If you are an adherent to single-ended amplifiers and high-efficiency loudspeakers then undoubtedly you came across to the thought what to do with LF sections and how to drive them. The high sensitivity at LF comes only along with the non-resolvable cost of delays (if it done properly) and therefore it is highly likely that your LF would require much more power then your MF-HF channels would requires.

It is very common that people use SS PP to drive the LF sections. People attracted by many in theory objective benefits of SS amplification and amp-speaker interface. However, the truth of the subject is that the SS amplification (ANY SS amplification) can’t do bass. The bass of SS amp, although it is instantaneously impressive (and particularly for the people who have their audio taste at a typically barbarian level) is wrong bass, purely synthetic and NEVER real. I am not mentioning the fact that in biamping the different amps must not be used at all…. So, no matter what you do but do not biamp with SS PP at LF.

From another point of view the SE amplifier can’t do REAL bass by the verdure of the topological limitation. So, what to do? The answer is ridiculously simple, so simple and reasonable that I have no idea why the proposed solution is not a dominating solution in a given situations: use two SE amplifiers when one of them will be specifically optimized for LF operation only.

The dedicated LF SE amp is so powerful tool on context of your SE high-efficiency installation that it will take your “result” way out there. Perhaps it will even teach you REPRODUCED bass might sound….

Rgs,
Romy the Cat

Teflon wrote:

I'm interested in bi-amping so you have my interest - if you say a SET has a 'topological limitation' what is the ridiculously simple change needed to make it good for LF operation ?I was previously thinking about using triodes in PP, like Sakuma-san bi-amping.

Romy the Cat wrote:

So, Teflon, I do not think you got what I meant.  SET has no 'topological limitation' because exists DSET. DSET is free from any, even theoretical limitation, of cause if you prepared to deal with price and power demands. The DSET optimization for LF operation is well covered in multiple threads if this site. It might depend mildly from the specifics of your amps that you would like to use for LF but the underlining principles are the same across the board.

Romy the Cat wrote:

I do not remember that Sakuma-san use the DSET concept. The bi-amping that he demonstrated to me did not use DSET, used tow identical amps and in fact was implemented in what I call the “ridicules fashion”.

Teflon wrote:

If I understand you, your amplifier uses line level frequency selection at the input to each channel, and the output of each channel is optimized for the frequency range of interest -you worry not about the performance of a channel outside of the pass-band providing it doesn't create problems. Am I understanding this properly ?

Teflon wrote:

So, say I take an off-the-shelf stereo SET amplifier of good quality - i.e. designed to cover the full audio spectrum. Then say I take this amplifier and use it to bi-amp a single 2-way speaker. I would then install passive line level frequency filters at the input to each channel, one for LF and the other for HF. The output transformers would be wide band, so they would not be optimized for the frequency range they were used at but it would still work as a DSET topology ?

Teflon wrote:

If I were to replace the output transformers such that the HF channel used a transformer that is 'smaller' with less parasitic inter-winding capacitance and the OPT in the LF channel replaced with a 'larger' one with higher inductance - then I am creating an optimized DSET topology ?

Teflon wrote:

I don't claim to be familiar with the works of Sakuma-san, I did read the web site with interest though. It seems to me that he had developed a high level of familiarity with the performance, the limitations and the sound of the components he used - especially the Tamura transformers. This allowed him to create the sound he was looking for. And I perceive that he knew how to listen to the sound and knew what he needed to change to achieve his goals. I think this aspect of his work is something you can appreciate. And the benefit he appears to have brought forth was to create in others, the interest to build and listen to tube amplifiers and to encourage others to listen for themselves and learn what they should do to achieve the sound they like - as far as I can tell he did not ask others to copy his work, but rather to develop their own. Unfortunately the website dedicated to his work is not his words and was not created by him and so reflects the interests of it's creators instead.