Pedalboard sized poweramps

[basshead56]

The Jule Simone 500w amp might be a worthwhile contender

[alexa3020]

On 29/03/2024 at 07:41, NancyJohnson said:

I've been cranking the thing up.  Blimey!  Epic.  I'm really impressed with the output, clarity, transparency etc.  It's completely silent too; no interference from dimmer switches (like the A/O 900).

 

I suppose the real test would be when I get in a room with people, but if it's no good for that, then I'll just use it at home.

 

It's stupid cheap; at £68 it's less than a night out at the pub and a kebab.  What's not to like?

 @NancyJohnson have you had the chance to play it in a band environment? 

 

[NancyJohnson]

3 hours ago, alexa3020 said:

 @NancyJohnson have you had the chance to play it in a band environment? 

 

 

Nope.  I hadn't touched it it for a few days and when it switched it on today it's conked out.  FFS.  It's been used about an hour.  It powers up, but nothing.

 

I'll need to chase up Thomann.

[alexa3020]

28 minutes ago, NancyJohnson said:

 

Nope.  I hadn't touched it it for a few days and when it switched it on today it's conked out.  FFS.  It's been used about an hour.  It powers up, but nothing.

 

I'll need to chase up Thomann.

Oh dear, well I was on the fence about getting one of these - but that's me put off. I think maybe an elf or gnome might be better as a backup. Played an elf last night and was super impressed.

[NancyJohnson]

On 27/04/2024 at 12:04, alexa3020 said:

Oh dear, well I was on the fence about getting one of these - but that's me put off. I think maybe an elf or gnome might be better as a backup. Played an elf last night and was super impressed.

 

Well, full credit to Thomann, they're just sending me a replacement, but I need to hang onto the old one for six months in case they want it back.

 

[JPJ]

Just spotted this over on FaceAche https://www.eich-amps.com/tb250#collapseExample0 Looks like it could be a contender for those who want to run a cab from pedalboard preamp like the OP? And as it’s coming from a recognised bass amp manufacturer I’d expect its roadworthy too. 

[nekomatic]

On 17/05/2024 at 14:01, JPJ said:

Just spotted this over on FaceAche https://www.eich-amps.com/tb250#collapseExample0 Looks like it could be a contender for those who want to run a cab from pedalboard preamp like the OP? And as it’s coming from a recognised bass amp manufacturer I’d expect its roadworthy too. 

Interesting, as it looks suspiciously similar to something like 

https://www.ebay.co.uk/itm/283964862682?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=SsSiHyWXTLi&sssrc=4429486&ssuid=O0J6pgZgSC6&var=&widget_ver=artemis&media=COPY which I had considered at in the past as a possible mini power amp - but a lot more expensive. I wonder how long these can sustain their rated output without overheating but as you say, if Eich are prepared to put their name on it one assumes it performs. 
 

The external power supply brick slightly detracts from the ultra-mini aesthetic though, which will be why they don’t show it in any of the photos 😁

[obbm]

1 hour ago, nekomatic said:

Interesting, as it looks suspiciously similar to something like 

https://www.ebay.co.uk/itm/283964862682?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=SsSiHyWXTLi&sssrc=4429486&ssuid=O0J6pgZgSC6&var=&widget_ver=artemis&media=COPY which I had considered at in the past as a possible mini power amp - but a lot more expensive. I wonder how long these can sustain their rated output without overheating but as you say, if Eich are prepared to put their name on it one assumes it performs. 
 

I have a 100-watt Nobsound, https://www.ebay.co.uk/itm/274444339477, which I use to drive an active stool or a platform with drums. I think the Eich could be an uprated version of this although the price hike is a bit alarming. The 19-volt power supply is 60% the size of the amp so it's all a bit messy.  I've modified mine so the speaker outlet is now a jack rather than terminal posts however the input is still a phono.  I have yet to try it with a bass through a decent speaker.

