BeePre2 amplifier matching

[sl-15]

Hi, I am interested in upgrading my amplifier to an Ayre V-3, input impedance 10 kohm, voltage gain 32db, power output 100W into 8ohm. I would like to know if it will work with my BeePre2. I have all the upgrades but they are not installed yet. BeePre2 has 3kohm output impedance. My speakers are Sonus Faber Grand Pianos Concerto, 87dB, power handling 30-200W. I am curious if the impedances match, going by the 10:1 rule they do not. And does the Ayre maybe have to much gain? My old amp, Pioneer Spec-4 has input attenuators and I never use it fully open. If I would I have almost no voltage adjustment on the BeePre2. Thank you.

 

[Paul Birkeland]

I had a V1XE here for a while on consignment. I don't normally like solid state, but Charley had a unique way of looking at his designs that seemed quite effective, even though it didn't always measure that way.

You will absolutely need both of the upgrades on the BeePre to drive the V-3 properly. The second upgrade drops the output impedance down to 400 ohms, which is perfect for the V-3. You'll also have no turn-on thump with the second upgrade, and that is certainly appreciated by solid state amplifiers.

As far as "too much gain", most systems definitely have too much gain. The BeePre has very, very low gain, so it's a good choice for what you're up to. The V-3 does, however, make its full power with 0.7V of signal coming into it. This is a good place to consider a pair of inline attenuators to reduce the sensitivity of your system, as even with 87dB sensitive speakers, your system is going to want to get really loud in a big hurry when you start turning up the volume!

-PB

 

[sl-15]

Thanks Paul. The V-3 appeals to me because it is available used locally and I like the idea behind the design, no feedback, almost running in Class A most of the time and added chokes in the power supply I believe. It also has a stand by switch so the turn on thump can be avoided.Thats what I like so much about my Spec 4, you can just turn the inputs down all the way.

Another local option is an Audio Research 100.2 power amp. It has an input impedance of 150KOhms. I guess that would be a better value for the BeePre2 without the updates?
The problem is I do not have any building time in the foreseeable future so the BeePre upgrades have to wait.
The gain structure in my system is only a problem with vinyl. I am using the Eros1 and it plays way louder than my DAC, which is a Wavelenght Brick N2. I dislike the idea of input attenuators, adding another link with RCAs but if it does not work any other way I guess I have to go that route.
My other options are to find someone who repairs vintage Pioneers but that repair will take a long time if I even find someone.

 

[Paul Joppa]

PB posted while I was writing, and said pretty much the same things, but I'll leave it here anyway:

Fortunately, the manuals for the Pioneer and the Ayre are available on the web. Based on those specs the Pioneer has about 14dB less gain than the Ayre, plus any attenuation adjustment at the Pioneer input. If you set the Pioneer input attenuators to -6dB, there's a 20dB difference. You would have to introduce something to attenuate the signal by 20dB.

That is well within the range of the Bee2Quiet stepped attenuator upgrade kit, or you can install inline attenuators. The stock RCA jack outputs should work well enough, since both impedances are resistive. The balanced output upgrade has a lower impedance (nominally 600 ohms).

 

[sl-15]

Thanks Paul J. It is so great to have both of your knowledge on this forum. I am not sure how you figured out these numbers, I do have the Pioneer manual and did not find the voltage gain anywhere.
Anyways two more questions here:
Quote: If you set the Pioneer input attenuators to -6dB, there's a 20dB difference. You would have to introduce something to attenuate the signal by 20dB.
Are you saying there is a 20 dB difference between the Ayre and the Pioneer? That seems huge.

And does the Bee2Quiet stepped attenuator upgrade kit provide more attenuation to the BeePre2?

 

[Paul Joppa]

Thanks Paul J. It is so great to have both of your knowledge on this forum. I am not sure how you figured out these numbers, I do have the Pioneer manual and did not find the voltage gain anywhere.
Anyways two more questions here:
Quote: If you set the Pioneer input attenuators to -6dB, there's a 20dB difference. You would have to introduce something to attenuate the signal by 20dB.
Are you saying there is a 20 dB difference between the Ayre and the Pioneer? That seems huge.

And does the Bee2Quiet stepped attenuator upgrade kit provide more attenuation to the BeePre2?

