[JoshK]

Looking good there KM!

[floobydust]

 I've put together a BOM for the amplifier. There are two build options: 1- Mono-block using SS rectifier/voltage-doubler or 2- Stereo using single power supply with 5V4G rectifier and end-bell power and choke units. I opted for good quality parts which include Dale resistors, Sprague and Axon caps, Hammond iron and NOS tubes sockets and sources for everything.

 Breakdown is simple, complete parts costs less tax and shipping. For a stereo amplifier, the total parts cost was $265 but this does NOT include your choice of output transformers or the 12AT7 and 45 tubes (it does allow $24 for a 5V4G rectifier). The Mono-block amps have a parts cost of $293 and again does not include your choice of output transformers or the 12AT7 and 45 tubes.

 I'm guessing most would prefer the Stereo amp which saves close to $30 in core parts and allows more $$ to go toward output trannies. If anyone is interested in building this up, I'll post the BOM and sources. Happy Holidays to everyone, enjoy time with family, friends, good food and good music, cheers!

 Regards, KM

[jrebman]

Kevin,

Can you post the BOMs?  My parents are visiting for the first time since their transcontinental move, and my dad has a box of old tubes for me, including some 45s, 26s, 227s, and  a bunch more.  He didn't even remember all that was in it, but he's giving the entire box to me, along with a 1927 RCA Radiola 17.

So, I want to add this amp along with the RH 84 to my project list for after the SimpleSE.

-- Jim

[floobydust]

 Hi Jim,

 Currently in SF for some work related activities... returning home morning of the 26th. My BOM list is on my other Mac at the house (and turned off so I can't access right now). I'll get a BOM posted once I return. I'm about to order the parts list (for 3 amps) and will also be building a 2A3 version for my Dad using Hammond iron (302AX power and a pair of 158M chokes) in the power supply with MQ TFA-204 outputs.

 I sourced all of the resistors (Vishay/Dale) from Mouser, sockets, potentiometers, fuse holders and some other bits from surplus sales and have options on capacitors in the power supply and circuit as either Axon or Sprague. The cost doesn't vary that much as you don't have many caps. I'll be building two of the 45 based versions, one using the James outputs and the other using MQ RH40 outputs, mono and stereo respectively.

 Regards, KM

[jrebman]

KM,

No rush.  Just curious, how much are those tfa-204 MQ OPTs?  I really wish MQ had a more informative web site.
-- Jim

[floobydust]

 Jim,

 Good point... Mike's site has limited info on his own stuff... who knew. You can actually find more details and pics of MQ iron at Doc Bottlehead's site.

http://www.bottlehead.com/et/MQ/magnequest.htm

 The TFA-204s are $250 a pair and can be bought directly from MQ and have a 9 ohm tap with 4- and 16-ohm as well.

 Regards, KM

[jrebman]

I lucked out (I think) as the box of tubes my dad had contained a nice pair of 45s.  Not sure of the make, but the slides of the bottles taped outwards moving up from the base, and then the top pinched in to a smaller diameter and had a flat top.  Not sure if these are the globe types or not as I've never seen them.  The pins need some cleaning up, but the bases are still well glued to the bottles.

When I get somebody over to look at them more closely, we can try to identify make and year, etc.

Also in the box were a number of 26s, some 227s, a GE 6sn7, an RCA gray plate 12au7, and a few tubes I still need to look up -- like 1x2s for example.

So, at least I think I could have a decent pair of 45s to play with, and the price was right.

-- Jim

[floobydust]

 Jim, sounds great... what you describe is ST glass 45s... which I actually prefer over the older balloon glass. I have two very nice pairs of RCA Balloons (and over a dozen of ST glass)... one which are the originals and the second pair are the "improved" version. The difference is simple: the original balloon version has a horizontal glass bead attached to a vertical support wire which holds the support wires for the elements (grid wires, filament loop supports, etc.) at the top of the tube internal structure while the "improved" version has a mica spacer which keeps the element spacing at the top but is also supported by a vertical support wire and glass bead. The latter version being cheaper to manufacture and better consistency. While many swear that the balloon versions are more magical sonically than ST glass versions, I don't agree... I find the balloon version to be far more sensitive to mechanical vibration and I've never been able to get the hum balance on the filament as good as ST glass versions. Also note that there are many variations of the internal support structures for the ST glass. I have at least 5 variations internally.

