What equipment are you currently working on?

56oval · « **Reply #120 on:** 3 Oct 2009, 02:45 am »

Quote from: poseidonsvoice on 1 Oct 2009, 10:32 pm

Quote
Hi Mike
I was looking at getting Dr Earl's speaker kit ,but the Oz dollars went south really quick and put a stop to it ,maybe next year a Summa kit would be cool .

He's a pick of the striplam's stack with the baffle

Cheers
Mal

Looks like you are going for that 'Magico' look. Very cool.

Anand.

Hi Anand

Cheers mate.

When the cab's are finished you won't end up seeing the ply . The striplam construction ended up being easier to make the cabinet's in the shape I wanted than using high quality bendy ply that could be bent in a small radius .

Cheers

nullspace · « **Reply #121 on:** 8 Oct 2009, 09:18 pm »

I've been working on a 6EW7->2A3 pushpull amp for a while, so here's an update.

The first jpg is the signal portion for one channel and the other jpg is the power supply for one channel. Here is a schematic if you're interested.

It's pretty straightforward: input transformer-buffered volume control (Penny&Giles RF11 in this instance), 6EW7 twin triode doing both input and driver duty with the little triode DC-coupled to the big triode, MQ autoformer as phase splitter, and 2A3 parafeed PP finals, with cathode biasing all around. The DC side of things is full-wave rectification with 6CJ3 TV damper diodes into a choke-input filter.

Results are preliminary, but suffice to say it's a much different amplifier than the 27 preamp/ 56->45 SE amp combination I've been living with for the last year or so. Very cliche, but with the PP amp I'm hearing all kinds of details/ articulation that were lost in the previous setup. But at the same time, I spend a whole lot less time singing along (which may be a good thing) as there seems to be less emotional content. If I could just get the transparancy of the PP amp along with the emotional connectedness of the SE amp I'd be all set...

Parafeed for SE amps is pretty well documented, but less so for PP amps; I've only seen a couple of amps that use it, none commercially. Here is a note from Mike @ Magnequest on why parafeed might be beneficial for PP amps. I have every intention of trying both series and parallel-feed, and attempted to wire things such that it wouldn't be too onerous to try.

Regards,
John

jeffdavison · « **Reply #122 on:** 8 Oct 2009, 09:40 pm »

Doing up a DIY Schroeder tonearm... more cost effective to build 3... piece price of the parts vs. setup and tooling make the first one pricey, but the 2nd and 3rd a helluva lot less ex$pensive
Some of the parts are still 30 days out.....lead times don't ya know

nullspace · « **Reply #123 on:** 8 Oct 2009, 09:48 pm »

Wow, that's very nice, Jeff.

You've been participating in the DIY Schroeder thread at diyAudio, right (it's been a while since I checked it out)? That thread is a classic example of how unbelievably awesome some manufacturers are in supporting the DIY community, IMO.

Regards,
John

JoshK · « **Reply #124 on:** 26 Oct 2009, 01:36 pm »

That DIY schroeder arm is inspiring. Where do you get the machining done?

I've been veneering my bins. Its very slow going, as I usually do one side at a time, which is usually one side every other day. I have one 2/3 done and the other 1/3 done.

On another note, I started constructing my First Watt clone chassiss. I've had some Conrad heatsinks for a while now, and I ordered some aluminum to make them into chassis. Gordy had given me a tap and die set some time ago so I am going to try to tap the heatsinks and mount the aluminum plates directly.

The faceplate is 1/2" thick aluminum. I was a little concerned that it would be hard to cut as I didn't order it precut. However, I bought a non-ferrous metal blade for my miter saw and as long as you went slow it cuts like butter. It didn't even make a lot of noise like I expected.

When I get it all tapped and cut, I am going to look up a powder coating/anodizer to finish them. Anyone know of a good resource, preferrably local to the NNJ/NY area?

BobM · « **Reply #125 on:** 26 Oct 2009, 02:09 pm »

Just finished building a Peter Millet "Mini-Max" headphone amplifier to use with my HD-600's. A nice, compact and inexpensive tube-hybrid design. It's got 25 hours on it so far and has started to open up nicely. No trace of grain or distortions with good air and deep punchy bass.

I needed to build something after my Sony DVD player crapped out and I bought a new Ayre CX7e CD player (no more headphone jack). This solution now lets me also listen to records on the headphones too!

http://www.diyforums.org/MiniMAX/MiniMAXoverview.php

jrebman · « **Reply #126 on:** 26 Oct 2009, 03:27 pm »

Hi Bob,

I'm 99% done with mine too. Can I contact you offline as I'm blind and my only question left is where to solder the connections on the board to the tube bias test points.

-- Jim

jeffdavison · « **Reply #127 on:** 26 Oct 2009, 10:52 pm »

The flat pattern pieces are being sourced from Front Panel Express, they work with 6mm, 8mm and 10mm thick aluminum, My pieces are 8mm thick.

THe other machined parts are being mad by eMachineshop.com. THey have a 30 working day leed time

JD

Quote from: JoshK on 26 Oct 2009, 01:36 pm

That DIY schroeder arm is inspiring. Where do you get the machining done?

I've been veneering my bins. Its very slow going, as I usually do one side at a time, which is usually one side every other day. I have one 2/3 done and the other 1/3 done.

On another note, I started constructing my First Watt clone chassiss. I've had some Conrad heatsinks for a while now, and I ordered some aluminum to make them into chassis. Gordy had given me a tap and die set some time ago so I am going to try to tap the heatsinks and mount the aluminum plates directly.

The faceplate is 1/2" thick aluminum. I was a little concerned that it would be hard to cut as I didn't order it precut. However, I bought a non-ferrous metal blade for my miter saw and as long as you went slow it cuts like butter. It didn't even make a lot of noise like I expected.

