Well from everyone's suggestions here on the forum my plan is the start out building the 12Vac preamp with an 18Vac Wallwart preamp to start. I'm also going to use the chassis John Broskie shows in the article that comes from mouser to keep things as simple as possible. Eventually though I really think the 5687 kit is what I really want.
Prior to finding this forum I planned on buying the VTA ST-70 amplifier kit to build and have as part of a stereo for my home office. I think what I'd do is then use the 12 Vac kit preamp as part of that system for my home office and then have my VTA ST-120 amp and the 5687 kit preamp as my system for the living room.
But...before I get ahead of myself I'm going to stay focused on the 12 Vac kit. To keep things as simple for as possible I will purchase all of the components from the Glassware web site other than the chassis, power supply and selector switch since he seems to be out of them. I'll either try to hunt one down elsewhere unless he tells me they will be in stock soon (I've already sent him a message). At this time I still have a few questions though. John Broskie offers choices for resistor/capacitor sets in 2 different parts of the online ordering form. Being new...I have no idea which is a better choice...other than that he has 2 sets for a 12Vac PS and 2 sets for the 18 Vac PS. Can someone tell me what the differences would be between the 1% and 5% choice and also the choices about the different dB levels? The price differences aren't that much different, if at all.
My guess is that it depends on what type of sound sources I'll be using and perhaps what kind of amp I have. Right now I have a Marantz CD5004 CD player and a Marantz ST6000 tuner. I'm not planning on going to anything more expensive than these. I also ave a Sony CD player. I know ..it's not the best but it is fairly new and in really good condition. I have Polk Audio LSiM 703 speakers that I am really happy with. They're ratted at 88 dB so they aren't the most efficient but they aren't bad...and they do sound really nice in my opinion.
So...any suggestions? Thank again....Blake
Prior to finding this forum I planned on buying the VTA ST-70 amplifier kit to build and have as part of a stereo for my home office. I think what I'd do is then use the 12 Vac kit preamp as part of that system for my home office and then have my VTA ST-120 amp and the 5687 kit preamp as my system for the living room.
But...before I get ahead of myself I'm going to stay focused on the 12 Vac kit. To keep things as simple for as possible I will purchase all of the components from the Glassware web site other than the chassis, power supply and selector switch since he seems to be out of them. I'll either try to hunt one down elsewhere unless he tells me they will be in stock soon (I've already sent him a message). At this time I still have a few questions though. John Broskie offers choices for resistor/capacitor sets in 2 different parts of the online ordering form. Being new...I have no idea which is a better choice...other than that he has 2 sets for a 12Vac PS and 2 sets for the 18 Vac PS. Can someone tell me what the differences would be between the 1% and 5% choice and also the choices about the different dB levels? The price differences aren't that much different, if at all.
My guess is that it depends on what type of sound sources I'll be using and perhaps what kind of amp I have. Right now I have a Marantz CD5004 CD player and a Marantz ST6000 tuner. I'm not planning on going to anything more expensive than these. I also ave a Sony CD player. I know ..it's not the best but it is fairly new and in really good condition. I have Polk Audio LSiM 703 speakers that I am really happy with. They're ratted at 88 dB so they aren't the most efficient but they aren't bad...and they do sound really nice in my opinion.
So...any suggestions? Thank again....Blake
I have a bunch of 12AU7 tubes. I thought from the article those sound better than the 6DJ8 tubes. If not I don't have a problem with going with that option. Any feedback or suggestions is appreciated.
The amp I have uses the 12AU7's as well as KT88's as output tubes. I thought it would help keep what need in inventory down as well.
The amp I have uses the 12AU7's as well as KT88's as output tubes. I thought it would help keep what need in inventory down as well.
After you asking that question I think I just might give the 6DJ8's a try. From the description on the Glassware site it says the E88CC tube can be used. I keep seeing that's a low noise tube. That kinda peaks my interest. On the selection part of the order form there is a choice of resistor packs and the differences it offers are -1, -1.5 and -2 dB. Can you tell me what those choices mean? Of course those too are offered on 1% and 5% also and I'd choose the 1% from your previous suggestion. Now I need to know what the - decibel levels mean.
As usual...thanks for your patience and tolerance for walking me through this project...Blake
The DB level is for the volume and balance controller.
I'd do without that part and use an Alps Blue Velvet or TKD pot.
However....John's mini stepper A-3 Balance/Volume has peaked my interest lateley, I'd go with 2db increments.
