Alex, It might be useful if you enable the forum e-mail thinggy (sorry, I don't know its proper name 
)
Click on 'user cp' at the top, 'edit options' and check 'no' under 'hide e-mail address?'
On the matter of RDH4, you can always set the computer to download it overnight... It is certainly worth it.
)Click on 'user cp' at the top, 'edit options' and check 'no' under 'hide e-mail address?'
On the matter of RDH4, you can always set the computer to download it overnight... It is certainly worth it.
Yes, that would be a most excellent idea.
audiousername said:Alex, It might be useful if you enable the forum e-mail thinggy (sorry, I don't know its proper name
Click on 'user cp' at the top, 'edit options' and check 'no' under 'hide e-mail address?'
On the matter of RDH4, you can always set the computer to download it overnight... It is certainly worth it.
Yes, that would be a most excellent idea.
Alex is mebbe purposelly disabled this E-mail forum thingie
regarding RDH4 ,it's easier that I send CD version to him,and preserve some valuable Greggggggggggggggggg's bandwith
I can only say it works great with EL84's, so much so that I am buying 807's to do another amp this time not a retrofit but complete chassis.
Maybe I am a bit crazy to do this without first hearing the 807 version but this is the sound I like, very punchy and realistic (with EL84's anyway). I will try it as per Alexsanders original but also with the g2 fed from a voltage divider and perhaps also with tube regulation. I already ordered the parts which should be here on Wednesday. The only thing left to order is the opt of which I still have not decided on.
R.I.P. D.H.T.'s
Andrew
Maybe I am a bit crazy to do this without first hearing the 807 version but this is the sound I like, very punchy and realistic (with EL84's anyway). I will try it as per Alexsanders original but also with the g2 fed from a voltage divider and perhaps also with tube regulation. I already ordered the parts which should be here on Wednesday. The only thing left to order is the opt of which I still have not decided on.
R.I.P. D.H.T.'s
Andrew
Dave,
yes I got 10 hopefully (they are being tested) coming which should last me the rest of my life. Or maybe one day I might get industrious and build a pp.
Audiousername,
They go on ebay for US$5 - US$10. each but you can get them from David Crittle at Retrovox for A$22.00. He has Sylvanias' in stock.
Or you could get the 12v 7 pin 1625 which is almost an 807 equivalent from A.E.S. for US$5
Andrew
yes I got 10 hopefully (they are being tested) coming which should last me the rest of my life. Or maybe one day I might get industrious and build a pp.
Audiousername,
They go on ebay for US$5 - US$10. each but you can get them from David Crittle at Retrovox for A$22.00. He has Sylvanias' in stock.
Or you could get the 12v 7 pin 1625 which is almost an 807 equivalent from A.E.S. for US$5
Andrew
807 indiscretion...
Hi, guys!
I've been busy, as always... new developments on the RH field... RH6550 reaching a point where further thinking and trying is not necessary (except trying the pentode version)... and, I'm also working on a new RH with powerful tubes
But, regarding Andrewbee's confidence, I have to commit an indiscretion -- I have received a few days ago an email from a person who has finally completed his RH807... and am hereby quoting him in part:
The amp looks nice, too... another reason why am I mentioning this is his suggestion for parts. What makes me a little sad is the fact that he did not state the RH807 outclassing the WAD300B PSE monoblocks... and I think that is due to a difference i power, mostly
Regards to all,
Aleksandar
Hi, guys!
I've been busy, as always... new developments on the RH field... RH6550 reaching a point where further thinking and trying is not necessary (except trying the pentode version)... and, I'm also working on a new RH with powerful tubes
But, regarding Andrewbee's confidence, I have to commit an indiscretion -- I have received a few days ago an email from a person who has finally completed his RH807... and am hereby quoting him in part:
The amp looks nice, too... another reason why am I mentioning this is his suggestion for parts. What makes me a little sad is the fact that he did not state the RH807 outclassing the WAD300B PSE monoblocks... and I think that is due to a difference i power, mostly
Regards to all,
Aleksandar
I just took a look at the Sowter SA02 and it looks to be on the small side for this application.
45mA Dc for the primary and 5Watts max @20 cycles.
I have not built so have not measured nor looked at the curves but looking at the RH807 I would the 807 think its pulling close to 60mA or so , correct me if I am wrong. So, if I am correct then that core must be more than saturated with so much current going through it.
Andrew
45mA Dc for the primary and 5Watts max @20 cycles.
I have not built so have not measured nor looked at the curves but looking at the RH807 I would the 807 think its pulling close to 60mA or so , correct me if I am wrong. So, if I am correct then that core must be more than saturated with so much current going through it.
Andrew
Seeing as we're getting into other valves like 307A, EL34, 6550, 807 etc... I've started a new thread to continue the discussion.
This thread was originally meant for discussion of an EL84 SE design, but has grown wider than that. Having these ideas buried in another long thread makes it difficult to access for others.
Jason
This thread was originally meant for discussion of an EL84 SE design, but has grown wider than that. Having these ideas buried in another long thread makes it difficult to access for others.
Jason
I'm building the RH 84 SE
I'm collecting parts for Alex's RH 84 SE. I recently picked up an old console and now have a chassis, 2 GE el84, 2 GE 12at7, and a Amperex EZ81 rectifier.
