Pumpkin preamp - More Boring Making Thread

spavleski · 2008-03-30 11:15 am

@Zen, Pot problem with "Crrrr" during rotation has gone after setting Bias to ZERO.

T H A N K S !!!

Zen Mod · 2008-03-30 11:39 am

spavleski said:
@Zen, Pot problem with "Crrrr" during rotation has gone after setting Bias to ZERO.

............

not likely "BIAS" .........

"offset" ..........more likely .........

:rofl:

spavleski · 2008-03-30 11:43 am

Zen Mod said:
not likely "BIAS" .........

"offset" ..........more likely .........

Yes, "Biasing" the offset ;-)

dviswa · 2008-03-30 9:44 pm

Hi Guys,

Now that my plitron "Over Kill trafo" has pretty much turned into "kill trafo", I need to find other sources for a transformer.

Has anybody successfully used the Apex Jr Mercury Magnetics TA110-W? Which other trafos have you guys been using?

Thanks,
Dinesh

Zen Mod · 2008-03-30 9:59 pm

dviswa said:
Hi Guys,

Now that my plitron "Over Kill trafo" has pretty much turned into "kill trafo", I need to find other sources for a transformer.

Has anybody successfully used the Apex Jr Mercury Magnetics TA110-W? Which other trafos have you guys been using?

Thanks,
Dinesh

why not - if you use two of them , to have twice 40Vac

you can always ask AR2 which one from Apex he use

zettelsm · 2008-03-30 10:56 pm

Apex Jr TA110-W transformer

dviswa said:
Hi Guys,

Now that my plitron "Over Kill trafo" has pretty much turned into "kill trafo", I need to find other sources for a transformer.

Has anybody successfully used the Apex Jr Mercury Magnetics TA110-W? Which other trafos have you guys been using?

Thanks,
Dinesh

I am going to use the MM TA110-Ws for my Pumpkin-Shunty AC power supply. Doing a quick hookup to check voltage, two MM TA110-Ws can be hooked up to supply a nominal 40V - 0 - 40V or 48V - 0 - 48V, the latter too much probably for all but the lowest of line voltages -- Japan perhaps @ 100VAC line.

The transformers appear to be good quality E-I core and should have no problem supplying the required current to a stereo pair of preamp-regulators. In typical DIY overkill fashion, I picked up 4 of the TA110-Ws so I can go dual-mono.

The price is certainly very right!

Steve Z

dviswa · 2008-03-31 3:52 am

Re: Apex Jr TA110-W transformer

Zen Mod said:
why not - if you use two of them , to have twice 40Vac

you can always ask AR2 which one from Apex he use [/B]

Thanks, ZM. PM sent to AR2

zettelsm said:
I am going to use the MM TA110-Ws for my Pumpkin-Shunty AC power supply. Doing a quick hookup to check voltage, two MM TA110-Ws can be hooked up to supply a nominal 40V - 0 - 40V or 48V - 0 - 48V, the latter too much probably for all but the lowest of line voltages -- Japan perhaps @ 100VAC line.

The transformers appear to be good quality E-I core and should have no problem supplying the required current to a stereo pair of preamp-regulators. In typical DIY overkill fashion, I picked up 4 of the TA110-Ws so I can go dual-mono.

The price is certainly very right!

Steve Z [/B]

Steve,
Thanks. The price surely is right. I was planning on ignoring the 48V taps and use the 40V. Have you tried putting any load on them? Connect a 100W lamp maybe and see how they might perform. I might consider using 4 as well if I have enough space in the cabinet.

Regards,
Dinesh

zettelsm · 2008-03-31 4:02 am

Re: Re: Apex Jr TA110-W transformer

dviswa said:
Thanks, ZM. PM sent to AR2

Steve,
Thanks. The price surely is right. I was planning on ignoring the 48V taps and use the 40V. Have you tried putting any load on them? Connect a 100W lamp maybe and see how they might perform. I might consider using 4 as well if I have enough space in the cabinet.

Regards,
Dinesh

Hi Dinesh,

I have not checked out the load regulation of the trafos yet, but maybe tomorrow night a work I might have time to do so. Looking at the physical size and with my plan to use two per channel, I figured they would be well within their current capabilities and voltage droop loaded would not be a problem.

I plan on having the transformers and rectifiers in a separate box and bring only DC up to the preamp enclosure.

Steve Z

dviswa · 2008-03-31 4:10 am

Re: Re: Re: Apex Jr TA110-W transformer

zettelsm said:
I have not checked out the load regulation of the trafos yet, but maybe tomorrow night a work I might have time to do so.

