Dennis Had Inspire Amps

[straitwire]

Originally Posted by cgn-dt-n

nice preamp,
Is there a sonic advantage to replace the zener diodes with the voltage regulators?

I like to use voltage regulator tubes for the light show.
I'm not sure if they make much of a difference in the sound.

[cgn-dt-n]

thanks for the info, so more optics than technical necessity for the use of the voltage regulators.

Can you give us a description of the sound?
neutral, bass-heavy, high resolution, the right proportion of each?
how is the pre to be classified in relation to the LP2030 or the CJ5.

[cporada]

Is the LP 2030 limited to 0A3 VR tubes or can one also use 0B3s, OC3s, or OD3s to tailor the sound?
Also, is it safe to use a Globe 80 rectifier in the Firebottle KT88 SEP and/or the LP 2030 (with an adapter of course)?
Thanks!
Chris

[Analog Addict]

Originally Posted by cporada

Is the LP 2030 limited to 0A3 VR tubes or can one also use 0B3s, OC3s, or OD3s to tailor the sound?
Also, is it safe to use a Globe 80 rectifier in the Firebottle KT88 SEP and/or the LP 2030 (with an adapter of course)?
Thanks!
Chris

The function of the 0A3 or Voltage regulating/ VR75 is to lock in the voltage at a specific value, in this case, 75 volts. The other designations for the other tubes mentioned are

0B3/VR90
0C3/VR105
0D3/VR150

These tubes function as Zener diodes. However, they also need about 30% more voltage than their rating to fire/light. As far as substituting for the 0A3, it's not going to hurt the pre amp, but your 01As may not be so lucky.

An 80 rectifier is equivalent to a 5Y3, so if a 5Y3 is allowable, and 80 would also work.

[Analog Addict]

Dan and Dave came in from out of town to pick up some goodies and puruse the latest and greatest Inspire gear. Here we all are, enjoying lunch (Thanks Dennis!)

Untitled by analog addict, on Flickr

Untitled by analog addict, on Flickr

Untitled by analog addict, on Flickr

Untitled by analog addict, on Flickr



Featured are the new 300B monoblocks, the new RB84 amp, and the Slammer.
Also of note are a pair of speakers built by Scott, owned by Dave and brought to the shop for new and improved drivers.




Close up of the first 300 monoblocks...



Untitled by analog addict, on Flickr

Untitled by analog addict, on Flickr

Untitled by analog addict, on Flickr

These went home with Dave, and he can post his own impressions when he's ready, but these mono blocks are definitely the top of the heap. For a mere $12,500 you can have your own pair!!

As always PM me for details.

Untitled by analog addict, on Flickr

Untitled by analog addict, on Flickr

Lastly, some detail of the new Inspire 3.1 speakers as they are rounding into shape. These logos are inlaid folks, and when you run your hands over them, they feel like one continuous smooth piece of wood. and the Paduak veneer is amazing in itself. Hopefully we can get these finished up in the next couple of weeks.

Stay tuned!!

[cporada]

Hi AA,
Thanks for the info. If I understand correctly, which I may well not, the voltage rating on the VR tubes is the amount by which they drop the voltage, i.e., the 0A3 drops the voltage by 75 volts and the 0B3 drops it by 90 volts, isn't it? If so, this would mean the 0B3s would send 15 fewer volts to the 01As than the 0A3s. Or maybe I am completely wrong; I thought this was the case because I have read about people swapping in 0B3s in place of 0A3s to make the sound more "laid back" and "less forced", and I assumed this was because it was reducing the voltage going to the signal tubes. I certainly don't want to damage the 0A1s, though, so I am glad I asked.

Since Dennis shipped my LP-2030 with a 5Y3GT, I'll give the Globe 80 a try and see how it sounds!
Thanks again,
Chris

[Analog Addict]

No, the VR tubes lock the voltage at their rated number. A VR 75 tubes locks the voltage in at something very close to 75 volts. Other tubes lock the voltage in at their rated number, 90/105/105 volts. Assuming they would even fire, you would get higher voltage than the pre amp was designed to supply

Also the globe 80 is one of Dennis' favourite rectifiers, so hopefully you'll notice an improvement

[cgn-dt-n]

nice photos, great equipment.
The monos look great. Is there a special reason why these are made without the voltage regulators that were installed in the stereo version?
2 large transformers, 2 rectifiers, double number of electrolytic capacitors. are they no longer necessary, or is it a completely different circuit that is not comparable to the other.
if only the ducat could do a little more for me, I'd order one.
Although, I'm more into a stereo power amp than mono blocks, I had a bad experience with it a long time ago. these had a problem sounding the same. the middle between the speakers was indifferent, everything was a bit nervous. I never had this problem with a stereo power amplifier.
maybe someday the money will be enough to order a 45/2a3 pse from Dennis......

[cgn-dt-n]

discovered new toys at a small fair at the weekend. Raytheon 201a with embossed plate
in one of them there is unfortunately a small piece of plastic that rattles, but the function is perfect
the sound is indistinguishable from the Cunningham 301a
great show when the tubes light up
[IMG]IMG_20231116_163808 by cgn- dt-n, auf Flickr[/IMG]
[IMG]IMG_20231116_164053 by cgn- dt-n, auf Flickr[/IMG]

[cgn-dt-n]

I could borrow a few Elrog 300b from someone I know and try them out
I just saw that these have a different gain and slightly different specs than the original 300b
Can I try these out or will the tubes/amplifier be damaged?
here are the technical data
ER300B

Filament Voltage........................................... .....................5 V

Filament Current .................................................. ..........1.2 A

Amplification Factor .................................................. ........3.3

Transconductance .................................................. ......3.3 mS

Plate Resistance .................................................. ......950 Ohm

Max. Plate Voltage .................................................. .......600 V

Max. Plate Dissipation .................................................. ..40 W