Proof of existence...

JoshK · « **Reply #20 on:** 17 Jul 2008, 12:32 am »

Ah...yeah I have been in many a photo from the Rave pictures... But the amps are nicer to look at.

topround · « **Reply #21 on:** 17 Jul 2008, 12:43 am »

Here is a picture of Josh,,last guy on right

JoshK · « **Reply #22 on:** 17 Jul 2008, 02:34 am »

btw, the epoxy worked out well. easy to work with. drills well too...i drilled through the copper with it epoxied and it was just like aluminum.

nullspace · « **Reply #23 on:** 17 Jul 2008, 03:51 pm »

Hey Josh --

Since you're posting pictures of various projects, any chance you'd post a pic of the Geddes waveguides you just got and perhaps a snippet on what you plan to do with them? Thanks.

Regards,
John

mgalusha · « **Reply #24 on:** 17 Jul 2008, 04:11 pm »

I'd like to see them as well. I sent Dr. Geddes a check today for my deposit on the Abbey kits.

JoshK · « **Reply #25 on:** 17 Jul 2008, 05:18 pm »

I'll have to take some pictures of the waveguides. I didn't think to take some. They come unfinished in a light grey finish.

I plan to build the following type of OB system.
12" geddes WG + B&C DE250
JBL 2123H 10" mid
2 x Lambda TD15X per side
subs below ~50hz.

I want to passively cross the WG to the mids so that the tube amp can run from ~150-250hz up. Most likely the UcD400 monos I have will run the Lambda's and a Crown K1 will run the subs.

I have everything on hand already. I was thinking I might take a trip to the lumber yard on Sat to get some baltic birch.

nullspace · « **Reply #26 on:** 17 Jul 2008, 06:25 pm »

Thanks Josh. I'll be keeping an eye out for updates.

Myself, I'm working on a horn + open baffle setup as well but have been having a rough time with the crossover. Hopefully, you'll enjoy better luck than I've been having.

Regards,
John

JoshK · « **Reply #27 on:** 17 Jul 2008, 07:13 pm »

What problems are you having with the crossover?

I have a DEQX, so that should facilitate easy experimentation with the crossover. I also bought SoundEasy and a MAudio Firewire Solo card so that I could measure and play indepedent of the DEQX. But to date I've never measured anything, only read books and online how to do it.

nullspace · « **Reply #28 on:** 17 Jul 2008, 07:38 pm »

It's the whole 'reliable measurements' issue that's really the problem. And, specifically, getting decent measurements of the midbass on the baffle -- I feel pretty confident about my measurements of the horn. Without that, messing around with the crossover has largely been trial-and-error, with more setbacks than successes.

I would think that a DEQX would be an invaluable tool. I've thought about picking up a DCX2496, but I don't have all the other required pieces laying around -- no spare amps and the sloth-like speed with which I build them means it would be 2009 before I made much headway.

I started a thread over at diyAudio on the topic of measurement and it's been helpful to an extent; it sure would be nice to have someone looking over my shoulder to correct my mistakes as I fumble along.

Regards,
John

Geddes et al on Measuring Loudspeakers

JoshK · « **Reply #29 on:** 17 Jul 2008, 08:17 pm »

I think the dipole measurement takes a bit more care, for instance one cannot do near field measurement of the woofer in the case of dipole since it won't take into account the summation of the back wave. I am less clear on the dipole mid. Take a careful look at SL's site for procedure on how to measure dipoles.

My wild ass guess would be far field, gated measurement with a crap load of pillows and stuff to dampen the floor bounce or outside raised a few meters.

kyrill · « **Reply #30 on:** 17 Jul 2008, 09:27 pm »

i face the same problem now, how to measure dipole ( with DEQX)?

I have the DEQX so i will use it. The only reliable way is outside and high up so not on the ground
I will think of some way
I accept your "Proof of Life" Josh

nice and very human picture

BTW DEQX is more flexible with a LOT of more measurements or options than a DCX2496

JoshK · « **Reply #31 on:** 20 Jul 2008, 07:01 pm »

Dry fitting the Aikido chassis.

just when I thought I had it done, the patina that is, this is what happened, my failed attempt at patina'ing the UBM. It flaked in places, which actually came off with blowing on the chassis, and exposed a more copper color. It looks cool in a really distressed sort of way, but I am thinking about buffing it out and trying again.

JoshK · « **Reply #32 on:** 20 Jul 2008, 07:03 pm »

The patinaed plate is really hard to photograph and doesn't look quite like that in person. It looks a bit nicer in person, but still pretty wild.

