mono amps

audfile74

Member
2008-01-29 8:13 am
i have been curious about chip amps for a minute and i was wondering if there was a kit maker out there that has a front to back mono,not bridged stereo, design. i'd like to do a pair of mono amps . what type of power can i expect in comparison to a regular stereo setup?
 
I believe that monobloc amplifiers can potentially provide for additional dynamics.

Readily available mono "power amplifier" kits include, audiosector.com, chipamp.com, k50, and k106. There are more. You can find those with a search.

Perhaps Andrew will happen along and suggest the location(s) of readily available preamplifier kits? (hint) That would be great. ;)
 

audfile74

Member
2008-01-29 8:13 am
hi guys, i just got in from work. i took a look at the audiosector ssite and from what i caould see , his setup starts out as a stereo amp. i may be mistaken. i don't want to have to bridge to get mono. i want to go mono from the beginning. any suggestions? if you could please post links to sites. as far as volume control,i want to use the nht passive volume control for starts i may feel the need for dact at a later date.
 
That's altogether very interesting.

The link leads to a remarkably expensive potentiometer. Normally, I'd pay about $1. The challenge of quality on the item in the link isn't difficult because its 4.7k--not much in the way of audio signals because it doesn't do much (unless you use the XLR version).
However, that item comes with a slight risk, that if the source device has a capacitor (dc block role) at the output, then bass response could be insufficient, due to the unusual load.
Reference: Spec for line level is 10k, and I'd rather see 20k, just in case.

Suggestion: Instead of any sort of passive preamplifier, use those funds for the recommended preamplifier that fits, "known good" with your power amplifier modules of choice.

Suggestion: On shopping for power amplifier module kits, check out "monobloc" and "dual mono" configurations because those seem to fit with your description.
Reference: Check for reliance on preamplifiers, because "may be operated without" doesn't mean optimal results without an active buffer/active preamplifier. This occurs whenever the power amplifier module has already been engineered to operate optimially along with a active preamplifier--as an expected parameter.
Reference: You can find details on satisfying preamplifier-poweramp options (creates a complete amplifier) here at diyaudio.com with the search. There are many options.

Suggestion: If PA use or hearing damage isn't required, then you might want to widen the scope of the shopping to include LM1875, which in maximum sensible configuration produces only 30 watts--yet it is known to do so in high fidelity without a preamp, and still gives fierce driver control along with good dynamics. Its a "soft clip" style and it does operate 4 ohm drivers if you wish. Although it may miss the mark on your power requirements, it does accomodate your choice of potentiometer/passive preamp, as listed in the link above.

If these answers sound a bit odd, its because my writing skills are terrible and because I don't know the exact application for which to match up an amplifier. So, its going to make a lot more sense (no guarantee whatsoever) if you mention the application. ;)
What kind of music do you prefer? Is this for home theatre? Will it be operated without eq (quite difficult for popular music)? What is the nature, size, efficiency of the speakers? Are party volume levels expected? Is there a ready comparison point for this new project?

Hey, and, have fun!
 

leadbelly

Disabled Account
2002-12-22 2:13 am
Calgary, Alberta
audfile74 said:
i took a look at the audiosector ssite and from what i caould see , his setup starts out as a stereo amp. i may be mistaken. i don't want to have to bridge to get mono. i want to go mono from the beginning.

The LM3875 "setup" on Audiosector is dual mono, no bridging (although I don't understand your mysterious aversion to bridging). You can also get LM3886 dual mono boards/kits from chipamp.com.
 

CarlosT

Member
2006-10-20 6:00 pm
The LM3875 amp from Audiosector is a mono amp in that the PCB is pre-scored to be split into two mono sections. This is an excellent board if you're not combining channels which it sounds like you're not.

The rectifier section is also pre-scored and can be detached which is handy.
 

audfile74

Member
2008-01-29 8:13 am
thanks for the response daniel, that makes things clearer.i thnk the 4780 will work best for me.

i am a lowlevel beginner but i have a clear sense of what i want. murphy's law , there is probably not a kit that matches my ideas

also, i want to find a board that is designed as a one peice, not prescored

the audiosector kit uses 1 4780,is their a kit out there that uses 2 4780 per channel, and, has boards for individual channels?? if so, can some one post a link?

it may seem amateur of me but i think that a circuit that is designed to run mono from the start should have advantages over a bridged design due to reduced parts count, if designed as such, and less phase issues.bridging seems to add parts. just a preferance and opinions that's all.

another question. can the 4780 be used like a regular amp circuit in the sense that you have multiples of the same circuit in order to increase the power: example 2 4780 = 4 3886

i hope i am not lokking too stupid. i'm learning slowly and you all are makingme think.thanks for your patience
 
audfile74 said:
thanks for the response daniel, that makes things clearer.i thnk the 4780 will work best for me.

i am a lowlevel beginner but i have a clear sense of what i want. murphy's law , there is probably not a kit that matches my ideas

also, i want to find a board that is designed as a one peice, not prescored

the audiosector kit uses 1 4780,is their a kit out there that uses 2 4780 per channel, and, has boards for individual channels?? if so, can some one post a link?

it may seem amateur of me but i think that a circuit that is designed to run mono from the start should have advantages over a bridged design due to reduced parts count, if designed as such, and less phase issues.bridging seems to add parts. just a preferance and opinions that's all.

another question. can the 4780 be used like a regular amp circuit in the sense that you have multiples of the same circuit in order to increase the power: example 2 4780 = 4 3886

i hope i am not lokking too stupid. i'm learning slowly and you all are makingme think.thanks for your patience

The LM4780 kit from AudioSector can be used as a stereo kit.
Two can be used paralled, as monoblocs. This isn't a bridge configuration. See the documentation at AudioSector.com.

For thermal management, the technique mentioned in National Semiconductor AN1192.pdf is often done with the LM3886 chip, because of the opportunity to spread heat over a larger area.

Other topic:
I don't know why you're allergic to bridged, though. The most award winning amplifier in recent history, Sonic's little "T" amplifier, is a BTL type.
When done well, bridge application may have firmer driver control than the same amplifier used solo.
When not done well, extra driver control may only be exibited at low frequencies, leaving the midrange with less dampening that appears as a compression artifact (frequency density at midrange is annoying to ears) when observed in comparison with the total audio band.
I had to guess that this may be the error that you speak of. That issue isn't much different between a bridged or solo amplifier; however, the opportunity for greater dampening of bridge also brings with it the opportunity for a larger error in application.
It all depends on the amplifier and its application.
 
audfile74 said:
i have been curious about chip amps for a minute and i was wondering if there was a kit maker out there that has a front to back mono,not bridged stereo, design. i'd like to do a pair of mono amps . what type of power can i expect in comparison to a regular stereo setup?

The LM3875 and LM3886 can only be made in mono. A mono board looks like that: http://audiosector.com/images/lm3875pcb01.jpg
The kit contains two such boards and they can be used in separate enclosures (for dual mono)
http://www.diyaudio.com/forums/showthread.php?postid=584425#post584425

LM4780 can be also configured in stereo and the options have been explained here: http://www.diyaudio.com/forums/showthread.php?postid=636565#post636565
 

CarlosT

Member
2006-10-20 6:00 pm
I like the simplicity of the 3875 chip and I would not be afraid of the pre-scored splittable PCB issue with Audiosector's offerings. Peter makes a kicka** LM3875 board...very high quallity traces and layout and very compact. Unfortunately, I wasn't able to use it because I needed an inverting amp but I still used his rectifier board from the kit and other parts as well.