Must admit I am intrigued by the bare case that is offered.
I have long wanted to convert my J2 to dual mono.
Dear Mr. Pass, any chance you would sell a bare case to a J2 owner?
AS far as the completed amps: I have a feeling it would be like buying a new LOTUS car of the 60's to 70's vintage - they were considered kit cars assembled for easier shipping. I bet you would need to go through and re-do all of the solder connections.
Better than a fake ROLEX but just as unsatisfying to own something that you know is a fake and of questionable (at best) provenance.
Which brings to mind that great Orson Welles movie F FOR FAKE, something everyone should watch, especially those involved in the art world.
I have long wanted to convert my J2 to dual mono.
Dear Mr. Pass, any chance you would sell a bare case to a J2 owner?
AS far as the completed amps: I have a feeling it would be like buying a new LOTUS car of the 60's to 70's vintage - they were considered kit cars assembled for easier shipping. I bet you would need to go through and re-do all of the solder connections.
Better than a fake ROLEX but just as unsatisfying to own something that you know is a fake and of questionable (at best) provenance.
Which brings to mind that great Orson Welles movie F FOR FAKE, something everyone should watch, especially those involved in the art world.
If that is not possible for Papa and you are rich
, there is a guy that purchased two stereo J2 amps and he runs each amp parrallel mono. He says it's the best amp he's heard period in that configuration.
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That is an intriguing idea, though I would need counsel on how to do it.
It would be a little easier to do here, as far as the money, RENO HIFI always seems to have a used one for sale, not that they are giving them away but I know by the time they get to your part of the world the price is likely doubled.
Something to consider since I know my system is set - J2 for below 500 hz and SIT 1s above and no desire to make any changes.
Your suggestion just might be one I should take.
It would be a little easier to do here, as far as the money, RENO HIFI always seems to have a used one for sale, not that they are giving them away but I know by the time they get to your part of the world the price is likely doubled.
Something to consider since I know my system is set - J2 for below 500 hz and SIT 1s above and no desire to make any changes.
Your suggestion just might be one I should take.
It's not extra power. It's extra current capabilty (higher power into 4 Ohms) into reactive loads and better damping plus you get mono blocks but maybe you don't need that.
If you can wire up a J2 channel into a new chassis with new power supply etc, you're certainly capable of converting a stereo amp into parrallel mono. It wouldn't take longer than 30 minutes to set it up.
If you can wire up a J2 channel into a new chassis with new power supply etc, you're certainly capable of converting a stereo amp into parrallel mono. It wouldn't take longer than 30 minutes to set it up.
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One project would be physically more difficult while the bridge conversion would require knowledge I do not have. I can put together a duplicate power supply without much mental effort. Not that I mind having to think about something but I do not want to destroy the amplifier! I know I am perfectly capable of that.
I would need some kind of phase splitter on the input. From what I read there can be problems with bridging amplifiers with feedback and the J2 does use feedback.
I looked around and saw articles on using a transformer on the input or an active circuit. I would tend to gravitate towards the transformer since that seems easier. I do not pretend to have any business designing circuits. For something like this I am a "color by numbers" DIYer.
Is the feedback concern something I might have trouble with? is this overstated?
If you come across the article you mention please point me towards it. I searched and found nothing. I looked through many F4 posts and its owner's manual and saw nothing that enlightened me.
I am starting from less than zero!
I would need some kind of phase splitter on the input. From what I read there can be problems with bridging amplifiers with feedback and the J2 does use feedback.
I looked around and saw articles on using a transformer on the input or an active circuit. I would tend to gravitate towards the transformer since that seems easier. I do not pretend to have any business designing circuits. For something like this I am a "color by numbers" DIYer.
Is the feedback concern something I might have trouble with? is this overstated?
If you come across the article you mention please point me towards it. I searched and found nothing. I looked through many F4 posts and its owner's manual and saw nothing that enlightened me.
I am starting from less than zero!
Unfortunately no. Idss to order is not feasible. The quantities of unsorted LS devices made available to the store is not enough to have multiple SKU for more Idss range. And it wold incur a considerable premium in cost, making a possibly unattractive retail price.
I've use both and can't tell any difference in the finished product.
