Promethean owners...

[gafbass02]

To save me further hijacking WoT's new amp day thread I thought I'd post here. My promethean hisses a lot and although thomann have said they'll swap I don't want to send it off if it's just how these amps are. So I filmed this on my phone real quick and stuck it on YouTube for now. (my first ever video!)
I won't leave it for ages but I just wanted to garner opinion/comparison to others experience, my LM2 is dead quiet.

IVE NOW DELETED THE VIDEO, IT WAS ONLY A TEMPORARY MEASURE TO ESTABLISH WETHER MINE WAS THE NORM AND IT APPEARS NOT TO BE THE CASE!

Edited August 20, 2010 by gafbass02

[Beedster]

Hey mate, it's a Class-D amp, they hiss, full stop. It annoys some people whilst other seemingly don't notice it. Either way, I've returned two Class-Ds on that basis and won't own another until the technology has matured a little.

C

[JMT3781]

Is there a horn in it? if so, does it go away if you turn the control down?

[Musicman20]

It seems quite a low level of hiss.

Im assuming its either the horn, or indeed just part of the amp.

Hiss is annoying though, I agree.

If Thomann are prepared to swap out at no cost, it might be the safest bet.

[BB2000]

Class D amps shouldn't hiss any more than conventional class A or AB amps. If yours is very bad send it back to Thomann.

I do think there are QA issues with these. I had one on load about a month ago and thought it was a great little practice amp, so ordered one for myself. When it arrived it sounded crap (hard to describe but it was somehow muffled). I swapped heads with my mates unit and the my head sounded fine in his combo, but my combo still sounded crap with his known good head. Back it went, and I got a replacement in due course. The replacement sounded like it should (no hiss by the way).

But, turning it on the following day it made a hell of a rasping noise and died. There wasn't exactly a puff of smoke but I could smell that something had burned out inside the amp. So back it went. I decided to get a refund at that point, but I am in two minds whether to give the combo another shot. They are suprisingly nice (if you get a working one!) for the size.

[Beedster]

[quote name='BB2000' post='922177' date='Aug 11 2010, 11:52 PM']Class D amps shouldn't hiss any more than conventional class A or AB amps. If yours is very bad send it back to Thomann.[/quote]

I'm certainly no expert John, but as I understand it, there are issues around the power supply in some Class D amp models, especially with units designed to run on USA power supply. I have a lengthy email from Phil Jones on the topic somewhere, I'll try to dig it out.

C

[gafbass02]

Interesting stuff folks. I think my lm2 is class D too? But that's quiet as a mouse. I'm gonna take em up on the swap I reckon and try another, but just one more, like pringles!
The hiss is constant although the gain control affects it although it's still doing it through another cab and the lm2 dosnt hiss through the promethean cab so not the tweeters fault. It's def originating somewhere in the input gain stage. Ah well I'd like to see that article Chris. Cheers

Edited August 11, 2010 by gafbass02

[BB2000]

[quote name='Beedster' post='922179' date='Aug 11 2010, 11:58 PM']I'm certainly no expert John, but as I understand it, there are issues around the power supply in some Class D amp models, especially with units designed to run on USA power supply. I have a lengthy email from Phil Jones on the topic somewhere, I'll try to dig it out.

C[/quote]

That's likely specific to that particular design. One thing that you do sometimes find with some architectures of class-D amps that are noisy (due to poor design) is that the noise or audio feed through isn't white (broadband) but can have annoying tones in it. Even if you're not consciously aware of them I think they have a bearing on how annoying you find the noise. I've tried a few that I couldn't listen to for more than a few minutes (I'd just focus on the noise) even though I'd happily play through non-switching amps with higher levels of noise. It's a pity that the manufactures won't specify noise parameters since if you do get a bad one you're at the mercy of the dealer if you want to return it. At least Thomann are good in that respect.

[Marvin]

FWIW, I don't own a Promethean but I have got an Ibanez Soundwave SWX35 practice amp, and that one hisses like a snake on heat. It is quite annoying but on the Soundwaves they are known to be that way. If it was a Promethean though I would be tempted to seek a replacement, I think.

[wateroftyne]

Morning all!

First up - Chris, it's a little misleading to say Class-D amps hiss full-stop. It's not inherent in the design. For a start, most top-end Pro Audio is class-D these days... if it hissed, I don't think anyone would touch it...!

Back in the day, when I liked tweeters, treble and roundwounds, I used a class-D Acoustic Image Focus head for about four years and it was silent, even when recording and DI'd through big FOHs.

Back to the Promethean....

gafbass02 - after watching your clip, I've had another listen to mine.

With the volume down, if I get on my hands and knees and put my head at tweeter height from about a foot or less, then I can hear it hiss, but only if the room is dead silent.

I've used it almost every day in various situations and never noticed it before - even through headphones. I'm gigging it on Friday and Saturday night, so I'll see if much hiss makes it to the desk.