When I get it all tapped and cut, I am going to look up a powder coating/anodizer to finish them. Anyone know of a good resource, preferrably local to the NNJ/NY area?

jeffdavison · « **Reply #128 on:** 1 Nov 2009, 10:21 pm »

More parts coming in... partial assemblies built up, still waiting for more parts. Also a pic of the turnatable one of the arms will be mounted on.

Jeff

mgalusha · « **Reply #129 on:** 2 Nov 2009, 02:05 am »

That is going to be one sweet setup. Are the copper colored pieces solid copper or just plated?

mgalusha · « **Reply #130 on:** 2 Nov 2009, 02:14 am »

I have been slowly, ever so slowly, working on a Buffalo DAC for a good friend of mine. We picked up a couple of the first run of Buffalo boards with the 9008 chip, prior to ESS releasing the Sabre 9018 chip. We were able to score a couple of the 9018 chips, which I will be transplanting to the original boards soon.

He wanted a tube output stage and I went through several iterations before I had something that seemed like it would work well. I ended up using a 12B4 with a Pimm CCS and taking the output from the mu follower connection. Power supply for the tube section is a Tubecad dual supply configured for 12.3V and 300V for the B+.

I finally had some time today and drilled a lot of holes to mount everything to the chassis. Still waiting for the transformer for the tube section but everything else is more or less ready to wire up. Still have to drill the front and back panels but that will go quickly.

Couple of pics.

jeffdavison · « **Reply #131 on:** 2 Nov 2009, 03:33 am »

Solid. Copper 101 alloy.

JD

Quote from: mgalusha on 2 Nov 2009, 02:05 am

That is going to be one sweet setup. Are the copper colored pieces solid copper or just plated?

mgalusha · « **Reply #132 on:** 2 Nov 2009, 03:31 pm »

Very cool. I love the color and of course a bit more mass than brass.

Quote from: jeffdavison on 2 Nov 2009, 03:33 am

Solid. Copper 101 alloy.

JoshK · « **Reply #133 on:** 2 Nov 2009, 03:48 pm »

Truly drool worthy, Jeff.

Like the copper on silver too.

Nice project Mike! Keep us up to date.

Over the weekend, I did some more work on veneering and trimming. I had some house stuff to do so I didn't finish.

However, I started the audio cabinet project. I gutted the dresser and ordered the 80/20 parts. Its going to be interesting if it works out nice. Hopefully it will give some folks ideas on other ways to make a LR system WAF friendly.

I cut all the drawer faces off. They will be mounted on a plywood backer that will act as doors to the cabinet. The sides and top are left in tact and the back thin plywood was removed to gain access to the back.

The dresser was pretty scratched up so it will get painted black with the detail done in silver by my wife.

mackortoyota · « **Reply #134 on:** 20 Nov 2009, 11:58 pm »

I rebuilt a 1970's multimeter. New power supply (one of the previous owners pulled it out for some reason), cleaned the switch contacts, calibrated it, and oiled the gearbox (it has an ignition coil tester, but uses a mechanical inverter). One of the rotary switches I had to completely strip down, and the spark cap for the coil tester needed cleaned and adjusted. Stevens ST-70. 5" gauge, lots of rotary switches, and a 5w ohmite wire-wound pot, all for 20 bucks.

nullspace · « **Reply #135 on:** 11 Dec 2009, 05:25 pm »

I built a prototype to see if I could pull together a fullrange open baffle speaker. It's a 2.5way -- mids and treble are as before, Beyma CP380M + AH!1000 conical horn and ToneTubby 12" AlNiCo. The .5 is now a 4x Eminence Kappa-12A. Initial listening impressions are generally positive, and I'll be pulling out the measurement gear later today. I'm hoping for an f3 of around 40hz; we'll see...

Regards,
John

nullspace · « **Reply #136 on:** 11 Dec 2009, 09:57 pm »

Ran the freq. measurements. Strong down to 50hz, then rolls off very quickly thereafter. A little shy of expectations, but hopefully after the Eminence drivers break in a bit the suspensions will loosen up and Fs will drop closer to the book value of 45hz.

With such a larger baffle than I had previously been using, the ToneTubby now reaches <200hz. Consequently, I'm crossing over the .5 much lower, more than an octave lower. This is as I had planned, but I had not expected that with just one TT now covering 200-400hz, the mids are quite a bit more clear. A nice bonus.

nullspace · « **Reply #137 on:** 12 Dec 2009, 12:12 am »

Despite the loss of low-end extension, one reason for trying out fullrange speakers, rather than sticking with my previous arrangement of main baffles plus SS-driven helper (sub)woofer baffles, is that I like to build to amplifiers and the previous setup, to me, wasn't particularly well-suited to that endeavor for a couple of reasons.

For this go-around, I ws looking for something that was more-or-less fullrange and would be amenable to being driven by the type of amps I like to build -- low-powered, no feedback/ low-dampening DHT amps. So, here's what we get: a high-sensitivity, I'm guessing 97-98dB since that's about what the ToneTubby T/S #'s say it is and there isn't much to drag it down, and a benign load. I think the impedence generally looks pretty good, and should be a good match. It sounds that way so far, anyways...

Regards,
John

nullspace · « **Reply #138 on:** 12 Dec 2009, 12:37 am »

In case anyone would like to see the crossover. Really, it's not as bad as it looks...

JoshK · « **Reply #139 on:** 12 Dec 2009, 12:59 am »

Very cool. I understand the desire to want to run full range one amp for amp comparison. Looks quite good.

Do you find the bass keeps up with the highs in terms of perceived speed, attack and dynamics?