Questions for the Class A gurus! Need advice

DIY_newbie · 4th October 2005, 07:15 PM

Gentlemen,

I have just finished my first DIY speaker project and the results are amazing. I'll be posting some pictures of the completed pair in the loudspeaker forum tonight. I'm running an all active system with a DCX crossover. The drivers are all high efficiency designs Fountek JP2.0 tweeter (98db), PR170m0 midrange (98db) and 2x 12" Poly Paper woofers (93db per, 99db system).

I want to replace the mid and tweeter amplifiers with a Class A design. I don't think I need alot of power since most of the drivers are 98db+. Looking at the threads on the forum I'm thinking Aleph 3, Aleph 30, or maybe even a Pass F1? The amp would need to be able to accept balanced inputs. Any recommendations? Can you use an F1 to driver a speaker directly, I see that in the reviews Mr. Pass supplied custom filter networks to the reviewers.

Thanks in advance,

--Chris

PMA · 4th October 2005, 07:21 PM

Try this one:

http://www.pha.inecnet.cz/macura/follower_e.html

DIY_newbie · 4th October 2005, 09:11 PM

Thats interesting but I think I'll need more gain than that.

I'm leaning towards one of the lower power Alephs or trying my hand at the F1.

This will be my first amplifier project so I'd like to keep it relativly simple, but still achieve excellent results. The F1 in particular looks like a simple schematic that I could wire mostly point-to-point. I think I would probably do the powersupply on a PCB since ground shielding would probably help with noise on the supply. I've been reading Mr. Pass's comments in the F1 service manual about cross overs and which drivers are suitable for these transcoductance amplifiers. I think my mid/tweeter selection will work. I'm using a digital cross over before the amplifiers so the crossover should not be an issue.

Comments apreciated, Thanks!

--Chris

jh6you · 5th October 2005, 01:09 AM

As you say, F1 is easy for the p2p.
And very low noise without requiring any special care.

The sound is wonderful.

Regards
jH

DIY_newbie · 5th October 2005, 01:51 AM

Quote:

Originally posted by jh6you
As you say, F1 is easy for the p2p.
And very low noise without requiring any special care.

The sound is wonderful.

Regards
jH

You've heard one in person? I would love to here your comments on how it sounded. I'm really leaning towards the F1 and trying it out with my midrange. Possible changing to an MTM in order to get somemore efficiency to help with maximum SPL.

My concern is will the sound be affected by the protection cap on the ribbon tweeter? Is it ok to drive a ribbon with this kind of amplifier? Dc offset will kill a ribbon very fast and the documentation states that the amplifier idles at 13.7V DC offset on both outputs.

--Chris

Tweeker · 5th October 2005, 02:03 AM

Quote:

The outputs of the amplifier are balanced, and operate at a 13.8 Volt DC potential above ground, just like your car battery. Don't worry, the speaker sees only the difference between them, and not the DC, but don't expect the amplifier to operate properly if you attach either output to ground.

Its floating above ground, there should be very little DC current. They are both at 13.8V, no offset.

jh6you · 5th October 2005, 02:53 AM

Quote:

Originally posted by DIY_newbie

You've heard one in person? I would love to here your comments on how it sounded.

Click here

Regards
jH

DIY_newbie · 5th October 2005, 05:14 AM

Read through your comments on the F1.. sounds like a good first project. I'm still hoping someone chimes in with their experience with both Aleph and F1 amplifiers? Probably unlikely that someone would have built/heard both?

Best Regards,

--Chris

jh6you · 5th October 2005, 07:46 AM

I think only Nelson could answer your question, but he will never do it.

Good luck!

Regards
jH

djk · 5th October 2005, 08:56 AM

Are you going to do anything with the DCX?

The 4560 is a pretty good opamp for $0.13, but not up to the quality of the other items you are talking about. Did I mention there are 17 of these things in the I/O of the DCX?

Oh, and 15 polarized electrolytics too?

4th October 2005, 07:15 PM	#1
DIY_newbie diyAudio Member Join Date: May 2004 Location: Dallas, TX	Questions for the Class A gurus! Need advice Gentlemen, I have just finished my first DIY speaker project and the results are amazing. I'll be posting some pictures of the completed pair in the loudspeaker forum tonight. I'm running an all active system with a DCX crossover. The drivers are all high efficiency designs Fountek JP2.0 tweeter (98db), PR170m0 midrange (98db) and 2x 12" Poly Paper woofers (93db per, 99db system). I want to replace the mid and tweeter amplifiers with a Class A design. I don't think I need alot of power since most of the drivers are 98db+. Looking at the threads on the forum I'm thinking Aleph 3, Aleph 30, or maybe even a Pass F1? The amp would need to be able to accept balanced inputs. Any recommendations? Can you use an F1 to driver a speaker directly, I see that in the reviews Mr. Pass supplied custom filter networks to the reviewers. Thanks in advance, --Chris

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Need Advice from Amp Gurus	Juke425	Class D	5	28th July 2008 03:20 AM
Need advice from the analog gurus	davidlzimmer	Analogue Source	21	23rd July 2007 11:23 AM
Need the gurus advice on sub	undertoe	Multi-Way	18	16th December 2003 12:05 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

4th October 2005, 07:21 PM	#2
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Try this one: http://www.pha.inecnet.cz/macura/follower_e.html

4th October 2005, 09:11 PM	#3
DIY_newbie diyAudio Member Join Date: May 2004 Location: Dallas, TX	Thats interesting but I think I'll need more gain than that. I'm leaning towards one of the lower power Alephs or trying my hand at the F1. This will be my first amplifier project so I'd like to keep it relativly simple, but still achieve excellent results. The F1 in particular looks like a simple schematic that I could wire mostly point-to-point. I think I would probably do the powersupply on a PCB since ground shielding would probably help with noise on the supply. I've been reading Mr. Pass's comments in the F1 service manual about cross overs and which drivers are suitable for these transcoductance amplifiers. I think my mid/tweeter selection will work. I'm using a digital cross over before the amplifiers so the crossover should not be an issue. Comments apreciated, Thanks! --Chris

5th October 2005, 01:09 AM	#4
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	As you say, F1 is easy for the p2p. And very low noise without requiring any special care. The sound is wonderful. Regards jH

5th October 2005, 05:14 AM	#8
DIY_newbie diyAudio Member Join Date: May 2004 Location: Dallas, TX	Read through your comments on the F1.. sounds like a good first project. I'm still hoping someone chimes in with their experience with both Aleph and F1 amplifiers? Probably unlikely that someone would have built/heard both? Best Regards, --Chris

5th October 2005, 07:46 AM	#9
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	I think only Nelson could answer your question, but he will never do it. Good luck! Regards jH

5th October 2005, 08:56 AM	#10
djk diyAudio Member Join Date: Feb 2001 Location: USA	Are you going to do anything with the DCX? The 4560 is a pretty good opamp for $0.13, but not up to the quality of the other items you are talking about. Did I mention there are 17 of these things in the I/O of the DCX? Oh, and 15 polarized electrolytics too?