Sorry for the question, but it is not clear for me. You did compared active filter with two single FO with bridged FO + passive filter ?
No. Biamping means passive crossover, separate cables and separate amps. Amps and cables operate full range and are fed identical signals. 4 x FO are used and inputs of each pair are shorted together - thus the halved input impedance
Bridging/balanced - same 4 x FO but this time each pair receives a balanced signal
Biamping wins with a significant margin to both biwiring with a single pair and bridging.
One part of the test i am not entirely happy about is using different cables from the preamp - a cheap Furutech for SE and a bit more expensive Kimber for BAL. Difference is not huge and is anyhow biased towards the BAL connection which for me scored lower.
Active cross... maybe, some day.. the logistics behind it, if done properly... i can see it taking months and potentially leading nowhere. A hybrid solution with active bass drive and passive mid/hi seems a lot more realistic.
Bridging/balanced - same 4 x FO but this time each pair receives a balanced signal
Biamping wins with a significant margin to both biwiring with a single pair and bridging.
One part of the test i am not entirely happy about is using different cables from the preamp - a cheap Furutech for SE and a bit more expensive Kimber for BAL. Difference is not huge and is anyhow biased towards the BAL connection which for me scored lower.
Active cross... maybe, some day.. the logistics behind it, if done properly... i can see it taking months and potentially leading nowhere. A hybrid solution with active bass drive and passive mid/hi seems a lot more realistic.
Thanks reporting experience where your system gets best sonics.
Though above is not best choice for your system setup it must be most same equal tecnical setup in your system for comparing bridged verse non bridged FO (except the cable from preamp), did you notice sonic difference in that setup. Forgive if wrong or i misunderstood about the wiring setup it's rather technical setup up in head and see the right picture
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Are you asking about the comparison between normal 2 x FO in stereo against 4 x FO in bridge? This was the main event of the audition, as i already had a pretty good idea of what to expect from biamping.
If so, let me expound a bit on this. I had high expectations for the balanced version but the sound was quite disappointing. It gave a pleasant impression of calmness and serenity but it was at the expense of less detail and focus in the mids and highs. Generally not an improvement. Not sure if the increase in headroom was audible at all. Deepest bass may have been better defined but it was a very subtle difference.
Without any doubt, if the additional power of bridging is not required, the non-bridged version is better and more resolved. Again - for my set of ears and in my system.
Bi-amping offered very little additional improvement to the non-bridged and already biwired version. It is probably not cost efficient - it is, after all, an entire extra amp for only a marginal increase in dynamics, bass quality and soundstage. From my POV though it is very much worth the price and effort.
Further details - PS voltage, loaded with the 4 FO modules came to just over 40v at idle per rail. All tests were conducted with the 4 modules always on, irrespective of how many were actually used. A single shared transformer PS of only 500VA was used but the amp was not pushed hard at all. The two module, two channel version was the only one that was entirely hum free - both the bridged and biamped version had a bit of hum. Next step before building a "proper" version will be to see if using a remote transformer will eliminate the hum.
If so, let me expound a bit on this. I had high expectations for the balanced version but the sound was quite disappointing. It gave a pleasant impression of calmness and serenity but it was at the expense of less detail and focus in the mids and highs. Generally not an improvement. Not sure if the increase in headroom was audible at all. Deepest bass may have been better defined but it was a very subtle difference.
Without any doubt, if the additional power of bridging is not required, the non-bridged version is better and more resolved. Again - for my set of ears and in my system.
Bi-amping offered very little additional improvement to the non-bridged and already biwired version. It is probably not cost efficient - it is, after all, an entire extra amp for only a marginal increase in dynamics, bass quality and soundstage. From my POV though it is very much worth the price and effort.
Further details - PS voltage, loaded with the 4 FO modules came to just over 40v at idle per rail. All tests were conducted with the 4 modules always on, irrespective of how many were actually used. A single shared transformer PS of only 500VA was used but the amp was not pushed hard at all. The two module, two channel version was the only one that was entirely hum free - both the bridged and biamped version had a bit of hum. Next step before building a "proper" version will be to see if using a remote transformer will eliminate the hum.
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Thanks analog_sa taking further time it is good info. Think a lot of work/testing until now wish you good building with the so called "proper" version.
Ignore if not already knowing, following is just info and my admiration what member metallicus69 did over the VSSA thread. The bridged VSSA amp called XVSSA metallicus69 did was configured some non conventional way by PSU and grounds. He did the ESP safety earth trick. Floating PSU without center but a added virtual ground think something ala first picture but with added CM. Second picture his drawing where feedback caps are X'ed and floating such this point and feedback do not pollute virtuel ground (don't know if FO schematic is same here and be accepted). Think he reported he could safely connect only signal +/- from preamp without ground connected, whereafter LC posted that's called real H bridge if I remember correct.
