Tube amp conundrum

[Superman541]

I am biamping currently. The preamp goes to a pair of simple RCA splitter cords. One pair goes to a SET amp, and the other pair goes to a Schiit SYS which is not much more than a box with a volume knob, and on to a pair of EL84 monoblocks. The SET feeds the mids and highs, while the monoblocks feed the bass. I can adjust the balance of HF and LF using the SYS. My speakers have crossovers and two sets of binding posts. It sounds pretty good.

 

[FlaCharlie]

Thanks @FlaCharlie, I am going to grab one of those and test it out! Will report back once I get the chance.

Also, there was a Yaqin CD2 tube buffer with GE tubes on eBay for $110 last night, so I grabbed it. Pretty well reviewed and may accomplish some of what I’m looking for in a much simpler configuration.

I'm not sure what a buffer has to do with any of what's been discussed.

I looked that unit up and it is indeed a buffer, not a preamp. Unlike a preamp, a buffer has no gain and it doesn't divide the frequencies like a crossover.

Buffers are mostly useful for driving long interconnects and their very low output impedance is a better match for SS and Class D amp inputs. Tube amps tend to have much higher input impedance so both SS and tube preamps usually work fine with them.

Buffers actually have slightly less than unity gain so, as is pointed out in one of the questions posted about it on Amazon, they will actually reduce the volume a bit. Not sure how noticeable that will be, if any, though. This unit also doesn't have a volume pot, so it can't be used to control the volume.

So I'm a little unclear about what you expect it to do.

 

[FlaCharlie]

I am biamping currently. The preamp goes to a pair of simple RCA splitter cords. One pair goes to a SET amp, and the other pair goes to a Schiit SYS which is not much more than a box with a volume knob, and on to a pair of EL84 monoblocks. The SET feeds the mids and highs, while the monoblocks feed the bass. I can adjust the balance of HF and LF using the SYS. My speakers have crossovers and two sets of binding posts. It sounds pretty good.

I've done this before myself and it can sound pretty good, but that's not really bi-amping as it's typically used because you're sending the same full range signal to each amp and that gets sent to both the woofers and the mid / tweeters.

If the woofer still has its higher frequencies limited by the passive crossover it will function the same as it did with a single amp. But if disconnecting it from the mids / tweeters results in it running full range that will affect the results. Some woofers will roll off higher frequencies gracefully and some really require a low pass filter, which is typically part of most passive crossovers, to sound their best.

Bi-amping typically employs the use of an active crossover which sends only a certain range of frequencies to each amp.

 

[Superman541]

Agreed. The change did not cause the woofer to go full range, so I am left wondering if the speakers are working as designed in terms of frequency rolloffs. Dunno. My knowledge of electronics can best be termed "dangerous." But this effort was $0 cost to do. Of course, after a time, I will likely go back to the single power amp setup to compare some more.

 

[lattiboy]

I'm not sure what a buffer has to do with any of what's been discussed.

I looked that unit up and it is indeed a buffer, not a preamp. Unlike a preamp, a buffer has no gain and it doesn't divide the frequencies like a crossover.

Buffers are mostly useful for driving long interconnects and their very low output impedance is a better match for SS and Class D amp inputs. Tube amps tend to have much higher input impedance so both SS and tube preamps usually work fine with them.

Buffers actually have slightly less than unity gain so, as is pointed out in one of the questions posted about it on Amazon, they will actually reduce the volume a bit. Not sure how noticeable that will be, if any, though. This unit also doesn't have a volume pot, so it can't be used to control the volume.

So I'm a little unclear about what you expect it to do.

There are scores of posts by AudioKarma users swearing by these Yaqin buffers brining a bit of a warmer tube sound to solid state systems. I figure it’s worth $110 to try it out before I do this elaborate active crossover two-amp situation that may not even work because of the crossovers of my speakers.

I can also now do DSP with my Raspberry Pi / Volumino streamer, so I may try that too.

 

[FlaCharlie]

There are scores of posts by AudioKarma users swearing by these Yaqin buffers brining a bit of a warmer tube sound to solid state systems. I figure it’s worth $110 to try it out before I do this elaborate active crossover two-amp situation that may not even work because of the crossovers of my speakers.

I can also now do DSP with my Raspberry Pi / Volumino streamer, so I may try that too.

My point was that a buffer does something totally different than any of the things previously mentioned in this thread.

Lots of people add tube preamps, like the little FX, to their SS and Class D setups and they seem to like the results. I've heard some reports that buffers make less difference than a tube preamp with gain, but I've never used a buffer myself and every system is different. The tube preamp I built does work well with both SS and tube gear.

An active crossover will work well and it's not particularly elaborate since you already have a SS amp to use for the bass and a tube amp you can use for the mids/highs. The only question is whether it will work well using only your Vandersteen speakers and their crossover configuration or if you would need to use a different speaker(s) for the bass.

