tcpip's darbari and a bit of nostalgia

[HormusPeston]

Hello all and a special hello to tcpip,

I noticed tcpip's post on the DIY Gainclone thread here. On his website he narrates his early excursions into speaker building, which I'm sure filled people (of a certain age, like myself) will warm nostalgia. If you have not read his website, I propose that in the company of your favourite music and a nice glass of your chosen poison to lubricate the mind and bones, an hour or two on his site would be time well spent.

Before I continue -- I just checked my bookmarks and the site tcpip.dhandanought.org/ doesn't open -- has this site moved to a new location?

Regardless, I remember one of the things he said: "My chest filled with pride when my friends commented that the Darbari was over-engineered..." Someone once said the same thing to me and I too felt immensely proud ("What a waste of wood, a three-layer front baffle?")

I too share ("shared," perhaps, is more appropriate) his fetish for Kevlar cones!

Anyway, this post was just to say hello to him, and to ask other members of this forum if they built the Darbari. I'm looking for a project for this summer...

Cheers,

~hp

 

[GeorgeO]

Shri tcpip aka Tarun, is very much around and on this forum and he and I have met on multiple occasions. I will send him a message, in case he hasnt seen this post, and ask about his site.

 

[tcpip]

Sirs, you honour me.

My site is down temporarily, because of some screw-up with Drupal themes. I'll fix it ASAP. The URL you wrote is correct.

And as far as I know, no one has even suggested wanting to make the Darbari. The reasons are fairly simple. My earlier speakers, the Asawaris, can't be replicated any more because those drivers are no longer available. And the Darbari is an expensive pair of speakers, and most DIYers with that kind of budget are spoilt for choice.

Thanks for the kind words.

 

[Kannan]

Sirs, you honour me.

My site is down temporarily, because of some screw-up with Drupal themes. I'll fix it ASAP. The URL you wrote is correct.

And as far as I know, no one has even suggested wanting to make the Darbari. The reasons are fairly simple. My earlier speakers, the Asawaris, can't be replicated any more because those drivers are no longer available. And the Darbari is an expensive pair of speakers, and most DIYers with that kind of budget are spoilt for choice.

Thanks for the kind words.

Sir I am running the same drivers except for the midbass which is not from the Dayton reference but the Classic range (1/3rd the cost), but since they are crossed below 400hz, they perform pretty well.
the other two drivers are Dayton refernce 6 inch midrange and Dayton reference silk dome tweeters.
Since I don't have the skill to design passive crossovers, the setup is running active through a dbx 3-way analogue active crossover.
I DIYed the enclosures, though not enterprising as your's, but quite functional

 

[tcpip]

I don't use the Dayton tweeters. I used the Peerless HDS. A second choice would be the Seas TDFC. I don't know of any tweeter better than this one, if the xo is designed well.

And if made the Darbari again, I'd definitely make the enclosure simpler in shape, and the wooden enclosure would be about a foot shorter.

 

[greenhorn]

If reading is your objective, the internet archive has you covered
https://web.archive.org/web/20160808213609/http://tcpip.dhandanought.org/audio

Edit: seems only some pages

 

[Kannan]

I don't use the Dayton tweeters. I used the Peerless HDS.

oh sorry, i had read your blog long back and remembered all the drivers as Dayton.

 

[tuff]

The original site has some chinese alphabets and goodly baba says this site may be hacked.:sad:

 

[tcpip]

The site is up. What a relief. The "drush" command worked.

Managed to safely switch the theme too, to a new one which is responsive. Now the pages view relatively better on a cellphone. Hope you like it.

I also switched off comments. The site had been taken down by my hosting service because spammers had posted thousands of comments and consumed a few GB of database space.

 

[Naturelover]

The site is up. What a relief. The "drush" command worked.

Managed to safely switch the theme too, to a new one which is responsive. Now the pages view relatively better on a cellphone. Hope you like it.

I also switched off comments. The site had been taken down by my hosting service because spammers had posted thousands of comments and consumed a few GB of database space.

Abracadabra! Yes, it does. Super. Thanks. I remember having read it a long time ago.

