matthewmckay
New member
I would like to see a bottlehead tuner kit. Mostly becuase there doesn't seem to be much information on attempting a DIY tuner for FM reception, and I know you guys would make a good one.
Bottlehead Fantasy Products/Wish List
- Thread starter Dr. Toobz
- Start date
defenestration
New member
a sub $500 microphone preamp would be an amazing Bottlehead entry into the pro audio world... which has quite deep pockets and a taste for DIY
would love a kit or two aimed at studio applications - tempted to build a foreplay just so I could run some mixes through it... I want to run some program material through my Crack and re-record it but to do it properly I'll have to build a box like the one I use for guitar amps - https://taweber.powweb.com/weber/masslite.htm
would love a kit or two aimed at studio applications - tempted to build a foreplay just so I could run some mixes through it... I want to run some program material through my Crack and re-record it but to do it properly I'll have to build a box like the one I use for guitar amps - https://taweber.powweb.com/weber/masslite.htm
Paul Joppa
Moderator
Mic preamp - what functions are needed? A Seduction, deprived of RIAA, is all the amp you need; we've been using one with a B&K measuring mic for years. It's all the gain switches, impedance choices, proximity filters, etc. that gets expensive and fussy. Got an example of a minimalist mic pre that's on the market? Does it need to be rackmount?
saildoctor
New member
I would like see a 1-5 watt guitar amp with headphone output! Maybe just as a head unit? My roommate would be grateful of this one. 
That's interesting but as nice as those philips can sound I doubt they can deliver the resolution and dynamics I love from my current setup. What I'm looking for is something for my current speakers. They're about 106 db per watt efficient and I triamp. Ever since I saw the following PJs post I've been dreamin' about it:
It would be something like a big boys Crack!
defenestration
New member
a few commercial examples as requested:
http://www.mercenary.com/vt1vactubmic.html
http://www.mercenary.com/alltub40dbmo.html
http://www.mercenary.com/rmstubule.html
not tube but a respected (and cost-effective) minimal solid state design - http://www.fmraudio.com/rnp.htm
my picks for a minimal design - some of this might be a given but I'll spell it out anyways -
XLR in, balanced TRS out
switchable +48v phantom power
input polarity switch
input attenuation (switched -15db pad would be enough, variable is much nicer)
variable gain (6-12 stepped is nice but not necessary - notice that the Manley linked above is only 5 steps)
Hi-Z unbalanced input for use with electric guitar/bass (I'm curious how much this 'active DI' would add to the cost of the design?)
signal and clip indicators
rackmount isn't completely necessary but that would be a big step towards making such a Bottlehead product very studio friendly - a 1/2 rack form factor that is optionally rackable or desktop is, in my opinion, the approach most likely to find a home in project as well as professional studios - 2 channels of a particular preamp flavor in 1 or 2 rackspaces high is very desirable to many studio owners.
and . . . here are my votes for extra features beyond the bare bones -
variable input impedance
unbalanced insert jack
VU Meter
but really it doesn't need much at all... I have a solid state mic preamp within spitting distance of me right now that besides the in/out jacks only has a gain pot, a clip LED, and a phantom power switch
http://www.mercenary.com/vt1vactubmic.html
http://www.mercenary.com/alltub40dbmo.html
http://www.mercenary.com/rmstubule.html
not tube but a respected (and cost-effective) minimal solid state design - http://www.fmraudio.com/rnp.htm
my picks for a minimal design - some of this might be a given but I'll spell it out anyways -
XLR in, balanced TRS out
switchable +48v phantom power
input polarity switch
input attenuation (switched -15db pad would be enough, variable is much nicer)
variable gain (6-12 stepped is nice but not necessary - notice that the Manley linked above is only 5 steps)
Hi-Z unbalanced input for use with electric guitar/bass (I'm curious how much this 'active DI' would add to the cost of the design?)
