Hi
Does anyone know much about these amps? I've purchased a couple and they would seem to be in excellent condition. PSU caps replaced and all working as they should.
My questions regard input specs. They seem to be relatively insensitive and require much higher volume settings than other power amps. Secondly, they seem very 'sharp' at the top end - as if there is a certain amount of lift at higher frequencies. They certainly produce thunderous bass in prodigious amounts but do not sound balanced. I'm wondering if they have particular input requirements and are not well suited to a passive preamp. Anyone had any experience with them?
Does anyone know much about these amps? I've purchased a couple and they would seem to be in excellent condition. PSU caps replaced and all working as they should.
My questions regard input specs. They seem to be relatively insensitive and require much higher volume settings than other power amps. Secondly, they seem very 'sharp' at the top end - as if there is a certain amount of lift at higher frequencies. They certainly produce thunderous bass in prodigious amounts but do not sound balanced. I'm wondering if they have particular input requirements and are not well suited to a passive preamp. Anyone had any experience with them?
Well, not swamped with replys but have no fear, things have improved. Firstly these Cepiars completely change their sound when they warm up, unlike any other amp I've tried. The sharpness reduces considerably after 30 minutes - although they still sound a little edgy. I'm bi-amping them and things are improved greatly by just tweaking the treble down a couple of notches. The bass really is astonishing. I'm playing them through Tannoy D700's and they just fill the air with atmospheric bass that you really feel.
I'm now wondering if they are just very ruthless and revealing and show all the limitations of the CD format. I've only tried them with a Marantz DR700. I'll try a different CD player and see if things change.
I'm now wondering if they are just very ruthless and revealing and show all the limitations of the CD format. I've only tried them with a Marantz DR700. I'll try a different CD player and see if things change.
Like the Ebay offer said, these are cinema amplifiers and will be designed and built for reliability at high power rather than for domestic high-end sound qualities at a few watts.
They wouldn't be my choice for personal use and probably have minimal bias levels, explaining the edgy sound which at cinema power levels would settle quickly. If I were running a PA business or needed general purpose amplifiers for live or background music on a budget, they would be an option. Some real cinema (not home cinema) amps are monitors for use in the projection booth, working at high line levels from the speakers. Perhaps this is some of the reason for insensitivity. They are balanced line inputs on some models, at least. If curious what to expect for input levels, check the cinema amp packages by Crown, QSC etc. for related specs. Those newer products would supersede the Cepiar models which may be on the market for that simple reason. As usual, the company is no more.
Cepiar Amps - Speakerplans.com Forums - Page 1
They wouldn't be my choice for personal use and probably have minimal bias levels, explaining the edgy sound which at cinema power levels would settle quickly. If I were running a PA business or needed general purpose amplifiers for live or background music on a budget, they would be an option. Some real cinema (not home cinema) amps are monitors for use in the projection booth, working at high line levels from the speakers. Perhaps this is some of the reason for insensitivity. They are balanced line inputs on some models, at least. If curious what to expect for input levels, check the cinema amp packages by Crown, QSC etc. for related specs. Those newer products would supersede the Cepiar models which may be on the market for that simple reason. As usual, the company is no more.
Cepiar Amps - Speakerplans.com Forums - Page 1
I actually bought the pair mainly for the power supply components. The toroidals and smoothing caps are very meaty and decent quality. The cases are good too. I was intrigued to see how well they perform and I'm quite pleasantly surprised. They do have balanced inputs. A DPA CD player has made a big difference to the sound. The harshness has gone and sensitivity is no longer an issue. Maybe it was an impedance mismatch.
I suspect the bias is reasonably high. They get quite warm just idling. Its surprising just how much power you use when its clean and available. I've has all the level led's flickering when I turn the wick up - not quite the peak one - but all the others. D700's are not a particularly difficult load or particularly inefficient. They do go loud though! I'm going to substitute the amps into my home cinema setup for a little while and see how they suit. Seems a shame to rip them apart when they're so beautifully made and working just as they should!