I think some DSPs may have an active crossover function.

 

[lattiboy]

My point was that a buffer does something totally different than any of the things previously mentioned in this thread.

Lots of people add tube preamps, like the little FX, to their SS and Class D setups and they seem to like the results. I've heard some reports that buffers make less difference than a tube preamp with gain, but I've never used a buffer myself and every system is different. The tube preamp I built does work well with both SS and tube gear.

An active crossover will work well and it's not particularly elaborate since you already have a SS amp to use for the bass and a tube amp you can use for the mids/highs. The only question is whether it will work well using only your Vandersteen speakers and their crossover configuration or if you would need to use a different speaker(s) for the bass.

I think some DSPs may have an active crossover function.

I’m looking for some tube-ish smoothing effect on the highs as my system is extremely transparent and can be a little bright with some material. I use my THX onyx as a preamp / DAC as it just matches perfectly with my Denon POA2200 and allows me to adjust volume with my phone. My understanding is the Yaqin has a small volume drop which can be easily compensated for and it simply passes through the signal when off, which is ideal for me.

Maybe in a few months when I have time I’ll drop the $$$ to get a 50wpc tube amp and see if I prefer it, but I think with the odd Vandersteen configuration I’m going to run into a lot of problems trying to bi-amp like adding a bass speaker i don’t have room for.

Thanks to everybody in the thread for de-mystifying this for me!

 

[FlaCharlie]

I’m looking for some tube-ish smoothing effect on the highs as my system is extremely transparent and can be a little bright with some material. I use my THX onyx as a preamp / DAC as it just matches perfectly with my Denon POA2200 and allows me to adjust volume with my phone. My understanding is the Yaqin has a small volume drop which can be easily compensated for and it simply passes through the signal when off, which is ideal for me.

Maybe in a few months when I have time I’ll drop the $$$ to get a 50wpc tube amp and see if I prefer it, but I think with the odd Vandersteen configuration I’m going to run into a lot of problems trying to bi-amp like adding a bass speaker i don’t have room for.

Thanks to everybody in the thread for de-mystifying this for me!

Ahhh . . . well this is the first time you've mentioned that you have an issue with the system being overly bright.

Just curious . . . my impression was that you were usually running the speakers with just a tube amp or, at other times, with just a SS amp. Correct?

If so, is the system too bright when powered by the Analogue Acoustics AA-001 tube amp you linked in the first post? Or just when you run the system with a SS amp?

You should be able to solve the brightness issue with your streamer's DSP.

I don't have DSP but, among other functions, they generally have sophisticated EQ capabilities, including a parametric EQ. Semi-Parametric allows you to boost or cut the frequency of your choice. Full parametric adds the ability to boost or cut in an adjustable (narrow or wide) range on either side of the chosen frequency. I believe most DSPs offer full parametric.

Just set it to cut a bit and then adjust the frequency until you find the one that you find troublesome. Then fine tune it from there to determine how much of a cut is needed and then adjust the width. DSPs typically have numerous customizable presets which can be switched in and out as necessary, so you can come up with several of them.

EQ adjustments often solve a lot of problems. Traditional "tone controls" are often shunned these days, yet the use of DSP to make "room corrections" to the frequency response is considered to be quite acceptable. Go figure.

Please let us know how the Yaqin buffer works out, though. It's entirely possible that it will smooth out the highs nicely.

When I said that buffers sometimes don't have much effect on the sound, that was based on comments I'd heard about one of the Schiit preamps. As I recall, it's a SS preamp but it has a tube buffer section that can be switched in and out. Many users report that switching it in has little to no effect on the sound. Hopefully, the Yaqin circuit is more noticeable.

I looked up the Vandersteens and they are relatively inefficient speakers, only 85 dB sensitivity. Were you getting enough volume using only the AA-001?

If you want more power I still think you will get better results, at a much lower cost, by trying an inexpensive active crossover, or your DSP's if it has one, with your existing amps rather than spending big $$$ unnecessarily on a 50w tube amp.

It's entirely possible that an active crossover could work fine without having to add another set of speakers or a sub. I would at least try running the lows through your SS amp to your speakers lower bi-wire terminals and the highs, through your AA-001 to the higher bi-wire terminals. The key is to set the correct crossover point on the active crossover.

Earlier it was suggested that the higher bi-wire terminals divide the signal at 900 hz. If that's true, set the crossover there. If you ran the mids/highs with your APPJ tube amp previously you can confirm if the division is at 900 Hz, which is quite high, or 80 Hz, which is where the woofer crosses. If it's at 80 Hz, that would be preferable but the higher point would work too. The higher the frequency, the less power is needed so your tube amp will likely have plenty of power in either case.