Pumpkin preamp - ordered by Steen , official making thread

Manu · 2007-11-18 8:22 pm

You know : no need to hurry,
but I'am impressed and excited like Carpenter

thats all.
Yes its cold now in Beeetsch, very good for Aleph 5, fine heather, good mood.

hehe

carpenter · 2007-11-18 10:51 pm

Zen Mod said:
if you want absolute phase in puritan way then ground + output and use - as main one .

When you say, "absolute phase in puritan way", do you mean that preamps don't invert, or they do invert?

It can get complicated very quickly if one has many amplifiers that invert, or don't invert the output signal. Do most amps invert?

Zen Mod · 2007-11-18 10:59 pm

carpenter said:
When you say, "absolute phase in puritan way", do you mean that preamps don't invert, or they do invert?

It can get complicated very quickly if one has many amplifiers that invert, or don't invert the output signal. Do most amps invert?

woodie - it's not hard to me that I repeat some thing 1000 times , but you must learn to trust own eyes more ......... :clown:

you have + and - inputs ;
you also have + and - outputs ;

they are labeled in that manner with purpose

so - if I wrote drek on forum - because I'm tired or because my brain is in red ......... trust to your own eyes ;

on input ground "-" leg , and use it unbalanced

on output ground "-" leg and use it unbalanced

in that case absolute phase is correct, not as I wrote previously .......

what I meant with previous post (where I wrote that you can ground whatever you want ) is exactly that - ground whatever you want and have phase as you wish .........

:clown:

carpenter · 2007-11-18 11:04 pm

Sorry to bother you, Choky. I'll do more reading on my own.

Many thanks for the kit.

Bye.

Zen Mod · 2007-11-18 11:58 pm

carpenter said:
Sorry to bother you, Choky. I'll do more reading on my own.

Many thanks for the kit.

Bye.

you aren't bothering me .......

point is that I wrote drek even if answer is obvious ....... I hope that was just temporary glitch :clown:

so - you have that answer just in front of your nose and relayed on not so reliable :rofl:

carpenter · 2007-11-19 12:51 am

I'm currently operating a balanced, bi-amped stereo.

In the interest of economy, I wish to use unbalanced F4 for treble horns.

I wish to use mono balanced F4 for midbass units (dual 12" Eminence per channel) where I can use more wattage.

I've considered using Pumpkin for midbass F4 where I can use the extra gain. For the treble, I can use the electronic crossover, or my xbosoz.

You can see where operating balanced with unbalanced configurations can become confusing.

mpmarino · 2007-11-19 4:28 am

In the interest of economy, I wish to use unbalanced F4 for treble horns

Why not look at the Babaleph J for the horns?

carpenter · 2007-11-19 4:46 am

mpmarino said:
Why not look at the Babaleph J for the horns?

Darn good question. Tell me more.......

mpmarino · 2007-11-19 5:09 am

carpenter said:
Darn good question. Tell me more.......

There's only so much I can say. Nelson's Aleph J or Choky's Babelfish J (almost the same) are both balanced topology. You could probably build yourself a nice 'mini' and keep the whole shebang balanced.

sorry for the OT post

Hey Choky,

Re: fancy pants shunty reg. Is 82v CT tranny the ABSOLUTE MINIMUM for +-36v? I'm seeing what I have 'in drawer'. Greedy boys don't like to spend money

:clown:

edit: Carpenter - my pump boards came USPS registered mail. I had to sign. I see you asked a while back.

carpenter · 2007-11-19 7:14 am

mpmarino said:
There's only so much I can say. Nelson's Aleph J or Choky's Babelfish J (almost the same) are both balanced topology. You could probably build yourself a nice 'mini' and keep the whole shebang balanced.

edit: Carpenter - my pump boards came USPS registered mail. I had to sign. I see you asked a while back.

That's a good idea. I was once pretty interested in the babelfish.

My receipt from the PO is probably going to arrive any day...guess that means a trip to the Post Office.

Zen Mod · 2007-11-19 7:55 am

carpenter said:
That's a good idea. I was once pretty interested in the babelfish.

My receipt from the PO is probably going to arrive any day...guess that means a trip to the Post Office.

keep it simple - stay with F4 only - at least because of gain uniformity

mpmarino · 2007-11-19 12:14 pm

Zen Mod said:
keep it simple - stay with F4 only - at least because of gain uniformity

Whoops, this is very true!

How much gain has the F4? Is there a preamp that will drive it?

:devilr:

Zen Mod · 2007-11-19 3:27 pm

mpmarino said:
Whoops, this is very true!

How much gain has the F4? Is there a preamp that will drive it?

if you put all N mosfets in it - it have zilch gain :devilr:

if you make it as planned by Papa - probably is there some preamp capable to drive it

for instance This one

:devilr:

Magura · 2007-11-19 4:14 pm

Zen Mod said:
if you put all N mosfets in it - it have zilch gain

I've seen some guy do that, I'm not sure if it worked though

Do a search, the thread may pop up :clown:

Magura

lykkedk · 2007-11-19 4:37 pm

keep it simple - stay with F4 only - at least because of gain uniformity

Hmmm.... strange thing's happend here...
Could it be possible, that the :Pumpkin:

drive's the F4 perfectly... But not being able to drive my LeachAmp 2x125w ???

It's just, that if i attach my Leachamp to :Pumpkin:

+out (and -out/-in grounded), Leachamp is making HUUUGE!!! noise / hum / distortion ... etc ... ???