I suspect the bias is reasonably high. They get quite warm just idling. Its surprising just how much power you use when its clean and available. I've has all the level led's flickering when I turn the wick up - not quite the peak one - but all the others. D700's are not a particularly difficult load or particularly inefficient. They do go loud though! I'm going to substitute the amps into my home cinema setup for a little while and see how they suit. Seems a shame to rip them apart when they're so beautifully made and working just as they should!
Certainly, the louder you go, the cleaner the audio will be - that's how biasing should be for pro. applications and should sound fine for you if neighbours don't object to high SPL. It's easy enough to check bias level by measuring the mV drop across any of the large source resistors on the output Mosfets and using ohms law to calculate current for each pair of output devices - with no speakers or input connected and due care (clips) not to slip, short or shock yourself, of course.
If they are Bipolar transistors, they are called emitter resistors. Optimum class AB current for normal Bipolar Emitter Follower stages will be around 120 Ma per transistor pair. Mosfet stages could be anything from 100-200 mA with no optimum, just as much as your devices can take without thermal instability or failure up to their sustained maximum rated power level.
Frankly though, I don't think Hi-fi levels of bias are needed or used in pro. applications. As I guess you don't have schematics or even full specifications, you'll also need to take care of these units if you decide to keep them, since help will be limited when you run into difficulties and there are no specific design details available.
If they are Bipolar transistors, they are called emitter resistors. Optimum class AB current for normal Bipolar Emitter Follower stages will be around 120 Ma per transistor pair. Mosfet stages could be anything from 100-200 mA with no optimum, just as much as your devices can take without thermal instability or failure up to their sustained maximum rated power level.
Frankly though, I don't think Hi-fi levels of bias are needed or used in pro. applications. As I guess you don't have schematics or even full specifications, you'll also need to take care of these units if you decide to keep them, since help will be limited when you run into difficulties and there are no specific design details available.
The run 4 pairs of Exicon 10P16 mosfets per channel. I found that one channel on each was running very hot and checked the bias. It was way up so brought it down to the level of the other channel. It works out at around 140ma per pair. They all run nicely warm to the touch now at idle and all the harshness has gone. Would too high a bias cause harshness? I wouldn't have thought so. Anyway, suffice to say I'm pleasantly surprised by the quality and I won't be stripping them down just yet!
140mA bias is quite high for the application and should sound near to the best possible in class AB, which is what you have. Mosfets don't have a sweet spot of minimum distortion as do BJTs but using bias under 100 mA and in some designs, you begin to hear a little distortion creeping in - usually as occasional harshness or a related effect.
The higher the bias - the better, in principle at least, so long as the hardware and bias controller is designed for the extra heat and dissipation requirements. It will be virtually running in class A if you keep raising bias but you can be certain the amplifier was never designed to support operation in even partial class A.
It seems you do have a good find though, with lateral mosfet output stages but keep an eye on that bias setting stability, such that it returns to your setting under similar temperature conditions each time. I'd suggest leaving it as you have, at 140 mA.
The pots may need replacing if bias drifts permanently or jumps about. I have no idea why one channel in both amplifiers would be set high, other than as a bias comparison experiment but was never reset. Anyway, hope you enjoy them!
The higher the bias - the better, in principle at least, so long as the hardware and bias controller is designed for the extra heat and dissipation requirements. It will be virtually running in class A if you keep raising bias but you can be certain the amplifier was never designed to support operation in even partial class A.
It seems you do have a good find though, with lateral mosfet output stages but keep an eye on that bias setting stability, such that it returns to your setting under similar temperature conditions each time. I'd suggest leaving it as you have, at 140 mA.
The pots may need replacing if bias drifts permanently or jumps about. I have no idea why one channel in both amplifiers would be set high, other than as a bias comparison experiment but was never reset. Anyway, hope you enjoy them!
- Status
- Not open for further replies.