I've never done a comprehensive shootout between all possible candidates. I might do that once the acoustics in my new house has been improved.IVX said:
Bruno Putzeys said:
Probably you're right, but why not save some work if possible as well as eliminating some error sources, apart from myself 😉
JP or Bruno,
I've got the 180's now and want to test without the caps, the 2 off 22uf/50V, just make a shortcut there. Is there any risc involved? Is there an offset runaway if you direct couple it? I know you do this for the low LF rollof but you can do that on the input as well and use a proper polyester cap. Are there any nasties I've to watchout for? I always use a fast reacting DC protection anyway.
I've got the 180's now and want to test without the caps, the 2 off 22uf/50V, just make a shortcut there. Is there any risc involved? Is there an offset runaway if you direct couple it? I know you do this for the low LF rollof but you can do that on the input as well and use a proper polyester cap. Are there any nasties I've to watchout for? I always use a fast reacting DC protection anyway.
Bgt said:
Which version do you have (in terms of input op amp)?
The NE5532 version can produce an offset if the impedance matching on the inputs is really large. The 8620 version has no such problem and will only produce DC when you actually feed it DC.
In any case, there's nothing that can go horribly wrong. If a small DC offset occurs (enough to pump the supplies), the module will protect itself. If there is a larger DC offset, your DC protection will catch it.
So, the worst that can happen is that you may have to put the coupling caps back.
Hi Bruno,
I've the 5532 but will change them for another one(low offset).
Ok so it is quite harmless. Just want to know if there is a difference because they're not in the feedback loop.
Just have to make the DC protection now so it will save my Driades in case it goes wrong.
I've the 5532 but will change them for another one(low offset).
Ok so it is quite harmless. Just want to know if there is a difference because they're not in the feedback loop.
Just have to make the DC protection now so it will save my Driades in case it goes wrong.
The links supplied by Stef1777
indicates that the 8066 might be even better than the 8620 in the bass region...
I run a system with 8 channels of ucd amplification (soon to be 12 ch🙂 )... do you think that it might be a good idea to use 8066 in the the 8 ch of sub-amplification... and use 8620 in the 4 ch for midbass/mid and treble?
/Stefan
indicates that the 8066 might be even better than the 8620 in the bass region...
I run a system with 8 channels of ucd amplification (soon to be 12 ch🙂 )... do you think that it might be a good idea to use 8066 in the the 8 ch of sub-amplification... and use 8620 in the 4 ch for midbass/mid and treble?
/Stefan
You're invited to experiment and let us know the result! All I can offer is the (by now hopefully old and well known) story about bass and HF THD. Higher THD at high frequencies increases the sense of "tight bass" beyond the natural. Clearly in the bass region there is no difference but the behaviour of the op amp at higher frequencies produces that feeling. I forgot who said "you wouldn't believe what a good tweeter can do for the bottom end".OA51 said:
Whether this is a factor in your set-up is easily tested. Equip 4 modules with the 8066 and 4 with the 8620 (for the time being don't care about the other 4).
Do one listening test with the 8620 modules in the tweeters and the 8066 in the woofers, then do another one with the reverse.
Do report the results here. My hunch is that you will have the "8066 bottom end" by actually using them in the highs. Unfortunately you will also have the 8066 highs. Actually I strongly doubt that the op amp choice in the woofer channel is of much consequence in an active system.
But again, by all means do the test. I've never built an active system so your findings will count more than my hunches.
Master Bruno said: "I've never built an active system"
Really???
You should... 😎
I built one with your UcD180 that made me want to sell my main amps!
You are a great philantrope 😉
Thank you for taking the time to answer...
Mauricio
Really???
You should... 😎
I built one with your UcD180 that made me want to sell my main amps!
You are a great philantrope 😉
Thank you for taking the time to answer...
Mauricio
Re: Master Bruno said: "I've never built an active system"
Yes, I agree, you should.
My first active system I made around 25 years ago or so when I was in high-school. It was just a super simple system with a few ILP amp modules and using a few cheap car speakers. Of course those car speakers had bad x-overs with cheap coils and caps, so the improvement by going active was huge.
Currently I'm back to DIY active after many years of listening to a commercial system. The attractive price of UcD and the very good performance of UcD makes it possible for a reasonable price. Especially if you consider what high-end passive x-over components cost. Of course now you need active X-over. I use the DEQX PDC for that. DEQX and UcD = killer combination. But there are of course many cheaper solutions as simple as a couple of passive RC filters. Also computerized solutions with multi-channel soundcards are coming up. The guys from Acoustic Reality that sell the ICE amps are promising some nice multi-channel converters that can be used for active digital X-over and room correction. Tempting to try it but I spend my AV budget for this year already :-(
Bottomline, try active, you can sell 3x more modules, you will have less IMD and you will need less powerfull amps (or have more reserves) as the power is dvided in 2 or 3 frequency bands. A clipping bass-amp will also not blow your tweeters. The UcD modules behave very well on start-up and down, so very good for active systems.
Best regards
Gertjan
maxlorenz said:Really???
You should... 😎
I built one with your UcD180 that made me want to sell my main amps!
You are a great philantrope 😉
Thank you for taking the time to answer...
Mauricio
Yes, I agree, you should.
My first active system I made around 25 years ago or so when I was in high-school. It was just a super simple system with a few ILP amp modules and using a few cheap car speakers. Of course those car speakers had bad x-overs with cheap coils and caps, so the improvement by going active was huge.