[Phil Starr]

On 19/05/2024 at 11:53, obbm said:

I have a 100-watt Nobsound, https://www.ebay.co.uk/itm/274444339477, which I use to drive an active stool or a platform with drums. I think the Eich could be an uprated version of this although the price hike is a bit alarming. The 19-volt power supply is 60% the size of the amp so it's all a bit messy.  I've modified mine so the speaker outlet is now a jack rather than terminal posts however the input is still a phono.  I have yet to try it with a bass through a decent speaker.

I don't think there is anything too suspicious about these amps, there are a whole rash of class D amplifier chips they are used in that are the basis of a lot of cheap hi-fi/television sound bars and the like. Generally thay are the basis of anything that is rated as 2.1 i.e. a stereo amp with a subwoofer output. Basically each chip has a four channel class D amplifier. Each amplifier can be bridged with another so you can get extra power. Typically one pair are used for the subwoofer and the other two as a stereo amp. Other chips have just two amps as used in this Nobsound.  These amplifier chips are incredibly cheap as they are mass produced and the reliability of the final product depends to a certain extent upon the quality of the few external components they need and the power supply. I'd assume Eich will use better components. The power you will actaully get will depend upon the power supply and 19V is an odd choice for a 24Vchip. It's not unusual for a laptop power supply though so my guess is that is what you are getting. We've all probably got a collection of domestic bluetooth speakers using these amps, it's why this stuff is so cheap.

 

 

During Lockdown I bought a whole collection of these on uncased boards to try out for building a combo. I still haven't got round to making anything but I know @Chienmortbb has got them going

 

This is one of the amps based upon a TDA3116 chip which is hidden under the black heatsink. In this case the board is rated at 100W @4ohms  with a 24V supply.  It's £9.99 from ebay it could be what is in the4 Nobsound but there are other options.

 

 

 

 

Edited May 21 by Phil Starr

[bassman7755]

On 19/05/2024 at 10:28, nekomatic said:

Interesting, as it looks suspiciously similar to something like 

https://www.ebay.co.uk/itm/283964862682?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=SsSiHyWXTLi&sssrc=4429486&ssuid=O0J6pgZgSC6&var=&widget_ver=artemis&media=COPY which I had considered at in the past as a possible mini power amp - but a lot more expensive. I wonder how long these can sustain their rated output without overheating but as you say, if Eich are prepared to put their name on it one assumes it performs. 
 

The external power supply brick slightly detracts from the ultra-mini aesthetic though, which will be why they don’t show it in any of the photos 😁

 

I think all these "ebay special" mini amps are based on single chip switched mode amps like TPA3255 as @Phil Starr says, they perform very decently according to various reviews I've read with the limiting factor being the power supply rather than the amp itself. Very tempted to give one a go.

 

Another decent looking one is this https://www.ebay.co.uk/itm/355582766811?itmmeta=01HYFTFC2VWKW18NHKQN7HRDAK

Edited May 22 by bassman7755

[Chienmortbb]

Do not get me started on these amps. Oops you already have.  Many of them are based as is said earlier on chips amps like the TPA3255 and the TPA3116.

These are single supply rail amps often driven by a laptop style "brick".

 

The amps can go loud under the right conditions. For example the TPA3255 can reach high powers however you need to run them with a  48V+ power supply AND at low impedances. Under those conditions, the heatsink fitted is almost totally inadequate. In addition te headline powers quoted are at 10% distortion. This is unusable IMHO for bass.

[Phil Starr]

40 minutes ago, Chienmortbb said:

For example the TPA3255 can reach high powers however you need to run them with a  48V+ power supply AND at low impedances. Under those conditions, the heatsink fitted is almost totally inadequate. In addition te headline powers quoted are at 10% distortion.

 

This is all true. The best thing you can do to get a real picture is to go to the chip manufacturers data sheets TPA3255

[agedhorse]

On 22/03/2024 at 02:49, Dan Dare said:

 

 

You can't really blame companies for being leery about fixing something bought used.

Why not? A used amp is a used amp unless somebody’s already attempted to repair it or modified it. 
 

Every amp is a used amp once it’s been used. 