I'd do without that part and use an Alps Blue Velvet or TKD pot.
However....John's mini stepper A-3 Balance/Volume has peaked my interest lateley, I'd go with 2db increments.
Yes, and if one likes to tube-roll the russian 6N23P-EV can be used directly without any changes in the circuit. The EV-edition is the premium type of 6N23P - aka 6922 and E88CC. Please note that this is one of the few russian tubes which doesn´t need a higher heater current than its western cousin.
How much difficulty does using a toroidal transformer as a power source add to the difficulty of the electronics assembly of the preamp as opposed to just a Wallwart PS?
The article someone posted on this thread pointed to John Broskie's article on the preamp and I that got me really interested as an alternative to the Wallwart PS.
i really like the idea of that build instead of just using a Wallwart PS. I'd like to have it set up to also have inputs for 3 sound sources. Would the resistors that say they are for a Wallwart PS work for a toroidal transformer? I'm asking because the order form specifies Wallwart PS for the resistor choices in the options. I understand I'd need a larger enclosure than the one specified in that article and that's not a problem either.
...Blake
The article someone posted on this thread pointed to John Broskie's article on the preamp and I that got me really interested as an alternative to the Wallwart PS.
i really like the idea of that build instead of just using a Wallwart PS. I'd like to have it set up to also have inputs for 3 sound sources. Would the resistors that say they are for a Wallwart PS work for a toroidal transformer? I'm asking because the order form specifies Wallwart PS for the resistor choices in the options. I understand I'd need a larger enclosure than the one specified in that article and that's not a problem either.
...Blake
Last edited:
I can't say for certain on the WallWart transformer resistors but it may be for a little filtration.
OTOH doing an internal toroid would just require a larger case and an IEC Power Inlet Module.
I have used these IEC's for three projects now and they are great because they have the socket, fuse and power switch all in one.
Broskie has an input source selector kit but I think they are sold out for now.
OTOH doing an internal toroid would just require a larger case and an IEC Power Inlet Module.
I have used these IEC's for three projects now and they are great because they have the socket, fuse and power switch all in one.
Broskie has an input source selector kit but I think they are sold out for now.
I saw that about the selector switch. I sent an email on Friday and I imagine I will get a response sometime next week.
Thanks for the info. I may build the enclosure out of wood on the four sides and base and perhaps use sheet aluminum for the top cover. It's easy to work with and I have the tools.
I can also start planning the build using 3D CAD modeling software since I can get sizes for the PCB and transformer off the web.
Thanks for the info. I may build the enclosure out of wood on the four sides and base and perhaps use sheet aluminum for the top cover. It's easy to work with and I have the tools.
I can also start planning the build using 3D CAD modeling software since I can get sizes for the PCB and transformer off the web.
Well if you go with the 6DJ8 tubes then you would need the Antek AS-0512.
The dimensions are right on the product page, the measurements found there are a little on the big side from actual.
An aluminum Top and Bottom would be ideal.
The dimensions are right on the product page, the measurements found there are a little on the big side from actual.
An aluminum Top and Bottom would be ideal.
That looks like the transformer specified in John Broskie's article. That's exactly what I'm looking for. After thinking about it an all aluminum enclosure is probably a better choice.
I'm not sure how the selector switch on ebay is supposed to work. I thought it would be just a rotary switch on a small PCB where I'd connect wires from the 12 Vac preamp board. Not something as complicated as that looks. Excuse by lack of understanding from ignorance of electronics.
I looked more closely at the link you posted for the selector relay. To be honest I looked the first photo and didn't scroll down to even bother looking at the schematic. I then scrolled down further and saw the ribbon cable and rotary selector....so....this looks interesting...but...
Can you tell me what the benefit of something like this relay selector is as opposed to just a simple rotary switch?
I take it from the schematic the left and right outputs go to RCA jackets and the ground can just go to the chassis?
If you really want an "All in One" kit with everything, maybe a Bottlehead Foreplay Preamp may be recommended...
I run an Aikido 6DJ8 / 12BH7 that I really really like, but it was a lot of finding parts and pieces...while the Foreplay comes complete and sounds great (maybe a little behind the Aikido)
I run an Aikido 6DJ8 / 12BH7 that I really really like, but it was a lot of finding parts and pieces...while the Foreplay comes complete and sounds great (maybe a little behind the Aikido)
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.