[Brad]

I've seen Richard's posts on the $2k amplifier.

Just wondering if you could spell out some of the differences between that one and the $6k deluxe 45 amp?

thx

[-Richard-]

Hi Brad ~

I see you posted quite a few days ago... hummmmm.

Of course you will want to hear from Roger on this... however I have heard them both and as you know I did own the 245.1 SET 45 tube amplifier for quite a while.

Roger allowed me to visit him in his home/studio/laboratory over 2 years ago because I was very interested to hear his new 245 SET 45 tube amplifier... based on a recommendation from Louis Chochos of Omega speakers who spoke very highly of Roger and was aware of his new 45 amp.

I could not afford Roger's $6,000 45 amp and I was entirely unfamiliar with the magical sound of 45 SET amps at the time... although I was thoroughly intrigued to want to hear it. I offered to bring my just completed Open Baffle speakers down to hear them played by Roger's then new 245 amp. Roger was very accommodating and told me he would gladly allow me to hear his new amp.

I was thrilled not only by the sound of the 245 amp but also by its design. It was quite clear that Roger was an extraordinary designer... not only in terms of the ingenuity of his circuit designs but also by the physical layout of his 245 amplifier which has enormous control over quite a range of variables that impact directly on the sound and can accommodate different tubes that require unique biasing strategies.

The sound of Roger's 245 SET 45 amp was so stunning on my Open Baffle speakers that I asked Roger if it was possible for him to design a lower priced version that had essentially the same level of control as his state-of-the-art 245 amp. Roger immediately said yes... and to my surprise actually described how the new 245.1 would look and function without skipping a beat... it was clear that Roger was a highly creative and innovative audio designer.

Within a few weeks he had a prototype built and I came back up to Santa Barbara (I live in Ojai California less than an hour away) for a listen. I was truly amazed by the sound of his smaller but no less sophisticated and more reasonably priced 245.1 SET 45 tube amplifier. Roger very soon after built one for me and the rest is history.

To my ears I heard no difference between the 2 amps... if someone is looking for the ultimate design and control statement in a 45 SET amplifier the 245 is by far the most sophisticated design I have ever seen... it gives the end-user exquisite control over every variable imaginable. But the 245.1 gives the end-user almost as much control for 1/3 the price; hum pot control knobs in the back, manual biasing that uses LED lenses in top and feedback control via a NOS knob on top as well. Unlike so many SET 45 amps out there Roger's 245.1 SET 45 tube amp is light and elegant looking.

But in terms of sound quality I never heard a difference. Roger built everything he learned about 45 SET amps into his 245.1 SET amplifier for a very modest price. I still have hopes that Roger will design a 2A3 amp sometime in the future... with his genius for circuit design perhaps he will build-in the possibility for it to play both 2A3 and 45 tubes at the flick of a switch. The audio world needs it.

I hope this sheds some light on your question, Brad. Best of luck to you.

Warmest Regards ~ Richard

[Roger A. Modjeski]

Richard hit the nail on the head and I thank him for including his observations.

The 245.1 is a rare bird in that it encourages tube rolling and makes it easy. If one wants to compare output tubes from different makers it is important that the tubes be operated under the same conditions of bias for instance. Otherwise one is listening to how the tube is biased in the particular amplifier more than the tube itself.

Alternately, one can find the sweet spot for a particular tube, record the plate current on the handy built-in meter and return to that setting at any time with no need for any tools or meters. It's all self-contained. On the 245 there are 3 silver knobs (we have some nice retro Bakelite ones now that match the larger meter selector knob) that control the bias, hum null and driver operating point. Few amps have all 3 of these and none I know of make them this accessible. The 241 will now accomodate 2A3 tubes without a switch. One simply changes the bias point using the internal meter. 45s typically run around 28 mA and 2A3s around 60 mA.

We are doing more custom work now and have several amps in progress for customers desiring to hear something where they had some input as to what the amp can do. It is entirely possible to provide amplifiers that encompass a larger range of triodes, 45, 2A3, 300B, 320B etc.

[bullwnkl999]

The 241 will now accomodate 2A3 tubes without a switch.

Hi, Roger - I assume the above is a typo.  Do you mean the 245.1 or the 245, or both?  I have a growing interest in the 245.1, and even more so if it has this flexibility...

Thanks!

[Roger A. Modjeski]

The 2A3 is more easily applied to the 245.1 as there is a built in bias meter to allow the user to set the increased (1.5x) plate current of the 2A3. In the 245.1 the LED is setup for the 45's idle current and increased bias would be set with an external meter.

For my taste a built in meter is a great addition to a SET amp. I built the 245.1 for myself as a tool to explore the differences in output triodes. Putting all the necessary controls up front makes this exploration both easy and repeatable. I offer it to those who have a keen interest in these tubes and want to make their own explorations.

[wilsynet]

This is a pretty old thread that I thought I'd revive.

Anyone have any thoughts on how the RM-245 would compare to a Yamamoto A-08S?  Wondering if I should phone up Roger and see if he has any old RM-245 amplifiers around that he would sell to me.

For the record, I am keeping the RM-10, but I want to know what the fuss about SET 45 is all about.

[tybee]

I own a 245.1 that was modded by K&K to handle both 2A3 and 45s. Since I have not heard the other amps, I  cannot comment.  I am currently using 2A3s with an 88db efficient speaker with excellent sonic results.  I also have an RM10 for these speakers, but prefer the SET sound. The bias meters work very well, so it is very easy to switch between 2A3 and 45 tubes.

Since Roger lost his cabinet maker, I suspect he will not be able to built the 245 design unless he has some older inventory of the wooden enclosures or he has another cabinet to provide.

[tybee]

Wilsynet,

I see you are seeking advice on other forums regarding a 45 amp.  Let me say I really like the 45 tube and use several vintage 45s in my 245.1. There are many flavors of 45 tubes which can be an expensive tube rolling experience.  The 245.1 and RM10 are similar in that they provide a very detailed presentation, but the 45 tube provides detailed SE magic that an EL84 PP pentode will not have. I find the 45 more extended in both bass and treble when compared to the 2A3, but the 45 cannot muster the headroom when compared to a 2A3 or better yet a RM10.

If you finally pick up a 45 amp,  I suggest you have at least a 96 db speaker or better yet a speaker over 100 db to retrieve the headroom you may miss.

My Thanksgiving $.02  By the way, I also own a MR C4 preamp and ane EM7 2.5 watt amp.