Please do.

zettelsm said:
I plan on having the transformers and rectifiers in a separate box and bring only DC up to the preamp enclosure.

Wow, 2 Box design huh? Worried about interference or simply no space in the cabinet? The rectifiers are on the Shunty board, just curios, what would you gain, by building a rectifier in the other box?

steenoe · 2008-03-31 6:34 am

Re: Pumpkin volume control

zettelsm said:
So Mr. Steen, do I see potentiometers in place of the Twisted Pear stepped volume control and input-output boards?

Would you care to elaborate on the changes and effects on sound, if any? I would like to benefit from your experience and reasons for the changes. . .

Thanks!

Steve Z

Hi Steve. I had the Elma's lying around, and since I am building the Pumpkin into this other wooden box I decided to use hem. I didnt really feel like taking the twisted setup apart

It took a long time to put it together, anyway. The main effect soundwise is the scratching noise with the Elma's

. The Twisted attenuator is much better, and I will probably be using the Joshua/Darwin, with a pair of Shunty supplies and the UGS modules that will show up shortly

zettelsm · 2008-03-31 7:13 pm

Re: Re: Pumpkin volume control

steenoe said:
Hi Steve. I had the Elma's lying around, and since I am building the Pumpkin into this other wooden box I decided to use hem. I didnt really feel like taking the twisted setup apart It took a long time to put it together, anyway. The main effect soundwise is the scratching noise with the Elma's. The Twisted attenuator is much better, and I will probably be using the Joshua/Darwin, with a pair of Shunty supplies and the UGS modules that will show up shortly

Thank you very much for your reply -- I am relieved. I saw the slick Joshua/Darwin implementation you used and ordered enough stuff for a balanced set-up . . . imitation being the most sincere form of flattery. Well, other than money.

Pardon another question -- what are UGS modules? A URL is fine.

Thanks for your time.

Steve Z

steenoe · 2008-03-31 8:13 pm

Steve,
Just stick with the Joshua/Darwin, its a very good choice. Dont ever worry about me changing stuff, I do that all the time :devilr:

Here is the UGS:http://www.diyaudio.com/forums/showthread.php?s=&threadid=116621
There is a link to the original thread in one of the first posts.

spavleski · 2008-03-31 8:33 pm

Magura said:
How warm does it become after a couple of hours?

Magura

Magura - Temperature measured on Shunty Heatsink (midle of it in between the fins) after 2 hours is 50 Degree Celsius. At the same time Pumpkin Heatsink is 53 Degree Celsius.

Too much ?

:xeye:

Zen Mod · 2008-03-31 8:40 pm

spavleski said:
Magura - Temperature measured on Shunty Heatsink (midle of it in between the fins) after 2 hours is 50 Degree Celsius. At the same time Pumpkin Heatsink is 53 Degree Celsius.

Too much ?

crazy danske metal boy will tell ya that's too cool ........... knowing his habits of burning mosfets as popcorns in oil bucket ............

hehehe

btw - temp is exactly as prescribed

hershann · 2008-04-02 12:31 am

Because of space and ventilation issues - my (future) pumpkin will be separated from the F4 by quite some distance - 5m.

Is running a shielded RCA or XLR cable for that kind of distance an issue with regards to sound quality?

her shann

Zen Mod · 2008-04-02 12:46 am

hershann said:
..........
Is running a shielded RCA or XLR cable for that kind of distance an issue with regards to sound quality?

her shann

certainly is , but also less critical than running same length od speaker cable ;

in any case - have a life with your gadgets ; it's better that you rule them than vice - versa

hershann · 2008-04-02 12:59 am

Zen Mod said:
certainly is , but also less critical than running same length od speaker cable ;

in any case - have a life with your gadgets ; it's better that you rule them than vice - versa

How true! Sometimes these gadgets seems to take over our home and lives and make us more miserable when they're suppose to give us joy.

her shann

steenoe · 2008-04-03 8:22 pm

Here is a temporaray pic of my Pumpie. The plexi-lid is really a nerve-wrecking piece of work!! Other than that, it goes as planned

Ballbearings in front are for extension rods. The rubber washers are for decoupling of the transformers!! Minor details, but important.

steenoe · 2008-04-03 8:28 pm

As you can see on the previous pic, there are vent holes at the rear. I have made similar holes in the bottom plate (alu) But at the front! The plan is ; when the inner get hot, the convection will start going, pulling air out of the entire cabinet. Any ideas that you think could better my approach, is welcome! Here is a pic of the rearplate, it will get fairly packed....

BTW the earplugs are for when the Pumpkie starts singing :clown:

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