis and ls6 cables were icing on the cake. Then Richard kindly offered me the chance to build some amps with his amp boards. I have done a couple already but the experiments are not finished yet and i need to build another 4 so i can put a 6 pack on my speakers. A one step stepped attenuator ( 2 resistor potential divider) was the last modification. I cant alter the volume but it sounds awesome especially with no selector switch or volume control contacts in the way. That is a brief over view of what i have been up to. I will go in to more detail with pics if anyone is interested. So far i have had no thoughts to cosmetics as i am still experimenting with every part of the chain. So dont expect to see tidy builds with flashy bling cases, stupid wiring looms etc etc. Its how it sounds that matters. A big thank you must go out to people who have helped me along the way. Martin Clark (pfm & acoustica.org) Les W (Avondale audio), John R (Analogue innovation) and Richard Dunn (NVA). A special thanks to Richard though as he has taken the time and patience to guide me along the path to bullsh*t free, quality sound reproduction. Keep it simpke stupid . More installments to come.
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Post by ChrisB on Mar 24, 2018 19:33:24 GMT
Interesting. Yes, photos would be good. About this bit: I was going to say that would be a step too far for most people, but in a way, it's entirely the opposite! It must be a bit frustrating at times to be confined to one volume setting. Have you thought about using binding posts, so the resistor can be swapped easily? My Bent Audio Mu SUT uses that arrangement for loading and I am able to swap them extremely quickly. Here's a photo (not of mine)
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Post by karatestu on Mar 25, 2018 7:28:46 GMT
Hi Chris, It is rather annoying sometimes not being able to change volume. But i expect the music will suffer when a selector and stepped attenuator switch are introduced. I am having such a ball with just the resistors soldered in that i am going to stay with it for a while anyway. Your binding post idea is an interesting one. Swapping resistors to change the volume would not be too much hassle. It would be interesting to compare a soldered connection with binding posts. Currently the resistors i am using are welwyn rc55y (10k in series and 604R to ground) often used in feedback and other important positions. They are nothing special and i am intending to try some fancy ones like charcroft z foils and audio note tantalums. Keep it simple
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Post by ChrisB on Mar 25, 2018 10:40:17 GMT
When I first got the Mu, I spent a while determining the best value of resistor. It came with an envelope containing a range of values and I had been told by the maker that they were a cheap and cheerful brand of resistor just to get you going. Once I settled on a value, I bought some from a range of manufacturers and my wife and I spent a few hours swapping them around to find the best sounding brand. It was a simple thing to do the change while the music was playing and took just seconds. I was surprised just how different two resistors of the same value could sound.
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Post by karatestu on Mar 26, 2018 6:11:32 GMT
Hi Chris,
So which resistors did you try and which one won ?
I will probably try a few from hificollective but some of the prices are a bit eye watering. For a full 23 step attenuator the price can end up at £400 and more.
I had the idea of finding out the highest resistor value i need for the shunt position and mising out the last few steps that will never be used. That also gives me a volume limiter so nobody can turn it right up and possibly blow my amps through thermal runaway or blow the speakers via clipping. Peace of mind as i have two young children.
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Post by ChrisB on Mar 26, 2018 6:46:23 GMT
Gosh, it was a while ago now! I tried about 5 or 6 different brands, as well as the ones supplied and I can't remember what any of them were except the ones that I felt sounded best, which were Shinkoh. However, I'm pretty sure they weren't the most expensive.
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Post by karatestu on Mar 26, 2018 20:49:00 GMT
Yes, Shinkoh have a good reputation. The audio note tantalums are the most expensive at hificollective I think.
I fancy trying the charcroft z foils first. They are running out of a lot of the values of shinkoh which is a shame as I would liked to have tried those too.
Stu
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Post by karatestu on Mar 27, 2018 8:03:39 GMT
My diy adventures at HFS started with a proposed Doc mod project. As 12" doped drivers were available I decided to look for some old knackered speakers which were in ok condition cosmetically. Watched ebay for a while and found a pair of early 1970's Marantz Imperial 7. 3 way speakers with a 12" woofer, port and crossover. Of course the drivers were going to get binned along with the crossover and the port sealed. Looked forward to getting them but parcelfarce put a dampener on things as they managed to damage the corners of the cabs. I took the executive decision to take the "bumpers" back to the baffle thus getting rid of the damage. By using the baffle as a guide I managed to get a very neat finish and the baffle ended up as smooth as a baby's bum Richard sent me some doped drivers - 12" Kevlar bass, 5" Kevlar mid and a Visaton G25 tweeter. Yum yum. The 12 inchers fitted straight in where the old ones came out but the mid and tweeter were going to require some more woodwork I soldered some low gauge wire straight to the driver terminals - no faffing about with crimped spade connectors. More to follow.
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Post by karatestu on Mar 27, 2018 11:27:23 GMT
I decided I wanted to give the semi Omni approach a go and did not want to cut a hole in the top of the Marantz cabs until I had tried semi Omni and decided if I liked it. To that end I had a look around for scraps of wood to build two very small speakers with a hole in the front and the top for the 5" mid. That way I could try it both ways and compare (as long as I put a blanking plate in the unused hole. Came up with this which I could sit on the top of the big Marantz cabs. It is only a prototype by the way and will not be the finished article A sneaky look inside The crossover (or lack of) I decided to give semi Omni a try first. But to use the big Marantz cabs I had to block the mid & tweeter cut outs plus the port The full thread at HFS can be found HERE . Its a long one.
