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cv wrote:

On the matter of the DHT having a plate resistance of 500-700... you do realise that running the 6E5p with an unbypassed cathode resistor is giving you an effective Rp of about 12k, right? The formula is, IIRC, Rp + (mu+1)Rk.

The DHT that I meant was a candidate for a single stage gain with DHT. To find a DHT to substitute just my 6E5P driver is not too difficult.

cv wrote:

Regarding the inductive attenuator - in using an LR filter at the input, the series R will give the inductor a chance to express any non-linearities in voltage terms. With a 6db attenuator, the signal is tapped half-way through the core, so I can almost visualise cancellation of non-linearities in each half...whatever they might be. Then there is also the benefit of the driver tube seeing 1/4 of the filter R.

… and the part of the signal that need to be NOT attenuated still will be flowing through the part of the coil. The flowing across the DCR of the tap is not a big deal but it is INSIDE of a choke and theoretically it is influenced by all issues of magnetic non-linearity.   Do not forget that to the magnetic non-linearity exposed the part of the signal the shunted to ground AND the part of the signal that shall flow top load with no impact. This is my theoretical beef with the idea of magnetic attenuation.

nl wrote:

Why do we use DHT tubes?

You mean the driver DHT tubes?  Yes, it might be an interning idea but at this point I see no need.

nl wrote:

In Romy's case, I would suggest experimenting with various driver stages. The primary quality is how it sounds -- how it combines with the DHT sound to make an appealing overall result.

nl, what in your view might be the “appealing overall result” that you feel might be accomplished by substitution of my driver with DHT? I understand that you never heard the sound I get from 6E5P and I never used the DHT driver and therefore there are no points of reference, still what would you your hypoteti9cal assumptions?

nl wrote:

Why are we experimenting with DHTs at all here? It is because of the possibility of a different sound character than the 6E5P.

I do not looking for “different sound character”. That is what most of the DIYers do not get. I am looking for the very specific character of sound that I know, understand and comprehend. The differences that many “soldering people” are getting out there are completely irrelevant to me as I very seldomly experienced that DIY build any “tailored” or sensible sound. it does not mean that I shall not experiment with DHT drivers but it means that a promise of “ the different sounds” is not something that motivates me.

nl wrote:

Thus, it doesn't make a lot of sense to me to keep the 6E5P as a driver tube. Why not try something else? I would suggest a 6SN7 or possibly a signal DHT like a 26, 112, 01A, 30, etc. etc. Direct coupled with resistor load (as already exists) is fine. Some people like the combo of a high-gm tube like 417, 6H30, 6S45, etc. etc. as a driver tube. Other people find them hard, glassy, and not emotionally involving -- the typical complaints of the high-gm series. The main advantage is that they allow the elimination of a gain stage. Also, they provide a rather low Rp to drive the output tube harder.

Interesting, those people who “like” or “do not like” something about the DHT drivers, do they make their judgments in context of full-range SETs or in context of the narrow- band DSETs?

nl wrote:

The second thing I would suggest (again) is to try your DHT amp running the large horn (600hz up) as far up as it will go -- ie no lowpass filter. That should give a better idea of the overall sound quality of the DHT amp without having to make two to run both horns simultaneously.

That is interning as I thigh about it myself when I started to use my YO186. The YO186 has VERY lucrative lower range and it might be fun to expose it to my upperbass horn. I do not know about the run the upperbass with no lowpass filter but the notion to try YO186 full-range very much crossed my mind. A local guy snatched my prototyping San Audio amp otherwise I would put the YO186 in full-range use and would try to drive with it different things. I still do not know if it will be able compete with 6C33C as the 6C33C drivers my upperbass with VERY idle plate. The DHT tubes would not have power to idle plates too much. If I put the YO186 with 45:1 transformer then it will suffocate to drive my upperbass driver.  Still, the idea is worth trying…

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