Stuart, one question about the input pentode D3a:
Even though I am from Germany, it seems these are not that easy to these days, although the were know as "Poströhre" used by the German post. What about replacing it with a Siemens EF280F? Do you have any experience with this one?
Thank you!
Best
poli
Even though I am from Germany, it seems these are not that easy to these days, although the were know as "Poströhre" used by the German post. What about replacing it with a Siemens EF280F? Do you have any experience with this one?
Thank you!
Best
poli
Hi Stuart,
the data sheet pdf for the E280F ist located here:
http://frank.pocnet.net/sheets/190/e/E280F.pdf
Maybe you find the time to have a look. I the values are not clear, I can translate it into English.
Thanks a lot!
Best regards
poli
the data sheet pdf for the E280F ist located here:
http://frank.pocnet.net/sheets/190/e/E280F.pdf
Maybe you find the time to have a look. I the values are not clear, I can translate it into English.
Thanks a lot!
Best regards
poli
A.) I'd like to use an XLR cable for the input and also support RCA. My phono cable also has a shield. What do you think of this configuration, leaving pin 1 open?
B.) where do the CT and the can connections go on the Sowter 8055?
C.) What do you think of the Zobel? I'm using the recommendations on the datasheet as well as your schematic. Is this flexible enough for some experimentation?
D.) On the output, what about (ab)using a XLR connector as shown? It will be going to an Impasse most of the time, so I was thinking about using both a RCA and XLR connector here as well, for symmetry. Is tying the two pins together as shown a reasonable practice?
E.) I've explicitly added earth connections to the XLR connectors, as they are available on the connectors I'm using. Am I connecting them properly?
Just a few finer points to clarify. Thanks!
B.) where do the CT and the can connections go on the Sowter 8055?
C.) What do you think of the Zobel? I'm using the recommendations on the datasheet as well as your schematic. Is this flexible enough for some experimentation?
D.) On the output, what about (ab)using a XLR connector as shown? It will be going to an Impasse most of the time, so I was thinking about using both a RCA and XLR connector here as well, for symmetry. Is tying the two pins together as shown a reasonable practice?
E.) I've explicitly added earth connections to the XLR connectors, as they are available on the connectors I'm using. Am I connecting them properly?
Just a few finer points to clarify. Thanks!
Great work. Really admirable. I want one
@SY. Your article has inspired me to upgrade my turntable.
It’s just an old RP3. Nothing fancy, but it’s simple and easy to modify.
And please. Before any of you read on. Please bear with me, and my entry-/intermediate level.
First I want to replace the old MM Denon cartridge with an Ortofon MC 20 Super II. That demands your RIAA Tube preamp. And so I have a couple of questions, which I sincerely hope you (or anyone) will answer.
1. For my Ortofon, Sowter recommendes the 9990: http://www.sowter.co.uk/phono-cartridge-transformers.php . Does that alter any of the parameters in the schematic? (Please say no)
Great tip, by the way, to create a balanced signal and carry it via CAT5 (or bigger) LAN cable.
2. You write “Yet it is almost invariably done single ended, making a mockery of all further effort. It becomes doubly incredible when one considers that a cartridge (the odd Decca excepted) is not inherently single-ended; it can have both ends float just as well as it can have a leg staked to the ground.” Does that mean that I can alter the connected wires on the cartridge, and get a balanced signal? Without a transformer at the turntable to convert the single ended signal into a balanced?
3. On Figure 9: The raw supplies, high voltage and heater, you illustrate terminal 1-5. Where do they all go? Are some of them supplying the HV Regulators at Raw B+ ?
4. Figure 7: Heater supply regulators.
a. What goes in at H+, H- and Hcommon?
b. What does the down-pointing arrow in the lower right corner indicate? Please bear with me.
I hope to hear from you.
Best regards
Sabroe
@SY. Your article has inspired me to upgrade my turntable.
It’s just an old RP3. Nothing fancy, but it’s simple and easy to modify.
And please. Before any of you read on. Please bear with me, and my entry-/intermediate level.
First I want to replace the old MM Denon cartridge with an Ortofon MC 20 Super II. That demands your RIAA Tube preamp. And so I have a couple of questions, which I sincerely hope you (or anyone) will answer.
1. For my Ortofon, Sowter recommendes the 9990: http://www.sowter.co.uk/phono-cartridge-transformers.php . Does that alter any of the parameters in the schematic? (Please say no)
Great tip, by the way, to create a balanced signal and carry it via CAT5 (or bigger) LAN cable.
2. You write “Yet it is almost invariably done single ended, making a mockery of all further effort. It becomes doubly incredible when one considers that a cartridge (the odd Decca excepted) is not inherently single-ended; it can have both ends float just as well as it can have a leg staked to the ground.” Does that mean that I can alter the connected wires on the cartridge, and get a balanced signal? Without a transformer at the turntable to convert the single ended signal into a balanced?