Currently I'm back to DIY active after many years of listening to a commercial system. The attractive price of UcD and the very good performance of UcD makes it possible for a reasonable price. Especially if you consider what high-end passive x-over components cost. Of course now you need active X-over. I use the DEQX PDC for that. DEQX and UcD = killer combination. But there are of course many cheaper solutions as simple as a couple of passive RC filters. Also computerized solutions with multi-channel soundcards are coming up. The guys from Acoustic Reality that sell the ICE amps are promising some nice multi-channel converters that can be used for active digital X-over and room correction. Tempting to try it but I spend my AV budget for this year already :-(
Bottomline, try active, you can sell 3x more modules, you will have less IMD and you will need less powerfull amps (or have more reserves) as the power is dvided in 2 or 3 frequency bands. A clipping bass-amp will also not blow your tweeters. The UcD modules behave very well on start-up and down, so very good for active systems.
Best regards
Gertjan
A Question to BRUNO.
Yesterday I work with a couple of UcD180 (8620 version) to solve some noise problem.
What has been detected.
When I switch on one module (Right channel) everithing with noise is Ok.
But when I startin' to ON the second one (left) some minor 50 Hz noise apeared in BOTH channels.
If reconnect right cable to the left unit and so on, everything is similar. When startin first (silent) modul everything is OK and when the other is ON noise apeared in both channels.
In any configuration the left UcD produce minor 50 Hz noise when starting them ON.
So whats can be wrong out there?
Yesterday I work with a couple of UcD180 (8620 version) to solve some noise problem.
What has been detected.
When I switch on one module (Right channel) everithing with noise is Ok.
But when I startin' to ON the second one (left) some minor 50 Hz noise apeared in BOTH channels.
If reconnect right cable to the left unit and so on, everything is similar. When startin first (silent) modul everything is OK and when the other is ON noise apeared in both channels.
In any configuration the left UcD produce minor 50 Hz noise when starting them ON.
So whats can be wrong out there?
Sounds like a grounding problem. Can you post a detailed electrical diagram of how you connected everything?Alex_J said:
Re: Master Bruno said: "I've never built an active system"
I designed my speakers with active drive in mind. The passive crossover is a temporary concoction lying on the floor behind the box with wires sticking out on all sides. It's just screaming "make me active". Especially when you consider that the intended 1x400+2x180 active system would take up exactly as much space as the passive xover.
The only excuse I can always make of course is that a passive system makes it easier to do listening tests on amps.
It will probably happen once I have finished developing the new 8-ch DAC and DSP unit (you might know of my involvement in www.grimmaudio.com. The DSP unit is referred to as DD1 there). That would make a neat digitally filtered active system.
I know that I should but I'm even scrambling for time to treat the acoustics of my living room so how am I supposed to find time to build an active system? That bit of spare time I have goes into posting on forumsmaxlorenz said:Really???
You should... 😎
I designed my speakers with active drive in mind. The passive crossover is a temporary concoction lying on the floor behind the box with wires sticking out on all sides. It's just screaming "make me active". Especially when you consider that the intended 1x400+2x180 active system would take up exactly as much space as the passive xover.
The only excuse I can always make of course is that a passive system makes it easier to do listening tests on amps.
It will probably happen once I have finished developing the new 8-ch DAC and DSP unit (you might know of my involvement in www.grimmaudio.com. The DSP unit is referred to as DD1 there). That would make a neat digitally filtered active system.
I Just put modules in my old amp for immediate check.
1.+/- and power ground connected directly to the PCU caps by wires appr 10-15 cm length for both units
2.signal In connected to the original RCA input jack via twisted pair cable
(inverted In wire grounded at RCA gnd pin)
3.turn on wire grounded for both units at one point near the RCA ground
4. T-shape radiators possibly not grounded, only bolted to the back plate of the amp. I am not check the ground at this points so I'm not sure on it.
1.+/- and power ground connected directly to the PCU caps by wires appr 10-15 cm length for both units
2.signal In connected to the original RCA input jack via twisted pair cable
(inverted In wire grounded at RCA gnd pin)
3.turn on wire grounded for both units at one point near the RCA ground
4. T-shape radiators possibly not grounded, only bolted to the back plate of the amp. I am not check the ground at this points so I'm not sure on it.
Why i believe that AD8066 would be better vs AD8620, it is open loop frequency response: Analog devices spice models shows 350hz for 8620 vs 17khz for 8066 (e.g. >30khz for UcD180), audio band in the data sheets directly isn't pointed yet. So 8066 is preferable for the flat THD/Freq response 20-20k.
Funny. The data sheet says open loop gain = 113dB typ (450e+3). GBW (see gain plot for large gain settings) is 60MHz. 60E+6Hz/450E+3=133HzIVX said:
133Hz is a far cry from the 17kHz suggested by the spice model.
(Has anyone noticed how op amp spec sheets have stopped putting GBW in the data sheet, preferring to quote unity gain bandwidth instead? Specmanship again eh? Can't salespeople even keep out of engineer-to-engineer communication like data sheets?) 😡
Oops, it seems AD8066 spice model too much far from the datasheet one. Only 75db DC open loop gain, 100db for 8620 model, OTOH AD825 pretty ok correlation model/ad825.pdf.
Sorry but I've forgotten and not sure.
The new UcD180 v2.0 is still with 10KOhms input or with a 100 KOhms input as the UcD400?
Thanks.
Stef...
The new UcD180 v2.0 is still with 10KOhms input or with a 100 KOhms input as the UcD400?
Thanks.
Stef...