I upgraded mine too, to Mardone Burl:
An externally hosted image should be here but it was not working when we last tested it.
LM4780 Dual Mono Kit
Peter,
I had recently e-mailed you with some questions and you kindly answered all. I now have a few more but thought I would post here for all to benefit from the answers.
Quote e-mail
"I'm a newbie to all this amp building stuff, so excuse the "dumb" questions. (I've built speakers before.)
If I was to order the LM4780 dual mono kit and wired it up (as in your schematic) as a stereo chip, would this give me 4 channnels of input/output for the kit?
If the above answer is "yes", or even if all I can get from a kit is two channels, would a 300va dual 22v sec be good?"
answer from you "Yes, if you wire it for stereo, you will be getting 4 channels from the kit. Although 300VA transformer should be sufficient, I'd rather go with 400 VA unit (2 x 22V)"
What I plan to do is order three LM4780 Dual Mono Kits so as to have six channels, either bridged or parallel.
Now would I use only one psu per two channels or each channel have one?
Should I use one lrg transformer for all six or one per two channels or one per three channels?
I checked with Plitron and the largest they have with dual 22v sec is 400va but they do have a 1500va with dual 45v which I could hook up in parallel to get 22.5v sec. or a 1000va with dual 24v sec. (I'm thinking one 400va per two channels but it would be less expensive to buy one lrg one)
Now, my speakers are 8 ohm, so I' m guessing that the 24v sec would be okay in a bridged configuration and I could get away with the 1000va 24v sec.
Could you help in the transformer decision?
Dean
Peter,
I had recently e-mailed you with some questions and you kindly answered all. I now have a few more but thought I would post here for all to benefit from the answers.
Quote e-mail
"I'm a newbie to all this amp building stuff, so excuse the "dumb" questions. (I've built speakers before.)
If I was to order the LM4780 dual mono kit and wired it up (as in your schematic) as a stereo chip, would this give me 4 channnels of input/output for the kit?
If the above answer is "yes", or even if all I can get from a kit is two channels, would a 300va dual 22v sec be good?"
answer from you "Yes, if you wire it for stereo, you will be getting 4 channels from the kit. Although 300VA transformer should be sufficient, I'd rather go with 400 VA unit (2 x 22V)"
What I plan to do is order three LM4780 Dual Mono Kits so as to have six channels, either bridged or parallel.
Now would I use only one psu per two channels or each channel have one?
Should I use one lrg transformer for all six or one per two channels or one per three channels?
I checked with Plitron and the largest they have with dual 22v sec is 400va but they do have a 1500va with dual 45v which I could hook up in parallel to get 22.5v sec. or a 1000va with dual 24v sec. (I'm thinking one 400va per two channels but it would be less expensive to buy one lrg one)
Now, my speakers are 8 ohm, so I' m guessing that the 24v sec would be okay in a bridged configuration and I could get away with the 1000va 24v sec.
Could you help in the transformer decision?
Dean
More N00b Questions - SPLs
Hi Peter, I have a friend who has a passion for classical music and also for Black Sabbath.
I am reasonably confident that (with efficient speakers) I could send him your way for one of the amp kits and the SPLs would be satisfactory for the classical bit. However, I'm not so sure about the Black Sabbath bit...
He's got a couple of grand to play with for 'the works' and there's a part of me that's tempted to just have him pickup a vintage Marantz receiver and have it restored, if budget and power are the primary considerations.
So, now that I've blasphemed, I'm hoping that I'll learn something in the process of having my post ripped to pieces.
(I'm sorry if these kinds of questions make you shudder)
Cheers.
Hi Peter, I have a friend who has a passion for classical music and also for Black Sabbath.
I am reasonably confident that (with efficient speakers) I could send him your way for one of the amp kits and the SPLs would be satisfactory for the classical bit. However, I'm not so sure about the Black Sabbath bit...
He's got a couple of grand to play with for 'the works' and there's a part of me that's tempted to just have him pickup a vintage Marantz receiver and have it restored, if budget and power are the primary considerations.
So, now that I've blasphemed, I'm hoping that I'll learn something in the process of having my post ripped to pieces.
(I'm sorry if these kinds of questions make you shudder)
Cheers.
Re: LM4780 Dual Mono Kit
I'm currently using 2 x 22V transformer with bridged amp, but if you read National's datasheet, they actually recommend lower supply voltage for bridged configuration. My chips run very hot when pushed (more than 50 deg heatsink temp).
I never tried large transformer (1000VA or so ) with those amps so it's really hard for me to comment on possible results. The best bet would be using 300-400 VA transformers per 2 channels, especially if you combine two chips in parallel or bridged mode. For bridged, lower voltage supply would be recommended, for parallel, 2 x 24 V is fine.
