Hi Guys, newbie here.
I’m in the process of constructing a pair of Amp Camp amps because I’ve been without decent audio equipment for far too long. Cost is a big consideration right now, so I’m ordering and building as my budget allows. I’m currently waiting for custom PCB’s that I designed in KiCad and the heatsinks are on their way too. Next will be the actual components and case.
In the meantime I’m considering my options w.r.t. a preamp. So far, I’ve looked at the following:
Or the DIY X29F Single-ended DC Class A preamplifier kit stereo preamp kit.
What really bothers me is that I don’t know what specs to look for in a preamp. I have read that an output of about 3V is required to drive the ACA’s to full power, but very few spec sheets give output voltage. I’ve seen the O2, B1 and BOZ being recommended for use with the Amp Camps.
This is really a difficult decision for me. Obviously, I need something that would do the new amps justice, but without breaking the bank or being a major construction project.
Any guidance and/or recommendations will be appreciated.
I’m in the process of constructing a pair of Amp Camp amps because I’ve been without decent audio equipment for far too long. Cost is a big consideration right now, so I’m ordering and building as my budget allows. I’m currently waiting for custom PCB’s that I designed in KiCad and the heatsinks are on their way too. Next will be the actual components and case.
In the meantime I’m considering my options w.r.t. a preamp. So far, I’ve looked at the following:
Objective2 Headphone preamp
Bride of Zen
Doug Self preamp
New PASS preamp
All are relatively complicated (and maybe too expensive) as a first build. Therefore I’m leaning towards a quick and dirty solution for now. Maybe something simple off eBay, like the LME49720+Shield+ALPS Potentiometer stereo preamplifier kit. Bride of Zen
Doug Self preamp
New PASS preamp
Or the DIY X29F Single-ended DC Class A preamplifier kit stereo preamp kit.
What really bothers me is that I don’t know what specs to look for in a preamp. I have read that an output of about 3V is required to drive the ACA’s to full power, but very few spec sheets give output voltage. I’ve seen the O2, B1 and BOZ being recommended for use with the Amp Camps.
This is really a difficult decision for me. Obviously, I need something that would do the new amps justice, but without breaking the bank or being a major construction project.
Any guidance and/or recommendations will be appreciated.
I used Gregg-the-Geeks MooseFET with the Amp Camps & i was thrilled with the performance.
http://classicvalve.ca/docs/MooseFET_docs_v1.pdf
dave
http://classicvalve.ca/docs/MooseFET_docs_v1.pdf
dave
This is not correct.
The ACA has 14dB of gain, 1.7V peak at the input of the ACA will have the amp clipping.
A buffer preamp is the most sensible choice if you are using cd/dac.
Try with just a Buffer instead of a pre-amplifier.
Add the Buffer after the vol pot and then run the buffer output cable to the power amplifiers.
You may find that you get sufficient volume for all except a drunken party night.
Buffers can be ultra cheap (at least at this testing stage) by using a unity gain dual opamp or two PassB1 channels.
Don't add on a case/ enclosure until after you know what you finally need.
Add the Buffer after the vol pot and then run the buffer output cable to the power amplifiers.
You may find that you get sufficient volume for all except a drunken party night.
Buffers can be ultra cheap (at least at this testing stage) by using a unity gain dual opamp or two PassB1 channels.
Don't add on a case/ enclosure until after you know what you finally need.
Thanks Dave, I'll have a gander. Your website is very interesting, btw. I found the speaker information particularly useful, since I still also have to get those. I'm leaning towards Tang Band 5" full range drivers in TL enclosures - DIY of course.
Christo
Thanks 2picoDumbs. All info is greatly appreciated by me. The source will mainly be a dedicated PC playing flac files (for now at least).
Christo
Ah, ok. I should have mentioned that the mentioned 3V is for both channels. It's just the way my source put it. What you're saying ties up nicely with the 1.5V per channel that I read about.
I still have to make the connection between dB and the input sensitivity of an amp. Electronics, and audio in particular, has not been my field of expertise. But I'm learning fast...
Christo
Ah, ok.
I still have to make the connection between dB and the input sensitivity of an amp. Electronics, and audio in particular, has not been my field of expertise. But I'm learning fast...
Christo
Amp starts clipping around 8V peak ÷ by gain of 5.
8 ÷ 5 = 1.6V peak input
Man... this is the kind of information I'm after, Thank you so much!
Stuff like "unity gain dual opamp"is way over my head, but like I said in a previous post, I'm learning fast! And I might just be able to extract and use "two Pass B1 channels", although a diagram would be much easier to work from.
Christo
Nice! Thanks Koja, more options.
So, according to my newly discovered dB calculator, 8dB = 2.51 voltage gain and 6.31 times the power. Dang! I think I'm getting the hang of it now.
Christo
AmpCampAmp & TangBand???
@Skylar88
You should keep in mind that those speakers have low efficiency 90dB or less.
So with ACA you might not reach desired listening levels. With a preamp you will only drive into distortion.
Check needed voltage for your speakers (there's a thread somewhere here).
cheers
A.
@Skylar88
You should keep in mind that those speakers have low efficiency 90dB or less.
So with ACA you might not reach desired listening levels. With a preamp you will only drive into distortion.
Check needed voltage for your speakers (there's a thread somewhere here).
cheers
A.
Thanks, you guys are great! Without your help it would surely have been a disaster.
So, if I might ask, what kind and size drivers should I be looking at for a good listening experience in a medium sized lounge? I just want to enjoy good quality HiFi sound at decent levels. It's not for parties at all. That's not my style!
From what I've read, the ACA's is powerful enough for my need.
Christo
So, if I might ask, what kind and size drivers should I be looking at for a good listening experience in a medium sized lounge? I just want to enjoy good quality HiFi sound at decent levels. It's not for parties at all. That's not my style!
From what I've read, the ACA's is powerful enough for my need.
Christo
the now unfashionable 8" mid bass and 1" treble does nicely.
It was designed to be cheap but still gives very acceptable performance.
You can go down to a 5" or 6" mid bass, but this limits the low bass too much for many. However it may give a cleaner upper mid and a nicer cross from mid to treble.
That could be enough to make it seem better than an 8".
If you go for a reasonably efficient 6"+1" because you like the upper bass, mid and treble, you can at some later date add in a low bass only speaker and amplifier.
It was designed to be cheap but still gives very acceptable performance.
You can go down to a 5" or 6" mid bass, but this limits the low bass too much for many. However it may give a cleaner upper mid and a nicer cross from mid to treble.
That could be enough to make it seem better than an 8".
If you go for a reasonably efficient 6"+1" because you like the upper bass, mid and treble, you can at some later date add in a low bass only speaker and amplifier.
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