[planet10]

Chris and Dave: wouldn't those Metronomes benefit from some BSC?

Maybe, maybe not. Personally i try to avoid passive BSC filters.

dave

[DaveC113]

My preamp's volume control went out last week, so I was forced to put it aside along with the tube amp it was driving.The preamp was an Anthem Pre1 with remote tube rectified power supply and 6922 output tubes. The amp is a Simple SE single ended el34 / kt88 amp built with high end parts running triode strapped with no feedback of any sort.

In their place went a Trends tripath amp with battery power supply and upgraded resistors and caps. Let's just say my system fell apart with the Trends amp. Soundstage and imaging went to heck, and the tone became sort of annoying, it just didn't sound natural. If I had to keep the Trends I would have gotten tired of listening to it and stopped listening to music as much. With the tubes, I enjoy listening to music a lot more.

I'm sure other digital amps are better than the Trends, but there's no way I'd get one. I have my  doubts that any SS or Digital amp would compare to the Simple SE driving my Omega 4.5" XRS speakers.   

[Docere]

So this is what it feels like to come out of retirement?

To answer the original poster:
If you find that a system's musical presentation lacks impact, balance, weight, dynamics, and live-ness etc. at lower levels, but is okay at higher levels, then one contributing factor could be explained by the loudness curves (ISO, Fletcher-Munson, etc.). That is, we are more sensitive to bass and treble when music is louder, meaning that at low listening levels we do not hear it as well, creating a tendency for... There are other factors, but this one is significant. Therefore, you may want to choose/design your system to sound as you like it at your preferred volume. Tone controls can also be a help, although I am not suggesting they be used, per se.

As for SETs and 91dB speakers, well, many folks with similar priorities to yours could quite happily live with such a combination, especially those listening at lower levels. Would SE be more appropriate for you than a tripath or other lower (or higher) power digital amp? Probably. However, would SE be more appropriate than the trioded pentode PP or pentode PP? Well, it depends on the qualities of the amps, your musical preferences, presentation preferences etc. There is no definitive answer when asking relative and conceptual questions. However, I would suggest that you give SETs and other lowish power topologies a crack if you can do so at minimal risk. Also, read the opinions of experienced folks from all over - perhaps you will begin to build a picture (though that can take mucho time).

Caution:
There is a whole lot-o-opinion posted in this thread that does not fit with my experience/reading/study/practice. Read and consider the contents of the thread but please understand that there is no substitute for your own experiences in matters of subjectivity. This is especially the case when you are relatively new to a field and you have little context and base knowledge.

Hope this makes some sense - I did not have much time.

Edit: amended some typos and clarified some sentences.

Cheers
Raymond

[hebrer]

Hi Raymond,
Thanks for taking the time to share your view. Reading the posts in this thread I was introduced to a number of new concepts in audio such as the Fletcher-Munson curves that you also mention, the OTL amplification design, the TVC preamplifier idea, etc.

The number of variables seems to have increased in my mind but I am richer for these ideas.

Right now, I am doing some exploring in several different directions to see if the low-volume listening gets more enjoyable:
a) room acoustics - speaker placement, sound wave reflections etc. (investment of US$44 on Get Better Sound manual by Jim Smith)
b) tuning my speakers
c) adding (for the first time for me) a pre-amplifier (another low-cost and low-risk experiment: SET class A preamplifier with 6N11 tube)

The argument with equal-loudness curves seems very convincing but I am reluctant to introduce a separate equalizer into my system. Some people using transformer-based volume control suggest low-level listening is improved but unfortunately I have no easy way to verify it in my system.

I hope to report later on the progress.

[Docere]

Hi Tiger

I think what you are doing is very sensible - you will begin to accumulate knowledge, which may even help you assemble a system that better meets your wants. However,  I pray that you do not become infected with audiophilia nervosa or musicalis pleasuritis!

I look forward to reading of your adventures.

Enjoy and appreciate, for what you are listening to/through will be 'better' than most will regularly experience.

Cheers
Raymond

[Niteshade]

You should try using your EL84 amp in tetrode mode. You will have more power and it will operate cleaner. I never liked triode mode. It never felt right to me because it doesn't use the tubes to their full potential.

What is your opinion on matching single driver speakers (in my case Fostex FE127eN with 91 dB sensitivity) with

A) a SET tube amp (I never had one and hear the second harmonic magic is something that must be heard)
or
B) a digital amp (e.g. Virtue ONE using Tripath chip) in compination with a single ended triode pre-amp (or possibly just a tube stage output in CD player)
?

I currently use push-pull tube amp with 4 EL84 tubes used as triodes and cannot decide which of the options above would most likely bring an improvement...

Thanks for sharing your experience or thoughts on this.

Peter

[hebrer]

Nightshade,
I bought the amplifier as a ready-made solution. I may be able to find someone to do some this modification but only if it is easily reversible. I am doubtful having more power is the right way to go in my case since most SETs have even less power than my current PP topology and they are reportedly fine with 91 dB sensitivity speakers for lower-level listening.
Of course, if I were handier/more confident in making soldering mods myself, a whole new world of experimentation would open up to me. As of now, I prefer solutions that I can try out myself and those do not include soldering mods to a high-voltage tube amp.
Thanks anyway.
Peter

[planet10]

You should try using your EL84 amp in tetrode mode.

How is that even possible?

The EL84 is a pentode with the suppressor grid internally tied to ground. You'd need to disconnect that to turn it into a tetrode.

dave