There is no difference, if it's with or without my inputselector attached. (I even tried to deattach my new 4deck 10k log pot, and place my old thrusted there too, with no change at all)

I am thinking of something with impedancematch between :Pumpkin:

---> Leachamp... but it's something i really don't know.

I will, just to be 100% sure attach one of my F4 to :Pumpkin:

. to see if it's still working! (can't se why not, don't think there will be any problem's here)

Jesper.

Zen Mod · 2007-11-19 4:53 pm

lykkedk said:
Hmmm.... strange thing's happend here...
Could it be possible, that the drive's the F4 perfectly... But not being able to drive my LeachAmp 2x125w ???

It's just, that if i attach my Leachamp to +out (and -out/-in grounded), Leachamp is making HUUUGE!!! noise / hum / distortion ... etc ... ???

There is no difference, if it's with or without my inputselector attached. (I even tried to deattach my new 4deck 10k log pot, and place my old thrusted there too, with no change at all)

I am thinking of something with impedancematch between ---> Leachamp... but it's something i really don't know.

I will, just to be 100% sure attach one of my F4 to . to see if it's still working! (can't se why not, don't think there will be any problem's here)

Jesper.

when you find what's wrong - I'm sure that will be collective :rofl:

audio and safety grounds , both in :Pumpkin:

and Leach?

what's with them?

besides - why you need Leach now ?

:devilr:

lykkedk · 2007-11-19 5:23 pm

Hmmm... no need to worry, i have found the 'error' ... so to say...

Nothing wrong with :Pumpkin:

--- Nothing wrong with LeachAmp... Nothing wrong with F4...

The meganoise was comming from the dual 5vdc psu's located near inputselector / signaltraces --- OR (donno yet) from the relay's on inputselector.

What tricked me before, was that i attached Leachamp, after the inputselector, but still the psu for driving relay's / toslink was on all the time.... same second i unplugged that all noise / hum whatever dissapeared.

Now i will take a break... next move is to make the psu / xformer move 1m or more away from inputselector to see, if some relay also are making some noise.

The relay's i am using are 5vdc omron g5v -2 signalrelay's... i think they are good enough through.

.... hmmhhmmmhhmmm i really learned something today ... right ZenMod !

Jesper.

Zen Mod · 2007-11-19 5:55 pm

lykkedk said:
Hmmm... no need to worry, i have found the 'error' ... so to say...

Nothing wrong with --- Nothing wrong with LeachAmp... Nothing wrong with F4...

The meganoise was comming from the dual 5vdc psu's located near inputselector / signaltraces --- OR (donno yet) from the relay's on inputselector.

What tricked me before, was that i attached Leachamp, after the inputselector, but still the psu for driving relay's / toslink was on all the time.... same second i unplugged that all noise / hum whatever dissapeared.

Now i will take a break... next move is to make the psu / xformer move 1m or more away from inputselector to see, if some relay also are making some noise.

The relay's i am using are 5vdc omron g5v -2 signalrelay's... i think they are good enough through.

.... hmmhhmmmhhmmm i really learned something today ... right ZenMod !

Jesper.

I told ya ...........

ROTFLMAO !!!!!!!!!!!!

:rofl:

EDIT:

Omrons are good enough for purpose , and can't be culprit for noise

lykkedk · 2007-11-19 8:06 pm

I give up on, and start all over again i think... This setup i have done is giving me sooo many problem's unfortunately.

This is where i am now...
:Pumpkin:

is working 100% (told before i know

), as long as i use 1 'directly' input with wire's soldered directly on +in pin's.

I will try to make a new inputselector, with balanced input's only. When i use unbalanced input, the -in will be shorted inside XLR ---> RCA adapter cable.
(ZenMod suggested this earlier in thread)

This time it should be perfect!

1. quistion. what about the -in connection on other side of attenuator ?

2. quistion. should i us a ''star'' ground attached in middle of chassic, where all GND wires go to...
including the 3 or 4 gnd connections from input XLR ?
including gnd from psu
including gnd from output XLR
etc.....
etc....

3. quistion. Will it be good to GND unused input connection's or should i gnd them through e.g 100K or 10K resistors, i mean... Can all sources stand up for a shorted output ? (dac / riaa / squeezebox / walkman

etc.... ...)

Jesper.

Zen Mod · 2007-11-19 8:14 pm

lykkedk said:
I give up on, and start all over again i think... This setup i have done is giving me sooo many problem's unfortunately.

This is where i am now...
is working 100% (told before i know ), as long as i use 1 'directly' input with wire's soldered directly on +in pin's.

I will try to make a new inputselector, with balanced input's only. When i use unbalanced input, the -in will be shorted inside XLR ---> RCA adapter cable.
(ZenMod suggested this earlier in thread)

This time it should be perfect!

1. quistion. what about the -in connection on other side of attenuator ?

2. quistion. should i us a ''star'' ground attached in middle of chassic, where all GND wires go to...
including the 3 or 4 gnd connections from input XLR ?
including gnd from psu
including gnd from output XLR
etc.....
etc....

3. quistion. Will it be good to GND unused input connection's or should i gnd them through e.g 100K or 10K resistors, i mean... Can all sources stand up for a shorted output ? (dac / riaa / squeezebox / walkman etc.... ...)

Jesper.

hold your horses ;

I'll draw later tonight everything for you ........ balanced input selector with omrons or takamisawas , and grounding scheme, along with grounding of unused inputs

btw - source which cannot stand up shortie is good for nutin'

Pumpkin preamp - ordered by Steen , official making thread

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