signal and clip indicators
rackmount isn't completely necessary but that would be a big step towards making such a Bottlehead product very studio friendly - a 1/2 rack form factor that is optionally rackable or desktop is, in my opinion, the approach most likely to find a home in project as well as professional studios - 2 channels of a particular preamp flavor in 1 or 2 rackspaces high is very desirable to many studio owners.
and . . . here are my votes for extra features beyond the bare bones -
variable input impedance
unbalanced insert jack
VU Meter
but really it doesn't need much at all... I have a solid state mic preamp within spitting distance of me right now that besides the in/out jacks only has a gain pot, a clip LED, and a phantom power switch
saildoctor said:I would like see a 1-5 watt guitar amp with headphone output! Maybe just as a head unit? My roommate would be grateful of this one.
Same here - I've been wanting a small guitar amp for some time now. There's a couple of kits out there, but they all seem to be designed for sticking in a cabinet, and they're not cheap. Luckily, though, these appear to be very simple to do on one's own; a 12ax7 gain stage (with the second half of the triode used as a regulator or some other freebie function) and an EL84 pentode would net about 4-5W, single-ended.....plenty for headphones and a small speaker. The problem for those of us who live in apartments is fabricating a chassis. That's a big reason why I like Bottlehead's kits so much: everything you need for a complete amp is already there.
Count me in for a Bottlehead guitar amp!
Grainger49
New member
xcortes said:
Ok, Xavier, you have nailed my wish list there. I have the tubes and the sockets.
Hmm, I dunno about that 1 watt 6C33 thing. Sounds like three years of research for two sales. Maybe that could be a free design we put up on the site for DIY. But a small guitar amp, yes. I've been playing with some ideas for a while now. I believe the electric guitar on the new Jacqui Naylor album Lucky Girl (which is being released on Tuesday) might have been played through a protoype of mine. I'll know more when I see Art Khu next week. I think we will begin working on my latest guitar amp idea after we get the DAC finished up.
Re mic pres: when the option list starts to climb you have to let me know how much you want to pay. That will have a big influence on how many gadgets are added. My suggestion might be to forgo a complete rack cabinet and build it all on a front panel, with a simple Hammond die cast box on the back for shielding - roughly like tipping a seduction up on one side. I've laid out a rack style guitar amp design like this, with the tubes set back from the face, and it looks pretty cool. The full cabinets that we use for the Tube Repro and Tube Phono are very expensive.
Re mic pres: when the option list starts to climb you have to let me know how much you want to pay. That will have a big influence on how many gadgets are added. My suggestion might be to forgo a complete rack cabinet and build it all on a front panel, with a simple Hammond die cast box on the back for shielding - roughly like tipping a seduction up on one side. I've laid out a rack style guitar amp design like this, with the tubes set back from the face, and it looks pretty cool. The full cabinets that we use for the Tube Repro and Tube Phono are very expensive.
Grainger49
New member
Not to mention a new transformer. Look at the specs for the two filaments in each 6C33C-B.
Maybe just an SET using that tube.
Maybe just an SET using that tube.
Come on Grainger. What side are you on?
Besides I was gonna buy three kits so it was four, not two!
Seriously in the long term that's something I want to try.
Following a friend's advice my next system won't have iron or CFs, Right now I have to concentrate on my WOT 437A preamp.
Besides I was gonna buy three kits so it was four, not two!
Seriously in the long term that's something I want to try.
Following a friend's advice my next system won't have iron or CFs, Right now I have to concentrate on my WOT 437A preamp.
1. DAC (have been eagerly waiting a few years on this one)
2. KT88 or similar based amp 25-50ish WPC (not holding my breath)
3. Tube crossover
4. A TT kit would be fun
5. An active step up for phono stages would be nice as well
6. New speakers. I'm working on a slot loaded, semi open baffle line array and a 3 way, front loaded PPSL. So if you would just do the engineering for me it would free me up for more scuba diving and weekend track days. Not to mention the GAF on the pile of speakers sitting around is getting lower by the second.
And I would really like PJ to get on the flux capacitor thing. Would make it way easier to buy nice tubes if we could just go back in time and buy them new.