To be honest, I think it just bothers some people more than others. I wouldn't describe the hiss of my amp or in your clip as 'a nest of vipers', but we're all different!

[Beedster]

[quote name='wateroftyne' post='922260' date='Aug 12 2010, 07:25 AM']Morning all!

First up - Chris, it's a little misleading to say Class-D amps hiss full-stop. It's not inherent in the design. For a start, most top-end Pro Audio is class-D these days... if it hissed, I don't think anyone would touch it...!

Back in the day, when I liked tweeters, treble and roundwounds, I used a class-D Acoustic Image Focus head for about four years and it was silent, even when recording and DI'd through big FOHs.

Back to the Promethean....

gafbass02 - after watching your clip, I've had another listen to mine.

With the volume down, if I get on my hands and knees and put my head at tweeter height from about a foot or less, then I can hear it hiss, but only if the room is dead silent.

I've used it almost every day in various situations and never noticed it before - even through headphones. I'm gigging it on Friday and Saturday night, so I'll see if much hiss makes it to the desk.

To be honest, I think it just bothers some people more than others. I wouldn't describe the hiss of my amp or in your clip as 'a nest of vipers', but we're all different![/quote]

A lot do hiss though Michael, some people really pick it up (I do and clearly Gafbass does), whilst others (e.g., you) don't. Our guitarist couldn't believe the noise from my Phil Jones combo whilst our singer simply couldn't hear it!

C

[Beedster]

[quote name='Beedster' post='922284' date='Aug 12 2010, 08:16 AM']A lot do hiss though Michael, some people really pick it up (I do and clearly Gafbass does), whilst others (e.g., you) don't. Our guitarist couldn't believe the noise from my Phil Jones combo whilst our singer simply couldn't hear it!

C[/quote]

My 'hissues', and some discussion of potential causes etc, were at [url="http://basschat.co.uk/index.php?showtopic=72691&hl="]http://basschat.co.uk/index.php?showtopic=72691&hl=[/url]

C

[wateroftyne]

[quote name='Beedster' post='922284' date='Aug 12 2010, 08:16 AM']A lot do hiss though Michael[/quote]

And a lot don't - I was just gently correcting your 'Hey mate, it's a Class-D amp, they hiss, full stop' comment above, s'all.

Edited August 12, 2010 by wateroftyne

[Beedster]

[quote name='wateroftyne' post='922307' date='Aug 12 2010, 08:37 AM']And a lot don't - I was just gently correcting your 'Hey mate, it's a Class-D amp, they hiss, full stop' comment above, s'all. [/quote]

Mmm, I wonder whether they all hiss and it only gets to certain folks? You've never noticed it with any of your Class Ds, but I've noticed it with all of mine?

Perhaps I'll start a support group for bassist who have stupidly sensitive hearing at whatever the hiss frequency is

C

[wateroftyne]

[quote name='Beedster' post='922310' date='Aug 12 2010, 08:41 AM']Mmm, I wonder whether they all hiss and it only gets to certain folks? You've never noticed it with any of your Class Ds, but I've noticed it with all of mine?

Perhaps I'll start a support group for bassist who have stupidly sensitive hearing at whatever the hiss frequency is

C[/quote]
Heh, maybe. My hearing's OK - I've still got plenty of top-end for my age.

I should clarify that I can hear the hiss, but I don't find it to be intrusive. None of the users on TB have picked up on it either...?

Then again, the fan on the Walkabout Scout drives some people nuts, but it never bothered me...!

[Beedster]

[quote name='wateroftyne' post='922312' date='Aug 12 2010, 08:44 AM']I should clarify that I can hear the hiss, but I don't find it to be intrusive. None of the users on TB have picked up on it either...?[/quote]

Exactly my point, you didn't pick up on it, but it's there. When your attention was drawn to it, you could hear it! It's a good comparison with the Walkabout fan; I've never noticed fan noise as an issue, but others finds it drives them crazy. Is it just that certain types of noise get to certain types of people? The closest comparison I can get to the noise from my PJB was that it was like having a mosquito in the bedroom when you're trying to sleep; there's no reason a very low level buzzing/whistling should drive me crazy, it just does, Mrs Beedster, of course, can't even hear them!!!

C

[wateroftyne]

[quote name='Beedster' post='922318' date='Aug 12 2010, 08:55 AM']there's no reason a very low level buzzing/whistling should drive me crazy[/quote]
Oh, aye - A buzz / whistle, even at low levels, would have me tearing down the wallpaper.

A soft hiss, which disappears into background noise in any 'normal' situation, just doesn't bother me.

[BassBod]

I've used my EA 500 for a few years now and an Acoustic Image for about two years - to me and my aging ears there is an inherent hiss to these designs. I've also used a borrowed older Acoustic Image and a newer version - both were the same. Its not something you'd hear in a real setting, but it is very noticeable at home or in any very quiet situation. The hiss isn't on the preamp or DI, it seems to be a product of the power amp circuit.