 Also note that despite the branding on the base or glass, manufacturers frequently cross-branded tubes between them due to production line runs, etc. I actually have two RCA 45 ST glass tubes which came in identical boxes with identical print and codes on the bases, yet one is a true RCA manufacture while the other is a Sylvania, so even date codes mean little in some cases. Still, a good (matching) pair of 45 triodes are wonderful tubes.

 Regards, KM

[Wardsweb]

This looks like a very fun build. I look forward to your BOM. I may have to add yet another amp to my collection.

While I have built many of the Bottlehead kits (Foreplay, Paramours, Seduction, S.E.X. amp), I did do a custom one off 2A3 a few years ago. Here are a few pics.

[floobydust]

 Hello Ward,

 I recall visiting your website some time ago and saw some of your projects. You do very nice work and your amp looks great. I should have the BOM list here over the weekend. I'm sure you'll do a superb job should you decide to build it.

 Regards, KM

[planet10]

I'd like to add another potential source for iron. We recently picked up a set of O'Netics OPTs based on reputation. Bud makes a range of quality levels, from the low end at ~$250/pr up to stuff that is scary expensive.

No web presence you'll have to contact him by eMail hpurvine at gmail dot com

Not pertinent to this thread, but he has what he calls a kinkless PP OPT...

dave

[jrebman]

Dave,

Just curious, which ones did you get?  When I spoke with Bud about these he said that there were really only two levels in SE OPTs -- the lower end at about $250/pair, and the top of the line at a lot more -- more than I can afford right now.

-- Jim

[JoshK]

I've sourced quite a few transformers from Bud.  He is a truly nice guy. His prices are really reasonable and the quality is really high.  A lot better fit and finish than say a Hammond.   

He has level I, level 2 and level 3 iron, in his PP OPTs at least, but he is the first to say that most people won't appreciate the difference between level 2 and 3 for instance unless their system is really dialed in.  He'll recommend his Level 1 (which are priced like those $250/pr) transformers first and foremost.  He could be like a lot of other manuf who always recommend their high end stuff because it has higher margins.

That makes me have a lot of respect for his integrity.

[planet10]

Just curious, which ones did you get?  When I spoke with Bud about these he said that there were really only two levels in SE OPTs -- the lower end at about $250/pair, and the top of the line at a lot more -- more than I can afford right now

We got the inexpensive ones (and then put aside the project we were going to do and sent them off to Eddie Vaughn who is designin an SE amp specifically for the Fonken. By the way, the as yet undesigned version of the Fonken for your F120AeN will be called uberFonken. Bud seems VERY impressed with the drivers you sent him to do up.

dave

[jrebman]

Uber-Fonken -- I like that .  Goes well with the Uber Beam Machine -- at least that's what I intend to find out.

There's somebody else who is really interested in this f120a fonken idea as well, and I'm sure he'll chime in if he wants to.

Yes, Bud's comments both on diyaudio, and to me privately are very encouraging.  Treat the cabinet and the drivers for a super-fast sub, and good things can't help but happen.

Maybe I should send these drivers to you guys so you have something tangible to work with -- I have no enclosures for them anyway.

-- Jim

[jrebman]

Kevin,

Thanks for the tutorial on the various 45 variants, and the descriptions as well.  I always appreciate descriptions like this.

-- Jim

[aerius]

Also in the box were a number of 26s, some 227s, a GE 6sn7, an RCA gray plate 12au7, and a few tubes I still need to look up -- like 1x2s for example.

Ooh boy, 26s and 227s are a little hard to work with thanks to microphonics and hum which are rather common in my experience and from what I've read, but once you get them working right they're really incredible tubes.  Plus I think they look really nice.

[floobydust]

 Okay, here's basic BOM for building a single chassis stereo amplifier based on all Hammond iron.

 Note that this does not include any of the tubes but you'll need a decent pair of 45 triodes, a pair of 12AT7 twin-triodes and a single 5V4G rectifier tube. You could upgrade the power supply filter caps from the Sprague Atom caps to something like the Axon 630V HighVolt caps (also from Zalytron). Note that Zalytron only does $50 minimum order.... so maybe a group purchase or pick something to your liking to sub.

 Also count on some hardware costs unless you have adequate stock and some shipping costs from the various vendors.