2. KT88 or similar based amp 25-50ish WPC (not holding my breath)
3. Tube crossover
4. A TT kit would be fun
5. An active step up for phono stages would be nice as well
6. New speakers. I'm working on a slot loaded, semi open baffle line array and a 3 way, front loaded PPSL. So if you would just do the engineering for me it would free me up for more scuba diving and weekend track days. Not to mention the GAF on the pile of speakers sitting around is getting lower by the second.
And I would really like PJ to get on the flux capacitor thing. Would make it way easier to buy nice tubes if we could just go back in time and buy them new.
I'm chipping away this weekend at repackaging our prototype DAC for RMAF. It's not what the final one will be, but it should have a lot of the same nutritional goodness. I am indeed glad that I won't be responsible for your suffocation regarding the making of yet another PP 6550 amp in a saturated market. But we do continue to think about higher powered amps.
I think the active step up is about 80% worked out, with a prototype or two in operation. Tube crossover may happen depending upon some upcoming research and results thereof. TT kit would be fun. Unfortunately it's a tough one to do well, inexpensively. Speakers - talk to me in a bit. Working with Mr. Blumenstein on some ideas.
Re the flux capacitor, I'm selling them on ebay.
http://www.ebay.com/itm/120780999047?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649
I think the active step up is about 80% worked out, with a prototype or two in operation. Tube crossover may happen depending upon some upcoming research and results thereof. TT kit would be fun. Unfortunately it's a tough one to do well, inexpensively. Speakers - talk to me in a bit. Working with Mr. Blumenstein on some ideas.
Re the flux capacitor, I'm selling them on ebay.
http://www.ebay.com/itm/120780999047?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649
Doc B. said:
What about a single-ended 6550/KT88? What would be really cool is to do an integrated SEP/SET amp that not only straps the pentode to triode with the flip of a switch, but includes typical Bottlehead goodies like active loads, carefully-chosen components, high-quality irons, a shorting headphone jack, etc. to help the amp sound better than it normally might in pentode mode. (I've actually heard that KT88's sound good in a SEP configuration, if done properly, but I've never heard one wired that way, only PP). That would give builders a nice-sounding, 4 or 5W SET amp with the option of flipping a switch to SEP mode to double the wattage and/or get a different type of sound, depending upon one's speakers.
Ditto for an EL84-based amp, which I do know sound very good single-ended.
Grainger49
New member
ssssly,
Your numbers 1, 3 and 5 are either in the works or talked about. Number 4 has been done and was abandoned a few years back. It was a very nice looking table and it might still be marketed. Doc would know.
Your numbers 1, 3 and 5 are either in the works or talked about. Number 4 has been done and was abandoned a few years back. It was a very nice looking table and it might still be marketed. Doc would know.
Doc B. said:
Could be interesting in a Pmour or FPIII power supply.
Grainger49 said:
Indeed, and I am eagerly following the progress.
How's the Eros coming along?
And the breath holding is an overused scuba phrase. More concerned about exploding than suffocating. But you can rest easy on either account. The market is very saturated. Just prefer to spend my hard earned money in the Bottlehead camp.
A Bottlehead Blumenstein combo would be very interesting indeed.
A plasma tweeter kit would be nice. Never got my attempt working properly and abandoned it for other things.
Any take on active interconnects?
Grainger49
New member
I'm going slow with the Eros.
I made a pair of unshielded interconnect, KACG, active shielded interconnects using "Zippertubing." All it took was a 6V wall wart, two short pieces of shielded Zippertubing and a 6k resistor for each tube to limit the current to 1mA. It worked but was awfully awkward. I did change the current in steps up to 7 or 8mA and higher current shielded better.
http://www.zippertubing.com/
I made a pair of unshielded interconnect, KACG, active shielded interconnects using "Zippertubing." All it took was a 6V wall wart, two short pieces of shielded Zippertubing and a 6k resistor for each tube to limit the current to 1mA. It worked but was awfully awkward. I did change the current in steps up to 7 or 8mA and higher current shielded better.
http://www.zippertubing.com/
Paul Joppa
Moderator
Here's a little more brainstorming on the OTL power amp.
