The Burning Amp Festival-Burning Gadgets Preview

[Zen Mod]

seems that I must do all hard work here ..........
where is official Mod when you need it most ?


MOD EDIT: Please post schematics as Zen Mod asks, also construction plans and crossovers of speaker projects, also where and on what threads circuit boards are available, photos are shown, etc, etc. That way people who get inspired at the show can come here to find out about the projects that they got inspired by....
END MOD EDIT


anyway - let's try that this became "official" technical preview thread for BAF .

do not post your ugly faces - post nice pics and schematics of space shuttle you think to bring to SF happening ......


hehe - don't expect that Papa will reveal here what Fx he'll bring in da trailer .........

[Zen Mod]

let's see ..... there is Papa-like product , well buried in "official" thread about

position: Preamp

cause : why not

I'll send main pcbs , tested , on Monday to Mr. Simovic , AKA Ar2 , hoping that they will arrive to SF in time for BAF.

unfortunately , reg pcbs can't be finished for this occasion , and that will be main reason why :Pumpkin : will certainly sound awful , and soon I'll be just one of many ex members of this board...... I'll not survive that public humiliation .......
anyway...... there is main schmtc

[Zen Mod]

there is missing part ........ reg

[Zen Mod]

little darkie pic .......

I forgot to say - AR2 will arrange generic +/- reg, just because ashes of will belong to him,after burning........

and yes- decent pot,too .

and source ;

and amp

and spks

just one tip : hates mp3

[SY]

I have an F4-compatible preamp featuring a CV1988 purloined from Morgan Jones's collection. Balanced-only output, gain of 26dB. No loop feedback. All triode. Pretty impressive linearity. Now if it all goes together in the case... all the things magura is good at, I'm bad at.

John Curl tells me that he's got an interesting historic gadget or two to show.

This is gonna be fun.

[kstlfido]

Hey SY-

If you want to do some tube rolling, I have various 6SN7 types; metal base, tung-sol rounds and a B65 or two..

Best- Kent

[wrenchone]

OK, I'm bringing an open loop (no global feedback) preamp with RIAA stage and unity gain line driver. The schematic for the overall preamp is shown below. This is housed in a humble Ten-Tec box and serves as a test bed for various RIAA preamp and output buffer experiments. The box is powered with a +40VDC external supply which also contains a 25A relay for switching all my other audio components. The single 40V supply intentionally limits what I try to fairly simple single-ended circuits, which is the whole brief of this line of experimentation, about 2 years old now.

Some of the past and present occupants of this box are described in the threads "Open Loop Follies" and "JFET SRPP". The box currently uses a pair of Bourns 100k conductive plastic pots with 19k metal film law-fake resistors for volume/balance controls.

The RIAA amp currently in use is the JFET SRPP preamp described in the aforementioned thread, and the output buffer is a heavily biased NMOSFET/PNP Darlington "super Gm" follower with current sink loading.

Before I show up at Burning Amp, I'm swapping the SRPP preamp for an open loop single-ended discrete JFET/MOSFET amp, pieces of which are described in the threads mentioned. I just finished tweaking the bias on all stages Friday afternoon, and will be testing gain on Monday using the HP gain-phase analyzer at work. As soon as I'm satisfied, I'll post a schematic and picture. The JFETs/Mosfets used are very intentionally ones that can be easily found at Mouser, to prove a point....

The conductive plastic controls will be swapped for a pair of of NOS Clarostat 75k, 2W wirewound pots with a pair of Micro-Ohm 35k precision bobbin-wound resistors in parallel each for law-fake. The combination scans very flat on the impedance analyzer at work. I'm looking forward to hearing an all-metal volume control.

I may keep the super-Gm buffer, or swap it out for a cascaded MOSFET follower circuit. It would be interesting to bring an assortment of pieces along, as the RIAA and buffer modules I have built so far are interchangable and only require about 10-15 min of soldering to swap.

[SY]

Originally posted by kstlfido
Hey SY-

If you want to do some tube rolling, I have various 6SN7 types; metal base, tung-sol rounds and a B65 or two..

Best- Kent

Probably not enough time at this event, but it's a perfect place for us to conspire about doing it in a less-frenzied atmosphere. I've got a few exotics myself...

[Variac]

Please guys, I believe the Zen Mod was sincere in asking that posts here be on topic and include information about projects being presented at Burning Amp '07. This will allow attendees to easily find out more about project that they see at the show- Actually I guess it will allow anyone to find out more..

[Variac]

I have an F4-compatible preamp featuring a CV1988 purloined from Morgan Jones's collection. Balanced-only output, gain of 26dB. No loop feedback. All triode.

And I 'm making the F4 for it and other high output preamps such as that absolutely smashing Pumpkin Preamp


Here's the photo of just the power supply. I'm making one for each F4 stereo amp, BUT I'm running each stereo amp balanced 'cause I've always wanted a balanced system and the 100w/ch couldn't hurt..

http://www.diyaudio.com/forums/showt...42#post1316742

You'll have to see the rest of the amp at the show- or in the after show photos.. It's big!

ere are links about the F4

http://www.passlabs.com/np/f4-power-amp.pdf
WTB: F4 PCB boards
F4 power amplifier
F4 matched FET's