Paul Joppa
Moderator
Well, if Mike won't break up the set you will have to wait until he does another run of TFA-2004Jrs.
SR45 amplifier
- Thread starter debk
- Start date
Thanks Xavier, but I now have my plan in place and I certainly don't have the momey to get into an auction at this point as nice as the Co Jrs would be.
Today there will be a box arriving from a a guy in Philly with a couple of massive plate chokes in it, with more boxes to follow soon. This box will have a fresh pair of Dowdy chokes gapped for 60 mA in it, and which may just find their way into my planned Paramount 2a3 build.
Tomorrow another box from BH will be arriving -- this one with the last of the FP IIs, but with a few twists
.
Plan to be up with the SR-45s driving the Nagas and subs this weekend.
-- Jim
Today there will be a box arriving from a a guy in Philly with a couple of massive plate chokes in it, with more boxes to follow soon. This box will have a fresh pair of Dowdy chokes gapped for 60 mA in it, and which may just find their way into my planned Paramount 2a3 build.
Tomorrow another box from BH will be arriving -- this one with the last of the FP IIs, but with a few twists
.Plan to be up with the SR-45s driving the Nagas and subs this weekend.
-- Jim
Today is a great day!
My brother delivered from the US my new pair of 2004Jrs with Co pinstripes for a pair of "Mk I" SR45s to be used with the WEs. He also delivered the third pair of TL404s to build an equal number of SR45 "MK II" amps for the main system when the new design around PT-7s (maybe a new kit?) comes out.
My brother delivered from the US my new pair of 2004Jrs with Co pinstripes for a pair of "Mk I" SR45s to be used with the WEs. He also delivered the third pair of TL404s to build an equal number of SR45 "MK II" amps for the main system when the new design around PT-7s (maybe a new kit?) comes out.
johnsonad
New member
Just a ping for an anticipated project. We are awaiting it with baited breath PJ!
Half of my custom iron has arrived for this project already. In the mean time I've been enjoying a Firstwatt SIT 2 amp (impressive). I anticipate that the SR45 will trump in in sound but not in power.
Half of my custom iron has arrived for this project already. In the mean time I've been enjoying a Firstwatt SIT 2 amp (impressive). I anticipate that the SR45 will trump in in sound but not in power.
Paul Joppa
Moderator
Thanks Aaron, I need the push. There's another project just ahead of it but I should get back to it shortly.
Natural Sound
New member
Where might I pick up a schematic for the SR45?
Paul Joppa
Moderator
The SR45 was a one-time design, never a full kit, and is not currently supported. I am working on a replacement to resolve some of the issues with the first one. I discourage spreading the design around (beyond original purchasers) for several reasons, both technical and professional. For the latter, see post #58 in this thread.
Natural Sound
New member
Paul Joppa said:
I understand and respect that, Paul. I'll wait patiently until the replacement arrives. Please include me in the category of interested and considering purchase.
Tom, YGPM...
Also, I tried the SR-45s with my preamp and the Orcas and while a tiny bit better than with the nagas in terms of max volume, the fact is that there simply is not enough gain in this system, so I'm afraid I'm going to have to give up on the SR-45s. I'm afraid it will have to be the 2a3 paramounts that will poewr my blumenstein Nagas -- not that's a bad thing, but I was looking forward to the SR-45s as my mainstay amp.
PJ, I assume the new design will not have any significantly higher gain?
Thanks,
Jim
Also, I tried the SR-45s with my preamp and the Orcas and while a tiny bit better than with the nagas in terms of max volume, the fact is that there simply is not enough gain in this system, so I'm afraid I'm going to have to give up on the SR-45s. I'm afraid it will have to be the 2a3 paramounts that will poewr my blumenstein Nagas -- not that's a bad thing, but I was looking forward to the SR-45s as my mainstay amp.
PJ, I assume the new design will not have any significantly higher gain?
Thanks,
Jim
Paul Joppa
Moderator
So far, it has been my plan to repeat the choice of driver tube, with a fairly low gain. However, I think we'll have to convene a brainstorming session and revisit the gain structure question in a more consistent fashion - our preamp gains are less than they were a few years ago.Jim R. said:
For what it's worth, the SR45 needs a nominal 1.65v to generate full power. The BeePre has a gain of about 2.5, so an input of 0.65 volts should generate full power from the SR45. A redbook digital source with 2vFS should then be able to drive the SR45 into clipping by 10dB.
For comparison, Paramount 300B requires 1.56 volts but makes 8 watts instead of 1.5 watts. SEX and Stereomour take around half that, 0.75 volts for full power of 2 watts and 3.5 watts respectively.
However, some modern recordings may utilize more headroom than traditionally used, and some source devices deviate from the redbook output standard.
Thanks, Paul. I'm a little baffled by what's happening with my sr-45s then as in theory at least, a unity gain preamp fed from a 2v nominal cdsource should get the amps pretty close to clipping, and with the Blumensteins, they just don't appear to be anywherre near that.
Tomorrow I'll try my 3 watt LM mini amp that is much more sensitive. Wish I had some good test equipment to test all this stuff and see what's going on with the waveforms.
BTW, for those who haven't seen it, I'm looking at selling my SR-45s:
http://www.bottlehead.com/smf/index.php/topic,3924.0.html
Thanks,
Jim
Tomorrow I'll try my 3 watt LM mini amp that is much more sensitive. Wish I had some good test equipment to test all this stuff and see what's going on with the waveforms.
BTW, for those who haven't seen it, I'm looking at selling my SR-45s:
http://www.bottlehead.com/smf/index.php/topic,3924.0.html
Thanks,
Jim
