Analog frontend
If you look at offical reference board analog input pins of frontend board here above bypass NE5532 couples.
Sure it doest have big advantage over NE5532 but its possible to add gain in this board whicich is lack a bit due to feedback. One more improvement could be OPA1656 which is fet input and could be better than opa1612.
If you look at offical reference board analog input pins of frontend board here above bypass NE5532 couples.
Sure it doest have big advantage over NE5532 but its possible to add gain in this board whicich is lack a bit due to feedback. One more improvement could be OPA1656 which is fet input and could be better than opa1612.
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I’ve been listening to my board for the last 3 weeks almost. I go from my traktor s8 straight into the board using the xlr output. My iPhone is connected to the USB input of the S8. The board is powered buy a huge laptop brick 19.5V 16.9A into a dc-dc converter set at 50v output. The board output is going in my Ergo-IX bookshelf speakers on stands.
When I put my ears right against the tweeter I hear a very faint hiss which I can’t hear anymore as soon as I move a couple of inches away.
To me it sounds very good with tons of details and a good amount of bass. I’m very satisfied.
I’m now waiting for the connex smps 600W. I placed the order almost a month ago, I really hope I’ll get it soon so I can start working on the box.
I hope everyone is having great experience too.
When I put my ears right against the tweeter I hear a very faint hiss which I can’t hear anymore as soon as I move a couple of inches away.
To me it sounds very good with tons of details and a good amount of bass. I’m very satisfied.
I’m now waiting for the connex smps 600W. I placed the order almost a month ago, I really hope I’ll get it soon so I can start working on the box.
I hope everyone is having great experience too.
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Thanks XRK, they are the scanspeak 15w8530k01 for acoustic suspension design. I bought them second hand for 1/2 the price and built the speakers based on Jame’s design from pinkfishmedia.net (Ergo-IX) with the 1.125” Morel soft dome horn tweeter CAT378. I’m very very satisfied with those speakers, acoustic suspension is my favourite sound signature.
One other comment about the board, in my case with a decent heat-sink, the power brick, and the dc-dc converter in a small listening room it does not get warm at all.
One other comment about the board, in my case with a decent heat-sink, the power brick, and the dc-dc converter in a small listening room it does not get warm at all.
Things are slow to move out of Hong Kong lately. Due to a 3rd spike of Covid-19 there recently, shipping has slowed to a crawl. I'm tracking a package from Connex that sat in a staging warehouse there for 3 weeks. It finally got processed and sent to DHL last week. Now they seem to be sitting on it too.
That order was placed in April! But in fairness, Connex was doing a custom build for me, and a redesign was involved. Even normally, Connex builds to order I believe, so things take longer to process, as the products are not off the shelf.
Forward progress seems to be slow everywhere still due to C-19. Maybe the parcel will arrive before August! Patience is a virtue nowadays coping with C-19.
Report back when yours arrive.
TPA3255 Chassis Progress
Now that my panels have arrived, I thought I would share a few 'motivational' pics of my 3255 build. Still have a bit more wiring to complete and minor drilling for LEDs on the front panel. Enjoy. Will post more when it's completed and ready to properly 'show'.
Now that my panels have arrived, I thought I would share a few 'motivational' pics of my 3255 build. Still have a bit more wiring to complete and minor drilling for LEDs on the front panel. Enjoy. Will post more when it's completed and ready to properly 'show'.
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Thanks Vunce. It's a modushop chassis, the same model as the Yarra pre. I chose it by intent, because I want to use them as a matching pair. I design the cutting and engraving using the Front Panel Express software and send the panels off to them in WA. That's why it looks so professional. They really produce top-notch results. It does add some extra cost to the project, but I prefer an extra level of 'look' to my builds.
In a couple days I should have the finished product and will do a full reveal.
In a couple days I should have the finished product and will do a full reveal.
Hey guys
Read this entire thread, and now my questions.
I’m looking to build a new home theater amp to replace a really, really old NAD.
I need 3 channels to drive my left, right and center speakers, the main ones in this setup.
Wondering how SE output sounds vs BTL? Would be great if I could use just one module configured for SE vs two in BTL. Since this is for a HT movie only system, I don’t need the best, really good will do. Looking for good dynamics and clear vocals.
I have a Rythmik sub that handles the low end, so not concerned below 50 hz.
Will have some more questions, depending on the answer to this. I'm leaning to building a SE, 4 ch amp using this board. But I could possibly be talked into BTL. With any luck, will be using this for my HT for many years, so want to do it right once and just enjoy it.
Thanks
Randy
Read this entire thread, and now my questions.
I’m looking to build a new home theater amp to replace a really, really old NAD.
I need 3 channels to drive my left, right and center speakers, the main ones in this setup.
Wondering how SE output sounds vs BTL? Would be great if I could use just one module configured for SE vs two in BTL. Since this is for a HT movie only system, I don’t need the best, really good will do. Looking for good dynamics and clear vocals.
I have a Rythmik sub that handles the low end, so not concerned below 50 hz.
Will have some more questions, depending on the answer to this. I'm leaning to building a SE, 4 ch amp using this board. But I could possibly be talked into BTL. With any luck, will be using this for my HT for many years, so want to do it right once and just enjoy it.
Thanks
Randy
If you don’t need to drive difficult 4ohm loads and lower power (60w or less), the 4 ch SE output is fine. It is cap coupled output and some people don’t like that. Cap coupled is fine sounding to me. You need to read the TI EVM app note and find out how to reconnect the jumpers on the front end to be SE output. You need to change the DIP switch settings and add four large electrolytic caps on the output.
Thanks for that.
Made me look at the 3255 data sheet and evm manual.
