[Klipschorns with 300b amplifiers]

On 2/2/2020 at 11:48 AM, sns109 said:

Hello, this is my first post, although visit these forums often. I recently acquired a 300B SET amp to audition as a summer replacement for my two 845 SET amps which are space heaters. Both of my 845 amps have wonderful tonal balance, articulate bass, reasonably extended highs, fully involving mid range. This is the third summer replacement amp auditioned, the first two class a/b solid state, both nice enough but lacking the palpable, meat on the bones quality of my SETs. The 300B has a nice palpable mid range, highs are a bit rolled which I can probably live with. The big issue for me is lack of articulation in bass, this along with more rolled off highs gives a rather dark presentation.

 

Overly loose, warm bass has always bothered me, articulate bass is an absolute requirement for me. I suspect a 300b amp may be inherently unsuitable for me. Looking at the impedance curve of Klipschorns, below 8 ohms between aprox. 40hz to 225hz along with steep impedance curve is too much for this amp. No separate taps on amp, assuming 8 ohm on non-separate tap tube amp. It seems the 845 SETs with their 8 ohm taps overcome this limitation, the 300b tube can't handle it. I'm in midst of one mod which may or may not address bass issue in that I replaced the Russian K40Y9 coupling caps with VH Audio Vcaps.

 

Assuming this 300b isn't satisfactory for me, what amps do you guys think would work for me? At this point I'm planning on auditioning First Watt J2 or F7, another intriguing option would be AGD Audion GaN Tube monoblocks, class D amplifier that supposedly replicates SET amp sound to quite a degree. The class A solid state amps will also be hot, albeit not to the same degree as the 845's. Any other class D amps close to SET sound?

Get rid of the crossover and biamp. Your 300B amp will like it and so will your ears.

[Klipschorns with 300b amplifiers]

On 2/4/2020 at 8:58 AM, Jeffrey D. Medwin said:

 

 

Amp OFF, voltages drained.  Each lead of the choke, is connected to the positive lead of a supply cap.  Put the probes on those two caps - where the choke leads are attached to..  Ohms scale. 

 

EDIT on 2-6-20, 

 

The amp owner measured the choke at 111 Ohms, ..........over five times too high.. 

The wiring inside the amp is very poor IMHO, ...........as is every resistor..

Layout is sophomoric,, two-dimensional, not three, excessively long leads everywhere, tie wrapped together. 

Imagine an RCA Jack's input wires bundled and tie-wrapped together with the speaker leads, for about a thirteen inch span. !!!

Every cap inside appears to be an electrolytic, including Rk bypass caps .  We will decide in a week or two, what to do !!

 

You have incomplete knowledge. My Tube Fantasy 300B sounds terrific. You should actually listen to the amps before smearing them with your remarks. Must you shout by using a bold font? So what if the wiring doesn't have a bunch tightly twisted wires which just increases the length.

[Klipschorns with 300b amplifiers]

On 8/1/2020 at 6:49 PM, pallpoul said:

So, what did you to the amps? I am interested as I have similar ones, pair of tube fantasy 300 B SET,  driving the RF-7 III's, they do sound really nice with no mod. and not too expensive tubes. 

+1.....      I have a pair of Tube Fantasy's too and would be interested in any mods to improve the performance. I'm a new owner and don't have many hours on them. A pair of GL300B's are due to arrive today to replace the previous defective ones. I'm using Telefunken EF86, Phillips NOS 12au7 and Mullard GZ34 to complete the tube complement. I'm bi-amping my speakers.