G.TEN 500 series graphic eq (V3 revision) 21.11.21 back in stock

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Mr.Mezmerize

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Dec 1, 2015
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6
Location
Germany
Hi Igor!

I bought a pair of V3 G.TENs and received them yesterday. I just built the first unit and everything went great so far.

But I noticed something weird, when moving on to the DOA (I got the 2520 style DOA that was offered with the kits).

The parts and their descriptions on the bags don't make any sense at all for the supplied PCBs. Starting with the diodes, the bag says there are 1N4148 -> D1 (2x), D2, D3.
But the PCB has designations for D1-D8 (and there are no other diodes).
I checked the transistors as well and they seem to be weird, too.

Is there anything I'm missing? Or any build document to clear this up?

Thanks and cheers,
Lucas
 

Bobby Baird

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Jun 15, 2013
Messages
195
Location
Austin, TX
Hi Igor!

I bought a pair of V3 G.TENs and received them yesterday. I just built the first unit and everything went great so far.

But I noticed something weird, when moving on to the DOA (I got the 2520 style DOA that was offered with the kits).

The parts and their descriptions on the bags don't make any sense at all for the supplied PCBs. Starting with the diodes, the bag says there are 1N4148 -> D1 (2x), D2, D3.
But the PCB has designations for D1-D8 (and there are no other diodes).
I checked the transistors as well and they seem to be weird, too.

Is there anything I'm missing? Or any build document to clear this up?

Thanks and cheers,
Lucas
 

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Mr.Mezmerize

Member
Joined
Dec 1, 2015
Messages
6
Location
Germany
Thanks a lot!

I took another look at the parts I got and realised I have two different PCBs. I'll try to attach a picture.

Those documents seem to fit the markings on the component bags and one of the PCBs (right one).

However, I still can't make sense of the other PCB I started first (left one). Is it another revision or a completely different DOA?

Foto 03.06.21, 19 07 10.jpg
 

dirty1_1garry

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Oct 3, 2011
Messages
499
Location
Moscow
Looks like forgot to mention DOA information before. That's what Bobby Baird posted.
White DOA is 2520bc, pretty well known and used doa type. It has same part names and part values as 2520gar.

Cheers,
Igor
 

Mr.Mezmerize

Member
Joined
Dec 1, 2015
Messages
6
Location
Germany
Hi Igor,

I just did a search for 2520 style DOAs and I still can't find a match for the left PCB on my picture. The part count seems to be off, at least compared to most 2520 DOAs. 8 diodes, 10 transistors, etc...

Are you sure that's the right PCB for the kit? I don't see the reason for two different ones.
 

dirty1_1garry

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Oct 3, 2011
Messages
499
Location
Moscow
Are you sure that's the right PCB for the kit? I don't see the reason for two different ones.
Ha, my fault. That's Quad Eight AM10 pcb. Don't know how it ended up in the box with 2520bc boards and as a result you have. As I sad before - will send you 2520 kit for free, sorry about that. Please send me PM with your address.
 

Bobby Baird

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Jun 15, 2013
Messages
195
Location
Austin, TX
Finished one of my Ver.2 kits. Thank you for providing this eq project. One question. Is the transformer wiring of Ver.2 different than Ver.1? In Ver.1 manual there were guidelines to ground unused winding (ORG or YEL wires) and connect it to 0V, for example to RED pad, But in Ver.2 Manual no such guidelines. I assume I can just hook the Typical 2503 pinout color code to their respected pins wiring for ver.2 boards. As is, I have it wired like ver.1 and it seems to be 1:2 ratio unity gain.
 

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dirty1_1garry

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Messages
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Location
Moscow
Finished one of my Ver.2 kits. Thank you for providing this eq project. One question. Is the transformer wiring of Ver.2 different than Ver.1? In Ver.1 manual there were guidelines to ground unused winding (ORG or YEL wires) and connect it to 0V, for example to RED pad, But in Ver.2 Manual no such guidelines. I assume I can just hook the Typical 2503 pinout color code to their respected pins wiring for ver.2 boards. As is, I have it wired like ver.1 and it seems to be 1:2 ratio unity gain.
Hi Bobby,
My congrats!!

Well, regards transformers wiring.Yes, there is a little difference in V1 and V2 manuals. I think V2 is more correct.
Let me explain:
as I added balanced input buffer which gives -6dB on input, we need step up for +6dB on the output for equal gain bypass/active. 2503 type trx is quadfilar winded, so 1:2 or 1:3 ratio available. Original 560 used unbal input and 1:3 out trx connection which gives +9dB. We need +6dB. In different api equipment 2503 used in both 1:3 and 1:2 ratio, excess winding was used as additional cue output, as an example 312 preamp sch.
G.TEN V1 manual sad that connect your out trx for 1:2, one excess winding is useless. As it would be wrong to leave it hanging in the air, I suggested grounding it. But then I found that it's more efficient to connect that excess winding in parallel with primary, so in V2 and V3 manuals there is two winding in parallel as primary and two winding in series as secondary for pure 1:2 step up ratio.
 

Bobby Baird

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Jun 15, 2013
Messages
195
Location
Austin, TX
Would you recommend that I change the trx wiring on my ver.1 board to reflect this parallel primary wiring for the excess winding, or leave the orange wire grounded to 0v?

Thanks!
 

dirty1_1garry

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Joined
Oct 3, 2011
Messages
499
Location
Moscow
Would you recommend that I change the trx wiring on my ver.1 board to reflect this parallel primary wiring for the excess winding, or leave the orange wire grounded to 0v?

Thanks!
I think you can leave it.
Or you can try to ground YEL and disconnect ORG for V1 or connect ORG to BRN for V2. In theory lower pry resistance is better, but not so critical from listener side.

One more important aspect! Looks like you are using EA 2503 Litz transformer, make sure that you connect it right as Litz has different wire color code then standard non litz2503. I don’t know why EA didn’t leave the same one, one more reason to get confused.
 

dirty1_1garry

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Oct 3, 2011
Messages
499
Location
Moscow
Hi folk!
Should report that since the number of requests for the G.TEN kit remains stable, but we still have problems with the supply of spare parts to make a full kit, we decided to offer customers a partial G.TEN kit without an output transformer.
G.TEN uses a standard 2503 quadfilar transformer which can be obtained from Ed Anderson or Cinemag.
At the moment when our transformers are available, we will be happy to offer them for kit owners on special terms.
Available here:
 
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