DeanP said:
I'm currently using 2 x 22V transformer with bridged amp, but if you read National's datasheet, they actually recommend lower supply voltage for bridged configuration. My chips run very hot when pushed (more than 50 deg heatsink temp).
I never tried large transformer (1000VA or so ) with those amps so it's really hard for me to comment on possible results. The best bet would be using 300-400 VA transformers per 2 channels, especially if you combine two chips in parallel or bridged mode. For bridged, lower voltage supply would be recommended, for parallel, 2 x 24 V is fine.
I'm glad to hear that
I just noticed the closing page in 6moons Gaincard review: http://www.6moons.com/audioreviews/47labs5/gaincard_3.html
What seems interesting though, is that Mr. Ebaen points out that Patek in bridged configuration sounds quite favourably now. I've been using my LM3875 based amp in bridged configuration for last 6 months and I actualy prefer it this way; his words below are much in line with my observations:
Go out balanced from a pre into Peter Daniel's XLR-to-two-RCA adapter: presto, two 50-watt stereo chip amps turn 100-watt monoblocks, each with its own dedicated outboard power supply.
When I first acquired the Pateks, I felt that bridging them -- at the time necessitating the Bel Canto PRe2 for its balanced outputs -- overemphasized transients for too much sharpness at the expense of body or harmonic envelope. Perhaps due to further break-in; perhaps due to swapping out preamps for the Music First; perhaps due to different balanced cables (Analysis Plus Solo Crystal vs. Crystal Reference); I now feel differently. What I'm hearing is more meat especially in the midbass power zone, increased dynamic acceleration and a touch more image density, already a key point with the Pateks and chip amps in general.
Employing an unfair advantage is what sports are all about. If genetics made you 7'4", you belong on the basket ball court. The little white guy just has to put up with you and work harder for a goal. The Gaincard even in dual-mono mode was simply outmuscled, overrun and put in second place when I compared the four Canadian boxes in 100-watt bridged mode to the two Japanese cans plus aluminum postcard at 25 watts. The AudioSector quartet played beefier, with more excitement, harder-hitting attacks and, especially in the midbass-to-lower-midrange band, with more wallop and body. The only area where the Gaincard might have held the advantage was in the mid-to-upper treble which seemed more refined yet - still no Emission Labs solid-plate direct-heated 45 triode but a far far cry from transistor chalkiness and arguable more suave than the bridged Pateks which inject just a bit of bite here on occasion.
I just noticed the closing page in 6moons Gaincard review: http://www.6moons.com/audioreviews/47labs5/gaincard_3.html
What seems interesting though, is that Mr. Ebaen points out that Patek in bridged configuration sounds quite favourably now. I've been using my LM3875 based amp in bridged configuration for last 6 months and I actualy prefer it this way; his words below are much in line with my observations:
Go out balanced from a pre into Peter Daniel's XLR-to-two-RCA adapter: presto, two 50-watt stereo chip amps turn 100-watt monoblocks, each with its own dedicated outboard power supply.
When I first acquired the Pateks, I felt that bridging them -- at the time necessitating the Bel Canto PRe2 for its balanced outputs -- overemphasized transients for too much sharpness at the expense of body or harmonic envelope. Perhaps due to further break-in; perhaps due to swapping out preamps for the Music First; perhaps due to different balanced cables (Analysis Plus Solo Crystal vs. Crystal Reference); I now feel differently. What I'm hearing is more meat especially in the midbass power zone, increased dynamic acceleration and a touch more image density, already a key point with the Pateks and chip amps in general.
Employing an unfair advantage is what sports are all about. If genetics made you 7'4", you belong on the basket ball court. The little white guy just has to put up with you and work harder for a goal. The Gaincard even in dual-mono mode was simply outmuscled, overrun and put in second place when I compared the four Canadian boxes in 100-watt bridged mode to the two Japanese cans plus aluminum postcard at 25 watts. The AudioSector quartet played beefier, with more excitement, harder-hitting attacks and, especially in the midbass-to-lower-midrange band, with more wallop and body. The only area where the Gaincard might have held the advantage was in the mid-to-upper treble which seemed more refined yet - still no Emission Labs solid-plate direct-heated 45 triode but a far far cry from transistor chalkiness and arguable more suave than the bridged Pateks which inject just a bit of bite here on occasion.
I'm not sure, but it well may be. Here's some more info on using GC as headphone amp: http://www.diyaudio.com/forums/showthread.php?s=&threadid=62828&highlight=
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