Hit a snag. The plan was to use the two stereo S/PDIF outputs of the Flex into the two stereo DACs of the ADI-2 Pro.
One stereo pair to the solid state amp driving the step-up network, the other stereo pair to the DAC driving the direct drive.
This latter signal being EQd so the response at the stators is identical in level and response for the two cases. I showed the EQ results before.
But. One DAC of the ADI-Pro only accepts either an XLR/AES signal input, or the same S/PDIF that feeds the other DAC. Normally you can drive an AES input with an S/PDIF signal but this particular combination kept dropping out.
After a restless night and roaming the 'net in search for a real S/PDIF to AES converter, a light went off: I could drive both ADI-2 DACs by the same S/PDIF with a flat response signal, sending it unchanged to the setup stuff, and EQ the other DAC for the direct drive!
So back to the Flex, writing down the parameters of the EQ I worked out before (freq, gain, Q and type for 4 IIR filter), and copy these into the ADI-Pro filter screen, reset the Flex to flat, feed both ADI Pro DACs from the one S/PDIF it can read, and enable the EQ only in the DAC feeding the direct drive.
Lo and behold - it just worked!
So the Flex will only be used for the Dirac room correction and that will then affect both the step-up chain and the direct drive chain equally.
It's really simpler than it is to read it ;-).
I'll make a drawing.
Jan
One stereo pair to the solid state amp driving the step-up network, the other stereo pair to the DAC driving the direct drive.
This latter signal being EQd so the response at the stators is identical in level and response for the two cases. I showed the EQ results before.
But. One DAC of the ADI-Pro only accepts either an XLR/AES signal input, or the same S/PDIF that feeds the other DAC. Normally you can drive an AES input with an S/PDIF signal but this particular combination kept dropping out.
After a restless night and roaming the 'net in search for a real S/PDIF to AES converter, a light went off: I could drive both ADI-2 DACs by the same S/PDIF with a flat response signal, sending it unchanged to the setup stuff, and EQ the other DAC for the direct drive!
So back to the Flex, writing down the parameters of the EQ I worked out before (freq, gain, Q and type for 4 IIR filter), and copy these into the ADI-Pro filter screen, reset the Flex to flat, feed both ADI Pro DACs from the one S/PDIF it can read, and enable the EQ only in the DAC feeding the direct drive.
Lo and behold - it just worked!
So the Flex will only be used for the Dirac room correction and that will then affect both the step-up chain and the direct drive chain equally.
It's really simpler than it is to read it ;-).
I'll make a drawing.
Jan
So far, listening sessions (the few and short ones I've done) are interesting. With the EQ, switching between the two modes didn't change level or tonality.
I did hear a difference in voices, especially male. If you listen to a real male voice there's a rough, grating edge to most.
I clearly hear that in the direct drive mode, while in the step-up mode that edge is, how to say, glossed over. Sanded off.
I need to do a lot more listening to music. An adventure really.
Jan
I did hear a difference in voices, especially male. If you listen to a real male voice there's a rough, grating edge to most.
I clearly hear that in the direct drive mode, while in the step-up mode that edge is, how to say, glossed over. Sanded off.
I need to do a lot more listening to music. An adventure really.
Jan
Thanks for the update!
Also a big congratulations on DIY your Direct Drive tube amp. Legend.
Your experience with the male voice timbre with DD is exactly the kind of midrange nuance that DD has been able to deliver in other systems.
Ive heard a few memorable systems over the decades that left a lasting impression. All superb systems with very different approaches eg vinyl to digital, drivers to ESL. The very best midrange came from a DD to Acoustat. Sublime mid clarity with fully retained musical expression ie no etch highlighting details.
Enjoy the adventure and the music.
Do you have some recording that are revealing for you?
I find music that helps me is:
1. music I love - this prevents falling into the technical listening to the system trap and makes it fun
2. tracks with well micced single vocal with
- piano
- double bass
- complex beats
Apologies in advance but here comes some more gratuitous input (cringe)
- are you protecting your DD with a high and low pass?
- the more revealing your DD-ESL becomes the more the rest of your system will be a brake:
- can you listen to an R2R DAC and see if you hear what many of us do in terms of improved timbral flow?
- with your DIY expertise would you think about DIY a multi channel R2R DAC down the track as a later project e.g. a miniDSP USB to I2S plus Miro 1862/TDA1541a DACs?
Yes Patricia Barber is good music for this, but her recordings aren't top notch in my view.