3. On Figure 9: The raw supplies, high voltage and heater, you illustrate terminal 1-5. Where do they all go? Are some of them supplying the HV Regulators at Raw B+ ?
4. Figure 7: Heater supply regulators.
a. What goes in at H+, H- and Hcommon?
b. What does the down-pointing arrow in the lower right corner indicate? Please bear with me.
I hope to hear from you.
Best regards
Sabroe
Hi, since reading your article when it first come out i've been collecting parts and looking forward to realizing the project. I've really appreciated its simple design and your elegant and affable approach. Thanks so much.
I've got a few questions: I got a nice pair of lundahl transformer 9206's, here's a link to the data sheet: http://www.lundahl.se/wp-content/uploads/datasheets/9206.pdf
Are these comparable to the sowters? would it be a matter only of tuning the secondary?
I am not sure what you mean by re-doing the tonearm wiring. I got an old ortofon arm that's been rewired w/ four, no common ground and a 'chassis' tube grounding wire with a new five pin plug at the bottom of the arm base pivot tube, the mechanics/mass of the arm are configured for the denon 103 & 103r which i use.
both the arm and the xformer seem ready to drop into your design can you confirm?
sure would like to find a set of boards to build on
thanks, David
I've got a few questions: I got a nice pair of lundahl transformer 9206's, here's a link to the data sheet: http://www.lundahl.se/wp-content/uploads/datasheets/9206.pdf
Are these comparable to the sowters? would it be a matter only of tuning the secondary?
I am not sure what you mean by re-doing the tonearm wiring. I got an old ortofon arm that's been rewired w/ four, no common ground and a 'chassis' tube grounding wire with a new five pin plug at the bottom of the arm base pivot tube, the mechanics/mass of the arm are configured for the denon 103 & 103r which i use.
both the arm and the xformer seem ready to drop into your design can you confirm?
sure would like to find a set of boards to build on
thanks, David
I have received about a dozen request for boards -- the last set had all of the power supply regulators and filament "heater lifter". I'll do another set but ONLY the amplifier section, i.e. no power supply regulators. Will also leave out PCB mounting for the transformers since some prefer Sowter, Cinemag, ATT, Lundahl and they all have different layouts. I estimate the cost of the boards @$5.10 each. So they are sold at cost in respect of SY's intellectual property.
Since the first run the USPS has significantly raised costs, particularly for "small package overseas airmail" -- figure $7 for US and $13 ROW.
Since the first run the USPS has significantly raised costs, particularly for "small package overseas airmail" -- figure $7 for US and $13 ROW.
Sorry to the folks who asked questions that I missed.
The Lundahls look great, and yes, it's just a matter of finding the right load for the secondary. The Sowter 9990 are 1:20 which will give you 6dB more gain. Getting the secondary tuned will be a challenge. FWIW, Morgan Jones uses the 8055 with his Ortofon and is quite happy with that. Most tonearms are good to go for balanced as long as you can replace the external cables (many good arms have DIN plugs which make the process easier).
On figure 9, the terminals are as follows:
1. H+
2. H common
3. H-
4. Raw HT+
5. Raw HT- (power supply ground)
On fig 7, the arrow on the right is ground.
The Lundahls look great, and yes, it's just a matter of finding the right load for the secondary. The Sowter 9990 are 1:20 which will give you 6dB more gain. Getting the secondary tuned will be a challenge. FWIW, Morgan Jones uses the 8055 with his Ortofon and is quite happy with that. Most tonearms are good to go for balanced as long as you can replace the external cables (many good arms have DIN plugs which make the process easier).
On figure 9, the terminals are as follows:
1. H+
2. H common
3. H-
4. Raw HT+
5. Raw HT- (power supply ground)
On fig 7, the arrow on the right is ground.
Well, yes, but I don't think that there is anything remarkable with the regulators. I would like to see how they compare with the Maida, the LT3080 elevated regulator etc.
Like most of the PCB's for tube stuff, the power supply is connected via an umbilical to the amplifier chassis. I've developed a fondness for the Bulgin connectors.
I put one of the HMN's in a Hammond 1441 chassis and 1451 chassis cover. I still have the one which is in a repurposed Eico instrument case. It will take a bit of reworking
There isn't; the circuit is designed for high PSR. A Maida should work just as well. I chose the one I did because I had some power supply boards left over from The Heretical Preamp and that made the prototype go together faster and cleaner.
If I were a good storyteller, I'd wax lyrical about the hundreds of hours of listening that went into the regulator and how critical the capacitor types are- unfortunately, I just engineered the thing to work. I'll never get rich this way...