[bassman7755]

On 23/05/2024 at 21:53, Phil Starr said:

 

This is all true. The best thing you can do to get a real picture is to go to the chip manufacturers data sheets TPA3255

The 1% THD graph shows you can get 100w and change into 8ohm at 48v which would probably translate to a decently useful pedal board amp for monitoring / rehearsal perhaps paired with a PSU something like this https://docs.rs-online.com/2729/A700000007590264.pdf. With a higher current PSU you would have to option of running 2 speakers and probably getting gigable level output.

[Phil Starr]

5 hours ago, bassman7755 said:

The 1% THD graph shows you can get 100w and change into 8ohm at 48v which would probably translate to a decently useful pedal board amp for monitoring / rehearsal perhaps paired with a PSU something like this https://docs.rs-online.com/2729/A700000007590264.pdf. With a higher current PSU you would have to option of running 2 speakers and probably getting gigable level output.

Yeah I think that is realistic, and remember this is only using one amp on the chip. I'm not recommending these because I haven't trried them but TI are a recognised company and those specs are continuous rms power. the only reason I've put all this up is to say that given the state of the technology and how cheap it is the claims of the Nobsound and similar Chinese amps aren't ridiculous. I've a history of shooting down the ridiculous over claiming of Behringer/Yamaha/RCF/every single PA speaker on the basis of being technically impossible so it's nice to be able to say that this looks very feasable. I've no idea of the build quality but at that price I'd take the risk.

[nekomatic]

The TPA3255 datasheet says that for 250 W into 4 ohms (the Eich amp’s rating) the chip needs to get rid of nearly fifty watts, and even applying a factor for the actual power spectrum of bass that’s still going to be quite a lot of heat. Would be interesting to know if Eich have improved on the thermal management of the cheap amp board somehow, say by using the whole case as a heatsink rather than just the stick-on internal one in the eBay pictures. 

[JohnH89]

Went through a lot of these boards building a small amp powered by an 18v drill battery . TDA8932 and TPA3118 . Every TPA3118 board that I bought let out the magic smoke , except for one . Bought from various suppliers but all defective . Settled on the TDA8932 . 100% reliable so far . Caveat emptor .

[bassman7755]

4 hours ago, Phil Starr said:

Yeah I think that is realistic, and remember this is only using one amp on the chip.

Seems a lot of the boards have a bridging option but reading between the lines this seems to involve running both channels in parallel to be able to go down to 2 ohm rather than the more usual opposite phase setup, still I guess it doesn't do any harm.

[Phil Starr]

3 hours ago, bassman7755 said:

Seems a lot of the boards have a bridging option but reading between the lines this seems to involve running both channels in parallel to be able to go down to 2 ohm rather than the more usual opposite phase setup, still I guess it doesn't do any harm.

That's right, the chips actually have four amps on board. so the 300W @10% distortion figure for the TPA3255 is for two of them bridged and if you could get the heat away they can do 2x300W into 4ohms. If you go to the rating is BTL (bridge to load) You can't bridge a bridged amp and the individual amps won't handle the current to drive into 2ohms unless you run them in parallel. PBTL is parallel bridge to load.

 

There's so many practical problems in heatsinking for this power level that even bolting the chip hard against the case wouldn't work. Notice that Texas Instruments give the maximum operating temperature as 85deg so the case would probably reach 65deg which would be far too hot to touch. They do however give all the thermal information to calculate the heatsink needed.

[Chienmortbb]

Phil is right that the published specifications for the TI chips are really theoretical and cannot be achieved in a real world situation. This tree for a pedalboard app where you do not want a large heat sink and a fan.

 

 

The best of these amps are built by a company called 3E audio. They are based in China but they seem to build to a better standard and have a very good reputation. However, quality does not come cheap and the 3E boards are several times more expensive than the low-cost AliExpress, eBay or Banggood modules. The lower cost boards have components of questionable quality and are much more likely to burn out quite quickly.

