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Post by gar381 on Aug 18, 2013 1:12:18 GMT -6
Here is a little something I'm working on at the Barnett Ind. "Test Kitchen" It's A Sphere/CAPI hybrid 10x8x2 Desk/Sidecar |
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Post by gar381 on Aug 18, 2013 1:21:16 GMT -6
Here's some pics of my pcb preamp (just finish to drill the holes for components......) and doa 2520 I've build on Classicapi pcb. All the best Bruno. Hey Bruno.. Very interesting gar2520 mod. Bet it sounds very nice. Are those 20k resistors .1% Dales? Gary |
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Post by b2 on Aug 18, 2013 4:25:06 GMT -6
Hi Gary! It's a very nice mixing desk for sure!!I've never diy or work on a Sphere design..(close to Api..??). Yes thoses are 20k 55Y "Black" from TT electronics ...it's fine resistor as Dale but they're under 1%. For the caps I've fix a 1000pf styroflex ..and for the pair of Q1+Q2 as I said I seleted close matched bc184c (I've got a batch of 200 ...from some years so they found their place here in your Doa design, Great and nice Doa ,co,grats Gary! With the transformers and this 2520 ..it's great for my friends who used it on drums record session ... So....FriendsofRealDIY... Here's the next one I'nm working on ...HeHe!! I'm sure you see...what is it.. All the best bruno. Attachments:
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Post by svart on Aug 19, 2013 8:48:41 GMT -6
b2, those builds look great! It makes me happy to see someone etching and drilling their own PCBs! No offense Gustav and those who make great DIY PCBs of course!
gar381, man that's great! That's probably one of the more involved DIY projects I've seen.
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Post by b2 on Aug 20, 2013 1:21:18 GMT -6
Hi!
Thank's Svart!
I always like to began by a piece of paper and a pen for the electronic design (schematic..the place of each components....) do the concept of pcb.
After the "Mylar" (the printer for etching the pcb) and after the drill..with all this small holes (sometimes I'm fed up with....)
You see I'm a bit of "old school"...my pcb have large traces and thoses are only on one face ,not two...it's more easy !
More to come..
all the best,bruno.
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Post by Gustav on Aug 22, 2013 0:25:22 GMT -6
b2, those builds look great! It makes me happy to see someone etching and drilling their own PCBs! No offense Gustav and those who make great DIY PCBs of course! I DO etch and drill my own, so no offense taken  And I'm releasing this little bugger into the wild tomorrow.  Gustav |
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Post by b2 on Aug 22, 2013 1:09:19 GMT -6
Hi Gustav!
It's a great build!
8 channel is usefull for records..Just a question,You will recommanded this preamp for what kind of record?
I've never used and so I didn't know the THAT sound..
If i remenber correctly ...it's a transformeless (no transformers on the in and out ..)it's right?
so it's...more "linear"...no influence of the transformers.
For the input it drive how much impedance for the mic?
and so , for the output it's drive how much impedance?
How much gain you go with it?
I think it's run on + 15v and - 15v?
Thank's so much Gustav and congrats!
All the best ,Bruno.
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Post by Deleted on Aug 22, 2013 23:33:36 GMT -6
I guess the great thing about the newer THAT IC micpres is that they are DEAD quiet all up to a HUGE amount of gain (enough to drive ribbons...) >60dB range...
And pretty clean gain as well.
(Well, for a CHIP amp, of course. Compared to the older SSMs found in consoles. upgrading is like pulling away clouds from the sun. Of course one can achieve better figures with discrete or half-discrete circuits....)
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Post by b2 on Aug 23, 2013 0:49:34 GMT -6
Hi,
Thank's for information...driving ribbon need lots of gain due to the lower Z of ribbon.
If thoses can handle this...it's pretty great ..I 'm going to take a look at the data sheet.
I'm going to see how much this small amp can drive on the output ..
There's a base of the mic pre schematic on the datasheet.
