I use a pair of big Martin Logan ESL Monolith III (modified with much better bass drivers, ACI-SV-12's <130hz) bi-amped with a pair big current high (ESL amp up'ed to 30w classA) biased Krell like monoblocks called ME850's, everything is direct coupled from the PCM1704's outputs to the speakers.
Cheers George
Cheers George
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Nice setup!
Hi George, Very nice setup. I trust what you hear. Pretty similar to what I do. I'd love to have ESL's someday. For now the Magnepan MG2.5R with upgraded and redesigned crossovers will have to do. The ribbon tweeter really makes this speaker sing. Thanks for sharing! 😀
Just found another pic I had
This is what the insides of the amps look like. And the big ME1500
Cheers George
This is what the insides of the amps look like. And the big ME1500
Cheers George
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Nice to see some of Peter Stein's amps mentioned here - they always sounded superb and much better than they cost.
ME1500
That is quite the amplifier. Mine looks pretty tiny in comparison. I just have a "Class D Audio" Amplifier, I think it is the SDS-570. Made in California. Has 300 WPC into 4 Ohms. I pair it with the Nelson Pass BA-3, a Class A JFET and Mosfet design with Didden Super regulators in a dual mono setup. Both channels are totally separate with their own power supplies for the best possible separation between channels. Would love to have a set of ME1500's or comparable Krell's. 😉
Do you have any components on ad844 output pin 6 at all? I have plenty of opa627 and I'm willing to try but first I want to try paralell internal over 3x100ohms. Are you using separate power supplies for opa627? I presume opa is in noninverting config. Small schematic for opa627 and comp values used would be nice.
I will try this for TDA1541.
Regards, Milan
OPA 627 is stable Under x 2 gain ?
I surmise an even better result with a unity gain stable stage, why not discrete...
I surmise an even better result with a unity gain stable stage, why not discrete...
Ah, yes it is ! I mix with an other one 😱 !
Does anyone know if the double LM 13700 could do the job in lieu of the mono AD844 ? Outputtbuffer are bypassable !
http://www.ti.com/lit/ds/symlink/lm13700.pdf
Don't know if it has a mono equivalent ? sort of OPA861 ? but in dip 16...😕
Does anyone know if the double LM 13700 could do the job in lieu of the mono AD844 ? Outputtbuffer are bypassable !
http://www.ti.com/lit/ds/symlink/lm13700.pdf
Don't know if it has a mono equivalent ? sort of OPA861 ? but in dip 16...😕
Yes from pin 6 to analogue ground I have a 2.7kohm to set the gain I want and a 470pF across it to give me a first order LP of -3db @ 127khz, after that is my OPA627 buffer set for 2 x gain.
Cheers George
LM13700 is a very versatile chip - I've used it in a couple of places in my designs but probably unsuitable for this application. I think my old NAD cassette deck had one of these inside. There's very little GBW available (only 2MHz) so best not to expose it to steep steps such as come out of DACs. It can work as a voltage controlled volume element if you're not particularly concerned about THD.
But its a classA buffer!
There was CA3080 (also 2MHz, 50V/uS) but that's been obsolete for years.
Hi,
the LM13700 is no replacement for the AD844 or OPA861.
The DS talk of beeing a current controlled circuit is probabely misleading here, as it describes a Transconductance amplifier (voltage In, current Out) whith the specialty of access to Pins for biasing.
The Input Pins though just access the high-ohmic Bases of the input differential pair, while in the AD844 and OPA861 You can access the low-ohmic Emitters.
That way both function as Transresistance (Transimpedance) amplifiers (current In, current Out).
jauu
Calvin
the LM13700 is no replacement for the AD844 or OPA861.
The DS talk of beeing a current controlled circuit is probabely misleading here, as it describes a Transconductance amplifier (voltage In, current Out) whith the specialty of access to Pins for biasing.
The Input Pins though just access the high-ohmic Bases of the input differential pair, while in the AD844 and OPA861 You can access the low-ohmic Emitters.
That way both function as Transresistance (Transimpedance) amplifiers (current In, current Out).
jauu
Calvin
Hi There;
I ve been reading the 100 pages some month ago, and back on it today.
Well any one could point on the "final" schematic for the 3x stacked version ?
