[silent:arts]

V672X (Telefunken V672a in GDIY51X format)
« on: July 16, 2017, 11:39:02 AM »
I would like to present you a new member in my German Legends family, the V672X

based on the Telefunken UNIVERSAL AMPLIFIER V672a,
with improved output driver and added mic-pre features,
switchable series resistance (input impedance) and
switchable feedback resistance (gain)

[ original schematic | original data-sheet ]

NOTE: the V672X is NOT API500 COMPATIBLE, a GDIY511 Rack is required




Documents:

V672X Schematic
V672X PCBs
V672X Parts List

Full Kits are available in the White Market
« Last Edit: July 30, 2017, 05:25:23 AM by [silent:arts] »
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.


kante1603

Re: V672X
« Reply #1 on: July 16, 2017, 12:13:47 PM »
Wow,beauties they are!
The german writings are cool,hahaha....


Congrats Volker,


best regards,


Udo.

Re: V672X
« Reply #2 on: July 16, 2017, 06:21:54 PM »
Looks amazing! When will they be available?

[silent:arts]

Re: V672X
« Reply #3 on: July 22, 2017, 11:09:04 AM »
Schematics, PCB overlays and parts list added to the first post
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

kante1603

Re: V672X
« Reply #4 on: July 22, 2017, 11:41:04 AM »
Schematics, PCB overlays and parts list added to the first post

Excellent Volker!
May I ask a question:The parts list says that Ü1,Ü2 and Frontpanel "....are not included any kit....".
Will you offer them (I guess most of us don't have a good access to Haufe transformers,and the panels look really nice)?


Thank you in advance,


Udo.
« Last Edit: July 22, 2017, 11:44:16 AM by kante1603 »

[silent:arts]

Re: V672X
« Reply #5 on: July 22, 2017, 12:46:02 PM »
Hi Udo,

changed that to "* not included in the parts kit".
I will offer full kits.
However, it is easier for me and my stock inventory software to have the transformers and front panels as separated items.
Some people might have the transformers anyway (or V672D cards with broken thick film IC),
and the front panel can be either in silver or black.

Kind regards
Volker
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

kante1603

Re: V672X
« Reply #6 on: July 22, 2017, 12:52:54 PM »
Great,thank you very much indeed Volker!


Best regards,


Udo.

Potato Cakes

Re: V672X
« Reply #7 on: July 24, 2017, 10:59:12 AM »
When I come out from under the pile of things I have to finish building, I'd be interested in metal work, boards, and transformers.

Phenomenal job as always.

Thanks!

Paul

[silent:arts]

Re: V672X (Telefunken V672 in GDIY51X format)
« Reply #8 on: July 30, 2017, 05:23:48 AM »
Full Kits are now available in the White Market  8)
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

kante1603

Re: V672X (Telefunken V672 in GDIY51X format)
« Reply #9 on: August 21, 2017, 03:28:35 PM »
Hello Volker,


about adjusting,C8 is for symmetry trim,right?
Are there any rules or recommendations how to set the fine gain and the filters?


Thank you in advance,


Udo.


[silent:arts]

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #10 on: August 22, 2017, 01:41:51 PM »
Hi Udo, yes C8 is the input symmetry trim.

For calibrating we use the original V672D Meßvorschrift  8)
For the V5672 and V672X I adapted it like followed:
(for all steps my generators Zout is set to 200R, and analyzer Zin to 600R)

S1 =  dB Gain: 62dB / R Gegenkopplung: 240K
S2 = LPF OFF / Tiefpass Überbrückt to left position (on)
S5 = dB Input: -20dB / R Eingang: 2k2

GAIN ADJ R26:
Generator = 1kHz -40dBu
Set R26 to measure +2dBu

HF ADJ R37:
Generator = 15kHz -40dBu
Set R37 to measure +2dBu

LF ADJ R29
Generator = 40Hz -40dBu
Set R29 to measure +2dBu
« Last Edit: August 23, 2017, 07:20:37 AM by [silent:arts] »
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

[silent:arts]

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #11 on: August 22, 2017, 01:47:39 PM »
For C8 input symmetry you need a special cable.

(generators Zout is set to 200R, and analyzer Zin to 600R)

S1 =  dB Gain: 38dB / R Gegenkopplung: 5K6
S2 = LPF OFF / Tiefpass Überbrückt to left position (on)
S5 = dB Input: -20dB / R Eingang: 2k2

Generator = 15 kHz -5dBu
Adjust C8 for lowest possible output
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

kante1603

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #12 on: August 22, 2017, 02:11:01 PM »
Awesome Volker,


thank you very much!
Will order very soon (if I may of course).


Best regards,


Udo.

[silent:arts]

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #13 on: August 24, 2017, 07:02:26 AM »
You are welcome Udo.

Added the Service Manual I mainly used to design the V672X to the Technical Documents Section.
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

kante1603

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #14 on: August 24, 2017, 02:32:50 PM »
Thank you for the docs Volker!


Two kits received this afternoon,parts checking time now (most time-consuming thing,I look forward to assembly)  ;D
The kit looks very nice and professional,the frontpanels are awesome!


Best regards,


Udo.

kante1603

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #15 on: August 25, 2017, 10:29:42 AM »
Done!


Finished assembly and adjusting/trimming today,all went very well.An easy build,well prepared (Grayhills came with stopping pins set already!) and complete up to the last washer.
Haven´t heard too much,but what I heard was excellent sounding.
Did first tests with some music via (Bo´s) active D.I.s as well as some microphones I had here at home.
Sm57 was easy too bring up to a useful level at just speech,even an SM7b worked good enough when raising speech level.With a Cloudlifter the SM7b sounded very very nice.
CMC6+MK4 was fantastic.


Addendum:
Heard it with U87 and U87Ai on vocals today,as expected it sounded excellent.
I can only recommend building them.Not only is it easy to do -I built two in just one day-but the kit price is on the more lower side compared to other kits in this sound range (290 Euros+VAT).


A massive thank you to Volker for another great project!


Best regards,


Udo.


P.S.:As usual the pics of proof,here while CMRR-trimming:

Edit:Addendum added.

« Last Edit: August 31, 2017, 11:11:24 AM by kante1603 »

kante1603

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #16 on: August 25, 2017, 10:30:47 AM »
…and here while phase checking etc. and listening:

[silent:arts]

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #17 on: August 26, 2017, 05:07:05 AM »
Fast as always my friend:-)
Thanks for your kind words Udo.

Can you tell us something about your interesting looking module screws in the 2nd pic?
SSLtech: No bypass, I don't believe in it.
Gus: I think this build might have problems with DIY builders that don't know things like ohms law.

kante1603

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #18 on: August 26, 2017, 06:15:52 AM »
Hi Volker,


those are 4/40-thumbscrews,they're just temporary because a)we are in metric land and I had no fitting silver countersunk types here and b) they are usable without a screwdriver  ;D
They look very nice on black facias,I have them from Cemal ("sahib") for my TAC gear which make them look even better,hahaha......


Cheers and greets to Berlin,


Udo.

leadbreath

Re: V672X (Telefunken V672a in GDIY51X format)
« Reply #19 on: August 26, 2017, 09:16:57 PM »
Love these amps!!! Glad to see other people share the love of these units... :D
f**k marlbro's and weed ill stick to smoking germanium and silicon