The combination with a line driver as ssm ,or another IC to get symetrical output could be nice and between the both , just after the output of THAT1512 put a pot for the level out.
Or, put a nice bipolar driver with BD xxx ...on the output of the THAT to drive easily a transformer as 600/600 for the output, but NO pot for the level out .
If I had to do something with the THAT....I will go at first with the DBxxx output driver stage, simple and great!
transformeless input and transformer output with Bipolar driver stage.
All the best,Bruno.
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Post by b2 on Aug 23, 2013 1:05:17 GMT -6
...I've forget to said..
On the schematic of this preamp there's 2 capacitors (22µf) on each input to block the dc and pass the audio signal coming from the input.
Thoses capacitor needs to be great one, often electrolytics are used due to the cost and are smaller , than MKP .
For this it's important to fix here great capacitor , use electrolytics ....you will have a small pcb..
Use MKP ....you will have a a more biger pcb..
cheers,Bruno.
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Post by svart on Aug 23, 2013 7:15:07 GMT -6
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Post by b2 on Aug 23, 2013 8:45:07 GMT -6
Hi svart! Thank's a lot for this nice page! Very interesting! and far simple to fix on a pcb design ,it's great with the bc 337 /327 ,will be nice with bdxxx . I like so much this kind of improvement ..it's simple and efficient with few components. I didn't do it for this time if I will design a preamp based on THAT chip...you see may be in future life Ha Ha Ha!! I 've design other gear that's I had to finish for ....december 2022....no 2013! Generally ...I passed time on design and doing pcb ...and so solder components...from the first step design to the pcb with the components ...2 months..during this time another project is ended. Now , I' ve finish my tube preamp which is running wild.....!! I gone on a Handmade tube mic...("Big Mic")....and a Varimu compressor....He,He . This one is based on a mix of 436 and leveline.. with ecc189 tube for gain reduction in front and 6189 output stage. I've got all components for this time and so I've fix the pcb ,psu...transformers ,etc in a Rack 2"... Now just going to cabled it nicely,see what it do when running on?  BOM BOM!!
and do measurement to see if it do a great job or not....if it's so I will upgrade it with nice audio tranformers in and out.
You see I alway put at first "normal "transformers...in this case thoses are Edcor,which are great and not expensive one...may be if all is ok..I will go with Sowter. I will show pics on this w;end about the rack with the components.
all the best,Bruno.
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Post by svart on Aug 23, 2013 9:08:07 GMT -6
I feel that for line level output matching without the need to have something like gapped cores, Edcor would be fine. I would stick more to sowter/carnhill/jensen for mic level input transformers though.
However, the THAT parts don't need input transformers.
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Post by b2 on Aug 23, 2013 9:19:20 GMT -6
Yes You're right!!
It's the same for me ,I like more Edcor on the output than on the input..
For the Varimu..I've fix a Edcor XPP1-600-10k on the out...I know it , it's nice for this .
On the input ,I've fix and Edcor 10K/10 to for the start...will upgrade with Sowter 3575 .
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Post by b2 on Aug 25, 2013 1:39:03 GMT -6
Hi all!! I know its' sunday... for thoses who are not sleeping...I want to post some pics of my next project...HeHeHe!! For some months....I want to build a Varimu comp. I've got for years a bench a tube coming from old TV repair shop and other place...In this days,TV set tuner where using some tube as 6es8 and more commun in EU pcc189 and ecc189. The Holy grail with me....I got nice build one from Mazda....He He!! I know ...that's I didn't build the wheel for sure!! People Have design Varimu comp around this one ....many years ago. So I began to find some schematics based on 2 stages ..one for the GR reduction (ecc189) and one for amp out stage (ecc82,6189). The altec 436 ...give me idea ...and others too. So I've take some design of thoses comp....do mods...and design a pcb for this.The goal was: One Input Attenuator. One Output Attenuator. One Threshold. One Release. One Attack. a Vu meter (only for GR) and a calibration pots for the balance on the ecc189 plate voltage. One thing important,I didn't want to fix a pots for the Input Attenuator "after"the secondary transformer.I "didn't like this... So ,I've fix this one before the primary. Here's the rack with the components.. |
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Post by b2 on Aug 25, 2013 1:46:42 GMT -6
One more and here's a closeup of the pcb I've design.. You see one socket for the ecc189 ( gain reduction stage) , one for the ecc82 (amp output stage),one for the 12al5 (signal amp ctrl). At first ,I've build this prototype with Edcor transformers, If it's ok I will keep the Edcor on the output and upgrade the input with 10K/10K or 15K/60K from Sowter ...it will depend of the gain reduction...HeHe! All the best,Bruno. Attachments:
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Post by gar381 on Aug 25, 2013 13:53:42 GMT -6
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Post by jsteiger on Aug 25, 2013 14:00:48 GMT -6
Awesome work Gary!
