What equipment are you currently working on?

JoshK · « **Reply #20 on:** 22 Mar 2009, 10:21 pm »

I have a couple pics of the Abbey clone speaker baffles.

Here is a shot of what it took to machine my fiberglass version of the waveguides.

Yesterday I put a 1.25" roundover on all corners. Using that bit, even with a router table is a bit unnerving. I did some mild sanding and the baffles look pretty much ready for finishing. Will need to fill some cracks in with bondo and then start the tedious process of sanding, sealer, sanding, primer, sanding, primer sealer, sanding, painting, sanding, etc.

Guess I need to start making the rest of the box. Also need to make bass bin boxes (Lambda TD15X in 5cuft with slot port tuned to 28hz).

sts9fan · « **Reply #21 on:** 22 Mar 2009, 11:49 pm »

After a meeting with a local electronics expert who shall not be named I have completely taken apart my Zv9 and will be laying it out differently to fix a small hum issue.

SharkyRivethead · « **Reply #22 on:** 23 Mar 2009, 04:02 am »

Hey folks, after having had some problems with the amp in a sub, and finding out that there was a major complaint about poor design work with this piece in particular. I'm now thinking about rebuilding a amp from scratch. I've already replaced a lot of caps and resistors on the boards. If it was a bad design, what's the point of wasting anymore time on it.

Is there any good resources for this type of stuff that someone can recommend?

Also, I don't know where you guys buy your electronic parts from. My wife is in the electronic brokerage business. She turned me on to a company called Mouser Electronics. They sell to the public and have just about everything you can think of.
http://mouser.com/

Thought it might be helpful.

aerius · « **Reply #23 on:** 25 Mar 2009, 11:31 pm »

I'm in the planning stages for an all DHT headphone amp, I have the cases (large baking pans from the flea market) picked out & painted plus all the transformers, capacitors & chokes I'll ever need. I just need to decide which tubes I want to use and see if I can pick up a stash of nice sleeper tubes for cheap.

mgalusha · « **Reply #24 on:** 26 Mar 2009, 01:28 am »

I rebuilt the B+ power supply in my preamp last weekend with all polypropylene caps, no more electrolytic caps in there. I was using an Elna Cerafine dual section but another AC member offered up 4 22uF/600V Solen polypropylene for dirt cheap so I thought I'd give it a try. I took the opportunity to add a choke as well so it's now CLCRCRC as 5Y3GT -> 4uF -> 5H -> 44uF -> 1K -> 44uF -> 1K -> 22uF. Feeding the Mac 275 I used to have a little noise but the new choke seems to killed even that as I can't even tell the system is on with the 95dB Abbeys.

As for the sound, it seems very nice. A little less "tube like" but with more apparent clarity and improved bass. Certainly worth the minimal cost and a few hours worth of time.

JoshK · « **Reply #25 on:** 19 Apr 2009, 12:23 am »

Spent all day outside today bondo'ing my speaker baffles, sanding, bondo, sanding, shellacing. The shellac is to seal the mdf before primer.

These are moving along slowly but surely.

Started the Gary Pimm phono preamp. Basically I figured out the layout and started making the ground plane.

Need to find what I did with my bass bin (TD15X) dimension sketches.

BTW, this was my first time using bondo. Very useful! However, the stuff really stinks bad. It also dries so damn fast. I wish it would stay wetter longer so you don't have to keep mixing it up as you go.

JoshK · « **Reply #26 on:** 20 Apr 2009, 01:09 am »

Got to do some priming today. Weather stayed really nice.

Man does MDF ever drink up the primer, even with shellac covering. I had to made a HD run as I dusted my two rattle cans. I guess I didn't get enough shellac on (one rattle can for two baffles).

nullspace · « **Reply #27 on:** 20 Apr 2009, 03:06 pm »

Hi Josh,

The baffles are looking good. Are you building the Pimm phono 'stock' or are you making any changes to the circuit? I wonder just because Gary and Kurt Strain before him run those tubes at an awfully low current, sacrificing some of the benefits of high gm tubes. Of course, they know way better than me, but I was just wondering.

Regards,
John

JoshK · « **Reply #28 on:** 20 Apr 2009, 03:25 pm »

Re: Pimm's phono

I am planning to build it with little differences initially. The differences I will make are using the Pimm/Swenson regulator in lieu of the tube shunt reg and using the self-bias CCS instead of the battery bias CCS. This I disgused with Gary and he thought it was a good idea.

