[BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread

[kante1603]

Hi Jeff,

2 lovechildren arrived in germany.Everything is looking very beautiful,especially the pcbs.
Will check in depth for all parts at the weekend.

Thank you very much indeed,

Udo.

Addendum: Have done the main boards today.The milmax sockets are super-easy to solder in.
I use a Weller Magnastat from 1987,it's my companion since then and never failed.
Tearing the iron away horizontally does the trick,thanks for the hint Jeff.

Best regards,

Udo.

 

[kante1603]

Hello Jeff,

excuse me disturbing,but my package has been opened at the customs,so far everything seems o.k. except of small parts like 1 36k resistor(I have tons of them) and a rectifier diode 1n419 missing.
I have 1n4148 here,specs seem very similar.Can I take them as replacement (just wanted to get sure because it´s on the DT05 opamp and I don´t want start swapping parts on such a build,hahahaha....).

Thank you in advance,

Udo.

 

[jsteiger]

Udo, the 1N914's are "cut-tape" and typically cut off in 4pc groups for the DTO5. You mean there were only 3pc? Very strange. From what I know, the 1N914 and 1N4148 are interchangeable and essentially the same part.

The DTO5 does not have a 36k on it. Do you mean the Discrete Follower Kit?

 

[kante1603]

Udo, the 1N914's are "cut-tape" and typically cut off in 4pc groups for the DTO5. You mean there were only 3pc? Very strange. From what I know, the 1N914 and 1N4148 are interchangeable and essentially the same part.

Yes,only 3 of them on tape,but no biggie,was just curious if a 1n4148 will do the job.

The DTO5 does not have a 36k on it. Do you mean the Discrete Follower Kit?

Yes,the 36k didn´t mean missing from the DTO5 but from one of the DF.2 bags.It had a hole on one edge,parts have dropped out.As said the package was opened at our customs and looked a little messed up.
Excuse my bad english.

Thank you for the fast reply,

best regards,

Udo

 

[jsteiger]

No worries. Your English is just fine. I understand and must say.......customs = nimrods in any language.

Let me know if you need me to send anything.

 

[kante1603]

No worries. Your English is just fine. I understand and must say.......customs = nimrods in any language.

Nimrod,didn't know this word,but yes,after doing a search I must say it fits pretty good!

Let me know if you need me to send anything.

Yes,two VP28,but that's a different story
Thank you for taking care!

Best regards from germany,

Udo.

 

[kante1603]

Success!

Have built 2 of these now.
Had to wait for allen wrench(?) keys,but they were in my post today-HOOOOORRRRRAAAAYYYYY!
After some testing and giving them some listening I simply must say:
No,these are no good EQs-these are absolutely stunning!

Everything worked from first fire-up,no issues at all.Except of having left-over parts,exactly 18 pieces (guess..... ;D).
The sound is unbelievable,these guys can be anything from subtle and warm up to big and "having big co****s".
Pardon me,can´t find the words of what I feel in the english language.

Jeff-this was a great experience for me,and you did an outstanding work creating them!Thank you so much indeed!

I wonder what will happen when I start swapping DOAs-I have put in gar2520s,can these guys really be improved???

Oh,before I forget to ask:Jeff,can you please tell us roughly what the lpf and hpf frequencies are and at which slope?
Also,the bypass switch,does it connect the in and out stages (A1 and A2)?Just for my/our info.

You made me be a lucky guy sir,can´t wait to order 2 of the VP28 full kits now.

Attached a pic for those who are interested.

Best regards from germany,

Udo .

 

[jsteiger]

Excellent news and congrats Udo!  8)

The filters are essentially the same as the bandpass on a 550A only they can be used independently. Both have a 12dB per octave slope. HPF is stated as 50Hz and the LPF is stated as 15kHz.

The In/Out switch simply lifts all of the LCR networks from their respective connections to ground. The signal still flows thru all of the opamps, followers and the 2503. So, it is not a hardware bypass but neither was the 553 or any of the other API style EQ's. 

Thanks again for the outstanding review. I may need to add it to my new Customer Testimonials page. 

 

[kante1603]

Excellent news and congrats Udo!  8)

The filters are essentially the same as the bandpass on a 550A only they can be used independently. Both have a 12dB per octave slope. HPF is stated as 50Hz and the LPF is stated as 15kHz.

Thank you!

