Pumpkin Preamp - Perfect for F4 - Page 76 - diyAudio
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Old 5th June 2011, 01:43 PM   #751
Zen Mod is offline Zen Mod  Serbia
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what gain you need from ?
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Old 5th June 2011, 09:56 PM   #752
3GGG is online now 3GGG  Australia
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Not sure, I am not that smart or knowledgable, still learning.

Amp's are Aleph J's which are nearly finished.

Out of interest the complete system will be as follows
Diy Slate and acrylic TT
MY TT build
Dl103R Cart

HPS 5.1 Phono
Hps 5.1

Pumpkin

Aleph J's

4 Way horns
Fane 8m, 200hz LeCleach
Yamaha 6681b 400hz LeCleach
Fostex T500A MKII
Bass TBA

I hope to avoid digital X-Over so am looking at Passive line level for X-Over.
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Old 6th June 2011, 04:00 PM   #753
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Quote:
Originally Posted by 3GGG View Post
I am not that knowledgeable - Diy Slate and acrylic TT - HPS 5.1 Phono
Could have fooled me.
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Old 6th June 2011, 09:50 PM   #754
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Quote:
Originally Posted by jacco vermeulen View Post
Could have fooled me.

My skills are best used on the hands on building part. The technical side is where I am laccking and slowly learning.

So what gain should I set Pumpkin to and how do I go about working this out.

Cheers
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Old 6th June 2011, 10:59 PM   #755
Zen Mod is offline Zen Mod  Serbia
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set Pumpie for - say - 4x gain

meaning - input resistors in range of 15K , feedback resistors in range of 62K-68K
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Old 7th June 2011, 01:01 AM   #756
3GGG is online now 3GGG  Australia
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thanks again Zen:-)
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Old 14th January 2013, 09:15 AM   #757
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Originally Posted by Andy5112405 View Post
Here's my Shuntky / Pumpkin Stereo Pair

All I can say is ABSOLUTELY STUNNING

The GREEN GROUND wire that you see at the top left was experimental during build, it was eventually tidied away but connected to the IEC socket instead of the screw hole used in the photo.

Zen-Mod is wonderful and very helpful, I had a few problems which were quickly and easilly resolved. That is the DIY spirit.

Click the image to open in full size.

Incidentally the two transformers were not used, one for each channel. I just happened to have 2 x 50VA 20-0-20V Transformers which were perfect for 40-0-40V use.
Hi Andy and good year !Please why did you use that connection between the heatsink and chassis? You've got yourself a problem of background noise initially? It seems to me that by touching with my hands sinks the noise varies, please could you give me some advice?

Thanks in advance

Antonio.
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Old 13th August 2013, 07:01 PM   #758
lhquam is offline lhquam  United States
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What is the preferred front-end (voltage gain stage) for a single-ended F4?

I am looking at the BA3 FE, Pumpkin, Blowtorch, and various opamps. The difficulty is getting enough voltage swing and a voltage gain of 6x or better with low distortion, particularly higher order harmonics.
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Old 13th August 2013, 09:13 PM   #759
Zen Mod is offline Zen Mod  Serbia
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if you ask me - BA3 Bal FE , or
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Old 5th December 2013, 08:27 PM   #760
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Did anyone use Pumpkin to power high efficient speaker, e.g. 110db+
I have a 98% built pumpkin and might try it with my horn rig.
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