Low Cost 45 SET amplifier - Stereo Version with tube rectifier:

 Source - http://www.angela.com/
1 Hammond 272DX 300-0-300@125ma 5.0v/6.3v   $45.25   $45.25
1 Hammond 193D   8H@150ma 75 ohms         $29.99  $29.99
2 Hammond 166M2   2.5V@3A                          $ 8.99    $17.98
2 Hammond 125DSE output                            $32.50  $65.00
1 Hammond 1441-22BK3 12x8x2 chassis               $19.99   $19.99
1 Hammond 1431-22BK3 12x8 bottom plate          $ 8.49   $ 8.49
2 100uF/450V Sprague Atom                $ 7.50   $15.00
2 80uF/450V Sprague Atom                $ 7.25    $14.50
                  sub-total         $216.20

 Source - http://www.surplussales.com/
1 8-pin octal socket                  $ 6.00      $ 6.00
2 9-pin tube socket                  $ 6.00      $12.00
2 4-pin tube socket                  $ 6.00      $12.00
1 IEC Power inlet                   $ 1.25       $ 1.25
1 IEC Power Cord                  $ 3.50      $ 3.50
1 3AG fuse holder                   $ 2.25       $ 2.25
1 3AG 1 amp fuse                  $ 1.00      $ 1.00
2 100 ohm WW pot                     $ 5.00          $10.00
                  sub-total                 $48.00

 Source - http://www.tubesandmore.com/
1 Rubber feet P-H2082S                $ 3.20      $ 3.20
1 RCA Jack   S-H268R                $ 2.95       $ 2.95
1 RCA Jack   S-H268W                    $ 2.95      $ 2.95
2 Binding Posts S-H263                 $ 3.95       $ 7.90
1 0.001uF/1600V Orange Drop 16PS        $ 1.05     $ 1.05
                  sub-total         $18.05

 Source - http://www.mouser.com/
2 100K ohm   RN65D1003FB14            $ 0.65      $ 1.30
2 150K ohm   RN65D1503FB14            $ 1.95      $ 3.90
2 49.9K ohm   RN65D4992FB14            $ 0.65      $ 1.30
2 2.00K ohm   RN65D2001FB14            $ 0.65      $ 1.30
2 301K ohm   RN65D3013FB14            $ 0.65      $ 1.30
2 1.50K 10W   RS0101K500FB12            $ 1.83      $ 3.66
4 15.0 3W   CW02B15R00JB12            $ 0.44      $ 1.76
2 30.0 5W   RS00530R00FB12             $ 1.36       $ 2.72
2 50K 5W   RS00550K00FB12             $ 1.85       $ 3.70
3 SPST - MTF106D04                    $ 5.12        $15.36
                  sub-total                $36.30

 Source - http://www.zalytron.com/
2 0.10uF/630V Axon Tin foil              $ 3.69     $ 7.38
2 10uF/250V Axon True Cap            $ 3.23      $ 6.46
2 20uF/250V Axon True Cap            $ 5.16      $10.32
                  sub-total             $24.16

- Hardware - buy what you need                  $XX.XX

                  total            $342.71

 Well, the formatting wasn't so clean.... but you get the idea... not too pricey overall, upgrade output iron as you like - 5K primary.

 Regards, KM

[jrebman]

Kevin,

Nice -- thanks.  Lots of iron -- gotta like that.

Any recommendation for a level pot value in case somebody wants to build it as an "integrated"?

Would you happen to have the schematic as a PDF or something like it that I can try to make a tactile printout of?  These things just make so much more sense to me when I can see where things are .  Then I'm able to tell which resistors are what, etc.  A "budget" amp with hum balance pots -- nice touch.  I'm sure a few will want to know what changes to resistor values, etc. might be made when using a 2A3, but I'll let somebody ask before putting you to the trouble, because I don't necessarily want this myself.

Again, thanks, and I hope somebody can get to building one of these before I can.  At least I can start collecting parts piecemeal.

-- Jim

[JoshK]

Kevin,

Nice -- thanks.  Lots of iron -- gotta like that.

Any recommendation for a level pot value in case somebody wants to build it as an "integrated"?

Would you happen to have the schematic as a PDF or something like it that I can try to make a tactile printout of?  These things just make so much more sense to me when I can see where things are .  Then I'm able to tell which resistors are what, etc.  A "budget" amp with hum balance pots -- nice touch.  I'm sure a few will want to know what changes to resistor values, etc. might be made when using a 2A3, but I'll let somebody ask before putting you to the trouble, because I don't necessarily want this myself.

Again, thanks, and I hope somebody can get to building one of these before I can.  At least I can start collecting parts piecemeal.

-- Jim

Jim,  I am not Kevin, but 100K pot is pretty standard issue and would work fine.  Replace the grid leak resistor with the pot and away you go.  The value of the pot largely determines the input impedance of the amp, so choose as such.  50K is also a reasonable value.