What are your latest builds???

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What are your latest builds???

Postby johnmarc0 » Wed Dec 16, 2015 10:24 am

just wanna know :D :D :D :D
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Re: What are your latest builds???

Postby toobs » Thu Dec 17, 2015 7:09 am

Hi JM,
No new builds but mostly listening.
Whats your new project? :-)
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Re: What are your latest builds???

Postby rtsyrtsy » Thu Dec 17, 2015 11:01 am

JM! Long time! Hope so see more of your posts here on WS. I should dig up photos of those sessions with Racio, Ed, etc. Good times!
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Re: What are your latest builds???

Postby johnmarc0 » Sat Dec 19, 2015 1:15 am

Trying to rebuild my setup and searching for an inspiration. May build a new horn, a dac, bet a new table, definitely a new amp. Been sketching my plans lets see if it turns to be a tangible build. Thanks for welcoming me back guys!
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Re: What are your latest builds???

Postby johnmarc0 » Sat Dec 19, 2015 1:19 am

rtsyrtsy wrote:JM! Long time! Hope so see more of your posts here on WS. I should dig up photos of those sessions with Racio, Ed, etc. Good times!



Post them here man, those were days before the digital camera! :D
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Re: What are your latest builds???

Postby BenC » Sat Dec 19, 2015 8:12 pm

Musta na Prof JM! ... Am putting together a JELabs phonostage. Hopefully this one will not hum as the first one I did.
Maligayang pagbabalik!

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Re: What are your latest builds???

Postby johnmarc0 » Sun Dec 27, 2015 3:46 pm

BenC wrote:Musta na Prof JM! ... Am putting together a JELabs phonostage. Hopefully this one will not hum as the first one I did.
Maligayang pagbabalik!

BenC



Good luck with that build, just howl if you need anything to make that build successful. Like any non negative feedback hi gain amplifiers (>>50dB) stability is driven by isolation, thermal drift and plagued with microphonics.

Are you building the nicad biased or the cascaded 6SL7/variable eq?

Like any good catholic, all starts with the original sin, watch the first stage gain!! ]:) ]:) ]:)

jm
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Re: What are your latest builds???

Postby johnmarc0 » Wed Jan 06, 2016 4:23 pm

definitely its a 300B (saka na yun ST70 inspired project), here are the parts

6SN7 driver tubes & 5U4G rectifier tubes
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WE 300B tubes and Tone Factory Filter Non Inductive Caps
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Ironworks
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F2007 OPT (i auditioned the F7002 and the F2007, the F2007 for some reason is sonically better, then I found out it is more expensive than the F7002 and scarcier)
A4003 Choke
PC-3004W Special Run Power transformer with 230V input

All transformers will have the same color, the OPT and Power Transformer will be of the same size and foot print.

Just waiting for the custom case, plated tube sockets, billet rca sockets and we are ready to assemble
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Re: What are your latest builds???

Postby johnmarc0 » Sat Jan 09, 2016 4:06 pm

Image

This my eight design, 3rd 300B, slightly different from the TB300B proposal with the bias adjustment (an attempt to squeeze power to 7 watts), will use non inductive high power resistors. Modification 0 will exclusively use Tamura F series transformers.

MY apprehensions,
This configuration have been successful with the TB2A3 and it will show good bandwidth (TB2A3 prototype have good performance on the lows a sign of over engineered trannies, its objective inductance was initially set at 50H if my memory serves me right). BUT, will the 2A3 beat the crap out of this 300B incarnate.

So I tried to hedge my bets on this design

a.) I eliminated phase shifting components in the signal chain as possible
b.) weakest link are R7 and C1A
c.) R7 will be a candidate for a grid choke, may try the silk audio grid choke in modification 1 series
d.) May lower C1A for 2uF-3uF non doubling mode rectifier, recalculating the voltage budget and that brings us to
e.) R2, the cheat tweak, if I need to swap C1A in mod 1 or mod 2 and recalculate the voltage budget, I do not need to resolder, all i need to do is recalce the value of R2 and reset it to that objective voltage! viola!

Lastly, I may need to drive this with a variac as tamura provided 230V transformers !?1*@#$?!

I have my cad guys eugene and kevin layout the chassis, will update on that progress soon.
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Re: What are your latest builds???

Postby johnmarc0 » Sat Jan 09, 2016 4:16 pm

I just realized, how foolish I design amps, I chose the transformers first then the tubes before configuring it, I was debating whole december should I finally make another interstage amp (last one was in Mickey's place, the tube 101 class build amp) or should I go back to TB300B/TB2A3. Before I went to see Uchida and Sun Audio I was hell bent on an interstage amp, BUT after the fanboy moment with Uchida, rolling the F2007s , I wish to preserve that so I may need to go back to TB300B/TB2A3 configuration.

What did I get from all of this? foolishness from a fool! maybe I should name the amplifier HANGAL!


Now I have decided, my next design is an interstage amp, will be EL34, will have a lot of power and will be an attempt shoot it out with the venerable ST70! hah! take that interstage!
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Re: What are your latest builds???

Postby johnmarc0 » Mon Jan 18, 2016 11:58 am

Yamamoto Soundcraft Sockets

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No Error Rectifier Sockets (fourth socket from left)

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Three piece, hi load bearing chassis (may use this if the local version my engineers are building sucks :D :D :D )

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Just waiting for the silver wire and non inductive hi power carbon film resistors
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Re: What are your latest builds???

Postby johnmarc0 » Fri Jan 29, 2016 11:05 am

Most of the passives are here

Vdrop resistors, Plate load resistors, Bias adjustment rheostats, hum pot rheostats, B+ bypass capacitors

Still waiting for the IEC fused and switched inlet AC receptacle, Pilot lamps (as filament and B+/standby indicators), HV on-on toggle switches and the final chassis layout.


Image

Also debating about what cathode bypass caps to use hmmmmm...........
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Re: What are your latest builds???

Postby johnmarc0 » Fri Jan 29, 2016 2:03 pm

High Power Bias Resistors, IEC inlet/fuse & switch, more bypass caps

Image

Case na lang talaga!
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Re: What are your latest builds???

Postby johnmarc0 » Fri Jan 29, 2016 2:21 pm

CS8416 DAC Board and a Repurposed Tamura MC step up transformer as LVDS transformer with some voltage gain (with mu metal core sucking high freq clock imd, acting as in line common mode choke for clock freq product from the DA chip)

Image


Will not install the NE5532 audio chip that makes thing noisy, instead am taking the LVDS balanced out put to the MC step up maybe driving a sonically inert gain stage 6SL7 or 12AX7. Will experiment on this first.

The tamura step up I snagged from Akihabara lonely by a surplus store's window.
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