BL spans 6.0mA-12mA Idss. The LS devices currently in the store are fairly evenly distributed from 6.0-10.6, as my sorting rig didn't go higher and I haven't sorted the remainders. There is almost nothing past 11.5.
The bulk of the matched LS jfets in the store are in the sweet spot of 6-10, a value where they will work beautifully in any of the Firstwatt amps.
you're too humble .... knowing your setup a little .......
what picowakoododo implied is not "regular" bridging (where two halves/channels of amp are working antiphase , and load/speaker is connected to two hots, floating ref. to gnd) but simple paralleling of two channels
please - refresh my memory about your entire setup ( pics are always welcome , being boyz-porn is irresistible) ; as far I remember , you really don't need more "plain" power - meaning you don't need more voltage swing for your bass speakers (which bridging gives ) , but you can possibly benefit from more amps/current ...... which paralleling two channels in one will give
find enclosed (somewhat edited) adequate figure from F4 user/service manual (p9), applicable for possible paralleling of J2
feel free to ask whatever you want .... but more info about your speakers will certainly give us more clue ...... however - if you have buddy with J2 , paralleling test is easy - just cables .....
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WELL,
I am the master of turning the simple into the complicated.
I guess I saw those drawings and just did not think it through. I thought I was seeing an arrangement of op-amps instead of symbols for the amplifiers themselves.
But, ZM, do you approve of this arrangement? I am happy with what I am getting from the single J2, but being thoroughly afflicted with this disease I am hoping for something even better, if possible. Which approach would you guess as the better approach - conversion to monos or paralleling for monos?
System set up - I am in digital mode at the moment - the extraordinary SDTrans384 to a heavily modded SOEKRIS DAC which directly drives the amps (SIT1/J2/and two old YAMAHA crossovers (which use PCM33s) for crossing at 100 hz, works very well. Speakers - JBL2440/Inlow papier mache horn/Inlow designed round horn/B&C 12 driver/Fostex 500s/Edgar SEISMIC Subs/DIY cabinet RYTHMIC servo subs for below 40 hz.
The SD card player is the way to go for digital. At this point I prefer it to the turntable and had just installed a TRANSFIGURATION Proteus - no slouch, and I swear the tonal balance and tone from the digital is superior. I am still shaking my head in disbelief. Of course, all of this stuff has been tinkered with. Can't allow idle hands ...
As usual I have no photographs - you've seen my ability. I will take some pictures of the setup this weekend and send them to you. I must admit I think I am getting some interesting sound, as Roman Besnow would put it.
I am the master of turning the simple into the complicated.
I guess I saw those drawings and just did not think it through. I thought I was seeing an arrangement of op-amps instead of symbols for the amplifiers themselves.
But, ZM, do you approve of this arrangement? I am happy with what I am getting from the single J2, but being thoroughly afflicted with this disease I am hoping for something even better, if possible. Which approach would you guess as the better approach - conversion to monos or paralleling for monos?
System set up - I am in digital mode at the moment - the extraordinary SDTrans384 to a heavily modded SOEKRIS DAC which directly drives the amps (SIT1/J2/and two old YAMAHA crossovers (which use PCM33s) for crossing at 100 hz, works very well. Speakers - JBL2440/Inlow papier mache horn/Inlow designed round horn/B&C 12 driver/Fostex 500s/Edgar SEISMIC Subs/DIY cabinet RYTHMIC servo subs for below 40 hz.
The SD card player is the way to go for digital. At this point I prefer it to the turntable and had just installed a TRANSFIGURATION Proteus - no slouch, and I swear the tonal balance and tone from the digital is superior. I am still shaking my head in disbelief. Of course, all of this stuff has been tinkered with. Can't allow idle hands ...
As usual I have no photographs - you've seen my ability. I will take some pictures of the setup this weekend and send them to you. I must admit I think I am getting some interesting sound, as Roman Besnow would put it.
This is why I continue with fetaudio as long as they have Toshiba. I can get idss I want, cheap price even with delivery from Hong Kong. I know they wont last forever, but while they are there why not.
There will come a day in the not too distant future that the Toshibas will be gone. Thank goodness for the linear units in the Diystore!
