Neve 1073 using Lorlin and Pots?

[Spencerleehorton]

well i've fault finded a few things and now have a working pre amp!!
doesn't sound that hot with this voodoo labs output and input txf in it thought!!
thought id wired the gain switch up correctly but i'm getting 1-7 on gain switch ok but 8-11 gain settings start from nothing again?
will start to finish up other channel to test as well now.

Spence.

 

[Spencerleehorton]

Having a nightmare with this gain switch and need some help!!!

I've attached what resistance I get from either attaching to the wiper and then attaching to position 1 or position 11.
At the moment I have it attached with wiper and position 11 as this seems to be the way I understand it from the schematic.
I am misunderstanding something here but can't work out what?
Please help. 

Regards

Spence..

 

[Spencerleehorton]

I am starting from -20db as positions 1 and going up to -70db as position 11 and leaving out the off position.
Also getting strange shape wave after position 4?

I took out the 330 ohm and 120 ohm resistors as I'm not using those positions and the wave form looks better now but after pos 7 the gain resets down low again and raises  till pos 11

also the 4.7k pot doesn't change the collector voltage on the 2n3055?

Spence.

 

[Spencerleehorton]

Found about another 5 errors!!! Fingers cross it'll all work properly after I fix them!!!

Spence.

 

[Spencerleehorton]

I have edited this other earlier schematic and wondered whether someone could check I've done it right please?

Regards

SPence

 

[Spencerleehorton]

have a little bit of hum but this will probably go once i use all screened leads everywhere.
2n3055 is now adjusted to 22.66v
have installed 10k trimmer pot in between L and P on BA283 and adjusts bias of where clipping.

gain switch pot still not working properly? 1-7 working, 8 almost need to be position 1, 9-11 gradually get louder?
anyone have any ideas?

then i find this picture of the gain switch!?

regards

Spence.

 

[Spencerleehorton]

It seems I have all the right stages of the gain switch but in wrong order, 8-11 should be 1-4 and  1-7 should be 5-11.
Has anyone got any ideas, I'm really stumped with this!
Regards

Spence.

 

[Spencerleehorton]

Hi guys,
I have checked the voltages and I get the following:
Ba283
D - 2.7v
K - 0.338v
L - 0.729v
M - 22.90v
N - 19.90v
P - 8.46v
S, T, U, V - 0v
B - 22.66v
C - 3.31v
F - 0.54v

Ba284
A, B, C, F, G, V - 0v
D - 23.76v
E - 3.65v
N - 19.87v
L - 23.98v

Sine wave is good until pos 5 then it goes to square wave?

Any of these voltages look dodgy to you?

Regards

Spence.

 

[JessJackson]

i love how u don't give a fuck for aesthetics. you just throw shit together.. we should all care about the sound more than the look of things!

why your caps so big? they only need to be 25v.

J

 

[Spencerleehorton]

using some old vintage ones i got in a big box!! good to hear from ya Jess!! all good.

regards

Spence.

 

[Whoops]

Meanwhile I've gone though 100 Bc184c and only managed to get 12 at about 560hfe!

Will see what next batch brings!!! Hopefully over 600hfe.

Spence.

At what base current are you measuring HFE?

 

[Spencerleehorton]

channels all operational now, i had a transistor on the 284 pcb the wrong way round!!!
loadsa gain!!! sounds amazing with my newly wound 1066 style transformers.
Just need to tidy it all up now and put in some brackets to hold the pcbs.

regards

Spence.

 

[Spencerleehorton]

Got a bit further today, rebuilt the psu, moved psu into external box and neatened up all the layout.
Everything is screwed down now, need to fit a connector for the power to the box.
check psu is working then power up. Had some scope issues so thats being repaired as well!!!
hopefully on home run with this first stage, then i can move onto building the EQ sections.

Spence.

 

[pvision]

I'm a bit late in chipping in but was going to suggest disconnecting the switch from the board and measuring each step to check the resistance, if you hadn't done so already

You could link the units using DB25 connectors - there's a standard pinout for 8 balanced channels on a db25

You're building these with home-wound transformers? That's true DIY!

Nick Froome

 

[iprovlek]

Would you sell your 1066 transformers!?

 

[Spencerleehorton]

if a few people wanted me to do them a txf i suppose i could wind a few, someone has sent me a proper Neve txf to rewind as well.
i am going to do some API 2503 txf as well. Just msg me if you want.

Spence.

 

[Spencerleehorton]

Hi Nick,

Im just going to use XLR in and out plugs as i have some spare and this is going inside a mobile rack for recording on the road also with this CLX 160 which i'm going to gut this ART pro VLA case and put them in there!!
I need to compare these channels properly now to the EZ1290's i've already built, Im really impressed with the EZ1290 if i can get close to that sound i'm going to be well chuffed, if i can improve over it more the better!!!

Spence.

 

[Spencerleehorton]

after having one channel working perfectly and the other not i have found the culprit,  C15 was not working so changed and now everything sounds wonderful. left channel is a little louder but i still need to check i can bias them both to 22.66v
Once i get both channels in the patch bay i can run some tests against the EZ1290 channels.
better start making the EQ pcbs now!!!.

Spence.

 

[Spencerleehorton]

Need to get another patch bay so I'm able to compare, but bottom end and top end is wonderful, really powerful focused, open sound, looking to put in a D.I. Input for bass or guitar.
Anyone suggest some windings or ratio for transformer for D.I.?

Spend.