I have some very good recordings from Ulla Meinecke and Rickly Lee Jones for instance.
Some Chesky Reords CDs, Cassandra Wilson, Candy Dulfer, Mark Curry's CDs from the 1990-s.
Very often the music I like is not the best recorded music.
I'm compiling a library of excellent recordings, independent of the type of music. Not easy, time consuming.
As to DACs, I'm sceptic. In my experience, perceived differences are just that.
The DD has extensive safety features embedded in the operating software.
Example: if the cable between amp and speaker isn't connected it won't even start up.
While operating it continuously checks output offset, as well as the corona detector status. Problems will make it shut down.
Jan
I have some very good recordings from Ulla Meinecke and Rickly Lee Jones for instance.
Some Chesky Reords CDs, Cassandra Wilson, Candy Dulfer, Mark Curry's CDs from the 1990-s.
Very often the music I like is not the best recorded music.
I'm compiling a library of excellent recordings, independent of the type of music. Not easy, time consuming.
As to DACs, I'm sceptic. In my experience, perceived differences are just that.
The DD has extensive safety features embedded in the operating software.
Example: if the cable between amp and speaker isn't connected it won't even start up.
While operating it continuously checks output offset, as well as the corona detector status. Problems will make it shut down.
Jan
That's really impressive. What an amazing amp.
Does the protection software give any additional protection eg for a child with a fork or a cable chewing dog, from getting badly zapped?
Exactly.
Same here. I keep listening to live takes. I dont know if the live atmosphere is inspiring the musicians to new heights, or if the rough recordings are saved from the excesses of some studio processes.
Enjoy the music
If you copied the PEQ values (Q, Freq, etc) from one manufacturer to an other, changes are that the responses differ - appernelty, PEQ parameters are not very well defined - did you check measure the results?
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In case you guys missed it:
https://audioxpress.com/article/you-can-diy-edd-a-direct-drive-amplifier-for-electrostatic-speakers
Jan
https://audioxpress.com/article/you-can-diy-edd-a-direct-drive-amplifier-for-electrostatic-speakers
Jan
It has to do with the internal implementation of the biquads used to create the PEQ. Everything from FIR vs. IIR to single vs double precition vs sample rate etc. Some of the compromises don't show on fresponse graphs since they involve truncations etc. This is one of the better and more understandable intros to DSP filter issues. https://eclipseaudio.com/fir-filter...ering_in_fir_designer_v42&utm_term=2024-04-03
I don't doubt that Jan has an ecxelent grip on PEQ from a mathematical point of view. I have just observed that as 1auido says, the outcome on the RCA connector is apparently different between manufactures for the same PEQ. miniDSP was one that stood out compared to many others if I recall correctly...
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In yor indeed very insteresting writing you measure thd at the stators @ 500V RMS direct drive. And you get really impressivly low at -110dB! But then, how much resulting acoustic distortion, measured by a mic do you get at these 500V RMS input? And how much dB's of SPL does the Quad63 output at this 500V RMS feeding voltage? Assuming some max. SPL of around 95dB with full drive, then at 500V RMS this might boil down to some 85dB?
I am asking this because eventually many would dare to build a voltage-wise stripped-down, "little man's" direct drive amplifier outputting "only" up to 500V RMS. As for me, a max. SPL of 85dB would largly match my daily audio consumptions habits. Therefore, restricting the max. possible output voltage of such an amp along with sacrifying some dB of max. output would certainly come along with a much easyier approach for many DIY-ers. And talking about 500V RMS output, maybe also some high-voltage semiconductors might fit the bill. So maybe no more need to resort to valves at this voltage?
I didn't measure the output SPL but from experience I think your 85dB would be about right. Distortion of the speaker was below 0.1% for most of the frequency range, rising to above 1 or 2% below 400 Hz. I am currently working on an amp with double the output voltage (7800V pk-pk) but that's more than 2 x as hard. OTOH, I learned a lot and in some places can make it simpler.
But as you know, you often can hear amplifier distortion even if it is below the speaker distortion. One of the riddles that has not yet been solved I think.
Jan
I basically agree, no urge at all. Anyway, you may consider this one: A physically smaller and less heating unit might fit into one of the the two spare transformer's spacings of an ESL63 base. And you could fit the supply into the other spare spacing. This would make for a nice, electroshocksafe and lean all-in-one upgrade for ESL63's.
Could eventually a class D design be teached to output some 2kV? Still fitting into an average base of an average ESL?