Ignore if not already knowing, following is just info and my admiration what member metallicus69 did over the VSSA thread. The bridged VSSA amp called XVSSA metallicus69 did was configured some non conventional way by PSU and grounds. He did the ESP safety earth trick. Floating PSU without center but a added virtual ground think something ala first picture but with added CM. Second picture his drawing where feedback caps are X'ed and floating such this point and feedback do not pollute virtuel ground (don't know if FO schematic is same here and be accepted). Think he reported he could safely connect only signal +/- from preamp without ground connected, whereafter LC posted that's called real H bridge if I remember correct.
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I was afraid of this. So the bass/medium amp is feed with a full range signal and no charge in trebles, and the treeble amp, no charge at Low Frequencies ?
@Byrtt
Thanks for posting this - it's news to me. For all intents and purposes the FO schematic is identical, so all of the above should be valid. It is easy to have a hum-free amp using separate supplies per channel or ground isolating transformers at input. Not so easy with shared supplies. As for SMPS, the concept of adding additional RF sources to my listening environment does not greatly appeal. Purely anecdotal indeed, but i never heard a commercial amp using a SMPS that i liked.
@Esperado
Not sure what makes you afraid - me explaining what "bi-amping" means? This thread is about FO, various modes of connection and use. Adding an active crossover will turn the thread into something entirely different.
@Lazy Cat
Once again congratulations and thanks for designing this simple, cool and amazingly good sounding amp.
Thanks for posting this - it's news to me. For all intents and purposes the FO schematic is identical, so all of the above should be valid. It is easy to have a hum-free amp using separate supplies per channel or ground isolating transformers at input. Not so easy with shared supplies. As for SMPS, the concept of adding additional RF sources to my listening environment does not greatly appeal. Purely anecdotal indeed, but i never heard a commercial amp using a SMPS that i liked.
@Esperado
Not sure what makes you afraid - me explaining what "bi-amping" means? This thread is about FO, various modes of connection and use. Adding an active crossover will turn the thread into something entirely different.
@Lazy Cat
Once again congratulations and thanks for designing this simple, cool and amazingly good sounding amp.
....
Hi LC,
It would be nice if you also could test AMB's new fully balanced/differential line preamplifier. He still has some beta boards available for testing.
AMB Laboratories DIY Audio • View topic - ?24 introduction and development
It could be a great comparison with RelaixedSMD
What do ya think?
Do
It would be nice if you also could test AMB's new fully balanced/differential line preamplifier. He still has some beta boards available for testing.
AMB Laboratories DIY Audio • View topic - ?24 introduction and development
It could be a great comparison with RelaixedSMD
What do ya think?
Do
Open loop gain and bandwidth will measure as soon as I'll get heatsinks and chassis ordered. Report as usual here.
Yes, but commercial SMPS-s aren't good as SMPS1200A400. Believe me the First One sounds much better with SMPS1200A400, linear unregulated PSU is like someone would pull hand break to music.
Grounding and in chassis wiring layout is always very very important.
You're wellcome. Small PCB size makes the First One very usable in all kinds of chassis types, active amps, full balanced amps, etc.
Full balanced and bridge versions need good ballanced source, correct grounding and good interconnect cables. If any of these fails, sound's gone. One simple unbalanced interconnect cable makes a great difference, imagine all the rest.
Today Relaixed SMD was connected into the system, with great expectations I can only admit that I was disappointed. OK, it was inserted between Benchmark DAC2 and the First One, extra pair of interconnect cables also appeared as necessity.
Sound in terms of frequency linearity stayed quite the same but micro details, space/stage atmosphere, musicians locations, bodies all fell into speaker's plane, no real musical feeling, a lot more brain activity and less comfort.
I asume the problem is passive attenuator at the Relaixed output, no zero gain buffer present.
As expected all active and passive electronics in the chain exhibit worse than just simple plain twisted pair interconnect cables.
Integrated amplifier is more obsolete nowadays since there are a plenty of DAC-s having many source selection and preamps already built in, so why bother.
Regards, L.C.
Yea analog is sensitive when a certain soundstage quality is reached. Remind me you held VSSA and FO as simple as possible, seems it payed back together with other of your skills
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Well you're right that many DACs have preamps and source selection but if we want to stay in the DIY not so many are available. But I guess it is alright, I've got too many amps so I'll use one per source!
Ciao!
Do
i was very close to bargain about those results ;-)
I was surprised by the way the OPA was placed.
It seems more logical to use a 47 K constant impedance attenuator followed by a driver.
May-be it would be interesting to try a CFA OPA (AD811 ?) at the place of the original one ?
And/or add a buffer after the attenuator ?
To analog_sa, no need to: "me explaining what bi-amping means", sometimes, read my lips ;-)
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Excellent points. Cable in use is a Kimber Select Needle Doctor 1-800-229-0644, Kimber Kable Select KS 1111 Interconnects
and for balancing i rely on the symmetry of a Tango NP-8 line out transformer. TBH i have no idea how good that is - first time i am using the outputs balanced.
Btw, as an alternative SE line stage i use a pair of Shallcos into Calvin's buffer and really like the result.
Interesting, can you describe your system a little bit more in detail, source and speakers particularly.