 

[HormusPeston]

Revisited the site. Nice! In those days I suppose every town used to have a resident Jeetubhai -- the quality of the product differed but there was always someone like him. Tcpip, what were the different amplifiers used the Darbari 3-way system? The article on the Darbari would benefit from an additional page on the amplifiers used. Were they chip-amps by any chance? Thanks for the website and the memories, Cheers, ~hp

 

[tcpip]

Revisited the site. Nice! In those days I suppose every town used to have a resident Jeetubhai -- the quality of the product differed but there was always someone like him.

You wouldn't believe! I've dealt with a Notable Personality by the name of JS Monga (IIRC) through the connection of my speaker guru, Angshu. Mister Monga was an old sardar who used to own and run a company called Bolton. His sons run it now.

His speaker drivers used to be advertised on the back covers of many Indian electronics magazines. I'd actually asked Bolton to ship me 16 (yes, I was crazy!) 6.5" poly cone drivers with stamped steel frames. They were even poorer quality than the Peerless India stuff, or maybe as poor quality as the poorer stamped-steel basket models of Peerless. My aim was to make MTM, line arrays, etc, etc. They were inexpensive -- less than Rs.500 each. And they could handle 40-50W of power. Each of them had to be measured to get their T/S parameters. The parameters would vary more widely than Peerless India drivers, and there were no published figures.

Bolton's primary market was the sound reinforcement industry, I guess. That's the only industry which continues to sustain these speaker driver makers. See Parts Express of the US -- they are catering largely to this market, even though they have lots of more exotic drivers.

So, yes, one meets really interesting people on the way. I guess you may have read about my dealings with Uncle Harry of Shivaji Park, Bombay?

Tcpip, what were the different amplifiers used the Darbari 3-way system? The article on the Darbari would benefit from an additional page on the amplifiers used. Were they chip-amps by any chance?

I promise to tell you, if you promise not to write to the mods to ban me for being so plebian.

I am using a Marantz SR5200 AV receiver in pure power amp mode.

There goes all my reputation as a speaker designer, and all the reputation of my beautiful Darbari, into the Arabian sea. Did I just see you wince?

The story is as follows.

I had taken forever to build the Darbari, and it had been a big job. Just building bigger, more complex speaker enclosures is a bigger headache, and then came the entire unknown minefield of DSP active crossovers. At that time, I realised that at my consistent snail's pace of building, if I tried building the amps too, I'd be 80 years old by the time the project finished. So, I desperately started looking for alternatives. I need six channels of modest power, clean amplification.

I suddenly discovered that some (not all) of these vile, crass AV receivers have what they call "multi-channel analog input". If you use those inputs, you effectively reduce the complex AV receiver to a multi-channel power amp + volume control. Awesome. (The very recent models, and the cheapest models, don't have this option.) My prayers had been answered. I started reading up specs of these amps, and discovered that most had pretty bad distortion spec. The Marantz units of about 8-10 years ago were relatively better. I froze on one of these models, and imported one, used, from a seller on eBay UK. The shipping and Customs were all handled beautifully by Borderlinx, of which I've been a fan for 10+ years. The base price was UKP 100. Plus shipping from UK to India, plus Customs. All told, I think I spent about Rs.34K for the piece, landed cost in Bombay.

So, my beautiful Darbari, which continues to deliver spectacular sound, is currently driven by an AV receiver. Distortion spec on paper: 0.05% (whether at just 1KHz or upto 20KHz, I will never know). SNR 105dB. Power output: 85W/ch. Cross-talk: well, I didn't ask. Don't push your luck, was my policy.

I had bought 10 kits for making 10 channels of power amps, before all this happened. Those kits are still there. Each channel will deliver about 50W, but THD will be in the triple-zero range. These are kits sold by a chap called Panson Audio of HK, designed around the LME4981x driver chips and ThermalTrak OPS transistors. I also ordered two massive R-core transformers, one for each set of 4 channels. (I intend to make two 4-ch power amps with these kits, and keep the last two kits as spares.)

I will make those amps someday. I promise. Till then, listening to music is too much fun.

