The Phonoclone and VSPS PCB Help Desk

[rjm]

680 ohms or 1kohms should be fine...

[TB]

Hello, oh well I thought I will be able to go from here unatended, but..... I need an advice in the case of proper version circuits for adjustable regulators. I hope, someone will find a moment to help me. As I have mentioned before I want to use LT1033 negative regulators and LT1085 positive ones. Actually I have a three questions:
- which circuit is recommended from LT1033 sheet
- --------------------//--------------------- LT1085 --//--
- I do not know how to calculate R1 & R2 for LT1085
Thank you very much for the help

http://www.linear.com/pc/productDeta...Id=H0,C3,P1239
http://www.linear.com/pc/productDeta...40,C1055,P1283

[Ipanema]

Hi rjm,

Thanks for the answer. :-)

May I know what is the puporse in using two stages of inverting amplifier in Phonoclone? Can I ommit the first stage, while increasing the gain of the second stage?

What is the criteria in choosing opamp for phonoclone? Low noise, speed, slew-rate etc.? Can I use Jfet input opamp such as TL072/LF353?

Thanks.

[rjm]

Can I ommit the first stage, while increasing the gain of the second stage?

It was called the VSPS Ultra. It didn't by all accounts work very well so I deleted the web page.

The Phonoclone is a highly optimised circuit. Unless you know more than I do, messing about with it is unlikely to make it better.

Op-amp selection has been discussed both on this thread and the web pages. The OP27 works well, and the circuit is optimized to a considerable extent to work well with the OP27. Anything else you are on your own. Some work some dont, just ask Onvinyl.

[tube 300]

Finished today the phono amp
and here are some pics.
It is heavy i think about 1,5 kg

And here is also a question
I wil use 2 transformers (each board one) the XLR is a 7 pin plug
each wire is connected to his own pin (used total 5 pins)
The com. is connected together first on the chassis and then on one pin.
is this correct that they are connected together in de amplier case when i use 2 transformers?

[superhkm]

Ouch ! Tube 300, you are my new hero. The casing is to die for.

hk

[troystg]

Tube 300-

In the first picture it appears the left side signal in and out wiring are straight and the right side wires are crossed.

Am I seeing that right? If they are identical channels why would they be different?


I LOVE the case!.. How much did that cost you? Prolly more than the electronics.

[tube 300]

hi thanks
The right side is crossed because the inputs are left and right
from the xlr plug the outside plugs are the outputs
thats better for the cables that i use
if you do this on channel is crossed then.

I made the case myself out of 1 piece alluminium
i can use the skills on my work
the boards are mounted on a piece bronze 6mm thick
that fit exactly in the case

But i am not sure about the com connection

[rjm]

Ok, I see how you've done it. That should be OK.

Remembering Fran's recent difficulties however, I would test that everything is working and hum-free as soon as you can. You may need to wire a slightly different grounding arrangement, with the inputs grounded to the case and COMs not. In which case you'll need to keep both COMs independent ... i.e. run two separate wires from the power supply to each board, neither connected directly to the case or ground lug.

/R

[woodturner-fran]

Just to let you know what I did:

dual mono, separate cable run to 2 x 3 way XLR jacks. I used uninsulated rca sockets for the inputs, insulated for the outputs, and connecting the ground to the common made no difference - in my set up.

I must add though that in my set up, having the TT ground connected or not makes no difference anyway - on yours you may need to connect the ground lug to common.

For the kit build, I am using wooden cases so grounding the inputs is going to be a bit different and I may have to experiment a bit.

(PS my power supply and casework is done, I just need to build the kit now)

Fran