BPA300 mono block - Page 3

Fenris · 14th May 2007, 08:42 PM

Nothing wrong with EI cores - I use them in about 50% of my amps. They're bigger and have more potential for stray magnetic fields (and some hum), but they work just fine.

alexw88 · 15th May 2007, 02:14 AM

So far we have :

Member # of boards
========================
HIPCHECK 6-10
Tryonziess 6
Alexcd 8
Analogdiy 6-8

Let's wait a couple more days to see if more members want to join...

AR2 · 15th May 2007, 03:02 AM

Quote:

Originally posted by Upupa Epops
Very nice and clean construction, Alex... But try to think about different input amp - DRV 134 have little bit " synthetic " sound...

I agree with this as well. What would you suggest Upupa? I would prefer discrete circuit, or even better tube. If Lundahl or Jensen could be used that would be the best and the simplest solution in my mind. They are around $ 90.00 last I checked.

alexcd · 15th May 2007, 12:11 PM

$90 per mono for a premium front-end is a bargain but wouldn't the input impedance be a tad low for non-active preamps?

Alex, would it help if I bought 4 more?

alexw88 · 15th May 2007, 12:48 PM

For transformer at input you need to match impedance on both side. i.e. you need a low output impedance pre-amp (likely a active one) and a high input impedance at the PA150 PCB (which you need to change the 10k/200k resistors combo)

Don't worry about the magic number "40" I think we are close enough.

Member # of boards
========================
HIPCHECK 6-10
Tryonziess 8
Alexcd 8
Analogdiy 6-8

Total : 28-34

alexcd · 15th May 2007, 12:55 PM

The transformer sounds like an issue for me.

I'm going to need the DRV134 or similiar.

HIPCHECK · 15th May 2007, 01:21 PM

hey guys, just figured id let you know, I have talked to Alexw88 about getting started finding all the parts needed for the amp.

so far I will donate all 1% smd reesistors needed to parrallel the amps

If the 10uf solen is used for al the amps than we can get them @ $2.75 each x100 units. (avg price is $4.00 ish)

I would also like to know (and Im sure opinions will vary) what elec caps everybody would like. Panasonics FM/FC? Elna? Nichiconc? etc.

Is everybody happy with the Wimas (mkp?) (0.1uf)

Im waiting on an email about the 50k trimpots.

I would prefer to keep this OT, but if a parts order was made it would require some discussion of parts.

alexcd · 15th May 2007, 01:24 PM

Thanks for the effort hipcheck. Group buying all the parts would be a great idea!

HIPCHECK · 15th May 2007, 01:44 PM

it would be a huge cost per person to build this amp without buying bulk. I am just doing some digging right now, and if this buy goes active, maybe also we can buy parts together.

alexcd · 15th May 2007, 01:48 PM

I was just thinking.... 4 amps $$$$ yikes! If I can help track stuff down let me know.

14th May 2007, 08:42 PM	#21
Fenris diyAudio Member Join Date: Jun 2004 Location: The last frontier	Nothing wrong with EI cores - I use them in about 50% of my amps. They're bigger and have more potential for stray magnetic fields (and some hum), but they work just fine. __________________ Listen to the music through the stereo, not the stereo through the music.

15th May 2007, 02:14 AM	#22
alexw88 diyAudio Member Join Date: Mar 2004 Location: HK	So far we have : Member # of boards ======================== HIPCHECK 6-10 Tryonziess 6 Alexcd 8 Analogdiy 6-8 Let's wait a couple more days to see if more members want to join... __________________ My Audio Page

15th May 2007, 12:48 PM	#25
alexw88 diyAudio Member Join Date: Mar 2004 Location: HK	For transformer at input you need to match impedance on both side. i.e. you need a low output impedance pre-amp (likely a active one) and a high input impedance at the PA150 PCB (which you need to change the 10k/200k resistors combo) Don't worry about the magic number "40" I think we are close enough. Member # of boards ======================== HIPCHECK 6-10 Tryonziess 8 Alexcd 8 Analogdiy 6-8 Total : 28-34 __________________ My Audio Page

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15th May 2007, 12:11 PM	#24
alexcd diyAudio Member Join Date: Sep 2004 Location: US - Boston	$90 per mono for a premium front-end is a bargain but wouldn't the input impedance be a tad low for non-active preamps? Alex, would it help if I bought 4 more?

15th May 2007, 12:55 PM	#26
alexcd diyAudio Member Join Date: Sep 2004 Location: US - Boston	The transformer sounds like an issue for me. I'm going to need the DRV134 or similiar.

15th May 2007, 01:21 PM	#27
HIPCHECK diyAudio Member Join Date: Jun 2004 Location: ARKANSAS	hey guys, just figured id let you know, I have talked to Alexw88 about getting started finding all the parts needed for the amp. so far I will donate all 1% smd reesistors needed to parrallel the amps If the 10uf solen is used for al the amps than we can get them @ $2.75 each x100 units. (avg price is $4.00 ish) I would also like to know (and Im sure opinions will vary) what elec caps everybody would like. Panasonics FM/FC? Elna? Nichiconc? etc. Is everybody happy with the Wimas (mkp?) (0.1uf) Im waiting on an email about the 50k trimpots. I would prefer to keep this OT, but if a parts order was made it would require some discussion of parts.

15th May 2007, 01:24 PM	#28
alexcd diyAudio Member Join Date: Sep 2004 Location: US - Boston	Thanks for the effort hipcheck. Group buying all the parts would be a great idea!

15th May 2007, 01:44 PM	#29
HIPCHECK diyAudio Member Join Date: Jun 2004 Location: ARKANSAS	it would be a huge cost per person to build this amp without buying bulk. I am just doing some digging right now, and if this buy goes active, maybe also we can buy parts together.

15th May 2007, 01:48 PM	#30
alexcd diyAudio Member Join Date: Sep 2004 Location: US - Boston	I was just thinking.... 4 amps $$$$ yikes! If I can help track stuff down let me know.

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