JoshK · « **Reply #33 on:** 22 Jul 2008, 06:47 pm »

In the works:
Aikido preamp
KT88 E-linear SET amp (aka uber beam machine)
Karna amps
OB speakers

on deck (have all the parts and design):
Magnavox 6V6 pp rebuild
801/10A preamp
6LW6 PP amp (>100wpc from 2 tubes)
Squeezebox transplant
CD transport repair
Lite Dac60 mods
various subs

The above sadly is likely not exhaustive and doesn't include amps I have been thinking about doing like an 813 SET. Think I have enough?

mgalusha · « **Reply #34 on:** 22 Jul 2008, 09:45 pm »

I'm in the same boat as Josh, way too much I want to build or modify. It's the time and $$ that are hard to come by.

In the works as well:

tube/chipamp hybrid
GedLee Abbey's
rebuild of SP Tech time pieces
more changes to my tube output squeezebox
tweaks to my OB speaks
rebuild/rework of Twisted Pear TXO
tubed output for denon 2900
subs for the Abbey's
active triamp the BH2's (already active biamp)
mods to Audio Mirror 45W SET
new power supply for 100W OTL

JoshK · « **Reply #35 on:** 15 Jan 2009, 05:21 pm »

Mike,

Planning to start the Abbey's this w/e? What subs do you have in mind?

I have turned interested in a PP 8" tapped horn that JLH designed. It is in the "collaborative tapped horn" thread on diyA. I measured the spacing between my floor joists in the LR floor/basement ceiling. I was intending to mount an IB sub using the pair of Avalanche 15" I have, but now I am considering mounting this TH between the joists with the mouth venting into the LR floor instead of the IB.

Projects update:
-KT88 E-linear SET amp nearing completion (jinx)

-Aikido just needs wiring up, chassis fully done

-been dreaming up a way to design the main Karna chassis, so that it is modular and different front ends can be tried out without making tons of new holes in the chassis.

-been waffling on my OB speaker project...on fence whether I even want to do OB...I do and I don't. I've pretty much giving up on the idea that the Lambda TD15x's will make decent OB woofers. Thinking of using them the way they are intended, as midbass drivers. I am thinking sealed but in a PP slot loaded cab with 2 drivers each. Would cover the 50-200+ range and yield some pretty high SPL/db numbers. Box is getting a big large though.
The mid has changed to Lambda TD12M Apollo's instead of JBL 2123H. The JBLs might be used for a future horn project...don't know yet. Was thinking of doing hybrid dipole, but not certain my room is that conducive in the most sensible/WAF setup. So might go the boxed route for now and try OB later on.

-ordered some Gary Pimm self-bias CCS boards and Swenson regulator boards for 801a preamp, Pimm phono preamp and Karna monos. Have everything but the power transformers for these two projects. Got some big 30mH .7dcr 4A hammond chokes, schottky diodes and panasonic 22kuf tsha caps for LCL filament supply for the 801a preamp based on research for best sounding DHT filament supplies. This preamp won't be small! This is the chassis for this preamp (using the TVC that is already in there)

inspiration for my 801a preamp came from Gluca's waterbaby preamp

Differences are IXYS CCSs will be replaced with Pimm's SBCCSs. Tube shunt regs will be replaced with Swenson reg. Passive filtering will be LC and 83 mecury vapor rectumfryer will likely be a pair of damping diodes. The input transformer will be replaced with my TVC. I am using Magnequest B7-10Ks for the parafeed OPTs. Filament supply as described above.
Pimm phono will be similar to what is shown on Pimm's site with a few modifications based on Gary's own suggestions. BBCCS -> SBCCS and tube shunt reg -> Swenson reg.

-813 SET amp idea has meandered into a GM70 SET amp idea. P/u'd some Hashimoto OPTs for the task with the MS cashback deal. Acquired some insanely overspec'd Thordarson transmitter chokes (8H, 600mA, 50dcr, 6Kwv) for choke input supplies along with some Russian military 1KV PIO caps (50uf and 100uf). Driver tube will likely be some 3C24's (DHT, mu~30, thor-tung fil) I collected. Jim Dowdy has a nice schematic of this combo (B+ 700v, lower powered version) on the boatanchor club forum and speaks highly of it.

JoshK · « **Reply #36 on:** 15 Jan 2009, 05:40 pm »

My idea of Karna top plate modularity is based on inspiration I got from designs like this

If you can subdivide the top plate into sections then parts of the amp can be lifted out and replaced or designs changed.

BillB · « **Reply #37 on:** 16 Jan 2009, 01:45 am »

I think the chokes are cool...leave em exposed!!

Great work!!

topround · « **Reply #38 on:** 16 Jan 2009, 01:55 am »

I think someone's credit card is exposed

JoshK · « **Reply #39 on:** 16 Jan 2009, 02:50 am »

We don't carry balances on cc's. All total, the spending is under a couple thou. Less than one mid level commercial component and less than some pay for speaker cables.