Russellc
No, it doesn't. In the F6 both devices are part of the same loop, not
separated out as with the mu followers.
I'm not prepared to go into that business, being that it would require more
time and energy, the supply of which is short.
I'm not prepared to go into that business, being that it would require more
time and energy, the supply of which is short.
I would have been surprised if you said, "OK"!
Since I am considering paralleling two J2s instead would you care to give your opinion on that?
Thanks and take care,
from technical point of view - nothing wrong with paralleling ...... even if there is some one step back , two step forward logic at hand - there will always be some "smearing" of details when paralleling two of same active elements - be it just one transistor or entire amplification stage;
that would be one step back
measure of two steps forward is exactly in correlation with loading burden/demands - if load is easy - no benefit of headroom achieved by paralleling ........ if load is harder - measure of benefit is rising
so , in this case ( as in many others ) only your ears can decide
as I said - certainly least costly way of deciding is if someone near you is having J2 , to bring it for paralleling trial
cheapest one at RenoHiFi is around 2K3 Greenies ..... and I'm too much of a cheapskate to even think of buying one
hey - one day when I win a lottery ( first I need to learn how to , let alone to start buying tickets
) ..... I'll buy Ongaku and smaller XS-essssssjust to have them around , as Kudos
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Thanks, AP.
I certainly am not experiencing any sound of strain driving the loudspeakers with the single J2 and that possibility of smearing is a concern - as you say, anytime you parallel devices. Maybe if I got lucky and could obtain two amplifiers that were EXACTLY the same ..., which is not possible.
I am not one for buying back ups. When, and if, the J2 expires before I do, I bet my hearing will have degraded to the point where I could get by with anything.
I will probably (with shame) get that fellow's case and mono-fy my J2s. I detect a little bit of noise which I have attributed to the one stereo component in my system, well, in the important part of the system.
While I am displaying my heresies I should mention that I drive the SEISMICs with a CREST class D amplifier, the dolled up version of the Peavey amplifier, and have to report this thing, in this position, has everything you could want from an amplifier. It actually has tonal quality, it's not a sine wave generator. Cheap it is. Once one replaces the howling fan with something quieter it is damned good for sub duty. Best I have tried which doesn't mean a whole lot. But I did use the J2 there for awhile. It sounded good, of course, but was "limited in its dynamic expression", to quote one of my favorite audio writers, Herb Reichert, when he wrote for SOUND PRACTICES (about QUAD 57s).
As always your opinion is one I know I can trust. Thanks.
I certainly am not experiencing any sound of strain driving the loudspeakers with the single J2 and that possibility of smearing is a concern - as you say, anytime you parallel devices. Maybe if I got lucky and could obtain two amplifiers that were EXACTLY the same ..., which is not possible.
I am not one for buying back ups. When, and if, the J2 expires before I do, I bet my hearing will have degraded to the point where I could get by with anything.
I will probably (with shame) get that fellow's case and mono-fy my J2s. I detect a little bit of noise which I have attributed to the one stereo component in my system, well, in the important part of the system.
While I am displaying my heresies I should mention that I drive the SEISMICs with a CREST class D amplifier, the dolled up version of the Peavey amplifier, and have to report this thing, in this position, has everything you could want from an amplifier. It actually has tonal quality, it's not a sine wave generator. Cheap it is. Once one replaces the howling fan with something quieter it is damned good for sub duty. Best I have tried which doesn't mean a whole lot. But I did use the J2 there for awhile. It sounded good, of course, but was "limited in its dynamic expression", to quote one of my favorite audio writers, Herb Reichert, when he wrote for SOUND PRACTICES (about QUAD 57s).
As always your opinion is one I know I can trust. Thanks.
I have wondered the same thing, but then Nelson built his beast of 1000 jfets and he obviously likes it so I am starting to think this smearing concern with paralleling devices maybe a storm in a tea cup.
If you're speakers are better than 93dB I wouldn't bother with paralleling but if you want mono blocks the simplest way would be to buy a second hand J2.
Then once you've purchased them you can try one channel in each amp for conventional dual mono and then compare with dual parallel mono. Then just run it the way you think it sounds best. Just cause you have the two amps doesn't mean you have to do parallel mono you can just run conventional dual mono.