SR45 amplifier

[2wo]

Hi Jim, The increased DCR will drop a few more volts across it. So the voltage at the plate of the 45 will be 10-20V less...John

 

[jrebman]

John,

Thanks -- with my higher line voltage I'll probably not have to do anything to compensate then.

-- Jim

 

[debk]

Just finished one SR45 amp so far.  It is a very nice sounding amp!
Now to start on the second one

Deb

 

[johnsonad]

Congrats Deb!  Keep us posted!

 

[jrebman]

Hi Deb,

Glad to hear that this is under way.  Any details to share? Have you considered using the 6dn7 as a driverr tube? Pobably too late now. What are you using for iron? Purple, I assume

-- Jim

 

[debk]

I built the amp from the schematic of the SR45 and referred to the Paramour II manual for some of the construction.
Iron is:
Magnequest BCP-15 40ma/50H
Magnequest BH-5 Nickel outputs
Magnequest Grid choke
Triad C-7X Power supply Choke

Coupling capacitor:
V-cap CUTF 0.1uf
Parafeed Capacitor:
Clarity Cap MR 10uf

EML mesh plate 45 tube

I built it on a Paramount chassis panel

I have only listened to the amp in my lab, I will put them into my regular system when I finish the second amp.  I have been very impressed with the sound so far.  It made the old Klipsch Heresey I have in my lab sound very smooth, nicer than any other amp I have tried them with.

When they are both built and broken in a bit I will post my impressions

Deb

 

[jrebman]

Hi deb,

That should be a really nice setup with the Orcas and or your fe-206 speakers.

I too just can't get past how beguiling these amps sound, even with OS american 45s -- I'm getting very impatient waiting for  my 98 db speakers to arrive and I've decided to put off any new amp construction until I've got the sr-45s tuned /voiced to the new speakers, using the existing chasis as a test bed for those experiments. I also have a backlog of other projects to keep me busy through the cold weather months, and by then I should have a very good idea and detailed plan for rebuilding the sr-45s in a new chassis with a slightly modified layout. These are some seriously good amps even if PJ doesn't seem totally happy with the design.

If you want a couple of nice heat sinks for the sr/c4s board, PM me and I'll send you a couple.

-- Jim

 

[debk]

Thanks Jim!

I too think they will sound great with the Orca's
Like you I have way too many projects, maybe I will have time to finish them this winter.
I also have too many amps, ok that is a good thing 

I will PM you about the heat sinks, the ones included with the SR45 kit get quite warm.

I never thought this thread would get this big when I started it, it has over 17,000 views now!

Deb

 

[debk]

The SR45 amps are done!!  They sound great, probably the best sounding amp I have built to date.  Not as forceful as the 2a3 Paramount, but more detailed and refined.  Very, Very smooth sounding amp, a great match with the Orca's!  They will only sound better as the components break in.  Grainger, I know I should have burnt in the V-cap CUTF :-(

I have some film capacitors on order I want to replace the 47uF elecrtrolytics with.

Deb

 

[2wo]

Hi Deb,
looks nice, did you find a spot for the grid choke? You are using the same iron complement as my current amp, no V-cap though .
  I don't remember if you had a chance to hear it at the Bottleneck meet a a few years ago...John   

 

[debk]

John

The Grid choke is hidden by the large parafeed capacitor, it is mounted with the holes that the cathode resistors in the Paramount would have used.
Yes, I remember your amps, they sounded wonderful!

Deb

 

[Grainger49]

Deb,

I wasn't going to harass you about burn in.

But I was wondering when we would see the purple pictures.

Nice build, good looking amps.

I take it that the 47uF is the cathode bypass?

 

[debk]

The 47uf's are the power supply capacitiors

Deb

 

[xcortes]

After a looong and scary delay at customs my SR45 are right now being set up at room 845 at RMAF. So don't take Deb's words for granted and go and listen to them

 

[debk]

Iv'e been listening to the SR45's quite at bit.
they are sounding better and better every day.  I am amazed how much more I can hear.  I can decern individual instruments in the music, amazing detail and clarity.
Very impressed I really like the sound of the 45 tubes

Deb

 

[jrebman]

Hi Deb,

Great to hear! How's the solo piano material sounding?

BTW, my wife was curious to see what I sent to you, a woman, the other day .

-- Jim

 

[denti alligator]

I haven't been following this thread very closely. So are these superior to the Paramounts? How much work goes into them? Parts easily available?

 

[debk]

The solo piano material is amazing.  the closest to live I have ever heard.  I continue to marvel at the detail and clarity these amps have.

That's funny, hope your wife didn't give you a hard time .

Deb

 

[debk]

I haven't been following this thread very closely. So are these superior to the Paramounts? How much work goes into them? Parts easily available?

I personally like the sound of the SR45 better than my 2a3 Paramount.  The SR45 is a modified Paramour 2.  As for parts I was lucky enough to have someone sell me an unbuilt SR45 upgrade kit.

Deb

 

[denti alligator]

Does it sound better than a 45 modded Paramount?