 

[HormusPeston]

Wince? No. You didn't see me cheer! The motivation for the DIY culture is as diverse as DIY-enthusiasts. The fights over DIY ideology (discrete vs. integrated, distortion-haters vs. distortion seekers (yes, that means you, vinyl and valve-lovers) are good and an essential part of the culture. But sneering at inexpensive equipment is not. So your reputation was never at risk. Perish the thought.

My first "amplifier" was literally hacked out of a broken television (I used to repair them as a perpetually poor college student). I think it was a black-and-white, all-transistor Uptron that gave up its innards for my cause and I can tell you, I still search for the same emotional high I got when I built that! Since then, I've built a lot of radios, cassette players and "hi-fi systems," as they were called in those days. A chap called T.S. Shankar used to publish hi-fi projects in EFY, and one of his integrated cassette-decks was the first hi-fi project I built entirely from scratch (on veroboard) -- you could buy the double-cassette mechanism in those days or cannibalise it from an scrapped stereo.

Loved the story about Uncle Harry. Let me share one of my own. About twenty or so years ago I had found employment in Calcutta and, consequently, the nature of my poverty has taken on a semblance of predictability: an inverse exponential curve, asymptotic to the x-axis that would repeat itself every month. So, in the first half of the month, I could usually be found ferreting around the electronics market just off Dharmatala Street in the evenings. (The area had a few working-class bars with live music and other distractions, but that's another story.) In an American magazine, purchased second-hand, I found an exotic amplifier. Pretty standard push-pull design: the exotic part was the layout that required the use of a double-sided board. If you recall, pcb tracks in those days were free-hand curves. And this board had curves that looked like Madhubala. Like that song in Howrah Bridge, she was calling out to me. I had to build it! Unfortunately, in those days only one shop in Calcutta (Raltron? Relitron? Reltron?) carried double-sided blanks. This shop stocked a large selection of electronic deliciousness -- a wide selection of expensive imported instruments, meters and other goodies -- arranged provocatively in a display window. It was a delight to see, an oasis in an otherwise featureless street. Its owner, unfortunately, was a particularly rapacious individual, with the charm and manners of a flatulent bullfrog. He demanded Rs. 800 for a 6X4 paper-phenolic resin board, which was oxidised and smudged with greasy fingerprints. It was extortion to say the least and when I protested politely, he hissed and asked me to leave the shop. The next day, as I was walking past I noticed that he had placed the double-sided board in the shop window. The horrid little reptile was taunting me! So, I decided to make a double-sided board by gluing together two boards. I wasted a lot of money in the process (multiple failures -- the damned things would absorb water from the etching bath and warp) but finally I had a usable board. I never built the amplifier, but I think that board is still around somewhere!

I've drooled over a kevlar cone woofer in Delhi's Lajpat Rai Market (again, another story and digression.)

Cheers,

~hp

Post Script: Checked online: The shop is still in business. It is called Railton.

 

[tcpip]

Rapacious Railton. The name has a ring to it.

Good to know you HP. You're in Pune, are you? Please consider this an invite for you to come spend an afternoon or evening at my place, chatting and listening to music.

 

[HormusPeston]

That is most kind of you, tcpip. I will let you know via a private message before I next visit Bombay. Thanks and it is an honour to know you. Cheers, ~hp.

 

[keith_correa]

I had bought 10 kits for making 10 channels of power amps, before all this happened. Those kits are still there. Each channel will deliver about 50W, but THD will be in the triple-zero range. These are kits sold by a chap called Panson Audio of HK, designed around the LME4981x driver chips and ThermalTrak OPS transistors. I also ordered two massive R-core transformers, one for each set of 4 channels. (I intend to make two 4-ch power amps with these kits, and keep the last two kits as spares.)

Well, well, well!!! Panson Poon's kits. That brings back memories. Nice guy, that Panson. Very knowledgeable too. I think I have a couple of his boards/kits lying somewhere. Sometimes these [and other] orphaned boards/kits call out to me but I ignore the nasty creatures. Must. Not. Give. In. To. Temptation.

 

[tcpip]

I wish he had made more kits. He stopped at just one.