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Post by tonycamphd on Aug 25, 2013 15:01:19 GMT -6
Bruno! I love it man, great stuff, i love how into diy you are, i am not near as advanced as you, but i hope to be someday, thanx for the inspiration! T |
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Post by tonycamphd on Aug 25, 2013 15:16:10 GMT -6
I just updated my build post at groupdiy on my Sphere/CAPI project lots of picts and the running build of this guy. Gary, that is some AMAZING work you're doing there, extremely impressive..wow! I would love to hear that rig at some point, it's gonna be crazy cool Is that wood working shop yours? thanx for sharing T |
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Post by gar381 on Aug 25, 2013 23:20:40 GMT -6
I just updated my build post at groupdiy on my Sphere/CAPI project lots of picts and the running build of this guy. Gary, that is some AMAZING work you're doing there, extremely impressive..wow! I would love to hear that rig at some point, it's gonna be crazy cool Is that wood working shop yours? thanx for sharing T Thanks Tony for the kind words. I figure this to be a 3 year project. 2 down and 1 to go. This has been a labor of love. Yes the wood shop is mine. Nothing special just a couple of old sears saws... A table, a radial arm and a big pile of clamps all housed in an unused stall in my garage. As usual many thanks to Jeff at CAPI. This project would not be possible with out the CAPI store and Jeff's inspiration.  |
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Post by unit7 on Aug 26, 2013 2:04:29 GMT -6
Hi Guys I just updated my build post at groupdiy on my Sphere/CAPI project Have seen that thread. Unbelievable! |
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Post by b2 on Aug 26, 2013 4:13:24 GMT -6
Hi Tony! Thank's ! Well ,I've work during long time (many months...) on all thoses project...now ,it's time make them fire up!! The project which is in this days ...his the "Handmade Tube Mic"...I've work on it ...doing all mechanical work...and know waiting cash for the capsule and transformers .. You see ...project as you know need time...and money .. The Varimu compressor is an "old story".....for me!! from 3-4 years ago...when I've work on a "am864" type limiter ,I've build..That's was my first step in the "Varimu ..world"! See the pisc of my first "am864" type limiter! this one was ....a fu*****ing bastard for sure ...I've spend much more time on it baby ...to understand by trivial and measurements......the Varimu . All the best!! Bruno. Attachments:
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Post by b2 on Aug 26, 2013 4:17:20 GMT -6
Hi Gary,
Awesome!!
I like thoses "pretty DOA" you've build!
For sure.. it's take time..!
This is a great great project..!!
Very nice! Congrats, Bruno.
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Post by b2 on Aug 26, 2013 4:22:00 GMT -6
...More:
For Jeff, I'm completely right with Gary!
His work at Capi are important for me in my project...As the Doa pcb or the Great ea2622 and more transformers...or the 600 Pad attenuator all this parts and more ...are a big parts of the result!
You see....In the Varimu compressor ..I've build...The output attenuator ...came from Jeff ;HeHe!!
Thank's Jeff!
All the best ,Bruno.
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