As the Bottlehead reference system has gotten more refined we have been finding limitations with transformers, but also with cathode followers. And we have long felt that paralleled tubes have limitations when pursuing the highest degree of resolution, and so does feedback in general. OTLs keep coming up, to get around the transformer problem. However, the fact is that no tube has a low enough impedance to drive an 8-ohm speaker with a reasonable damping factor, without resorting to heavy feedback or massively parallel tubes. And I mean heavy; a cathode follower is not good enough. In addition, in order to get more than a watt you need more current than any practical tube can supply.
Both problems can be addressed with parallel tubes. Here's an example:
The 6AS7 or 6080 can have a plate resistance as low as 280 ohms according to the specification. Since cathode followers and other feedback approaches are out, that would be the output impedance. An 8 ohm output impedance would give a damping factor of 2 into a 16-ohm speaker, and would require 35 triodes in parallel. A stereo pair would be 35 tubes, drawing 8.75 amps at 135 volts, for a total dissipation of 1181 watts. Heater power would be another 87.5 amps at 6.3 volts, or 551.25 watts. Of course, if you are avoiding transformers you probably don't want to use plate chokes, so figure another 350 watts or so for the current source plate loads. For this, you'll get ideally 150 watts out; in practice due to the inability to find a set of 35 matched 6080 tubes you might get 100 watts - of parallel tube sound. The chassis plate could be as small as 20 square feet. You'll need a separate 20- or 25-amp circuit just for the amp.
This does not sound to me like a Bottlehead amp at a Bottlehead price. If anyone has a spare $10k-$15k to build one as an experiment, it would be interesting to find out whether it sounds OK or not.
At lower power, you need feedback to get the output impedance down. I must have been thinking of that when I suggested a single 6C33 for a 1-watt amp. That could be much easier to build - but, again, with heavy feedback it will not reach the highest level of resolution. I suppose we should try it; at least it won't be as expensive as the massively parallel approach.
As the Bottlehead reference system has gotten more refined we have been finding limitations with transformers, but also with cathode followers. And we have long felt that paralleled tubes have limitations when pursuing the highest degree of resolution, and so does feedback in general. OTLs keep coming up, to get around the transformer problem. However, the fact is that no tube has a low enough impedance to drive an 8-ohm speaker with a reasonable damping factor, without resorting to heavy feedback or massively parallel tubes. And I mean heavy; a cathode follower is not good enough. In addition, in order to get more than a watt you need more current than any practical tube can supply.
Both problems can be addressed with parallel tubes. Here's an example:
The 6AS7 or 6080 can have a plate resistance as low as 280 ohms according to the specification. Since cathode followers and other feedback approaches are out, that would be the output impedance. An 8 ohm output impedance would give a damping factor of 2 into a 16-ohm speaker, and would require 35 triodes in parallel. A stereo pair would be 35 tubes, drawing 8.75 amps at 135 volts, for a total dissipation of 1181 watts. Heater power would be another 87.5 amps at 6.3 volts, or 551.25 watts. Of course, if you are avoiding transformers you probably don't want to use plate chokes, so figure another 350 watts or so for the current source plate loads. For this, you'll get ideally 150 watts out; in practice due to the inability to find a set of 35 matched 6080 tubes you might get 100 watts - of parallel tube sound. The chassis plate could be as small as 20 square feet. You'll need a separate 20- or 25-amp circuit just for the amp.
This does not sound to me like a Bottlehead amp at a Bottlehead price. If anyone has a spare $10k-$15k to build one as an experiment, it would be interesting to find out whether it sounds OK or not.
At lower power, you need feedback to get the output impedance down. I must have been thinking of that when I suggested a single 6C33 for a 1-watt amp. That could be much easier to build - but, again, with heavy feedback it will not reach the highest level of resolution. I suppose we should try it; at least it won't be as expensive as the massively parallel approach.