The In/Out switch simply lifts all of the LCR networks from their respective connections to ground. The signal still flows thru all of the opamps, followers and the 2503. So, it is not a hardware bypass but neither was the 553 or any of the other API style EQ's. 

So that´s why,I simply put some music thru them without dialing anything in and it nearly blew me away!

Thanks again for the outstanding review. I may need to add it to my new Customer Testimonials page. 

Do it ;D

Cheers,

Udo.

 

[kante1603]

Hello,

for those who are interested:The current drawn of a LC53A with gar2520s is approx. 75mAs per rail (so you can run lots of them in your racks) ).
--------------------------------------------------------------------------------------------------------------------------------------------

And a little helper for CMRR adjustment,built in a couple of minutes-look:

I used some Neutrik XLR parts and cut them to my needs:

Only the contact inserts,2 resistors (I used 1Ks,closely matched),a piece of solid core wire,the female metall housing and a part of the cable cap is needed.

Inserting it:

Assembled:

Sticker put on for reference,done!

Cheers,have fun with your builds-I did

Udo.

 

[chunger]

Genius! 

 

[jsteiger]

Clever  8)

 

[kante1603]

Hello,

thank you for the nice comments

@chunger:

Sorry,I didn't notice you started your very nice photo documentary.
Perfect as always I must say!

Go chunger go!

Have fun,

Udo.

 

[emrr]

Worth noting that the color coding of the EA2503 is the same as found in the VP2x guide (and on the main pcb), but they likely come out of the bobbin in a different order than pictured in the VP2x guide. 

Chunger, do you work for LEGO in the manual dept?  Great work. 

 

[emrr]

2 on the bench with CB/main assembled, and all amps loaded.  One is passing unity, the other is +5-6db up.  This is on the same test jig channel, one at a time, and also in comparison with each other when alternating positions. 

Swapped all amps from one unit to the other, one at a time, no change noted. 

Double checked transformer wiring, both colored the same and ohm out the same.

Compared in circuit resistance readings for MAIN pcb and all R (but not CBR) on CB pcb; all match from amp to amp. 

Difficult to know where to look next, guessing at schematic and flow.  Pointers?

 

[jsteiger]

I would first verify the location of the shunt jumpers for both units.

If the main board is all good with R values, I would check the CB PCB for R values. You can ignore the CBR R's for the 3 switches.

Did you also swap the DF's around?

 

[emrr]

Shunts the same, also moved all 6 actives, one at a time, and checked the CB R's. 

 

[jsteiger]

OK.

I would start by taking some measurements from the properly working module. After injecting a signal, take a measurement of your choice at the output of each amplifier stage then see where the gain increases in the hot module.

1st reading: negative side of C2 on the Main PCB.
2nd reading: output pin of A1, DF on CB PCB
3rd reading: output pin of A2, DF on CB PCB
4th reading: output pin of A4, DTO5 on CB PCB
5th reading: output pin of A3, DTO5 on CB PCB
6th reading: neg side of C12 on the Main PCB

Those are in signal flow order.

We'll figure out the problem stage and go from there.

 

[area8]

Jeff - you're killing me here... just after I discover I haven't caught up with a "new" 2 stage preamp, you come up with a killer EQ. I'm gonna be broke. My wife is gonna be mad again.

This EQ is maybe the antithesis of the simplicity of a 312, but after looking at the way this fits together,
I think you might be the Massimo Tamburini of the audio world!

Frank

 

[emrr]

Unity unit fully assembled, tested in bypass.  Hot unit lacking LC-EP board.  Feeding them 1k at +4dBu:

1st reading: negative side of C2 on the Main PCB.  - both 0.592 VAC
2nd reading: output pin of A1, DF on CB PCB  - both 0.591 VAC
3rd reading: output pin of A2, DF on CB PCB  - both 0.586 VAC
4th reading: output pin of A4, DTO5 on CB PCB  - both 0.4 VAC
5th reading: output pin of A3, DTO5 on CB PCB  - both 0.402 VAC
6th reading: neg side of C12 on the Main PCB - unity unit 0.402 VAC, hot unit 0.74 VAC

So we have a winner around the output amp. 
Compared resistances on main board again, all seem to match.

Tried and tested the following with no change:
Retouched all joints on main and J1-1 points
Swapped A1 and A2 positions

Wish I'd held off on fully assembling the good unit for comparative purposes.

Next idea?