I asked EA about it and they said the level of noise does vary a bit from amp to amp, with variations in component values/quality (pretty normal for electronics?). If it was a problem they offered to replace some items on the circuit boards.

My personal take on it is - older amps tend to hum, have very noisy fans and get hot...."digital" amps have a slight hiss that you can't generally hear outside your own front room, but are small light and powerful. To me, I can live with a bit of hiss for the other benefits.

I'd use Thomann's replacement offer and see what the next one is like?

[gafbass02]

Right. Everyone round mine :-D we should all have a listen over a cuppa.

[derrenleepoole]

I've certainly not noticed a hiss on mine, so perhaps there might be a fault somewhere. However, the youtube video is misleading and is perhaps not good evidence of 'hiss!' Why? Well, youtube videos are highly compressed and as such introduce noise into the audio channel. Also, you've recorded this on a camera phone? Microphones on a camera are very noisy indeed, so any recording they make will inherently be noisy! Also, the hiss only got louder when you practically placed the camera inside the speaker cone - granted there is a hiss audible from a distance, but that could be any of the above flaws mentioned!

My observation would be to AB it against another Promethean cab, that is the only way you can be absolutely positive there's an issue. There seems to be a lot of conjecture here and none of it strictly accurate. FWIW, I've owned two Mark Bass items: a LM250 head and a CMD121P combo, both of which had a hiss of some sort. My Promethean is easily comparable in quality to the MB gear I had, both in terms of build quality and sound quality.

I'm not doubting your ear or skill here, but is there perhaps another underlying issue. When I announced that I was getting the Promethean (I was one of the first ones to get one on here), the immediate response was negativity - comments like "I wouldn't trust such cheap gear" - "poor build quality" etc etc - all made without anyone actually trying it out and people who had assumed that because it's by Ibanez it must be cheap or inferior or lacking in some way. Is it not possible therefore that you're subconsciously looking for faults because it's an item made by Ibanez, a company not known for high end amp gear?

If you're really convinced that there is a fault, why not try the head out of the combo with your other cabs and AB against the MB head. It could be something as simple as a crap lead that connects the head to the speaker for example.

[Beedster]

[quote name='derrenleepoole' post='922344' date='Aug 12 2010, 09:19 AM']Is it not possible therefore that you're subconsciously looking for faults because it's an item made by Ibanez, a company not known for high end amp gear?[/quote]

LOL, and you're the one talking of inaccurate conjecture?

I'm with Bassbod on this, Class D have a hiss whilst older classes had other, and louder, noises to which we'd become accustomed. There is sufficient variability in component tolerances, even within models, for the hiss to be more pronounced on some individual amps than others. Furthermore, some people are more bothered by the hiss than others. When these people meet these amps, they post here....

Simples

C

Edited August 12, 2010 by Beedster

[gafbass02]

I've tried all possible combinations of little mark 2, bfb compact, promethean head, promethean cab. This hiss is generated by the promethean head only, not the tweeter and it also hisses through the compact. Trust me, after 20 years experience with many, many bass amps including a hissy laney R5 combo not to mention working as a sound engineer for many years and ten years in Hi-Fi I'm pretty sure this is excessive. When you turn it on it's one of those, 'whoah, what's that!' moments.
I'm just gonna swap it and if the next one does it then I figure it's just what these amps do. Live I'm sure it won't be any worse than a gained up Marshall stack hissing between songs. But for home practice or studio use on this particular unit it would be a problem. Hopefully on another it won't.

[Musicman20]

[quote name='gafbass02' post='922367' date='Aug 12 2010, 09:39 AM']I'm just gonna swap it and if the next one does it then I figure it's just what these amps do. Live I'm sure it won't be any worse than a gained up Marshall stack hissing between songs. But for home practice or studio use on this particular unit it would be a problem. Hopefully on another it won't.[/quote]

Just chiming in. I can't stand that hiss that guitar amps produce when at higher volume levels!!!!

My RH450 is Class D and does not hiss.

The LM3 is Class A/B and is very quiet.

I tested a Markbass F500 and that DID hiss.

[Beedster]

[quote name='Musicman20' post='922381' date='Aug 12 2010, 09:52 AM']Just chiming in. I can't stand that hiss that guitar amps produce when at higher volume levels!!!![/quote]

Ahah, you see, there it is! I reckon us bassists don't mind a bit of manly hum, a deep soulful throb emanating from an 8-foot stack that adds to the overall gut-wrenching and earth moving effect of bass generally. It's when we get the sort of frequency out of out gear that we'd expect from a guitar amp we start getting angry

Class D in bass is doomed

[BassBod]

Just a thought - another big variable is the cab. My Euphonic Audio cabs are very clear/unforgiving, depending on your preferences. They show up the hiss, a lot if the co-ax tweeter is turned beyond half way. My Bag End is an "older" voiced cab and you have to listen for it to hear any hiss at all.

My guess is that modern speakers are more like the EA than the Bag End - people expect to hear more upper mid and detail than they did a few years ago?