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Post by karatestu on Mar 27, 2018 19:16:38 GMT
For those not familiar with the doc mods they entail 1) removing all wadding / stuffing 2) steel lining the cabs 3) throwing away the crossover 4) doping the driver(s) I cut and applied hammerite to a lot of steel, even angle profile to get right in the corners. This was for just the big Marantz cab, i did not bother with the little cuboid. The crossover was ditched The speakers weighed an absolute ton when full of 5mm steel. My kids will never knock them over , it would be like a car crashing in to a large tree .
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Post by ChrisB on Mar 27, 2018 19:55:20 GMT
Neat cuts on the steel there!
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Post by Tim on Mar 27, 2018 20:20:07 GMT
Stu, Just been reading your thread over at HFS - I have to say it's quite possibly one of the most enjoyable reads I've ever encountered on a Hi-Fi forum, brilliant and thanks so much for sharing. Your honesty is a rare thing in audio fora. Infinitely more gratifying than reading about folk messing around with fuses
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Post by karatestu on Mar 28, 2018 6:05:03 GMT
Neat cuts on the steel there! Thanks Chris. A have use of lots of tools and scrap metal on the family farm. I used a chop saw.
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Post by karatestu on Mar 28, 2018 6:14:25 GMT
Stu, Just been reading your thread over at HFS - I have to say it's quite possibly one of the most enjoyable reads I've ever encountered on a Hi-Fi forum, brilliant and thanks so much for sharing. Your honesty is a rare thing in audio fora. Infinitely more gratifying than reading about folk messing around with fuses Thanks very much Tim, that means a lot. I tried to make it informative and entertaining. Honesty - if something does not work or is not ideal i prefer to say so and back track if needed. Its all about the journey and learning. I have no intention of building myself up in to a hifi forum guru and if i dont know something i will ask. I find there is no better way to learn than trying things for yourself as following internet advice and taking it as gospel is sometimes dangerous. Did you read all 47 pages ? If you did you will know it is not even finished yet. Stu
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Post by Tim on Mar 28, 2018 9:17:52 GMT
Did you read all 47 pages ? If you did you will know it is not even finished yet. I did and yes, you still have a ways to go
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Post by karatestu on Mar 28, 2018 16:16:24 GMT
Did you read all 47 pages ? If you did you will know it is not even finished yet. I did and yes, you still have a ways to go Wow, you did well to read all that. I have similar threads over at hfs which i will link to when i get to the relevant bits here.
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Post by Tim on Mar 29, 2018 8:21:02 GMT
Well stuff like that I find interesting - I've a strange relationship with HI-Fi, it's the music that floats my boat, live especially. But DIY is cool, people making equipment just for the pleasure of listening to music is so different to what most audiophiles get excited about. It's uplifting
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Post by karatestu on Apr 4, 2018 7:38:25 GMT
Once I had the big Marantz cabs in a state that I could listen to them I hooked them up together with the little semi Omni cuboid speakers. The Marantz cabs were just about the right height to act ask a stand for the little cabs. Some blutack tack at the interface was added to stop them moving around or rattling. So, lots of steel added to the big bass cab and none in the little cabs. No crossover except a 3.3uf cap on the tweeter and a 12R padding resistor. Bass and mid drivers doped to attenuate unwanted driver output mechanically. No stuffing at all and all enclosures are sealed air tight. Bass drivers as close to the floor as possible for that Roy Allison effect. Amps and speaker cables were all diy Avondale at the time. I initially tried them with the bass and mid in series but also tried them in parallel with a 4 pack of power amps. Initially I was impressed, where did all that bass come from ? They sounded awesome with a lot of music. But I found with certain music (bass heavy) that the bass was just too much, bloated and not nice. Tried inserted a padding resistor, swapping phase on the bass drivers or mids and also inverting the bass cabs to get the bass driver away from the floor. The situation improved but did not go away fully. I then had the idea that the big cabs internal volume was too small. What to do ? Turn them isobaric or make some more cabs - which was a shame after all the work I had put into this so far. Some time elapsed where I went quiet on the forum about these. Unknown to everyone I had been busy and it was not until prompted that I posted what I had been up to. This was the result. Big bass cubes with a 90L volume and made out of the finest chipboard (old ikea furniture). As a prototype I paid little notice to aesthetics (as you can see) but made sure they were rigid and air tight. A big 56lbs weight was put on the top of each to try and stop any cabinet movement.
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Post by MartinT on Apr 4, 2018 8:01:58 GMT
I think your carpet and wallpaper are interfering with my 'listening experience' in your photos But seriously, that's a lot of work and I admire your drive to reach your goal. My DIY antics in earlier years looked a bit like this. By the way, achieving high quality, tight and tuneful bass is a difficult target and the room plays a serious (and sometimes very deleterious) part in it. Maybe my love of organ and electronic music plays a part, but I find that virtually all music benefits from an extended bass response even if there appears to be little bass content in the piece you're playing.
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Post by karatestu on Apr 4, 2018 8:18:55 GMT
The carpet and wall paper are genuine 1970's, introduced in 1978 when I was 5. I obviously have my own house these days but I still work at the family farm and do all my diy bits and bobs there (and in my old bed room). The bass was too annoying and I could not live with it. I do wonder now that it was possibly something to do with the drivers needing to be run in. Maybe I will revisit them cabs soon with the drivers back in or with a different driver that requires less cabinet volume (if the original ones still do not work). The story here is no where near the end of this speaker saga. It gets better
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