Time to say thank you once again

[docb]

to the latest subscribers. Here's where were at -

I have been assembling a high quality printing setup for the booklet that will be included in each album. This booklet will be about 10.5" square (how did he come up with that size?). On the cover will be the cover art (duh) and the rest will be liner notes, back cover art, etc., based on whatever was originally used on remastered work, and cover art, photos, liner notes and production info on our own recordings. The print will be by pro quality pigmented ink jet, on double sided archival quality art paper. The proofs have come out so nicely that I plan to frame a few, and hopefully others may wish to do the same.

A large order of tape has arrived and now we can get serious! Next week I will be heading to the Bay Area and we will be testing the duplicating line in preparation for tape production. The master machine in the duping line is an Ampex MM1200 modified to 1" two track by ATR Services, with Tim deParavicini modified MR-70 electronics. The slaves are three 1/4" ATR 100s that have been completely gone through and rebuilt. Real time monitoring will be done by the duplicating engineer through a custom Bottlehead headphone amp.

Packaging and reels are getting closer. We have been tweaking and adjusting our plans a bit and we hope to have final designs signed off and in production very soon. Meantime we will produce the first tapes so we can package them and get them out as soon as all the final bits arrive.

We're getting very close...

[ironbut]

Hey Doc, how about some details on the headphone amp. There's a handful of high $$ headamps out there ( nothing like speaker amps thank god!) Ray Samuals B52, Rudistor (Italy) RP1000, Singlepower SDS and EAR's HP-4 and the discontinued Angstrom Research which used 28 tubes I think. The photo you e-mailed me was certainly "drool worthy" and from the price, I'm sure it has some pretty bleeding edge components and ideas in it. So, when you get a bit of free time, let's hear some bragging!

[docb]

Fully dual mono
Single gain stage using a 6C45pi hi transconductance triode with Camille Cascode Constant Current Source (C⁴S)
Active loaded triode wired 6BQ5 hybrid shunt regulators
MagneQuest PGP 8.1 power transformers, MQ EXO-03 44H chokes in power supply
DC heater supply with Schottky rectifiers and filament chokes
startup delay to deter output autoformer magnetization from current inrush
low impedance solid state rectifers with reverse recovery spike filter
MQ TL-404 dual C-core output autoformers with switchable 500, 125, 50 ohm taps
Neutrik headphone jack
custom Jupiter parafeed coupling caps
3 balanced inputs with Jensen 10K:600 ohm transformers, phase switchable
Electroswitch ceramic and coin silver selectors for input and output
600 ohm Daven attenuators with 111dB range 1dB steps, 303 stainless shafts running in Rulon bearings, with vintage Dakaware knobs
ground lifts on each input, Switchcraft XLR and gold RCA available
copper vein powder coat finish throughout 3U rack mount cabinet
lacewood veneer front panel
about 30lbs. and about $400/lb. to make another one like it

[ironbut]

Well Doc. You might have a little interest in this amp,.. I just posted a link over on head-fi. I wouldn't doubt it if you sold a couple.

[docb]

I might change a couple of things if I did another one. For one thing I'd like to add a bias supply and a jack for Stax cans. I might also change the input transformer/600 ohm attenuator setup to 10K transformer attenuators for some applications. And I might use WE 437As instead of 6C45s if I ever get around to building one for myself.

In the configuration I built the amp can handle a smoking +26dB input level, run balanced in, flip phase on each channel independently for phase & balance checking, run with input shield grounds lifted, and will accomodate virtually any non-electrostatic headphone. At the studio it gets used a fair amount during mixing, in fact I used it a lot when we were mixing Jacqui's album, because I know its sound better than the control room monitors. We had it with us at CES with the intention of giving private demos of the tapes, but demand for our RS1500s for exhibitor systems left it sitting all alone in the hotel room...

[scully280]

Doc, that is one nice piece of studio equipment with all the little touches.  Not having been around studio gear for a while where does one look for those cool Daven attenuators?

[docb]

I had the ones I used in my stash - 10db per step and 1dB per step stereo units. Shallco bought Daven in the 70's and now sells them:

http://www.shallco.com/frameset.html

Look under "audio attenuators", "unmounted decade attenuators"

[ironbut]

Wow Doc.! The great electrostatic amp is kind of the holy grail for headphone folks. Part of the reason for this is the old Sennheiser HE90's. The headphones from the Orpheus system. They're still considered the heaven on headphone earth and a used pair for less than $6k are considered a bargain! Needless to say, I think that if you were to add bias for Stax 'statics, it would be a good idea to add an output for Senn.s. The Singlepower ES-1 is a 2 box tubed amp that starts at $4k and with upgrades goes for over 10. Another new electrostatic headphone amp is by Headamp , the Aristaeus which is said to be an update of the original Orpheus amp. There are still a few of the complete Orpheus systems which still command $10k+ prices. I don't believe that anyone with these top drawer es headphone systems think that they've really heard an amp that really pushes the limits of this headphone. Of course, this is getting into the realm where taste and listening habits really tip the scales.

[docb]

I've only had two pairs of electrostatic/electret cans, the heavy old Koss ones (ESP/6A?) with the transformers in the headphones and a Sony electret setup with step up trannies in a box. Seems like I had a loaner pair of entry level Stax for a little while, but they didn't leave an impression that I can recall. I'm thinking that augmenting the amp circuit to work with electrostats wouldn't be that big a deal. Now you wanna get crazy, show me someone with the cojones to wear a plasma headphone, and I'll build an amp for that. They might need a lot of sunscreen on their ears though...

If I ever find time I may build my own electrostatic cans.