Poor Man's Pultec EQP1-A Build Support Thread
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ruffrecords
Well-known member
ilfungo said:
It should not make a lot of difference. Thinking about your earlier post you said you got noise at -94dB when plugging straight into pro tools without any gain make up. Now, under those conditions, the EQ will have an insertion loss of about 20dB so the output level will typically be -20dB which means the signal to noise is about 74dB.
You then said with gain make up in place the noise became -65dB. The gain make up should bring the input signal back up to 0dB so the signal to noise is 65dB. So with gain make up it is actually only 10dB worse than without it. In practice the insertion loss is a little over 20dB so the difference is even smaller.
Having said all that, the actual figures are not very impressive. When you measured the noise, what did you have connected to the EQ input?
Cheers
Ian
ruffrecords
Well-known member
Were you able to look at the spectrum of the noise? Was there any hum evident?
Cheers
Ian
Cheers
Ian
Hi Ian now with 6.3v regulated all the hum is gone but my noise level is always too hight...
Two info:
My HT loaded was 350v , I've changed 3 x1k resistor with 2.2k 5w but my tension is too hight 339v...
Could this create some problems (6CG7 tube)?
Now I've insert in and out transformer and don't know why my noise with eq in go down to -80 (on pro tools)
It's good?
The only problem is that I have for the output only two Carnhill 600:600 and not 10k:10k....
Thanks !!!
Two info:
My HT loaded was 350v , I've changed 3 x1k resistor with 2.2k 5w but my tension is too hight 339v...
Could this create some problems (6CG7 tube)?
Now I've insert in and out transformer and don't know why my noise with eq in go down to -80 (on pro tools)
It's good?
The only problem is that I have for the output only two Carnhill 600:600 and not 10k:10k....
Thanks !!!
ruffrecords
Well-known member
The 6CG7 will be fine with 339V - each triode only has half this voltage across it so they are not stressed.heers
Ian
Noise at -80 is good! Looks like you had a hum loop as well which the transformer has broken.
600:600 transformer will be fine as long as it is a good quality one. Just make sure it only has a 10K load on it.
Cheers
Ian
Ian
Noise at -80 is good! Looks like you had a hum loop as well which the transformer has broken.
600:600 transformer will be fine as long as it is a good quality one. Just make sure it only has a 10K load on it.
Cheers
Ian
ruffrecords
Well-known member
ilfungo said:
it means:
1. Use a transformer such as a Sowter 5069
2. Make sure what it is connected to has an input impedance of 10K ohms or more.(your pro tools inputs should be OK).
Cheers
Ian
ruffrecords
Well-known member
Well done. excellent build. Would it be OK if I ask Pierre to copy these pics to include in the gallery of projects of my designs?
Cheers
Ian
Cheers
Ian
SteelyDan
New member
Hi all.
I'm a complete novice and I'm building this project for as part of my Music Production degree.
Ian's been very generous with his advice but I thought maybe for the more trivial queries I have that I shouldn't be flooding his inbox ;D
Anyway, thought I'd join in with this thread that I've been reading through. I've got a lot to learn and I've got a few books from the library on electronics and audio electronics but if anyone can recommend me any reading material then I'm all ears!
I'm a complete novice and I'm building this project for as part of my Music Production degree.
Ian's been very generous with his advice but I thought maybe for the more trivial queries I have that I shouldn't be flooding his inbox ;D
Anyway, thought I'd join in with this thread that I've been reading through. I've got a lot to learn and I've got a few books from the library on electronics and audio electronics but if anyone can recommend me any reading material then I'm all ears!
Attachments
Hello,
and at first thanks to all of your support.
I've got a newbie-question, so please be patient with me
I am building an EPQ with NE 5532 gainstage similiar to Frank's Power PCB http://groupdiy.com/index.php?action=dlattach;topic=44213.0;attach=29033 . Now I want to hookup an output transformer, the edcor xs1100. I searched and read a lot about transformers, but tbh, I can't get into it.
I am total confused about the connections of this tranny to the board. Is it true, that an 1:1 ratio is necessary? Would some give me a hint how to wire it correct to the output xlr?
Thanks a lot, pleased for every information.
Mike
and at first thanks to all of your support.
I've got a newbie-question, so please be patient with me
I am building an EPQ with NE 5532 gainstage similiar to Frank's Power PCB http://groupdiy.com/index.php?action=dlattach;topic=44213.0;attach=29033 . Now I want to hookup an output transformer, the edcor xs1100. I searched and read a lot about transformers, but tbh, I can't get into it.
I am total confused about the connections of this tranny to the board. Is it true, that an 1:1 ratio is necessary? Would some give me a hint how to wire it correct to the output xlr?
Thanks a lot, pleased for every information.
Mike
Attachments
ruffrecords
Well-known member
You probably want to wire this as a 1:1 transformer. This means you need to connect the primaries in parallel and the secondaries in series. So wire pin 2 to pin 4 and pin 1 to pin 5. Input is between pins 1 and 2. On the secondary connect pin 8 to pin 9 and take the output between pins 7 and 10.
Cheers
Ian
Cheers
Ian
Dear Ian,
Thanks a lot. I've read so much about this topic but I think I need to get in the fundamental stuff.
But I'm not sure what you mean with "between pin...and pin....". Does that mean any pin in that range oder that they have to be connected, too?
Sorry for the probably stupid question
Regards,
Mike
Thanks a lot. I've read so much about this topic but I think I need to get in the fundamental stuff.
But I'm not sure what you mean with "between pin...and pin....". Does that mean any pin in that range oder that they have to be connected, too?
Sorry for the probably stupid question
Regards,
Mike
ruffrecords
Well-known member
mike76 said:Dear Ian,
Thanks a lot. I've read so much about this topic but I think I need to get in the fundamental stuff.
But I'm not sure what you mean with "between pin...and pin....". Does that mean any pin in that range oder that they have to be connected, too?
Sorry for the probably stupid question
Regards,
Mike
For an input you need to make two connections, So when I say connect the input 'between' pins 1 and 2 I mean make one connection to pin1 and the other to pin 2. when I say connect the output 'between' pins 7 and 10 I mean make one connection to pin 7 and the other connection to pin 10. (Not obvious unless English is your mother tongue).
Cheers
Ian
But, one last question
the two inputs and outputs are + and - I suppose?
What about the grounds? Xlr to chassis? What about the ground from the transformer?
Hell, it seems so complicated, but I think Im thinking to complicated
the two inputs and outputs are + and - I suppose?
What about the grounds? Xlr to chassis? What about the ground from the transformer?
Hell, it seems so complicated, but I think Im thinking to complicated
ruffrecords
Well-known member
mike76 said:But, one last question
the two inputs and outputs are + and - I suppose?
What about the grounds? Xlr to chassis? What about the ground from the transformer?
Hell, it seems so complicated, but I think Im thinking to complicated
For the transformer primary, one connection goes to the NE5532 output and the other goes to 0V. For the secondary, one output goes to pin2 of the XLR and the other goes to pin 3. Pin 1 of your XLRs should be connected directly to chassis at the connector. Somewhere in your enclosure, 0V should be connected to the chassis. For more information of grounding in general I suggest you read this:
http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/SimpleMixer/grounding101v2.pdf
Cheers
Ian
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