I understood that we sum up all the TZ via say 100ohm ish and then go to ground with 1.k5 to 2k7 depending on which gain we need, and putting a 470pf in // in order to get a 125khz roll off.
also understand the best for georges is to have a 627 buffer 1.5x connected across the 2k7 resistor. So at then end the Diamond buffer on pin 6 is not used at all, right ?
also all the input (pin 2) are in paralell and therefore the dac current is spread across the ADs which keep them working in class A.
finally, a trim pot across pin 1 and 8 enables nulling offset.
is that all of it ? anyone made a clean Eagle schematic ?
for PSU, is it better to go with +/- 12V ?
Many thanks 🙂
I ve been reading the 100 pages some month ago, and back on it today.
Well any one could point on the "final" schematic for the 3x stacked version ?
I understood that we sum up all the TZ via say 100ohm ish and then go to ground with 1.k5 to 2k7 depending on which gain we need, and putting a 470pf in // in order to get a 125khz roll off.
also understand the best for georges is to have a 627 buffer 1.5x connected across the 2k7 resistor. So at then end the Diamond buffer on pin 6 is not used at all, right ?
also all the input (pin 2) are in paralell and therefore the dac current is spread across the ADs which keep them working in class A.
finally, a trim pot across pin 1 and 8 enables nulling offset.
is that all of it ? anyone made a clean Eagle schematic ?
for PSU, is it better to go with +/- 12V ?
Many thanks 🙂
If not using the 844's buffers. No 100ohms are used anywhere
3 x stack, pins 2 3 4 7 6 together.
Pin 6 (TZ) to 2.7kohm with 470pf across it to ground.
Pin 6 (TZ) to whatever external buffer your using.
Cheers George
3 x stack, pins 2 3 4 7 6 together.
Pin 6 (TZ) to 2.7kohm with 470pf across it to ground.
Pin 6 (TZ) to whatever external buffer your using.
Cheers George
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Hi George,
Getting confused here
Is pin 6 o/p or tz?
diag shows pin 5 as TZ and pin 6 as o/p.
Do you connect 627 and 2.7kohm/ cap to it and leave the three o/p pins (6?) floating?
I've got a pcm63k based Audio Synthesis DAC, with multiple battery supplies, which I want to try mod this on (when I've finished Rudi's LDR pre-amp).
I'm very happy that you decided that you preferred the 627 as that's what's fitted as the buffer in mine now (was ad811) and saves me £60 on the BUF03.
What difference did the woofers make on your Martin Logans, and are there any better ones around now. I have the Sequel IIs.
Thanks for the time and effort you and others have put in to this.
Getting confused here
Is pin 6 o/p or tz?
diag shows pin 5 as TZ and pin 6 as o/p.
Do you connect 627 and 2.7kohm/ cap to it and leave the three o/p pins (6?) floating?
I've got a pcm63k based Audio Synthesis DAC, with multiple battery supplies, which I want to try mod this on (when I've finished Rudi's LDR pre-amp).
I'm very happy that you decided that you preferred the 627 as that's what's fitted as the buffer in mine now (was ad811) and saves me £60 on the BUF03.
What difference did the woofers make on your Martin Logans, and are there any better ones around now. I have the Sequel IIs.
Thanks for the time and effort you and others have put in to this.
Sorry, brainfart, yes pin 5 is the output to an external buffer, and it gets stacked not pin 6.
I'll try to draw something.
The Eminance woofer were rubbish in the Monolith III and the ACI SV12's (bi-amped now) are a very good replacement, I don't know about the Sequels
Cheers George
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Thanks for clarifying that, George. Don't call me Brainfart😀😀 Don't worry I know what you are saying, at my age it's a common occurrence!!
I improved the bass response of my sequels by adding some internal battens and some matting on the rear, but the room is too small for them really, but I'm not going to let them go!
just made some "dust covers" for them out of some black, stretchy, see through material that I got for £2 a meter at a cloth shop. Makes no difference acoustically but may keep the dust/ c**p off them to some extent.
I improved the bass response of my sequels by adding some internal battens and some matting on the rear, but the room is too small for them really, but I'm not going to let them go!
just made some "dust covers" for them out of some black, stretchy, see through material that I got for £2 a meter at a cloth shop. Makes no difference acoustically but may keep the dust/ c**p off them to some extent.
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