 

 Even with the three boards, a good power supply is essential and again these do not come cheap. In fact in my opinion you need to spend as much on one of these TI modules and power supplies as you would buying an 300 W model from ICEPower. The 300AS/1 is an ideal paddleboard amp and the whole module which includes the mains power supply will set you back between 100 and £150. With the ICEPower modules, You have the added knowledge you are meeting all the required standards and that the unit has been tested in a proper manner as quality components and is almost ready to go. Be aware though that with the ICEPower modules you need to be aware of how to connect the mains so as not to affect the safety or integrity of the module with respect to conducted and radiated interference.

 

If you do decide to go the TI module route, remember that the powers quoted are often at much higher voltages and currents than you can get easily from a laptop brick type power supply. Even if you did have the high voltages available that many of the modules sold will not stand the higher voltages. For example, many of the TPA3255 modules, are only guaranteed to work at 36V dc. If you do use a power supply of 48-50 volts, you may find you run out of current before getting anywhere near the quoted power. 
 

As  @Phil Starrsays, heatsinking/thermal management is also an issue. The size of the heartsick needed to achieve really high powers is quite large, especially if you are trying to dissipate the heat without the help of a fan. It is also true that the maximum efficiency of a class D amp is close to its maximum power output power. So you cannot scale back the size of the heat sink as much as you might think at lower powers. 

Edited May 30 by Chienmortbb

[NancyJohnson]

I got a replacement amp from Thomann.  All good.

[bassman7755]

On 26/05/2024 at 17:39, Chienmortbb said:

If you do decide to go the TI module route, remember that the powers quoted are often at much I have voltages then you can get easily from a laptop brick type power supply and even if you did have the high voltages available that many of the modules sold will not stand the higher voltages. For example, many of the TPA 3255 modules, are only guaranteed to work at 36V dc. If you d use a power supply of 48-50 volts, you may find you run out of current before getting anywhere near the quoted power.

 

Yeah been watching a few youtube vids of people bench testing various modules, the worst offenders seem to be blessed with fake voltage regulators which over heat and marginally specced caps (50v). I've pulled the trigger on a module with 60v caps so now I just have to wait for the boat from china ... 

[nekomatic]

On 26/05/2024 at 17:39, Chienmortbb said:

In fact in my opinion you need to spend as much on one of these TI modules and power supplies as you would buying an 300 W model from ICEPower. The 300 AS/1 is an ideal paddleboard amp and the whole module which includes the mains power supply will set you back between 100 and £150.

 

Yeah, each time I've gone through the thought process of 'build my own power amp' I've ended up at this conclusion, and buying from the UK dealer with the cable set, VAT and delivery you're looking at at least £150, then you need to put it in a box with connectors and so on, and hope that your thermal design is OK, and by the time you've done all that then unless you cost your time and effort at zero you might as well just buy a Baby Sumo, or if you don't mind fan cooling then a BH250 or Gnome i-pro or something.

 

I'm still interested in other people's experience of the same thought process though!

[NancyJohnson]

Addendum.

 

Honestly surprised at the Harley Benton.  Loud.  I'm uncertain how transparent it is with everything set to the noon position; I feel 'flat' is more akin to the mid and treble at noon and the bass ramped up a notch or two.

 

Running a Sansamp BDDI into it and it's feeding the Barefaced Big One I won at the SE Bass Bash a few years back.  Sounds considerably more whumpy through that than the Darkglass 1x12s.  

[bassman7755]

4 hours ago, nekomatic said:

 

Yeah, each time I've gone through the thought process of 'build my own power amp' I've ended up at this conclusion, and buying from the UK dealer with the cable set, VAT and delivery you're looking at at least £150, then you need to put it in a box with connectors and so on, and hope that your thermal design is OK, and by the time you've done all that then unless you cost your time and effort at zero you might as well just buy a Baby Sumo, or if you don't mind fan cooling then a BH250 or Gnome i-pro or something.

 

Yes in practical terms this is very true, I've just been looking for an excuse to have a tinker trying to build my own as cheaply as possible. I think the thing is theres a certain satisfaction you get from doing something yourself even if it doesn't make economic sense, for example I bought a complete set of re-fretting tools including a gizmo to pre bend fret wire to the right radius all to be able to re-fret (one partially, one completely) two basses, probably cost me far more than paying someone to do it.