Hi,
Does somebody know what a double diamond buffer means.
They don't use a volume potmeter but I think they change the current of the balanced input pair.
Does somebody experiment with this kins of variable gain circuitry.
A friend of mine bought this amplifier and it sounds great.
I'm going to try to build something like this and see how it works and sounds.
Rob
Does somebody know what a double diamond buffer means.
They don't use a volume potmeter but I think they change the current of the balanced input pair.
Does somebody experiment with this kins of variable gain circuitry.
A friend of mine bought this amplifier and it sounds great.
I'm going to try to build something like this and see how it works and sounds.
Rob
Probably not a Pass topic, but the DD output circuit is based on a patent from the 60s, IIRC (but which I cannot find at the moment). The volume circuit is a different thing, but if the AX5 is anything like their reference series 20 preamp in that regard, it uses a stunning collection of discrete resistor pots ganged together by elaborate mechanical pulleys. I think it would be hard to DIY something like that, but the basic variable gain transconductance architecture could be done in various ways.
one way to do it is this:
the input stage is a transconductor (voltage in, current out). if you feed the output current through (variable) resistor to get a voltage output, as you vary that resistance, you change the gain of the transconductance. in your preamp, this will behave like a traditional volume control, but you get the S/N benefits Ayre mentions in their literature. works pretty well ...
the input stage is a transconductor (voltage in, current out). if you feed the output current through (variable) resistor to get a voltage output, as you vary that resistance, you change the gain of the transconductance. in your preamp, this will behave like a traditional volume control, but you get the S/N benefits Ayre mentions in their literature. works pretty well ...
Hi Aleph5,
I know this circuit and build it a couple of times, but I want to know what they mean with Double Diamond.
Are they two diamond buffers with the load between them, I don't understand what they mean.
I looked on the web but can't find a schematic of it.
Rob
I know this circuit and build it a couple of times, but I want to know what they mean with Double Diamond.
Are they two diamond buffers with the load between them, I don't understand what they mean.
I looked on the web but can't find a schematic of it.
Rob
@Rob Dingen: FWIW here is a quote from some Ayre literature on their website:
"So, in addition to some of the accepted Ayre hallmarks, such as a fully balanced, fully complimentary circuit topology, zero feedback, and the pre-amp’s Variable Gain Transimpedance (VGT) volume control, these new 5-Series models also benefit from some new developments. There’s the AyreLock power supply, which claims to lock the output voltage of the power regulator, regardless of load fluctuations, while the famous diamond output stage used by Ayre has undergone further development. It’s now referred to as a double diamond output stage. In the original, two pairs of bipolar transistors are connected via their emitters and bases as an alternative to the more common push-pull topology. The so-called double diamond configuration adds a new buffer stage, also employing the diamond circuit principle. This increases efficiency and reduces heat output. I
"So, in addition to some of the accepted Ayre hallmarks, such as a fully balanced, fully complimentary circuit topology, zero feedback, and the pre-amp’s Variable Gain Transimpedance (VGT) volume control, these new 5-Series models also benefit from some new developments. There’s the AyreLock power supply, which claims to lock the output voltage of the power regulator, regardless of load fluctuations, while the famous diamond output stage used by Ayre has undergone further development. It’s now referred to as a double diamond output stage. In the original, two pairs of bipolar transistors are connected via their emitters and bases as an alternative to the more common push-pull topology. The so-called double diamond configuration adds a new buffer stage, also employing the diamond circuit principle. This increases efficiency and reduces heat output. I
Hi,
I believe that Ayre uses a 3 stage diamond buffer, as opposed to the 2 stage "classic" diamond buffer. The output portion has 2 emitter followers in series (darlington-like) in this version. This approach allows the input stage to operate at lower current which reduces loading on the driving stage.
Two diamond buffers in series are required following the JFET + current mirror gain/input stage in the power amp. The first diamond buffer is used for current boost so the gain stage is lightly loaded. The first diamond buffer drives the output diamond buffer. The Ayre MX-R Twenty drives both the + and - outputs to the speaker (bridge mode), so there are 2 diamond buffers driving the speaker. Double diamond may refer to this, or to the modified diamond buffer topology to include 3 stages of current gain.
I have built several versions of a line level diamond buffer (up to +/-20V out, 2Kohm load), and with careful selection of devices, I have achieved distortions of -100 to -110 dB (0.001% to 0.00032%). This low distortion means that cascading diamond buffers is feasible in a design.
An input gain stage can use a change of a resistor value to change the gain of the stage instead of attenuating the signal going into a fixed gain stage. This minimizes noise, as no excess gain is used. In the KX-R Twenty, the volume control consists of 2 sets of resistors per channel. I suspect the switches that connect the various resistors are Shallco custom switches (with stepper motors for each channel).
Please note: I do not own any Ayre products, and have only seen photos and Charlie Hansen's comments on the web. Charlie was brilliant, and his ideas are worth considering for any similar design. I have run many simulations exploring Charlie's comments and built multiple circuits so I could measure the "real life" performance to reach these conclusions, but my conclusions are not verified w/r/t Ayre products.
-Morty
I believe that Ayre uses a 3 stage diamond buffer, as opposed to the 2 stage "classic" diamond buffer. The output portion has 2 emitter followers in series (darlington-like) in this version. This approach allows the input stage to operate at lower current which reduces loading on the driving stage.
Two diamond buffers in series are required following the JFET + current mirror gain/input stage in the power amp. The first diamond buffer is used for current boost so the gain stage is lightly loaded. The first diamond buffer drives the output diamond buffer. The Ayre MX-R Twenty drives both the + and - outputs to the speaker (bridge mode), so there are 2 diamond buffers driving the speaker. Double diamond may refer to this, or to the modified diamond buffer topology to include 3 stages of current gain.
I have built several versions of a line level diamond buffer (up to +/-20V out, 2Kohm load), and with careful selection of devices, I have achieved distortions of -100 to -110 dB (0.001% to 0.00032%). This low distortion means that cascading diamond buffers is feasible in a design.
An input gain stage can use a change of a resistor value to change the gain of the stage instead of attenuating the signal going into a fixed gain stage. This minimizes noise, as no excess gain is used. In the KX-R Twenty, the volume control consists of 2 sets of resistors per channel. I suspect the switches that connect the various resistors are Shallco custom switches (with stepper motors for each channel).
Please note: I do not own any Ayre products, and have only seen photos and Charlie Hansen's comments on the web. Charlie was brilliant, and his ideas are worth considering for any similar design. I have run many simulations exploring Charlie's comments and built multiple circuits so I could measure the "real life" performance to reach these conclusions, but my conclusions are not verified w/r/t Ayre products.
-Morty