Could be a next project. Looks simple and if I only have one input I don't need an input selector.
Looks as good as it sounds!
so far.......[/QUOTE]
A collective NICE! For all of your pics.
We spent a couple of hours the first night I had mine running putting rubber pads behind pictures because of the bass response is phenomenal. Good to see it, too. I was too lazy to drag all of that stuff out and measure it. Was too busy listening.. : )
so far.......[/QUOTE]
A collective NICE! For all of your pics.
We spent a couple of hours the first night I had mine running putting rubber pads behind pictures because of the bass response is phenomenal. Good to see it, too. I was too lazy to drag all of that stuff out and measure it. Was too busy listening.. : )
The Emotiva Stealth DC-1 DAC gets along very well with these amps. It has both balanced and unbalanced outputs (Level controlled for both).
Hello again friends!
So, I went one more time hunting for heat sinks. The original design description by Mr. Pass (Amp Camp Amp #1) reads:
I can get my hands on this:
http://disti-assets.s3.amazonaws.com/straightroadelectronics/files/datasheets/23768.pdf
Which is rated at 1.4ºC/W, which is about 50% less efficient than what is required in the literature. I was thinking I could put two of them in-line per channel, but they only have 3 in stock.
Is it really not enough or is there a chance that 1.4 may just work? They are sensibly smaller than those pictured in the kit cases, that is for certain.
Thanks for any feedback, best regards,
Rafa.
So, I went one more time hunting for heat sinks. The original design description by Mr. Pass (Amp Camp Amp #1) reads:
I can get my hands on this:
http://disti-assets.s3.amazonaws.com/straightroadelectronics/files/datasheets/23768.pdf
Which is rated at 1.4ºC/W, which is about 50% less efficient than what is required in the literature. I was thinking I could put two of them in-line per channel, but they only have 3 in stock.
Is it really not enough or is there a chance that 1.4 may just work? They are sensibly smaller than those pictured in the kit cases, that is for certain.
Thanks for any feedback, best regards,
Rafa.
How much are they for? Did you try the diyaudiostore site? You can buy same or better sized ones there
40mm Heatsinks – diyAudio Store
40mm Heatsinks – diyAudio Store
Both photos look good. The amp behaves admirably bearing in mind the simplicity, which is its main virtue.
Did you do the measurements with 19V DC or 24V DC?
Can you repeat the measurements with 4 ohms resistor loading?
Thanks,
Nick
Thanks. The ones I have access to are $16 each.
The ones from DIY store are magnificent and oh, so beautiful and perfect. But I live where shipping two of those costs $40 on heat sinks and $46 on shipment.
So 6L6, Jason and people here have been incredibly kind and helpful in counseling me on locally available options.
Perhaps I can somehow make enough area touch the entire chasis so that it can help also with the dissipation?
Thanks once more,
Rafa.
@RafaPolit
If you have problem with shipping to Ecuador may be is good to look for this DIY kit from ebay Hood 1969 Class A Power Amplifier Kit with 1083 Regulator Toshiba 5200 Output | eBay
I tried it and it sounds really great. Not so expensive (only 16,66$ per channel) with free shipping.
If you have problem with shipping to Ecuador may be is good to look for this DIY kit from ebay Hood 1969 Class A Power Amplifier Kit with 1083 Regulator Toshiba 5200 Output | eBay
I tried it and it sounds really great. Not so expensive (only 16,66$ per channel) with free shipping.
I use a Cambridge DAC Magic Plus which also has fixed or adjustable ouput (pre-amp). But I don't know if DAC can output more voltage that I get out in fixed mode. In pre-amp mode it adjusts output in the DSP by multiplying the digital input by a factor (usually < 1). I get better sound by using fixed output and passive pre-amp after DAC. Also when I put my ear close to the tweeter it is 99.99% silent but with DAC as active preamp the tweeter is "only" 97% silent or so......(the "sshhhyyyy" sound).
But I am looking for a DAC upgrade......but DAC Magic Plus was good sound for the money. Maybe a DIY Pass DAC?
I set the lab PSU to 24V DC (think you can see it at one of the previous pictures). I just got the lab PSU (made in China I think.....rigth display not working! ....I am in contact with the seller for a fix....but both PSU channels working).
Yes, I can do 2 x 8.2 ohm in parallel. I put two 50W resistors on an alu rack front plate and put rubber feets under it). Will do it during the comming days. But I can only get 1.9 V out of my generator which seems a bit to low to get full swing at output with the NFB resistors I use (33.2k and 121k).
Attachments
Lab power supply can really be useful when playing around with amplifiers, tone generator, oscilloscope and various loads (capacitive as well!!).
Try to load the amp with 4 ohms, set the voltage to 24V, feed it 1.9V (any frequency, sinewave is good - avoid square waves because they stress the amplifiers unnecessarily...), and then see how the amp behaves when you start changing the current on the laboratory power supply....
Try to load the amp with 4 ohms, set the voltage to 24V, feed it 1.9V (any frequency, sinewave is good - avoid square waves because they stress the amplifiers unnecessarily...), and then see how the amp behaves when you start changing the current on the laboratory power supply....
Ok.....I did a quick test here in the morning before driving to work.
One picture 8.2 ohm the other 4.1 ohm (10 kHz sine, 5V / div). You can see output voltage drops. Bias also drops to about 1.15 A. If I turn down the input signal to zero bias goes up again to approx. 1.4 A. It seems when the amp is cold the bias is a little higher than when it is hot (maybe 0.05 - 0.1 A less bias in hot condition).
One picture 8.2 ohm the other 4.1 ohm (10 kHz sine, 5V / div). You can see output voltage drops. Bias also drops to about 1.15 A. If I turn down the input signal to zero bias goes up again to approx. 1.4 A. It seems when the amp is cold the bias is a little higher than when it is hot (maybe 0.05 - 0.1 A less bias in hot condition).
Attachments
Yes, it could be an option to use shielded cable or maybe twisted shielded cable and the only connect the shield at the input side.
I may have had a bad connection from my signal source as I can't provoke the amp now by touching the input cable / input capacitor. So it is less noise sensitive now.
I may have had a bad connection from my signal source as I can't provoke the amp now by touching the input cable / input capacitor. So it is less noise sensitive now.
Thanks, that looks nice.@RafaPolit
If you have problem with shipping to Ecuador may be is good to look for this DIY kit from ebay Hood 1969 Class A Power Amplifier Kit with 1083 Regulator Toshiba 5200 Output | eBay
I tried it and it sounds really great. Not so expensive (only 16,66$ per channel) with free shipping.
But I will be getting the ACA parts, what I am looking into securing is a suitable case replacement. Thanks for the link anyways.
Rafa.