EVM manual says for SE, connect speaker of 2-4 ohm. Hmm
Then looked at data sheet, it only shows test conditions for 2,3 and 4 ohm for SE and PBTL.
For BTL, it shows 4, 6 and 8.
Seems like TI is telling me if I want to use the 3255 with my 8 ohm speaker, I should run in BTL mode.
Randy
Made me look at the 3255 data sheet and evm manual.
EVM manual says for SE, connect speaker of 2-4 ohm. Hmm
Then looked at data sheet, it only shows test conditions for 2,3 and 4 ohm for SE and PBTL.
For BTL, it shows 4, 6 and 8.
Seems like TI is telling me if I want to use the 3255 with my 8 ohm speaker, I should run in BTL mode.
Randy
Awesome redjr, I really like the marking upside down. I’m not sure but I think it’s the first time I see that, clever!
I got a tracking number from connex and by the look of it it’s slowly on its way.
@randytsuch? It could help to know the sensitivity of your speakers and the size of your room, I think knowing if you’ll get enough power out in the SE configuration is the first thing to confirm.
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Sorry if my info was not consistent with what TI recommends. Technically, bridge tied load (BTL) is like balanced drive with two outputs in 180deg out of phase and should handle double the voltage swing so it is better for 8ohms if you need lots of power. PBTL gives higher current and higher voltage swing.
If you are ok with about 43Vpp then SE is enough. If you need 86Vpp then BTL. 86Vpp 2ohms then PBTL. That’s only about 25w into 8ohms I think.
It does sound like you need more than 25w for your 8ohm HT speakers. My thought is stick to BTL which is much better suited for higher power at 8ohms.
If you are ok with about 43Vpp then SE is enough. If you need 86Vpp then BTL. 86Vpp 2ohms then PBTL. That’s only about 25w into 8ohms I think.
It does sound like you need more than 25w for your 8ohm HT speakers. My thought is stick to BTL which is much better suited for higher power at 8ohms.
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I have Ascend Audio Sierra I speakers
Sierra-1 Bamboo Loudspeaker
86.5 db efficient and 8 ohm
19 x 12 x 8 foot room (about 1800 cubic feet), but its a family room and one long wall is about 1/2 open into the kitchen, so it will look like a larger room to the speakers.
25w would be low, and based on the ti datasheets I'd would want to go btl
Started looking at your other amp, the FH9HVX instead. 2 BTL amps are more than I would like to spend.
Can you compare them?
Randy
Sierra-1 Bamboo Loudspeaker
86.5 db efficient and 8 ohm
19 x 12 x 8 foot room (about 1800 cubic feet), but its a family room and one long wall is about 1/2 open into the kitchen, so it will look like a larger room to the speakers.
25w would be low, and based on the ti datasheets I'd would want to go btl
Started looking at your other amp, the FH9HVX instead. 2 BTL amps are more than I would like to spend.
Can you compare them?
Randy
The FH9HVX is a superb Class AB amp capable of satisfying even the most discerning listener (myself, Vunce are the two anecdotal examples). In its previous life as FH9 and FH9HV it was well liked by builders in the Apex thread with probably hundreds of builders who were all very happy with the sound. It was so good, it was even cloned by the Chinese and sold fully assembled on AliExpress and eBay. The FH9HVX is even better with layout by JPS64 and the best components and some tweaked setpoints and lower distortion. The TPA3255 can drive lower impedance loads and has super low distortion and inaudible noise floor. It needs a powerful preamp though as it’s only 15dB gain with PFFB (post filter feedback) or 22dB without. One cannot tell it is even turned on with ear pressed to the cone when the inputs are shorted. Any noise heard without input shorted is the noise of the source or preamp. Both amps can be driven by SMPS so there is no advantage there except TPA3255 is single rail PSU. TPA3255 is significantly more difficult to build as it is 95% SMT and only an experienced SMT builder should attempt. Maybe as your 3rd or 4th 0805 size SMT project with experience soldering a few parts that have no exposed leads. There are over 70 unique components on the TPA3255.
FH9HVX is all through hole and a pleasure to assemble in one night. I think it’s best with a beefy linear supply using a toroidal transformer and an All Cee’s PSU.
Hope that helps.
If I only had the FH9HVX for the rest of my days, I would probably be fine with it. That’s how good it is.
If I only had the TPA3255 for the rest of my days, I would still be fine and have freedom to drive 2ohm or 4ohm speakers. The TPA3255 runs very cool.
The FH9HVX could be modified to drive 4ohm loads. And I use it to do so at lower power all the time. 30w to 45w is not a problem. It also runs fairly cool when not running full power. I leave mine on 24/7.
I would say that the midrange on the FH9HVX is smoother. This has to do with inherent difference in Class AB vs Class D and nothing against the TPA3255. But the bass authority of the TPA3255 is just as good as the FH9HVX. Highs on both about the same.
FH9HVX is all through hole and a pleasure to assemble in one night. I think it’s best with a beefy linear supply using a toroidal transformer and an All Cee’s PSU.
Hope that helps.
If I only had the FH9HVX for the rest of my days, I would probably be fine with it. That’s how good it is.
If I only had the TPA3255 for the rest of my days, I would still be fine and have freedom to drive 2ohm or 4ohm speakers. The TPA3255 runs very cool.
The FH9HVX could be modified to drive 4ohm loads. And I use it to do so at lower power all the time. 30w to 45w is not a problem. It also runs fairly cool when not running full power. I leave mine on 24/7.
I would say that the midrange on the FH9HVX is smoother. This has to do with inherent difference in Class AB vs Class D and nothing against the TPA3255. But the bass authority of the TPA3255 is just as good as the FH9HVX. Highs on both about the same.
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