I'm sure I have a few passives in the junk box. I'll report back once I get it working.
BTW, I was able to get the existing 12ax7->el84 SE working but before I start tweaking it (removing tone controls, swap in better coupling caps, ...), just build something from scratch.
I assume this schematic is still correct.
rick
I'm collecting parts for Alex's RH 84 SE. I recently picked up an old console and now have a chassis, 2 GE el84, 2 GE 12at7, and a Amperex EZ81 rectifier.
I'm sure I have a few passives in the junk box. I'll report back once I get it working.
BTW, I was able to get the existing 12ax7->el84 SE working but before I start tweaking it (removing tone controls, swap in better coupling caps, ...), just build something from scratch.
I assume this schematic is still correct.
rick
On Saturday, we converted my Mulligan to an approximation of the RH84 using parts i had kicking around... this amp shows real promise (we had Chris' EF86/EL84 monobloks for comparison)... it is now on the bench for some fine tuning, and Chris is considering converting his monoblocks...
With Alex, Gary Pimm, & Pete Millet championing this kind of circuit it looks like the Pentode is starting to get some respect
I wonder now about a separate regulated supply for the screens?
dave
With Alex, Gary Pimm, & Pete Millet championing this kind of circuit it looks like the Pentode is starting to get some respect
I wonder now about a separate regulated supply for the screens?
dave
EL84RH/DD
Since the "Mulligan Signature Series" consist of components from various vintage amp "organ donors" (FrankenAmp
) , none of our power supply configurations will necessarily match Alex's exactly. In addition, we're playing with our own experiments on filtering options.
In any case, Dave could you retreive that cocktail napkin sketch from the paper recycle with your notes as to the revised R & C values for this particular specimen?
planet10 said:On Saturday, we converted my Mulligan to an approximation of the RH84 using parts i had kicking around... this amp shows real promise (we had Chris' EF86/EL84 monobloks for comparison)... it is now on the bench for some fine tuning, and Chris is considering converting his monoblocks...
With Alex, Gary Pimm, & Pete Millet championing this kind of circuit it looks like the Pentode is starting to get some respect
I wonder now about a separate regulated supply for the screens?
dave
Since the "Mulligan Signature Series" consist of components from various vintage amp "organ donors" (FrankenAmp
) , none of our power supply configurations will necessarily match Alex's exactly. In addition, we're playing with our own experiments on filtering options. In any case, Dave could you retreive that cocktail napkin sketch from the paper recycle with your notes as to the revised R & C values for this particular specimen?
Dave, et all,
After having built numerous versions of SE EL84 amps from triode connected to pentode to shunt feed and many variations on each theme in between, I can say that the RH mode works best of all to my ears.
I built one soon after the original thread began and have not looked back. I am not using any fancy parts, Hammond pwr trannie, solen I think coupling caps, 125ese opt's and a mixture of metal film and metal oxide resistors, basically what I had lying around.
I had my doubts about the screen supply using just a series resistor but methinks with sufficient B+ capacitance it works, as a matter of fact I know it works because I left it as is and bass is not a problem.
I was so impressed with it that I bought parts to build an 807 version including Lundahl 1663 opt's, dynamicaps, mills resistors, ASC caps in the P.S etc. I am going all out with this one. I only hope that with the fancy parts the sound does not deteriorate.
The RH 84 really is an excellent sounding amp.
Andrew
After having built numerous versions of SE EL84 amps from triode connected to pentode to shunt feed and many variations on each theme in between, I can say that the RH mode works best of all to my ears.
I built one soon after the original thread began and have not looked back. I am not using any fancy parts, Hammond pwr trannie, solen I think coupling caps, 125ese opt's and a mixture of metal film and metal oxide resistors, basically what I had lying around.
I had my doubts about the screen supply using just a series resistor but methinks with sufficient B+ capacitance it works, as a matter of fact I know it works because I left it as is and bass is not a problem.
I was so impressed with it that I bought parts to build an 807 version including Lundahl 1663 opt's, dynamicaps, mills resistors, ASC caps in the P.S etc. I am going all out with this one. I only hope that with the fancy parts the sound does not deteriorate.
The RH 84 really is an excellent sounding amp.
Andrew
Hi Rick
I don't remember exactly what I measured it at but am sure its within at least 5% of what is on the schematic, and am using a single 5? H choke with about 300uF. If you really want to know I will check it again but I am going to pull it apart soon to build the 807 version as I need the pwr trans
I usually measure the voltages and currents and write them on the schematics but did not do it this time, probably because I they were all okay and I did not intend to leave the amp as is on it recycled chassis. I pulled apart a 5v6 se amp and cut out a piece and added a plate on top for the tubes. Even the inputs connectors are still extra long and hanging out.
Andrew
I don't remember exactly what I measured it at but am sure its within at least 5% of what is on the schematic, and am using a single 5? H choke with about 300uF. If you really want to know I will check it again but I am going to pull it apart soon to build the 807 version as I need the pwr trans
I usually measure the voltages and currents and write them on the schematics but did not do it this time, probably because I they were all okay and I did not intend to leave the amp as is on it recycled chassis. I pulled apart a 5v6 se amp and cut out a piece and added a plate on top for the tubes. Even the inputs connectors are still extra long and hanging out.
Andrew
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