As far as low/high current, I think this may not have to benefits you perceive as the CCS's mu output is where the output is being taken. Therefore the CCS drives the EQ and the output, not the tube, so the higher current isn't needed to lower the Zout. The tubes should last for ages at the lower point.

I haven't (for obvious reasons) played with the op points, either on paper or in circuit, to determine the linearity, but I trust Gary.

nullspace · « **Reply #29 on:** 20 Apr 2009, 03:38 pm »

Hi Josh,

The benefit of high gm tubes I was referring to is low noise. When you run high gm tubes at low current, well, they become low gm tubes and are more prone to noise. I knew rp was a non-issue with the mu-follower output from the CCS.

Did you find a suitable output transformer?

Regards,
John

JoshK · « **Reply #30 on:** 20 Apr 2009, 04:16 pm »

For output tranny, I plan to use Magnequest B7's. 4:1 parafeed nickel.

The noise is a good point, one I hadn't thought of.

nullspace · « **Reply #31 on:** 20 Apr 2009, 04:45 pm »

Just to be clear, I wasn't attempting to point out a flaw -- just something to think about. IIRC Gary inherited the operating points from Kurt Strain, who has posted his reasons for choosing the low-current op over at AA somewhere. There's a project over at diyAudio using the 6GK5 at more textbook currents here, which I suspect you've already seen.

If you talked the project over with Gary, I'm sure he mentioned this, but on the off-chance that he didn't, the MQ trannies would like to see a higher value parafeed cap than the one GP is using in his preamp, on account of the greater inductance. I think he has said that, in part, he used the UTC transformers so he can get away with a smaller cap.

Regards,
John

JoshK · « **Reply #32 on:** 20 Apr 2009, 09:54 pm »

Good point also about the caps/inductance. I hadn't done the calculation yet for the -3db point. I, though, have lots of suitable caps of varying values. I know it is not PC to use a large value cap in series with the signal but a poly cap bypassed by a smaller teflon or silver mica ought to do well.

jeenie67 · « **Reply #33 on:** 21 Apr 2009, 02:28 pm »

.....The Bloody Who! Well being somewhat incapacitated for the next four or five months I thought I'd ship some pics of all my busy-work to keep me occupied other than the Boob-Tube. My 1920's Victrola is my favorite. This will get a cherry wood cabinet and will be constructed as a floor stander. The 16" Altecs out of a pair of "W" enclosures are due for a complete recone as they are hard pressed in their duties as studio monitors and sound reinforcement for my band. IC re-assembly and changeover to complete balanced lines for all my components fills in the time between re-capping my tube radio collection....I love tubes....maybe it's the soft glow they exhibit....like a campfire. Then there's the vintage oak cabinet all the audio/theater components are housed in....that gets a complete new hairdo too!

dyohn · « **Reply #34 on:** 21 Apr 2009, 03:52 pm »

I'm building a Pass Labs First Watt B1 passive buffer feeding a diyparadise Charlize 2 t-amp as a little integrated amp for my office.

JoshK · « **Reply #35 on:** 22 Apr 2009, 02:59 am »

everyone is probably sick of the innundation of pictures, but have been trying to keep pictures of steps along the way.

I think the point is to perfectly smooth out all the warts before adding primer, but I guess i was getting antsy. I added a couple coats of primer to the baffles. I still need to do more bondo to fully hide the waveguide seams. You can really see them with the primer added, which aids in seeing them to fix them.

lonewolfny42 · « **Reply #36 on:** 22 Apr 2009, 08:34 am »

Quote

..everyone is probably sick of the innundation of pictures..

On the contrary Josh...their coming along nicely !!

Mariusz · « **Reply #37 on:** 22 Apr 2009, 11:08 am »

Very nice Josh! aa

Mariusz

Levi · « **Reply #38 on:** 22 Apr 2009, 01:42 pm »

I am not really a tweaker.

Here is my recent project. Please don't ask me for details as this is a fairly simple tweak.

It started as a CablePro NoiseTrapper

Then I added snake oil

So far so good. No smoke or fires comes out when I plugged it in. It is a much lower noise floor

Cheers
--Levi

Mariusz · « **Reply #39 on:** 22 Apr 2009, 01:46 pm »

I smell competition for well regarded Kaplan line of products.

Mariusz