BPA300 mono block

[bobgroger]

Got my boards today, arrived in perfect condition. Thank you for the effort in this project! Collecting parts now, these are in line right after 4 channels of Pavel's LM4780 PCB's I am building this weekend for mids and highs....

Bob G.

 

[Algar_emi]

Hi. This is a complete shematic of the BPA150 PCB and the detailled parts list that goes with it.
I hope it can be of some use to some of you.

 

[Pocoyo]

Very Fast Progress

I think algar_emi has finished his amp now

so we can ask him where his driver now ?
i will wait until he finish it

Algar after i calculate the driver some of my friend
want to use Jensen for bridge, maybe you can
make it design too for the pcb

 

[Algar_emi]

I'm working on a very simple DRV134 driver PCB that will include the +/-15V supplies. I'll post it when done, possibly by next week.

What do mean by Jensen. Is it to use Jensen as coupling cap on the driver PCB? The basic DRV134 PCB doesn't need any coupling cap. It is DC coupled. The BPA150 PCB are coupled using big 10-15uF fim caps. The PCB is big enough to accept Jensen cap if you like. Anyway the BPA150 PCB was not of my design. I ordered the superb PCB done by alexw88.

 

[alexw88]

Algar, your schematics looks very nice and complete! Much better than the one I drawn.

jeffry is talking about the jensen transformer used in the Jeff Rowland amp : http://www.jensentransformers.com/

BTW, I have got a pair of Lundahl 1545a input transformer and I will do some test / measurement later when I have time.

 

[Algar_emi]

I would like to add the option of using the Jensen transfo on my DRV134 PCB as an option but only if it is easy to do.

I understand that the DRV134 is providing gain for the BPA150. Using the transfo, I will need to use an op-amp to get the missing gain, correct? I suspect that a transfo driver PCB would be quite different than the DRV134 circuitry.

Thanks for any help you can provide.

 

[alexw88]

See the transformer discussion here :

http://www.diyaudio.com/forums/showthread.php?postid=1232356#post1232356

Pros of using DRV134 (or other balanced line driver)
- lower distortion
- better frequency response
- can handle higher source output impedance (e.g. passive preamp)
- much cheaper


Pros of using Transformer
- Better CMRR
- Ground loop isolation

 

[si_jopie0382]

Hi Alexw88,

Jeffry and i will use jensen JT-10KB-DPC for input transformer.

Please let us know if you finished test and measurement
with lundahl

Thanks
Jopie

 

[Pocoyo]

Hi Alexw88,

Jeffry and i will use jensen JT-10KB-DPC for input transformer.

Please let us know if you finished test and measurement
with lundahl

Thanks
Jopie

Build Best PCB for Jensen Transformer
Indonesia want to buy it 4 pcb EXACTLY

Why ? we cant afford JEFF ROWLAND Amp
So Build as good as he build, this another picture
http://www.shine7.com/audio/jeff.htm

 

[Algar_emi]

I'll see what I can do, if it can be done easily, I'll do it.

 

[si_jopie0382]

Drv 134

Dear Algar_emi

for your documentation for BPA 300 driver
some DIYer has make a new thread in

http://www.diyaudio.com/forums/showthread.php?s=&threadid=104608&perpage=10&pagenumber=1

For Jensen PCB, It is very simple
but i will get big headache if i make myself

You can ask your schematic there
and post your Jensen PCB too, of course JRDG

 

[alexw88]

I have done some measurements of the LL1545a :

http://www.shine7.com/audio/LL1545a.htm

 

[tryonziess]

alex88, it looks like the transformer is likely to degrade at very high frequencies regardless of the input impedance. the graph picture leaves of at about 11k. did you get a result at a higher frequency. do you expect the results to change when you add the buffer/driver into the equation. i believe you planned on using a predriver for impedance matching???? how did you choose that particular lundahl model from all of the choices offered. very nice work and thanks

 

[alexw88]

I think the frequency response is flat enough with low source impedance, at <-1dB @ 30kHz I would not worry. This test is only driven with my sound card which has a output impedance of 560ohm. If driven by active preamp or opamp the frequency response should get better.

I chose 1545a because Jeff Rowland used this model and it is not very expensive. (JRDG used LL1545a in Model 201/501 and the Concerto preamp)

I don't have a solid plan yet... but eventually I may build an active preamp and use the LL1545a in the BPA300.

 

[si_jopie0382]

Hi Alexw88,

Are Lundahl deliver a better sound then DRV134?

Thanks

 

[tryonziess]

alex88, do you mind if i ask how much the transformers cost and where you bought them. k and k audio in the u.s wants as much for the lundahl as jensen costs. about 65.00 u.s.

 

[alexcd]

digi01 is selling DRV134 boards 2 for $12. If you ask nicely he may even throw in the driver chips. You can't beat that deal.
http://assemblycraft.com/bld.htm

 

[alexw88]

I have not installed the Lundahl to my BPA300 yet, so I still not listened to them.

The lundahl costs USD 60, and I bought them from
http://www.my3c.net/product/default.asp?gid=192

BTW, I don't find anything wrong with DRV134, it sounds good to me.
Since the DRV134 board and the chip cost very little, may be you can give it a try first.

 

[Algar_emi]

Here an image of my own BPA150 PCB. I used Mundorf coupling cap. I also added some tie-wrap and bitumen vibration pads between the big caps to reduce microphony effect.

 

[alexw88]

Looks good! but would the speaker connector a bit small?