It seems huge because it IS huge! lol I made an error in my too-hasty calculations. Here's my thinking:

Service Manual:

https://www.cieri.net/Documenti/Vintage%20Audio/PIONEER/PIONEER%20-%20SPEC-4%20-%20Stereo%20Power%20Amplifier%20-%20Service%20Manual.pdf

page 3 says sensitivity is 1v/50kohm. I assumed that was for full rated power which is 150 watts, which is 35v at 8 ohms. So the gain is 31dB, not the 19dB I got before, and almost exactly identical to the Ayre. I'll edit my post.

The amps therefor have very close to the same gain, if the Pioneer is turned to maximum gain. Where do you normally set it? That's the amount of attenuation you want. If it's less than 6-10dB you're probably good to go with the stock BeePre II using RCA interconnects.

 

[sl-15]

It seems huge because it IS huge! lol I made an error in my too-hasty calculations. Here's my thinking:

Service Manual:

https://www.cieri.net/Documenti/Vintage%20Audio/PIONEER/PIONEER%20-%20SPEC-4%20-%20Stereo%20Power%20Amplifier%20-%20Service%20Manual.pdf

page 3 says sensitivity is 1v/50kohm. I assumed that was for full rated power which is 150 watts, which is 35v at 8 ohms. So the gain is 31dB, not the 19dB I got before, and almost exactly identical to the Ayre. I'll edit my post.

The amps therefor have very close to the same gain, if the Pioneer is turned to maximum gain. Where do you normally set it? That's the amount of attenuation you want. If it's less than 6-10dB you're probably good to go with the stock BeePre II using RCA interconnects.

Ah, very good, that makes a lot of sense now and I can go from there. Thank you again. Guess its time to put my Foreplay 3 extended back into duty until I fix up my BeePre2 with the upgrades to match impedances for the Ayre.

 

[sl-15]

I had a V1XE here for a while on consignment. I don't normally like solid state, but Charley had a unique way of looking at his designs that seemed quite effective, even though it didn't always measure that way.

You will absolutely need both of the upgrades on the BeePre to drive the V-3 properly. The second upgrade drops the output impedance down to 400 ohms, which is perfect for the V-3. You'll also have no turn-on thump with the second upgrade, and that is certainly appreciated by solid state amplifiers.

As far as "too much gain", most systems definitely have too much gain. The BeePre has very, very low gain, so it's a good choice for what you're up to. The V-3 does, however, make its full power with 0.7V of signal coming into it. This is a good place to consider a pair of inline attenuators to reduce the sensitivity of your system, as even with 87dB sensitive speakers, your system is going to want to get really loud in a big hurry when you start turning up the volume!

-PB

What would happen if I use the BeePre without the upgrades driving the V-3 improperly? Lack of low end and high frequencies extension?
And is there a product that you can recommend for inline attenuators? Thanks.

 

[Paul Birkeland]

Cable/input capacitance could be exaggerated depending on some factors that aren't so easily kept in mind. You can certainly try it, as it's not going to hurt anything.
https://www.rothwellaudio.16.ekm.shop/in-line-attenuators-2-p.asp

Rothwell makes -20dB attenuators, which could be a good idea for your system, or at least the -15dB set. You want the ones not denoted with the "source" label. Plug them into the inputs of your amplifier, not the output of the preamp.

 

[Paul Joppa]

Rothwell is recommended because they seem to use 100K series resistors. There are other makers but the ones I have tested all operate at 10K, which would not solve the impedance problem.

 

[Paul Birkeland]

I should add for clarification that I recommend the attenuators from an overall gain standpoint, not as a device to magically make the BeePre without the second upgrade work into a low impedance load.

 

[sl-15]

I should add for clarification that I recommend the attenuators from an overall gain standpoint, not as a device to magically make the BeePre without the second upgrade work into a low impedance load.

I am definitely planning to add the upgrades as soon as I can. Got the amp already, hooked it up and it sounded great for 15 min. Quite another musical dimension compared to my Pioneer Spec-4. But then a buzzing sound started to develop, not sure what is going on, I have to do further tests tomorrow. Luckily I have a warranty and will be able to return it if it is not working right. From the short time it seemed that I can get away without attenuators but I think if I want to use my turntable I will need them.